SH Stretching Vibrations

Several early workers studied the position of the SH stretching absorption band. Bell [1,2] was able to show that a number of simple mercaptans such as propyl, butyl and woamyl mercaptans gave a well-defined but rather weak absorption at 2650—2550 cm . He was also able to show that the bands near 2550 cm in thiophenol and thio-p-cresol were absent from the corresponding sulphides. 

Confirmation of this assignment of the SH mode was forthcoming from further work by Ellis, who found the first overtone in the 5000 cm region [3], and from Williams [4], who extended the series of compounds examined by Bell and showed that other mercaptans absorbed near 2630 cm .  

These early assignments have been fully supported by later 

In the Raman the SH stretch is invariably strong but the intensity in the infra-red is variable and usually weak. A moderately strong band is shown by thiophenol, but in alkyl mercaptans the band can be so weak as to be virtually undetectable. It is also obscured in compounds containing COOH groups which, exhibit general absorption in this region. However, if allowance is made for these factors the presence or absence of a band in this region can afford 

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The X-H stretch region (4000-2500 cm 1), where strong contributions from OH, NH, CH and SH stretch vibrations are observed,... 

The SH stretching vibration in dialkyl dithiophosphoric acids [(R0)2PSSH] absorbs broadly in the liquid state at 2480-2440 cm A band at 865-835 cm is probably due to SH bending. Dithiophosphinic acids (R2PSSH) absorb broadly in the condensed state at 2420-2300 cm due to SH S bonding. In dilute solution the free SH in the above dithiophosphoric and phosphinic acids absorbs sharply" " " at 2590-2550 cm" ... 

Mercaptans and thiophenols absorb at 2590-2540 cm due to the SH stretching vibration. Compounds with a BH group absorb at 2630-2350 cm . Compounds with a PH group absorb at 2440-2275 cm. Compounds with an SiH group absorb at 2250-2100 cm ... 

Co2(CO)6(tppts)2 is a brown-colored solid which is moderately stable in air, but is best handled and stored under an inert gas atmosphere. The compound is very soluble in water and insoluble in organic solvents like toluene or hexane. It exhibits in the 31P NMR (109.3 MHz, D20, 5°Q a singlet at 5 68.8 ppm. The IR displays a strong carbonyl stretching vibration at 1954 cm-1. The significant SO-absorptions are detectable at 1224 (sh, vst), 1200 (vst), 1039 (vst), and 623 (vst) cm-1. The compound has been used for carbonylation of phenyl ethyl bromide21 and on supported aqueous phase catalysts for the hydroformylation of olefins.22... 

Tris(dimethylphenylphosphine)pentahydridorhenium(V) is a white, crystalline solid, mp 97-98°. It may be remelted several times without apparent decomposition and is stable for several months at 20°. It is soluble in cold benzene but much less soluble in cold ethanol or light petroleum ether. The rhenium-hydrogen stretching vibrations, v(Re—H), are (in Nujol mull) 1949 (w, sh), 1931 (m), 1905 (m), and 1852 (m) (in benzene solution) 1969 (sh), 1898, 1855, 1817 (sh) cm-1. In the nmr spectrum (benzene at 34°) the hydridic hydrogens are apparently equivalent (fluxional molecule)... 

Acyl halide stretching vibrations Single-bridge compounds V, sh 3570-3450... 

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