ABSTRACT
As3C X2-As-Csp3 1.963 1.965 0.017 1.948 1.978 6 X2-As-Car 1.956 1.956 0.015 1.944 1.964 41
As3Cl X2-As-Cl 2.268 2.256 0.039 2.247 2.281 10 As6F in AsF6-1.678 1.676 0.020 1.659 1.695 36 As3I see OPIMAS (2.579, 2.590) As3N3 X2-As-N-X2 1.858 1.858 0.029 1.839 1.873 19 As4=N2 see TPASSN (1.837) As4O (X)2(O=)As-OH 1.710 1.712 0.017 1.695 1.726 6 As3O see ASAZOC, PHASOC01 (1.787-1.845) As4=O X3-As=O 1.661 1.661 0.016 1.652 1.667 9 As3=P3 see BELNIP (2.350, 2.362) † As3P3 see BUTHAZ10 (2.124) † As3S X2-As-S 2.275 2.266 0.032 2.247 2.298 14 As4=S X3-As=S 2.083 2.082 0.004 2.080 2.086 9 As3Se2 see COSDIX, ESEARS (2.355-2.401) † As3Si4 see BICGEZ, MESIAD (2.351-2.365) † As3Te2 see ETEARS (2.571, 2.576) † BnBn n = 5-7 in boron cages 1.775 1.773 0.031 1.763 1.786 688 B4B4 see CETTAW (2.041) B4B3 see COFVOI (1.698) B3B3 X2-B-B-X2 1.701 1.700 0.014 1.691 1.712 8 B6BR 1.967 1.971 0.014 1.954 1.979 7 † B4BR 2.017 2.008 0.031 1.990 2.044 15 † BnC n = 5-7: B-C in cages 1.716 1.717 0.020 1.707 1.728 96
n = 3-4: B-Csp3 not cages 1.597 1.599 0.022 1.585 1.611 29 1 n = 4: B-Car 1.606 1.607 0.012 1.596 1.615 41 n = 4: B-Car in Ph4B-1.643 1.643 0.006 1.641 1.645 16
BnC n = 3: B-Car 1.556 1.552 0.015 1.546 1.566 24 BnCl B(5)–Cl and B(3)–Cl 1.751 1.751 0.011 1.743 1.761 14
1 u B(4)–Cl 1.833 1.833 0.013 1.821 1.843 22
B4F B-F (B neutral) 1.366 1.368 0.017 1.356 1.375 25 B-–F in BF4-1.365 1.372 0.029 1.352 1.390 84
B4I see TMPBTI (2.220, 2.253) B4N3 X3-B-N(=C)(X) 1.611 1.617 0.013 1.601 1.625 8
in pyrazaboles 1.549 1.552 0.015 1.536 1.560 10 B3N3 X2-B-N-C2: all coplanar 1.404 1.404 0.014 1.389 1.408 40 2
for τ(BN) > 30º see BOGSUL, BUSHAY, CILRUK (1.434-1.530)
S2-B-N-X2 1.447 1.443 0.013 1.435 1.470 14 B4O B-–O in BO-4 1.468 1.468 0.022 1.453 1.479 24
for neutral B-O see Note 3 3 B3O2 X2-B-O-X 1.367 1.367 0.024 1.349 1.382 35 BnP n = 4: B-P 1.922 1.927 0.027 1.900 1.954 10
n = 3: see BUPSIB10 (1.892, 1.893) B4S B(4)–S(3) 1.930 1.927 0.009 1.925 1.934 10
B(4)–S(2) 1.896 1.896 0.004 1.893 1.899 6 B3S N-B-S2 1.806 1.806 0.010 1.799 1.816 28
(=X-)(N-)B-S 1.851 1.854 0.013 1.842 1.859 10 BrBr see BEPZEB, TPASTB 2.542 2.548 0.015 2.526 2.551 4 BrC Br-C* 1.966 1.967 0.029 1.951 1.983 100 4
Br-Csp3 (cyclopropane) 1.910 1.910 0.010 1.900 1.914 8 Br-Csp2 1.883 1.881 0.015 1.874 1.894 31 4 Br-Car (mono-Br + m.p-Br2) 1.899 1.899 0.012 1.892 1.906 119 4 Br-Car (o-Br2) 1.875 1.872 0.011 1.864 1.884 8 4
Br2Cl see TEACBR (2.362-2.402) † BrI see DTHIBR10 (2.646), TPHOSI (2.695) BrN see NBBZAM (1.843) BrO see CIYFOF 1.581 1.581 0.007 1.574 1.587 4 BrP see CISTED (2.366) BrS2 see BEMLIO (2.206) † BrS3 see CIWYIQ (2.435, 2.453) † BrS3+ see THINBR (2.321) † BrSE see CIFZUM (2.508, 2.619) BrSi see BIZJAV (2.284) BrTe In Br6Te2-see CUGBAH (2.692-2.716)
Br-Te(4) see BETUTE10 (3.079, 3.015) Br-Te(3) see BTUPTE (2.835)
Csp3Csp3 C#–CH2-CH3 1.513 1.514 0.014 1.507 1.523 192 (C#)2-CH-CH3 1.524 1.526 0.015 1.518 1.534 226 (C#)3-C-CH3 1.534 1.534 0.011 1.527 1.541 825 C#–CH2-CH2-C# 1.524 1.524 0.014 1.516 1.532 2459 (C#)2-CH-CH2-C# 1.531 1.531 0.012 1.524 1.538 1217 (C#)3-C-CH2-C# 1.538 1.539 0.010 1.533 1.544 330 (C#)2-CH-CH-(C#)2 1.542 1.542 0.011 1.536 1.549 321 (C#)3-C-CH-(C#)2 1.556 1.556 0.011 1.549 1.562 215 (C#)3-C-C-(C#)3 1.588 1.580 0.025 1.566 1.610 21 C*–C* (overall) 1.530 1.530 0.015 1.521 1.539 5777 5,6 in cyclopropane (any subst.) 1.510 1.509 0.026 1.497 1.523 888 7 in cyclobutane (any subst.) 1.554 1.553 0.021 1.540 1.567 679 8 in cyclopentane (C,H-subst.) 1.543 1.543 0.018 1.532 1.554 1641 in cyclohexane (C,H-subst.) 1.535 1.535 0.016 1.525 1.545 2814 cyclopropyl-C* (exocyclic) 1.518 1.518 0.019 1.505 1.531 366 7 cyclobutyl-C* (exocyclic) 1.529 1.529 0.016 1.519 1.539 376 8 cyclopentyl-C* (exocyclic) 1.540 1.541 0.017 1.527 1.549 956 cyclohexyl-C* (exocyclic) 1.539 1.538 0.016 1.529 1.549 2682 in cyclobutene (any subst.) 1.573 1.574 0.017 1.566 1.586 25 8 in cyclopentene (C,H-subst.) 1.541 1.539 0.015 1.532 1.549 208 in cyclohexene (C,H-subst.) 1.541 1.541 0.020 1.528 1.554 586 in oxirane (epoxide) 1.466 1.466 0.015 1.458 1.474 249 9 in aziridine 1.480 1.481 0.021 1.465 1.496 67 9
1 u in oxetane 1.541 1.541 0.019 1.527 1.557 16 in azetidine 1.548 1.543 0.018 1.536 1.558 22 oxiranyl-C* (exocyclic) 1.509 1.507 0.018 1.497 1.519 333 9 aziridinyl-C* (exocyclic) 1.512 1.512 0.018 1.496 1.526 13 9
Csp3Csp2 CH3-C=C 1.503 1.504 0.011 1.497 1.509 215 C#–CH2-C=C 1.502 1.502 0.013 1.494 1.510 483 (C#)2-CH-C=C 1.510 1.510 0.014 1.501 1.518 564 (C#)3-C-C=C 1.522 1.522 0.016 1.511 1.533 193
Csp3Csp2 C*–C=C (overall) 1.507 1.507 0.015 1.499 1.517 1456 5 C*–C=C (endocyclic) in cyclopropene 1.509 1.508 0.016 1.500 1.516 20 10 in cyclobutene 1.513 1.512 0.018 1.500 1.525 50 8 in cyclopentene 1.512 1.512 0.014 1.502 1.521 208 in cyclohexene 1.506 1.505 0.016 1.495 1.516 391 in cyclopentadiene 1.502 1.503 0.019 1.490 1.515 18 in cyclohexa-1,3-diene 1.504 1.504 0.017 1.491 1.517 56 C*–C=C (exocyclic): cyclopropenyl-C* 1.478 1.475 0.012 1.470 1.485 7 10 cyclobutenyl-C* 1.489 1.483 0.015 1.479 1.496 11 8 cyclopentenyl-C* 1.504 1.506 0.012 1.495 1.512 115 cyclohexenyl-C* 1.511 1.511 0.013 1.502 1.519 292 C*CH=O in aldehydes 1.510 1.510 0.008 1.501 1.518 7 (C*)2-C=O in ketones 1.511 1.511 0.015 1.501 1.521 952 11 in cyclobutanone 1.529 1.530 0.016 1.514 1.545 18 in cyclopentanone 1.514 1.514 0.016 1.505 1.523 312 acyclic and 6 + rings 1.509 1.509 0.016 1.499 1.519 626 C*–COOH in carboxylic acids 1.502 1.502 0.014 1.495 1.510 176 C*–COO-in carboxylate anions 1.520 1.521 0.011 1.516 1.528 57 C*–C(=O)(–OC*) in acyclic esters 1.497 1.496 0.018 1.484 1.509 553 12 in β-lactones 1.519 1.519 0.020 1.500 1.538 4 13 in γ-lactones 1.512 1.512 0.015 1.501 1.521 110 12 in δ-lactones 1.504 1.502 0.013 1.495 1.517 27 12 cyclopropyl (C)–C=O in ketones, acids and esters 1.486 1.485 0.018 1.474 1.497 105 7 C*–C(=O)(–NH2) in acyclic amides 1.514 1.512 0.016 1.506 1.526 32 14 C*–C(=O)(–NHC*) in acyclic amides 1.506 1.505 0.012 1.498 1.515 78 14 C*–C(=O)[–N(C*)2] in acyclic amides 1.505 1.505 0.011 1.496 1.517 15 14
Csp3Car CH3-Car 1.506 1.507 0.011 1.501 1.513 454 C#–CH2-Car 1.510 1.510 0.009 1.505 1.516 674 (C#)2-CH-Car 1.515 1.515 0.011 1.508 1.522 363 (C#)3-C-Car 1.527 1.530 0.016 1.517 1.539 308 C*–Car (overall) 1.513 1.513 0.014 1.505 1.521 1813 cyclopropyl (C)–Car 1.490 1.490 0.015 1.479 1.503 90 7
Csp3Csp1 C*–C≡C 1.466 1.465 0.010 1.460 1.469 21 15 C#–C≡C 1.472 1.472 0.012 1.464 1.481 88 15 C*–C≡N 1.470 1.469 0.013 1.463 1.479 106 7b cyclopropyl (C)–C≡N 1.444 1.447 0.010 1.436 1.451 38 7
Csp2Csp2 C=C-C=C (conjugated) 1.455 1.455 0.011 1.447 1.463 30 16,18 (unconjugated) 1.478 1.476 0.012 1.470 1.479 8 17,18 (overall) 1.460 1.460 0.015 1.450 1.470 38 C=C-C=C-C=C 1.443 1.445 0.013 1.431 1.454 29 18 C=C-C=C (endocyclic in TCNQ) 1.432 1.433 0.012 1.424 1.441 280 19 C=C-C(=O)(–C*) (conjugated) 1.464 1.462 0.018 1.453 1.476 211 16,18 (unconjugated) 1.484 1.486 0.017 1.475 1.497 14 17,18 (overall) 1.465 1.462 0.018 1.453 1.478 226 C=C-C(=O)–C=C in benzoquinone (C,H-subst. only) 1.478 1.476 0.011 1.469 1.488 28 in benzoquinone (any subst.) 1.478 1.478 0.031 1.464 1.498 172
1 u non-quinonoid 1.456 1.455 0.012 1.447 1.464 28 C=C-COOH 1.475 1.476 0.015 1.461 1.488 22 C=C-COOC* 1.488 1.489 0.014 1.478 1.497 113 C=C-COO-1.502 1.499 0.017 1.488 1.510 11 HOOC-COOH 1.538 1.537 0.007 1.535 1.541 9 HOOC-COO-1.549 1.552 0.009 1.546 1.553 13 –OOC-COO-1.564 1.559 0.022 1.554 1.568 9 formal Csp2-Csp2 single bond in selected non-fused
heterocycles: in 1H-pyrrole (C3-C4) 1.412 1.410 0.016 1.401 1.427 29 in furan (C3-C4) 1.423 1.423 0.016 1.412 1.433 62 in thiophene (C3-C4) 1.424 1.425 0.015 1.415 1.433 40 in pyrazole (C3-C4) 1.410 1.412 0.016 1.400 1.418 20 in isoxazole (C3-C4) 1.425 1.425 0.016 1.413 1.438 9 in furazan (C3-C4) 1.428 1.427 0.007 1.422 1.435 6 in furoxan (C3-C4) 1.417 1.417 0.006 1.412 1.422 14
Csp2Car C=C-Car (conjugated) 1.470 1.470 0.015 1.463 1.480 37 16,18
Csp2Car 1.488 1.490 0.012 1.480 1.496 87 17,18 (overall) 1.483 1.483 0.015 1.472 1.494 124 cyclopropenyl (C=C)–Car 1.447 1.448 0.006 1.441 1.452 8 10 Car-C(=O)–C* 1.488 1.489 0.016 1.478 1.500 84 Car-C(=O)–Car 1.480 1.481 0.017 1.468 1.494 58 Car-COOH 1.484 1.485 0.014 1.474 1.491 75 Car-C(=O)(–OC*) 1.487 1.487 0.012 1.480 1.494 218 Car-COO-1.504 1.509 0.014 1.495 1.512 26 Car-C(–O)–NH2 1.500 1.503 0.020 1.498 1.510 19 Car-C=N-C# (conjugated) 1.476 1.478 0.014 1.466 1.486 27 16 (unconjugated) 1.491 1.490 0.008 1.485 1.496 48 17 (overall) 1.485 1.487 0.013 1.481 1.493 75 in indole (C3-C3a) 1.434 1.434 0.011 1.428 1.439 40
Csp2Csp1 C=C-C≡C 1.431 1.427 0.014 1.425 1.441 11 7b C=C-C≡N in TCNQ 1.427 1.427 0.010 1.420 1.433 280 19
CarCar in biphenyls (ortho subst. all H) 1.487 1.488 0.007 1.484 1.493 30 (≥1 non-H ortho-subst.) 1.490 1.491 0.010 1.486 1.495 212
CarCsp1 Car-C≡C 1.434 1.436 0.006 1.430 1.437 37 Car-C≡N 1.443 1.444 0.008 1.436 1.448 31
Csp1Csp1 C≡C-C=C 1.377 1.378 0.012 1.374 1.384 21 Csp2=Csp2 C*–CH=CH2 1.299 1.300 0.027 1.280 1.311 42
(C*)2-C=CH2 1.321 1.321 0.013 1.313 1.328 77 C*–CH=CH-C* (cis) 1.317 1.318 0.013 1.310 1.323 106 (trans) 1.312 1.311 0.011 1.304 1.320 19 (overall) 1.316 1.317 0.015 1.309 1.323 127 (C*)2-C=CH-C* 1.326 1.328 0.011 1.319 1.334 168 (C*2-C=C-(C*)2 1.331 1.330 0.009 1.326 1.334 89 (C*,H)2-C=C-(C*,H)2 (overall) 1.322 1.323 0.014 1.315 1.331 493 5 in cyclopropene (any subst.) 1.294 1.288 0.017 1.284 1.302 10 10 in cyclobutene (any subst.) 1.335 1.335 0.019 1.324 1.347 25 8 in cyclopentene (C,H-subst.) 1.323 1.324 0.013 1.314 1.331 104 in cyclohexene (C,H-subst.) 1.326 1.325 0.012 1.318 1.334 196 C=C=C (allenes, any subst.) 1.307 1.307 0.005 1.303 1.310 18 C=C-C=C (C,H subst., conjugated) 1.330 1.330 0.014 1.322 1.338 76 16 C=C-C=C-C=C (C,H subst., conjugated) 1.345 1.345 0.012 1.337 1.350 58 16 C=C-Car (C,H subst., conjugated) 1.339 1.340 0.011 1.334 1.346 124 16 C=C in cyclopenta-1,3-diene (any subst.) 1.341 1.341 0.017 1.328 1.356 18 C=C in cyclohexa-1,3-diene (any subst.) 1.332 1.332 0.013 1.323 1.341 56 in C=C-C=O (C,H subst., conjugated) 1.340 1.340 0.013 1.332 1.348 211 16,18 (C,H subst., unconjugated) 1.331 1.330 0.008 1.326 1.339 14 17,18
1 u (C,H subst., overall) 1.340 1.339 0.013 1.332 1.348 226 in cyclohexa-2,5-dien-1-ones 1.329 1.327 0.011 1.321 1.335 28 in p-benzoquinones (C*,H subst.) 1.333 1.337 0.011 1.325 1.338 14 (any subst.) 1.349 1.339 0.030 1.330 1.364 86 in TCNQ (endocyclic) 1.352 1.353 0.010 1.345 1.358 142 19 (exocyclic) 1.392 1.391 0.017 1.379 1.405 139 19 C=C-OH in enol tautomers 1.362 1.360 0.020 1.349 1.370 54 in heterocycles (any subst.): 1H-pyrrole (C2-C3, C4-C5) 1.375 1.377 0.018 1.361 1.388 58 furan (C2-C3, C4-C5) 1.341 1.342 0.021 1.329 1.351 125 thiophene (C2-C3, C4-C5) 1.362 1.359 0.025 1.346 1.377 60 pyrazole (C4-C5) 1.369 1.372 0.019 1.362 1.383 20 imidazole (C4-C5) 1.360 1.361 0.014 1.352 1.367 44 isoxazole (C4-C5) 1.341 1.336 0.012 1.331 1.355 9 indole (C2-C3) 1.364 1.363 0.012 1.355 1.371 40
Car ≃ Car in phenyl rings with C*, H subst. only H-C ≃ C-H 1.380 1.381 0.013 1.372 1.388 2191 C*–C ≃ C-H 1.387 1.388 0.010 1.382 1.393 891 C*–C ≃ C-C* 1.397 1.397 0.009 1.392 1.403 182 C ≃ C (overall) 1.384 1.384 0.013 1.375 1.391 3264 F-C ≃ C-F 1.372 1.374 0.011 1.366 1.380 84 4 Cl-C ≃ C-Cl 1.388 1.389 0.014 1.380 1.398 152 4 in naphthalene (D2h, any subst.) C1-C2 1.364 1.364 0.014 1.356 1.373 440 C2-C3 1.406 1.406 0.014 1.397 1.415 218 C1-C8a 1.420 1.419 0.012 1.412 1.426 440 C4a-C8a 1.422 1.424 0.011 1.417 1.429 109
Car ≃ Car in anthracene (D2h, any subst.) C1-C2 1.356 1.356 0.009 1.350 1.360 56 C2-C3 1.410 1.410 0.010 1.401 1.416 34 C1-C9a 1.430 1.430 0.006 1.426 1.434 56 C4a-C9a 1.435 1.436 0.007 1.429 1.440 34 C9-C9a 1.400 1.402 0.009 1.395 1.406 68 in pyridine (C,H subst.) 1.379 1.381 0.012 1.371 1.387 276 20 (any subst.) 1.380 1.380 0.015 1.371 1.389 537 20 in pyridinium cation (N+ –H; C,H subst. on C) C2-C3 1.373 1.375 0.012 1.368 1.380 30 C3-C4 1.379 1.380 0.011 1.371 1.388 30 (N+ –X; C,H subst. on C) C2-C3 1.373 1.372 0.019 1.362 1.382 151 C3-C4 1.383 1.385 0.019 1.372 1.394 151 in pyrazine (H subst. on C) 1.379 1.377 0.010 1.370 1.388 10 (any subst. on C) 1.405 1.405 0.024 1.388 1.420 60 in pyrimidine (C,H subst. on C) 1.387 1.389 0.018 1.379 1.400 28
Csp1≡Csp1 X-C≡C-X 1.183 1.183 0.014 1.174 1.193 119 15 C,H-C≡C-C,H 1.181 1.181 0.014 1.173 1.192 104 15 in C≡C-C(sp2,ar) 1.189 1.193 0.010 1.181 1.195 38 15 in C≡C-C≡C 1.192 1.192 0.010 1.187 1.197 42 15 in CH≡C-C# 1.174 1.174 0.011 1.167 1.180 42 15
Csp3Cl Omitting 1,2-dichlorides: C-CH2-Cl 1.790 1.790 0.007 1.783 1.795 13 4 C2-CH-Cl 1.803 1.802 0.003 1.800 1.807 8 4 C3-C-Cl 1.849 1.856 0.011 1.837 1.858 5 4 X-CH2-Cl (X = C,H,N,O) 1.790 1.791 0.011 1.783 1.797 37 4 X2-CH-Cl (X = C,H,N,O) 1.805 1.803 0.014 1.800 1.812 26 4 X3-C-Cl (X = C,H,N,O) 1.843 1.838 0.014 1.835 1.858 7 4 X2-C-Cl2 (X = C,H,N,O) 1.779 1.776 0.015 1.769 1.790 18 4
1 u X-C-Cl3 (X = C,H,N,O) 1.768 1.765 0.011 1.761 1.776 33 4 Cl-CH(–C)–CH(–C)–Cl 1.793 1.793 0.013 1.786 1.800 66 4 Cl-C(–C2)–C(–C2)–Cl 1.762 1.760 0.010 1.757 1.765 54 4 cyclopropyl-Cl 1.755 1.756 0.011 1.749 1.763 64
Csp2-Cl C=C-Cl (C,H,N,O subst. on C) 1.734 1.729 0.019 1.719 1.748 63 4 C=C-Cl2 (C,H,N,O subst. on C) 1.720 1.716 0.013 1.708 1.729 20 4 Cl-C=C-Cl 1.713 1.711 0.011 1.705 1.720 80 4
Car-Cl Car-Cl (mono-Cl + m,p-Cl2) 1.739 1.741 0.010 1.734 1.745 340 4 Car-Cl (o-Cl2) 1.720 1.720 0.010 1.713 1.717 364 4
Csp1Cl see HCLENE10 (1.634, 1.646) Csp3F Omitting 1,2-difluorides
C-CH2-F and C2-CH-F 1.399 1.399 0.017 1.389 1.408 25 4 C3-C-F 1.428 1.431 0.009 1.421 1.435 11 4 (C*,H)2-C-F2 1.349 1.347 0.012 1.342 1.356 58 4 C*–C-F3 1.336 1.334 0.007 1.330 1.344 12 4 F-C*–C*–F 1.371 1.374 0.007 1.362 1.375 26 4 X3-C-F (X = C,H,N,O) 1.386 1.389 0.033 1.373 1.408 70 4 X2-C-F2 (X = C,H,N,O) 1.351 1.349 0.013 1.342 1.356 58 4 X-C-F3 (X = C,H,N,O) 1.322 1.323 0.015 1.314 1.332 309 4 F-C(–X)2-C(–X)2-F (X = C,H,N,O) 1.373 1.374 0.009 1.362 1.377 30 4 F-C(–X)2-NO2 (X = any subst.) 1.320 1.319 0.009 1.312 1.327 18
Csp2F C=C-F (C,H,N,O subst. on C) 1.340 1.340 0.013 1.334 1.346 34 4 CarF Car-F (mono-F + m,p-F2) 1.363 1.362 0.008 1.357 1.368 38 4
Car-F (o-F2) 1.340 1.340 0.009 1.336 1.344 167 4 Csp3H C-C-H3 (methyl) 1.059 1.061 0.030 1.039 1.083 83 21
C2-C-H2 (primary) 1.092 1.095 0.013 1.088 1.099 100 21 C3-C-H (secondary) 1.099 1.097 0.004 1.095 1.103 14 21 C2,3-C-H (primary and secondary) 1.093 1.095 0.012 1.089 1.100 118 21 X-C-H3 (methyl) 1.066 1.074 0.028 1.049 1.087 160 21 X2-C-H2 (primary) 1.092 1.095 0.012 1.088 1.099 230 21 X3-C-H (secondary) 1.099 1.099 0.007 1.095 1.103 117 21 X2,3-C-H (primary and secondary) 1.094 1.096 0.011 1.091 1.100 348 21
Csp2H C-C=C-H 1.077 1.079 0.012 1.074 1.085 14 21 CarH Car-H 1.083 1.083 0.011 1.080 1.087 218 21 Csp3I C*–I 2.162 2.159 0.015 2.149 2.179 15 4 CarI Car-I 2.095 2.095 0.015 2.089 2.104 51 4 Csp3N4 C*–NH3+ 1.488 1.488 0.013 1.482 1.495 298
(C*)2-NH2+ 1.494 1.493 0.016 1.484 1.503 249 (C*)3-NH+ 1.502 1.502 0.015 1.491 1.512 509 (C*)4-N+ 1.510 1.509 0.020 1.496 1.523 319 C*–N+ (overall) 1.499 1.498 0.018 1.488 1.510 1370
Csp3N3 C*–N+ in N-subst. pyridinium 1.485 1.484 0.009 1.477 1.490 32 C*–NH2 (Nsp3: pyramidal) 1.469 1.470 0.010 1.462 1.474 19 22 (C*)2-NH (Nsp3: pyramidal) 1.469 1.467 0.012 1.461 1.477 152 5,22 (C*)3-N (Nsp3: pyramidal) 1.469 1.468 0.014 1.460 1.476 1042 5,22 C*–Nsp3 (overall) 1.469 1.468 0.014 1.460 1.476 1201 Csp3-Nsp3 in aziridine 1.472 1.471 0.016 1.464 1.482 134 in azetidine 1.484 1.481 0.018 1.472 1.495 21 in tetrahydropyrrole 1.475 1.473 0.016 1.464 1.483 66 in piperidine 1.473 1.473 0.013 1.460 1.479 240 Csp3-Nsp2 (N planar) in: 23 acyclic amides C*–NH-C=O 1.454 1.451 0.011 1.446 1.461 78 14 β-lactams C*–N(–X)–C=O (endo) 1.464 1.465 0.012 1.458 1.475 23 13 γ-lactams C*–NH-C=O (endo) 1.457 1.458 0.011 1.449 1.465 20 13 C*–N(–C*)–C=O (endo) 1.462 1.461 0.010 1.453 1.466 15 13 C*–N(–C*)–C=O (exo) 1.458 1.456 0.014 1.448 1.465 15 13 δ-lactams C*–NH-C=O (endo) 1.478 1.472 0.016 1.467 1.491 6 14 C*–N(–C*)–C=O (endo) 1.479 1.476 0.007 1.475 1.482 15 14
1 u C*–N(–C*)–C=O (exo) 1.468 1.471 0.009 1.462 1.477 15 14 nitro compounds (1,2-dinitro omitted): C-CH2-NO2 1.485 1.483 0.020 1.478 1.502 8 C2-CH-NO2 1.509 1.509 0.011 1.502 1.511 12 C3-C-NO2 1.533 1.533 0.013 1.530 1.539 17 C2-C-(NO2)2 1.537 1.536 0.016 1.525 1.550 19 1,2-dinitro: NO2-C*–C*–NO2 1.552 1.550 0.023 1.536 1.572 32
Csp3N2 C#–N=N 1.493 1.493 0.020 1.477 1.506 54 C*–N=C-Car 1.465 1.468 0.011 1.461 1.472 75
Csp2N3 C=C-NH2 Nsp2 planar 1.336 1.344 0.017 1.317 1.348 10 23 C=C-NH-C# Nsp2 planar 1.339 1.340 0.016 1.327 1.351 17 23 C=C-N-(C#)2 Nsp2 planar 1.355 1.358 0.014 1.341 1.363 22 23 Nsp3 pyramidal 1.416 1.418 0.018 1.397 1.432 18 22 Csp2-Nsp2 (N planar) in: 23 acyclic amides NH2-C=O 1.325 1.323 0.009 1.318 1.331 32 14 C*–NH-C=O 1.334 1.333 0.011 1.326 1.343 78 14 (C*)2-N-C=O 1.346 1.342 0.011 1.339 1.356 5 14 β-lactams C*–NH-C=O 1.385 1.388 0.019 1.374 1.396 23 13 γ-lactams C*–NH-C=O 1.331 1.331 0.011 1.326 1.337 20 13 C*–N(–C*)–C=O 1.347 1.344 0.014 1.335 1.359 15 13 δ-lactams C*–NH-C=O 1.334 1.334 0.006 1.330 1.339 6 14 (C*)–N(–C*)–C=O 1.352 1.353 0.010 1.344 1.356 15 14 peptides C#–N(–X)–C(–C#)(=O) 1.333 1.334 0.013 1.326 1.340 380 24 ureas (NH2)2-C=O 1.334 1.334 0.008 1.329 1.339 48 25,26 (C#–NH)2-C=O 1.347 1.345 0.010 1.341 1.354 26 25 [(C#)n-N]2-C=O 1.363 1.359 0.014 1.354 1.370 40 25,27 thioureas 1.346 1.343 0.023 1.328 1.361 192 (X2N)2-C=S imides [C#–C(=O)]2-NH 1.376 1.377 0.012 1.369 1.383 64 [C#–C(=O)]2-N-C# 1.389 1.383 0.017 1.376 1.404 38 [Csp2-C(=O)]2-N-C# 1.396 1.396 0.010 1.389 1.403 46 [Csp2-C(=O)]2-N-Csp2 1.409 1.406 0.020 1.391 1.419 28 guanidinium [C-(NH2)3]+ (unsubst.) 1.321 1.320 0.008 1.314 1.327 39 (any subst.) 1.328 1.325 0.015 1.317 1.333 140 in heterocyclic systems (any subst.) 1H-pyrrole (N1-C2, N1-C5) 1.372 1.374 0.016 1.363 1.384 58 indole (N1-C2) 1.370 1.370 0.012 1.364 1.377 40 pyrazole (N1-C5) 1.357 1.359 0.012 1.347 1.365 20 imidazole (N1-C2) 1.349 1.349 0.018 1.338 1.358 44 imidazole (N1-C5) 1.370 1.370 0.010 1.365 1.377 44
Csp2N2 in imidazole (N3-C4) 1.376 1.377 0.011 1.369 1.384 44 CarN4 Car-N+–(C,H)3 1.465 1.466 0.007 1.461 1.470 23 CarN3 Car-NH2
(Nsp2: planar) 1.355 1.360 0.020 1.340 1.372 33 23 (Nsp3: pyramidal) 1.394 1.396 0.011 1.385 1.403 25 22 (overall) 1.375 1.377 0.025 1.363 1.394 98 28
CarN3 Car-NH-C# (Nsp2: planar) 1.353 1.353 0.007 1.347 1.359 16 23 (Nsp3: pyramidal) 1.419 1.423 0.017 1.412 1.432 8 22 (overall) 1.380 1.364 0.032 1.353 1.412 31 28 Car-N-(C#)2 (Nsp2: planar) 1.371 1.370 0.016 1.363 1.382 41 23 (Nsp3: pyramidal) 1.426 1.425 0.011 1.421 1.431 22 22 (overall) 1.390 1.385 0.030 1.366 1.420 69 28 in indole (N1-C7a) 1.372 1.372 0.007 1.367 1.376 40
1 u Car-NO2 1.468 1.469 0.014 1.460 1.476 556
CarN2 Car-N=N 1.431 1.435 0.020 1.422 1.442 26 Csp2=N3 in furoxan (+N2=C3) 1.316 1.316 0.009 1.311 1.324 14 Csp2=N2 Car-C=N-C# 1.279 1.279 0.008 1.275 1.285 75
(C,H)2-C=N-OH in oximes 1.281 1.280 0.013 1.273 1.288 67 S-C=N-X 1.302 1.302 0.021 1.285 1.319 36 in pyrazole (N2=C3) 1.329 1.331 0.014 1.315 1.339 20 in imidazole (C2=N3) 1.313 1.314 0.011 1.307 1.319 44 in isoxazole (N2=C3) 1.314 1.315 0.009 1.305 1.320 9 in furazan (N2=C3, C4=N5) 1.298 1.299 0.006 1.294 1.303 12 in furoxan (C4=N5) 1.304 1.306 0.008 1.300 1.308 14
Car ≃ N3 C ≃ N+–H (pyrimidinium) 1.335 1.334 0.015 1.325 1.342 30 C ≃ N+–C* (pyrimidinium) 1.346 1.346 0.010 1.340 1.352 64 C ≃ N+–O-(pyrimidinium) 1.362 1.359 0.013 1.353 1.369 56
Car ≃ N2 C ≃ N (pyridine) 1.337 1.338 0.012 1.330 1.344 269 C ≃ N (pyrazine) 1.336 1.335 0.022 1.319 1.347 120 C ≃ N ≃ C (pyrimidine) 1.339 1.338 0.015 1.333 1.342 28 N ≃ C ≃ N (pyrimidine) 1.333 1.335 0.013 1.326 1.337 28 C ≃ N (pyrimidine) (overall) in any 6-membered N-containing aromatic ring:
1.336 1.337 0.014 1.331 1.339 56
H-C ≃ N ≃ C-H 1.334 1.334 0.014 1.327 1.341 146 H-C ≃ N ≃ C-C* 1.339 1.341 0.013 1.336 1.345 38 C*–C ≃ N ≃ C-C* 1.345 1.345 0.008 1.342 1.348 24 C ≃ N ≃ C (overall) 1.336 1.337 0.014 1.329 1.344 204
Csp1≡N2 X-S-N≡C-(isothiocyanide) 1.144 1.147 0.006 1.140 1.148 6 Csp1≡N1 C*–C≡N 1.136 1.137 0.010 1.131 1.142 140
C=C-C≡N in TCNQ 1.144 1.144 0.008 1.139 1.149 284 19 Car-C≡N 1.138 1.138 0.007 1.133 1.143 31 X-C≡N 1.144 1.141 0.012 1.138 1.151 10 (S-C≡N)– 1.155 1.156 0.012 1.147 1.165 14
Csp3O2 in alcohols CH3-OH 1.413 1.414 0.018 1.395 1.425 17 C-CH2-OH 1.426 1.426 0.011 1.420 1.431 75 C2-CH-OH 1.432 1.431 0.011 1.425 1.439 266 C3-C-OH 1.440 1.440 0.012 1.432 1.449 106 C*–OH (overall) 1.432 1.431 0.013 1.424 1.441 464 in dialkyl ethers 29 CH3-O-C* 1.416 1.418 0.016 1.405 1.426 110 C-CH2-O-C* 1.426 1.424 0.011 1.418 1.435 34 C2-CH-O-C* 1.429 1.430 0.010 1.420 1.437 53 C3-C-O-C* 1.452 1.450 0.011 1.445 1.458 39 C*–O-C* (overall) 1.426 1.425 0.019 1.414 1.437 236 5 in aryl alkyl ethers 29 CH3-O-Car 1.424 1.424 0.012 1.417 1.431 616 C-CH2-O-Car 1.431 1.430 0.013 1.422 1.438 188 C2-CH-O-Car 1.447 1.446 0.020 1.435 1.466 58 C3-C-O-Car 1.470 1.469 0.018 1.456 1.483 55 C*–O-Car (overall) 1.429 1.427 0.018 1.419 1.436 917 in alkyl esters of carboxylic acids 12,29 CH3-O-C(=O)–C* 1.448 1.449 0.010 1.442 1.455 200 C-CH2-O-C(=O)–C* 1.452 1.453 0.009 1.445 1.458 32 C2-CH-O-C(=O)–C* 1.460 1.460 0.010 1.454 1.465 78 C3-C-O-C(=O)–C* 1.477 1.475 0.008 1.472 1.484 6 C*–O-C(=O)–C* (overall) 1.450 1.451 0.014 1.442 1.459 314 in alkyl esters of α,β-unsaturated acids: C*–O-C(=O)–C=C (overall) 1.453 1.452 0.013 1.444 1.459 112 in alkyl esters of benzoic acid C*–O-C(=O)–C(phenyl) (overall) 1.454 1.454 0.012 1.446 1.463 219 in ring systems oxirane (epoxides) (any subst.) 1.446 1.446 0.014 1.438 1.456 498 9
1 u oxetane (any subst.) 1.463 1.460 0.015 1.451 1.474 16 tetrahydrofuran (C,H subst.) 1.442 1.441 0.017 1.430 1.451 154
Csp3O2 tetrahydropyran (C,H subst.) 1.441 1.442 0.015 1.431 1.451 22 β-lactones: C*–O-C(=O) 1.492 1.494 0.010 1.481 1.501 4 16 γ-lactones: C*–O-C(=O) 1.464 1.464 0.012 1.455 1.473 110 12 δ-lactones: C*–O-C(=O) 1.461 1.464 0.017 1.452 1.473 27 12 O-C-O system in gem-diols, and pyranose and
furanose sugars: 30,31
HO-C*–OH 1.397 1.401 0.012 1.388 1.405 18 C5-O5-C1-O1H in pyranoses O1 axial (α): C5-O5 1.439 1.440 0.008 1.432 1.445 29 O5-C1 1.427 1.426 0.012 1.421 1.432 29 C1-O1 1.403 1.400 0.012 1.391 1.412 29 O1 equatorial (β): C5-O5 1.435 1.436 0.008 1.429 1.440 17 O5-C1 1.430 1.431 0.010 1.424 1.436 17 C1-O1 1.393 1.393 0.007 1.386 1.399 17 α + β (overall): C5-O5 1.439 1.440 0.008 1.432 1.446 60 O5-C1 1.430 1.429 0.012 1.421 1.436 60 C1-O1 1.401 1.399 0.011 1.392 1.407 60 C4-O4-C1-O1H in furanoses (overall values) C4-O4 1.442 1.446 0.012 1.436 1.449 18 O4-C1 1.432 1.432 0.012 1.421 1.443 18 C1-O1 1.404 1.405 0.013 1.397 1.409 18 C5-O5-C1-O1-C* in pyranoses O1 axial (α): C5-O5 1.439 1.438 0.010 1.433 1.446 67 O5-C1 1.417 1.417 0.009 1.410 1.424 67 C1-O1 1.409 1.409 0.014 1.401 1.417 67 O1-C* 1.435 1.435 0.013 1.427 1.443 67 O1 equatorial (β): C5-O5 1.434 1.435 0.006 1.429 1.439 39 O5-C1 1.424 1.424 0.008 1.418 1.431 39 C1-O1 1.390 1.390 0.011 1.381 1.400 39 O1-C* 1.437 1.438 0.013 1.428 1.445 39 α + β (overall): C5-O5 1.436 1.436 0.009 1.431 1.442 126 O5-C1 1.419 1.419 0.011 1.412 1.426 126 C1-O1 1.402 1.403 0.016 1.391 1.413 126 O1-C* 1.436 1.436 0.013 1.428 1.445 126 C4-O4-C1-O1-C* in furanoses (overall values) C4-O4 1.443 1.445 0.013 1.429 1.453 23 O4-C1 1.421 1.418 0.012 1.413 1.431 23 C1-O1 1.410 1.409 0.014 1.401 1.420 23 O1-C* 1.439 1.437 0.014 1.429 1.449 23 Miscellaneous: C#–O-SiX3 1.416 1.416 0.017 1.405 1.428 29 C*–O-SO2-C 1.465 1.461 0.014 1.454 1.475 33
Csp2O2 in enols: C=C-OH 1.333 1.331 0.017 1.324 1.342 53 in enol esters: C=C-O-C* 1.354 1.353 0.016 1.341 1.363 40 in acids: C*–C(=O)–OH 1.308 1.311 0.019 1.298 1.320 174 C=C-C(=O)–OH 1.293 1.295 0.019 1.279 1.307 22 Car-C(=O)–OH 1.305 1.311 0.020 1.291 1.317 75 in esters: C*–C(=O)–O-C* 1.336 1.337 0.014 1.328 1.346 551 12,29 C=C-C(=O)–O-C* 1.332 1.331 0.011 1.324 1.339 112 Car-C(=O)–O-C* 1.337 1.335 0.013 1.329 1.344 219 12 C*–C(=O)–O-C=C 1.362 1.359 0.018 1.351 1.374 26
1 u C*–C(=O)–O-C=C 1.407 1.405 0.017 1.394 1.420 26 C*–C(=O)–O-Car 1.360 1.359 0.011 1.355 1.367 40 12 in anhydrides: O=C-O-C=O 1.386 1.386 0.011 1.379 1.393 70 in ring systems: furan (O1-C2, O1-C5) 1.368 1.369 0.015 1.359 1.377 125 isoxazole (O1-C5) 1.354 1.354 0.010 1.345 1.360 9 β-lactones: C*–C(=O)–O-C* 1.359 1.359 0.013 1.348 1.371 4 13 γ-lactones: C*–C(=O)–O-C* 1.350 1.349 0.012 1.342 1.359 110 12 δ-lactones: C*–C(=O)–O-C* 1.339 1.339 0.016 1.332 1.347 27 12
CarO2 in phenols: Car-OH 1.362 1.364 0.015 1.353 1.373 551 in aryl alkyl ethers: Car-O-C* 1.370 1.370 0.011 1.363 1.377 920 29,32
CarO2 in diaryl ethers: Car-O-Car 1.384 1.381 0.014 1.375 1.391 132 in esters: Car-O-C(=O)–C* 1.401 1.401 0.010 1.394 1.408 40 12
Csp2=O1 in aldehydes and ketones: C*–CH=O 1.192 1.192 0.005 1.188 1.197 7 (C*)2-C=O 1.210 1.210 0.008 1.206 1.215 474 5 (C#)2-C=O in cyclobutanones 1.198 1.198 0.007 1.194 1.204 12 in cyclopentanones 1.208 1.208 0.007 1.203 1.212 155 in cyclohexanones 1.211 1.211 0.009 1.207 1.216 312 C=C-C=O 1.222 1.222 0.010 1.216 1.229 225 (C=C)2-C=O 1.233 1.229 0.010 1.226 1.242 28 Car-C=O 1.221 1.218 0.014 1.212 1.229 85 (Car)2-C=O 1.230 1.226 0.015 1.220 1.238 66 C=O in benzoquinones 1.222 1.220 0.013 1.211 1.231 86 delocalized double bonds in carboxylate anions: H-C ≃ O2-(formate) 1.242 1.243 0.012 1.234 1.252 24 C*–C ≃ O2-1.254 1.253 0.010 1.247 1.261 114 C=C-C ≃ O2-1.250 1.248 0.017 1.238 1.261 52 Car-C ≃ O2-1.255 1.253 0.010 1.249 1.262 22 HOOC-C ≃ O2-(hydrogen oxalate) 1.243 1.247 0.015 1.232 1.256 26 –O2 ≃ C-C ≃ O2-(oxalate) 1.251 1.251 0.007 1.248 1.254 18 in carboxylic acids (X-COOH) C*–C(=O)–OH 1.214 1.214 0.019 1.203 1.224 175 C=C-C(=O)–OH 1.229 1.226 0.017 1.218 1.237 22 Car-C(=O)–OH 1.226 1.223 0.020 1.211 1.241 75 in esters: C*–C(=O)–O-C* 1.196 1.196 0.010 1.190 1.202 551 12 C=C-C(=O)–O-C* 1.199 1.198 0.009 1.193 1.203 113 Car-C(=O)–O-C* 1.202 1.201 0.009 1.196 1.207 218 12 C*–C(=O)–O-C=C 1.190 1.190 0.014 1.184 1.198 26 C*–C(=O)–O-Car 1.187 1.188 0.011 1.181 1.195 40 12 in anhydrides: O=C-O-C=O 1.187 1.187 0.010 1.184 1.193 70 in β-lactones: C*–C(=O)–O-C* 1.193 1.193 0.006 1.187 1.198 4 13 γ-lactones: C*–C(=O)–O-C* 1.201 1.202 0.009 1.196 1.206 109 12 δ-lactones: C*–C(=O)–O-C* 1.205 1.207 0.008 1.201 1.209 27 12 in amides: NH2-C(–C*)=O 1.234 1.233 0.012 1.225 1.243 32 14 (C*–)(C*,H-)N-C(–C*)=O 1.231 1.231 0.012 1.224 1.238 378 14 β-lactams: C*–NH-C=O 1.198 1.200 0.012 1.193 1.204 23 13 γ-lactams: C*–NH-C=O 1.235 1.235 0.008 1.232 1.240 20 13 C*–N(–C*)–C=O 1.225 1.226 0.011 1.217 1.233 15 13 δ-lactams: C*–NH-C=O 1.240 1.241 0.003 1.237 1.243 6 14 C*–N(–C*)–C=O 1.233 1.233 0.007 1.229 1.239 15 14 in ureas: (NH)2)2-C=O 1.256 1.256 0.007 1.249 1.261 24 25,26 (C#–NH)2-C=O 1.241 1.237 0.011 1.235 1.245 13 25 [(C#)n-N]2-C=O 1.230 1.230 0.007 1.224 1.234 20 25,27
Csp3P4 C3-P+–C* 1.800 1.802 0.015 1.790 1.812 35 33
1 u C2-P(=O)–CH3 1.791 1.790 0.006 1.786 1.795 10 C2-P(=O)–CH2-C 1.806 1.806 0.009 1.801 1.813 45 C2-P(=O)–CH-C2 1.821 1.821 0.009 1.815 1.828 15 C2-P(=O)–C-C3 1.841 1.842 0.008 1.835 1.847 14 C2-P(=O)–C* (overall) 1.813 1.811 0.017 1.800 1.822 84
Csp3P3 C2-P-C* 1.855 1.857 0.019 1.840 1.870 23 CarP4 C3-P+–Car 1.793 1.792 0.011 1.786 1.800 276
C2-P(=O)–Car 1.801 1.802 0.011 1.796 1.807 98 Ph3-P=N+=P-Ph3 1.795 1.795 0.008 1.789 1.800 197
CarP3 C2-P-Car 1.836 1.837 0.010 1.830 1.844 102 (N≃)2P-Car(P ≃ N aromatic) 1.795 1.793 0.011 1.788 1.803 43
Csp3S4 C*–SO2-C (C* = CH3 excluded) 1.786 1.782 0.018 1.774 1.797 75 C*–SO2-C (overall) 1.779 1.778 0.020 1.764 1.790 94 C*–SO2-O-X 1.745 1.744 0.009 1.738 1.754 7 34 C*–SO2-N-X2 1.758 1.756 0.018 1.746 1.773 17 34
Csp3S3 C*–S(=O)–C (C* = CH3 excluded) 1.818 1.814 0.024 1.802 1.829 69 C*–S(=O)–C (overall) 1.809 1.806 0.025 1.793 1.820 88 CH3-S+–X2 1.786 1.787 0.007 1.779 1.792 21 C*–S+–X2 (C* = CH3 excluded) 1.823 1.820 0.016 1.812 1.834 18 C*–S+–X2 (overall) 1.804 1.794 0.025 1.788 1.820 41
Csp3S2 C*–SH 1.808 1.805 0.010 1.800 1.819 6 CH3-S-C* 1.789 1.787 0.008 1.784 1.794 9
Csp3S2 C-CH2-S-C* 1.817 1.816 0.013 1.808 1.824 92 C2-CH-S-C* 1.819 1.819 0.011 1.811 1.825 32 C3-C-S-C* 1.856 1.860 0.011 1.854 1.863 26 C*–S-C* (overall) 1.819 1.817 0.019 1.809 1.827 242 in thiirane 1.834 1.835 0.025 1.810 1.858 4 9 in thiirane: see ZCMXSP (1.817, 1.844) in tetrahydrothiophene 1.827 1.826 0.018 1.811 1.837 20 in tetrahydrothiopyran 1.823 1.821 0.014 1.812 1.832 24 C-CH2-S-S-X 1.823 1.820 0.014 1.813 1.832 41 C3-C-S-S-X 1.863 1.865 0.015 1.848 1.878 11 C*–S-S-X (overall) 1.833 1.828 0.022 1.818 1.848 59
Csp2S2 C=C-S-C* 1.751 1.755 0.017 1.740 1.764 61 C=C-S-C=C (in tetrathiafulvalene) 1.741 1.741 0.011 1.733 1.750 88 C=C-S-C=C (in thiophene) 1.712 1.712 0.013 1.703 1.722 60 O=C-S-C# 1.762 1.759 0.018 1.747 1.778 20
CarS4 Car-SO2-C 1.763 1.764 0.009 1.756 1.769 96 Car-SO2-O-X 1.752 1.750 0.008 1.749 1.756 27 Car-SO2-N-X2 1.758 1.759 0.013 1.749 1.765 106 35
CarS3 Car-S(=O)–C 1.790 1.790 0.010 1.783 1.798 41 Car-S+–X2 1.778 1.779 0.010 1.771 1.787 10
CarS2 Car-S-C* 1.773 1.774 0.009 1.765 1.779 44 Car-S-Car 1.768 1.767 0.010 1.762 1.774 158 Car-S-Car (in phenothiazine) 1.764 1.764 0.008 1.760 1.769 48 Car-S-S-X 1.777 1.777 0.012 1.767 1.785 47
Csp1S2 N≡C-S-X 1.679 1.683 0.026 1.645 1.698 10 Csp1S1 (N≡C-S)– 1.630 1.630 0.014 1.619 1.641 14 Csp2=S1 (C*)2-C=S: see IPMUDS (1.599)
(Car)2-C=S: see CELDOM (1.611) (X)2-C=S (X = C,N,O,S) 1.671 1.675 0.024 1.656 1.689 245 X2N-C(=S)–S-X 1.660 1.660 0.016 1.648 1.674 38 (X2N)2-C=S (thioureas) 1.681 1.684 0.020 1.669 1.693 96 N-C(≃S)2 1.720 1.721 0.012 1.709 1.731 20
Csp3Se C#–Se 1.970 1.967 0.032 1.948 1.998 21 Csp2Se2 C=C-Se-C=C (in tetraselenafulvalene) 1.893 1.895 0.013 1.882 1.902 32 CarSe3 Ph3-Se+ 1.930 1.929 0.006 1.924 1.936 13 Csp3Si5 C#–Si-–X4 1.874 1.876 0.015 1.859 1.884 9 Csp3Si4 CH3-Si-X3 1.857 1.857 0.018 1.848 1.869 552
C*–Si-X3 (C* = CH3 excluded) 1.888 1.887 0.023 1.872 1.905 124 C*–Si-X3 (overall) 1.863 1.861 0.024 1.850 1.875 681
1 u CarSi4 Car-Si-X3 1.868 1.868 0.014 1.857 1.878 178 Csp1Si4 C≡C-Si-X3 1.837 1.840 0.012 1.824 1.849 8 Csp3Te C#–Te 2.158 2.159 0.030 2.128 2.177 13 CarTe Car-Te 2.116 2.115 0.020 2.104 2.130 72 Csp2=Te see CEDCUJ (2.044) ClCl see PHASCL (2.306, 2.227) ClI see CMBIDZ (2.563), HXPASC (2.541, 2.513),
METAMM (2.552), BQUINI (2.416, 2.718) ClN see BECTAE (1.743-1.757), BOGPOC (1.705) ClO1 in CIO-4 1.414 1.419 0.026 1.403 1.431 252 ClP (N≃)2P-Cl (N ≃ P aromatic) 1.997 1.994 0.015 1.989 2.004 46
Cl-P (overall) 2.008 2.001 0.035 1.986 2.028 111 ClS Cl-S (overall) 2.072 2.079 0.023 2.047 2.091 6
see also longer bonds in CILSAR (2.283), BIHXIZ (2.357), CANLUY (2.749)
ClSe see BIRGUE10, BIRHAL10, CTCNSE (2.234-2.851) ClSi4 Cl-Si-X3 (monochloro) 2.072 2.075 0.009 2.066 2.078 5
Cl2-Si-X2 and Cl3-Si-X 2.020 2.012 0.015 2.007 2.036 5 ClTe Cl-Te in range 2.34-2.60 2.520 2.515 0.034 2.493 2.537 22 36
see also longer bonds in BARRIV, BOJPUL, CETUTE, EPHTEA, OPNTEC10 (2.73-2.94)
FN3 F-N-C2 and F2-N-C 1.406 1.404 0.016 1.395 1.416 9 FP6 in hexafluorophosphate, PF-6 1.579 1.587 0.025 1.563 1.598 72 FP3 (N≃)2P-F(N ≃ P aromatic) 1.495 1.497 0.016 1.481 1.510 10 FS 43 observations in range 1.409-1.770 in a wide variety
of environments; F-S(6) in F2-SO2-C2 (see FPSULF10, BETJOZ)
1.640 1.646 0.011 1.626 1.649 6
F-S(4) in F2-S(=O)–N (see BUDTEZ) 1.527 1.528 0.004 1.524 1.530 24 37 FSi6 in SiF26 – 1.694 1.701 0.013 1.677 1.703 6 FSi5 F-Si-–X4 1.636 1.639 0.035 1.602 1.657 10 FSi4 F-Si-X3 1.588 1.587 0.014 1.581 1.599 24 FTe see CUCPlZ (F-Te(6) = 1.942, 1.937), FPHTEL(F-
Te(4) = 2.006) HN4 X3-N+–H 1.033 1.036 0.022 1.026 1.045 87 21 HN3 X3-N-H 1.009 1.010 0.019 0.997 1.023 95 21 HO2 in alcohols C*–O-H 0.967 0.969 0.010 0.959 0.974 63 21
C#–O-H 0.967 0.970 0.010 0.959 0.974 73 21 in acids O=C-O-H 1.015 1.017 0.017 1.001 1.031 16 21,38
II in I-3 2.917 2.918 0.011 2.907 2.927 6 IN see BZPRIB, CMBIDZ, HMTITI, HMTNTI,
IFORAM, IODMAM (2.042-2.475) IO X-I-O(see BZPRIB, CAJMAB, IBZDAC11) 2.144 2.144 0.028 2.127 2.164 6
for IO-6 see BOVMEE (1.829-1.912) IP3 see CEHKAB (2.490-2.493) † IS sec DTHIBR10 (2.687), ISUREA10 (2.629), BZTPPI
(3.251) ITe4 I-Te-X3 2.926 2.928 0.026 2.902 2.944 8 N4N3 X3-N+–N0-X2 (N0 planar) 1.414 1.414 0.005 1.412 1.418 13 N3N3 (C)(C,H)–Na-Nb(C)(C,H) 5,39
Na, Nb pyramidal 1.454 1.452 0.021 1.444 1.457 44 40 Na pyramidal, Nb planar 1.420 1.420 0.015 1.407 1.433 68 40 Na, Nb planar 1.401 1.401 0.018 1.384 1.418 40 40 overall 1.425 1.425 0.027 1.407 1.443 139
N3N2 in pyrazole (N1-N2) 1.366 1.366 0.019 1.350 1.375 20 in pyridaznium (Nl+≃N2) 1.350 1.349 0.010 1.345 1.361 7
N2 ≃ N2 N ≃ N (aromatic) in pyridazine with C,H as ortho substituents 1.304 1.300 0.019 1.287 1.326 6 with N,Cl as ortho substituents 1.368 1.373 0.011 1.362 1.375 9
N2=N2 C#–N=N-C# cis 1.245 1.244 0.009 1.239 1.252 21 trans 1.222 1.222 0.006 1.218 1.227 6 (overall) 1.240 1.241 0.012 1.230 1.251 27
1 u Car-N=N-Car 1.255 1.253 0.016 1.247 1.262 13 X-N=N=N (azides) 1.216 1.226 0.028 1.202 1.237 19
N2=N1 X-N=N=N (azides) 1.124 1.128 0.015 1.114 1.137 19 N3O2 (C,H)2-N-OH (Nsp2: planar) 1.396 1.394 0.012 1.390 1.401 28
C2-N-O-C (Nsp3: pyramidal) 1.463 1.465 0.012 1.457 1.468 22 (Nsp2: planar) 1.397 1.394 0.011 1.388 1.409 12 in furoxan (N2-O1) 1.438 1.436 0.009 1.430 1.447 14
N3O1 (C≃)2N+–O-in pyridine N-oxides 1.304 1.299 0.015 1.291 1.316 11 in furoxan (+N2-O6-) 1.234 1.234 0.008 1.228 1.240 14
N2O2 in oximes (C#)2-C=N-OH 1.416 1.418 0.006 1.416 1.420 7 (H)(Csp2)–C=N-OH 1.390 1.390 0.011 1.380 1.401 20 (C#)(Csp2)–C=N-OH 1.402 1.403 0.010 1.393 1.410 18 (Csp2)2-C=N-OH 1.378 1.377 0.017 1.365 1.393 16 (C,H)2-C=N-OH (overall) 1.394 1.395 0.018 1.379 1.408 67 in furazan (O1-N2, O1-N5) 1.385 1.383 0.013 1.378 1.392 12 in furoxan (O1-N5) 1.380 1.380 0.011 1.370 1.388 14 in isoxazole (O1-N2) 1.425 1.425 0.010 1.417 1.434 9
N3=O1 in nitrate ions NO3-1.239 1.240 0.020 1.227 1.251 105 in nitro groups C*–NO2 1.212 1.214 0.012 1.206 1.221 84 C#–NO2 1.210 1.210 0.011 1.203 1.218 251 Car-NO2 1.217 1.218 0.011 1.211 1.215 1116 C-NO2 (overall) 1.218 1.219 0.013 1.210 1.226 1733
N3P4 X2-P(=X)–NX2 Nsp2: planar 1.652 1.651 0.024 1.634 1.670 205 Nsp3: pyramidal 1.683 1.683 0.005 1.680 1.686 6 (overall) 1.662 1.662 0.029 1.639 1.682 358 subsets of this group are: O2-P(=S)–NX2 1.628 1.624 0.015 1.615 1.634 9 C-P(=S)–(NX2)2 1.691 1.694 0.018 1.678 1.703 28 O-P(=S)–(NX2)2 1.652 1.654 0.014 1.642 1.664 28 P(=O)–(NX2)3 1.663 1.668 0.026 1.640 1.679 78
N3P3 –NX-P(–X)–NX-P(–X)–(P2N2 ring) 1.730 1.721 0.017 1.716 1.748 20 –NX-P(=S)–NX-P(=S)–(P2N2 ring) 1.697 1.697 0.015 1.690 1.703 44 in P-substituted phosphazenes: (N≃)2P-N (amino) (aziridinyl) 1.637 1.638 0.014 1.625 1.651 16
1.672 1.674 0.010 1.665 1.676 15 N2=P4 Ph3-P=N+=P-Ph3 1.571 1.573 0.013 1.563 1.580 66 N2=P3 Ph3-P=N-C,S 1.599 1.597 0.018 1.580 1.615 7 N2 ≃ P3 N ≃ P aromatic
in phosphazenes 1.582 1.582 0.019 1.571 1.594 126 in P ≃ N ≃ S 1.604 1.606 0.009 1.594 1.612 36
N3S4 C-SO2-NH2 1.600 1.601 0.012 1.591 1.610 14 35 C-SO2-NH-C# 1.633 1.633 0.019 1.615 1.652 47 35 C-SO2-N-C(#)2 1.642 1.641 0.024 1.623 1.659 38 35
N3S2 C-S-NX2 Nsp2: planar 1.710 1.707 0.019 1.698 1.722 22 23 (for Nsp3 pyramidal see MODIAZ: 1.765) X-S-NX2 Nsp2: planar 1.707 1.705 0.012 1.699 1.715 30 23
N2S2 C=N-S-X 1.656 1.663 0.027 1.632 1.677 36 N2 ≃ S2 N ≃ S aromatic in P ≃ N ≃ S 1.560 1.558 0.011 1.554 1.563 37 N2=S2 N=S in N=S=N and N=S=S 1.541 1.546 0.022 1.521 1.558 37 N3SE see COJCUZ (1.830), DSEMOR10 (1.846, 1.852),
MORTRS10 (1.841) N2Se see SEBZQI (1.805), NAPSEZ10 (1.809, 1.820) N2=Se see CISMUM (1.790, 1.791) N3Si5 see DMESIP01, BOJLER, CASSAQ, CASYOK,
CECXEN, CINTEY, CIPBUY, FMESIB, MNPSIL, PNPOSI (1.973-2.344)
N3Si4 X3-Si-NX2 (overall) 1.748 1.746 0.022 1.735 1.757 170
1 u X3-Si-NHX 1.714 1.719 0.014 1.702 1.727 16 X3-Si-NX-Si-X3 acyclic 1.743 1.744 0.016 1.731 1.755 45 N-Si-N in 4-membered rings 1.742 1.742 0.009 1.735 1.748 53 N-Si-N in 5-membered rings 1.741 1.742 0.019 1.726 1.749 33
N2Si4 X3-Si-N-–Si-X3 1.711 1.712 0.019 1.693 1.729 15 NTe see ACLTEP (2.402), BIBLAZ (1.980), CESSAU
(2.023) O2O2 C*–O-O-C*,H
τ(OO) = 70-85º 1.464 1.464 0.009 1.458 1.472 12 τ(OO) ca. 180º 1.482 1.480 0.005 1.478 1.486 5 overall 1.469 1.471 0.012 1.461 1.478 17 O=C-O-O-C=O see ACBZPO01 (1.446), CEYLUN
(1.452), CIMHIP (1.454) Si-O-O-Si 1.496 1.499 0.005 1.490 1.499 10
O2P5 X-P-(OX)4 41 trigonal bipyramidal: axial 1.689 1.685 0.024 1.675 1.712 20 equatorial 1.619 1.622 0.024 1.604 1.628 20 square pyramidal 1.662 1.661 0.020 1.649 1.673 28
O2P4 C-O-P(≃ O)32 – 1.621 1.622 0.007 1.615 1.628 12 (H-O)2-P(≃ O)2-1.560 1.561 0.009 1.555 1.566 16 (C-O)2-P(≃ O)2-1.608 1.607 0.013 1.599 1.615 16 (C#–O)3-P=O 1.558 1.554 0.011 1.550 1.564 30 (Car-O)3-P=O 1.587 1.588 0.014 1.572 1.599 19 X-O-P(=O)–(C,N)2 1.590 1.585 0.016 1.577 1.601 33 (X-O)2-P(=O)–(C,N) 1.571 1.572 0.013 1.563 1.579 70
O2P3 (N≃)2P-O-C (N ≃ P aromatic) 1.573 1.573 0.011 1.563 1.584 16 O1=P4 C-O-P(≃ O)32-(delocalized) 1.513 1.512 0.008 1.508 1.518 42
(H-O)2-P(≃ O)2-(delocalized) 1.503 1.503 0.005 1.499 1.508 16 (C-O)2-P(≃ O)2-(delocalized) 1.483 1.485 0.008 1.474 1.490 16 (C-O)3-P=O 1.449 1.448 0.007 1.446 1.452 18 C3-P=O 1.489 1.486 0.010 1.481 1.496 72 N3-P=O 1.461 1.462 0.014 1.449 1.470 26 (C)2(N)–P=O 1.487 1.489 0.007 1.479 1.493 5 (C,N)2(O)–P=O 1.467 1.462 0.007 1.462 1.472 33 (C,N)(O)2-P=O 1.457 1.458 0.009 1.454 1.462 35
O2S4 C-O-SO2-C 1.577 1.576 0.015 1.566 1.584 41 C-O-SO2-CH3 1.569 1.569 0.013 1.556 1.582 7 C-O-SO2-Car 1.580 1.578 0.015 1.571 1.588 27
O1=S4 C-SO2-C 1.436 1.437 0.010 1.431 1.442 316 42 X-SO2-NX2 1.428 1.428 0.010 1.422 1.434 326 C-SO2-N-(C,H)2 1.430 1.430 0.009 1.425 1.435 206 C-SO2-O-C 1.423 1.423 0.008 1.418 1.428 82 in SO42-1.472 1.473 0.013 1.463 1.481 104
O1=S3 C-S(=O)–C 1.497 1.498 0.013 1.489 1.505 90 5 OSe see BAPPAJ, BIRGUE10, BIRHAL10, CXMSEO,
DGLYSE, SPSEBU (1.597 for O=Se to 1.974 for O-Se)
O2Si5 (X-O)3-Si-(N)(C) 1.663 1.658 0.023 1.650 1.665 21 O2Si4 X3-Si-O-X (overall) 1.631 1.630 0.022 1.617 1.646 191 O2Si4 subsets of this group are:
X3-Si-O-C# 1.645 1.647 0.012 1.634 1.652 29 X3-Si-O-Si-X3 1.622 1.625 0.014 1.614 1.631 70 X3-Si-O-O-Si-X3 1.680 1.676 0.008 1.673 1.688 10
O2Te6 (X-O)6-Te 1.927 1.927 0.020 1.908 1.942 16 O2Te4 (X-O)2-Te-X2 2.133 2.136 0.054 2.078 2.177 12 P4P4 X3-P-P-X3 2.256 2.259 0.025 2.243 2.277 6 P4P3 see CECHEX (2.197), COZPIQ (2.249) P3P3 X2-P-P-X2 2.214 2.210 0.022 2.200 2.224 41 P4=P4 see BUTSUE (2.054) P3=P3 see BALXOB (2.034)
1 u P4=S1 C3-P=S 1.954 1.952 0.005 1.950 1.957 13
(N,O)2(C)–P=S 1.922 1.924 0.014 1.913 1.927 26 (N,O)3-P=S 1.913 1.914 0.014 1.906 1.921 50
P4=Se1 X3-P=Se 2.093 2.099 0.019 2.075 2.108 12 P3Si4 X2-P-Si-X3: 3-and 4-rings 2.264 2.260 0.019 2.249 2.283 22
excluded (see BOPFER, BOPFIV, CASTOF10, COZVIW: 2.201-2.317)
P4=Te1 see MOPHTE (2.356), TTEBPZ (2.327) S2S2 C-S-S-C
τ(SS) = 75-105º 2.031 2.029 0.015 2.021 2.038 46 τ(SS) = 0-20º 2.070 2.068 0.022 2.057 2.077 28 (overall) 2.048 2.045 0.026 2.028 2.068 99 in polysulphide chain-S-S-S-2.051 2.050 0.022 2.037 2.065 126
S2S1 X-N=S-S 1.897 1.896 0.012 1.887 1.908 5 SSe4 see BUWZUO (2.264, 2.269) SSe2 X-Se-S (any) 2.193 2.195 0.015 2.174 2.207 9 S2Si4 X3-Si-S-X 2.145 2.138 0.020 2.130 2.158 19 S2Te X-S-Te (any) 2.405 2.406 0.022 2.383 2.424 10
X=S-Te (any) 2.682 2.686 0.035 2.673 2.694 28 Se2Se2 X-Se-Se-X 2.340 2.340 0.024 2.315 2.361 15 Se2Te2 see BAWFUA, BAWGAH (2.524-2.561) † Si4Si4 X3-Si-Si-X3 3-membered rings excluded: see
CIHRAM (2.511) 2.359 2.359 0.012 2.349 2.366 42
TeTe see CAHJOK (2.751, 2.704) † The standard deviation in the sample for the bond type is greater than for the other entries.
