S-O bond lengths

The sulphite ion, SO3, has a pyramidal structure and the short S—O bond length suggests the presence of double bonding, i.e. 

Transition-metal complexes of the thionylimide anion exhibit characteristic vibrations in the regions 1260-1120, 1090-1010 and 630-515 cm , which are assigned to Oas(NSO), Os(NSO) and <5(NSO), respectively. X-ray structural data for several M-NSO complexes reveal N-S and S-O bond lengths of ca. 1.46 0.04 A indicative of double bond character in both of these bonds. 

Although the S—O bond lengths in sulphoxides and sulphones seem to indicate that these are covalent double bonds, the dipole moments of these compounds obtained by calculation or by experimental measurements support the semipolar single-bond character in these compounds, and they should be represented as S - O, with about 66% ionic character14,15. 

S-N bond cleavage 159 S-O bond lengths 543 Solvated electrons 897, 905 Solvent effects 672 in elimination reactions 772 S-O stretching frequencies 543, 545, 546, 552-555, 560-562 Spiroconjugation 390 Stereoselectivity 779, 789 of cylcoaddition reactions 799 of sulphones 761 Steroids... 

An average value obtained from the two relevant S—O bond lengths. >SCS. 

S-O bond as a result of it bond formation, and the S-O bond lengths are shorter than expected for a... 

Writing the formula as (H0)S(0)2S(0)20H shows that it is a strong acid. The S-S bond is slightly longer than a typical single bond, but the S-O bond length is close to that in sulfuric acid. Sulfites can be oxidized to give dithionates. 

The bent [NSO]- anion (36) in the tetramethylammonium salt [Me4N][NSO] has approximately equal S-N and S-O bond lengths of 1.43 and 1.44 A, respectively, and a bond angle transition-metal and main group element thionyl imides by metathetical reactions.70... 

The structural determination of diphenyl sulfoxide has also been performed (4), ahd shows that this diaryl sulfoxide also has an approximately pyramidal structure. The S—O bond length in this molecule is reported as 1.47 A, again suggesting some double-bond character. 

In S-bonded examples the reported S—O bond lengths span 1.45-1.51 A but are mostly around 1.47 A, e.g. 1.476(2) A in trans-[PdCl2(SMe20)2] 22 MSC and MSO angles fall between 109 and 118° with the latter commonly the larger. On balance, S—O bonds seem to be shorter in the S-bonded cases, suggesting an enhanced contribution from (1) in these structures. 

In the thiosulfate ion, a terminal S atom replaces an O atom of the sulfate ion. The S-S bond length is 201.3 pm, which indicates essentially single-bond character, while the mean S-O bond length is 146.8 pm, which indicates considerable n bonding between the S and O atoms. 

The gas-phase structure of FOSF5 has been redetermined by electron diffraction [129,152]. The S—F and S—O bond lengths derived from this study are ca 2% longer than those reported previously with bond angles in excellent agreement. The mean S—F in FOSF5 is shorter by 0.7 pm than in SF6. 

The S3N3O6 anion (36) in the ammonium salt has a chair conformation with approximately equal S-O bond lengths. ... 

Studies on sulfate complexes with transition metals indicate that coordination causes an enlargement of the S - O bond length of the oxygen atoms coordinated to the metal. This causes a decrease in the bond strength with a subsequent shift of the corresponding S-O stretch to lower wavenumbers [152]. At the same time the S-O bond involving non-coordinated O atoms is shortened. 

Similar arguments can be used for these molecules as in part (a). In SO2 and SO3, the Lewis structures with the lowest formal charge at S have double bonds between S and each O. In the sulfite ion, however, there are three Lewis structures that have a zero formal charge at S. Each has one S—O double bond and two S—O single bonds. Because these S—O bonds would have a substantial amount of single bond character, they would be expected to be longer than those in SO2 or SO3. This is consistent with the experimental data that show the S—O bond lengths in... 

More revealing on a qualitative basis are the IR spectra of type F77. Due to the relative short distance between O and S the expected carbonyl frequency is shifted to lower frequencies (1500—1610 cm ) 8). It was possible to assign the band with a large vco character on the basis of 0 8 studies ). Supplementary to these studies were the measurements of the carbonyl stretching frequencies of the trans-VII compounds 8) [see Eq. (19)]. The observed shifts Av have been in the order of 40—80 cm towards higher wave numbers in the trans configuration. This research could lead to a correlation between v or dv and the S - - O bond length. 

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