Triple bond length

A well-known example of the effect of bond order on bond length is provided by the bonds in ethane, ethene, and ethyne, which have the lengths of 154, 134, and 120 pm, respectively. Covalent radii for doubly and triply bonded atoms can be obtained from double and triple bond lengths in the same way as for single bonds. Some values are given in Table 2.2. 

Fluoro-o-benzyne (41) has also been isolated in cryogenic matrices by photolysis of the corresponding phthalic anhydride. The C=C stretching vibration of 41 has been observed at 1866 cm Compared to the parent, the triple bond length is only modestly increased according to DFT calculations (Fig. 16.2). Note, however, that the observed frequency shifts upon fluorine substitution in 4 are not reproduced at the B3LYP or BLYP level of theory (Fig. 16.2). Thus, the performance of different DFT functionals to account for the properties of o-arynes still remains a matter of debate,and casts some doubts on the results of certain DFT studies. 

In agreement with prior calculations at low levels of theory, it could be shown that 3,4-pyridyne (101) is significantly more stable than the 2,3-isomer (97). " The formal C—C triple bond length is similar in 4 and 101, while it is markedly elongated in 97 (4 124.1 pm 101 124.8 pm 97 126.7 pm B3LYP/ cc-pVTZ). " In addition, the singlet-triplet gap of 4 and 101 is comparable, whereas it is reduced by 16 kcal/mol in 97. This difference is caused by a... 

This structure, which may be described as involving a 2 bond, is expected to lead to a bond length intermediate between that for a double bond and that for a triple bond. The N—O single-bond length is 1.44 A (Sec. 7-2), and the double-bond and triple-bond lengths may be taken as 0.04 A less than for N—N and N=N, and hence equal to 1.20 A and 1.06 A, respectively. This triple-bond value agrees well with the experimental value 1.062 A for NO+, which has the structure... 

The tungsten-carbon single, double, and triple bond lengths in this compound are 225.8, 194.2. and 178.5 pm, respectively, and the accompanying W—C—C bond angles are 124°. 150°. and 175 , all of which is quite consistent with tungsten-carbon bond orders of 1,2. and 3. 

Agreement between the calculated78 geometry and experimental geometry of silyl isocyanide is poor. The calculated Si—N bond length in I SiNC is 1.745 A, and the NC triple bond length is 1.165 A. The experimental values are 1.819 and 1.785 A for the... 

Bonding of iron to the CO unit is not symmetrical Fe-C and Fe-O bond lengths of 1.8-1.83 and 2.19-2.25 A, respectively, are typical. IR spectra give a typical vc=o of 1586-1605 cm. The acyl carbon resonance appears at 280 ppm in the C NMR spectra but is not always observable at room temperature. Structurally, ) -iminoacyl complexes (124) are strictly analogous to ) -acyl complexes (115), with a C-N bond length intermediate between double and triple bond length (1.21-1.30 A). 

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