Infrared spectra hydride complexes

The redox condensation shown in Eq. (9) gives rise to the dianion [Fe3Ni(CO)12]2 and it has also been possible to isolate salts of the corresponding hydride, [Fe3Ni(CO)12H]- (30.5 r). The presence of infrared absorptions due to bridging carbonyls and the complexity of the infrared spectrum indicate a structure similar to Co4(CO)i2 with the nickel in the basal plane171). 

Hydridonitrosyltris(triphenylphosphine)ruthenium(I) is stable in air in the solid state, but slowly oxidizes in solution. The infrared spectrum of the complex shows absorptions at 1965 cm-1 [v(Ru—H)] and 1640 cm-1 [v(N—O)]. The H nmr spectrum (which is temperature-independent) shows a high-field quartet at t16.6 (2Jph = 30 Hz), consistent with a trigonal bipyramidal structure with axial hydride and equatorial phosphines.1 This structure has been confirmed in the solid state by x-ray crystallography,3 which reveals a slightly distorted trigonal bipyramid. The axial nitrosyl is coordinated in a linear fashion (Ru—N—O angle = 176°). 

Chlorohydridobis(tricyclohexylphosphine)nickel is a yellow-brown solid. It is thermally stable at ambient temperature but reacts with air. It is very soluble in benzene, tetrahydrofuran, and dichloromethane and is soluble in diethyl ether and petroleum ether. Carbon tetrachloride, carbon disulfide, and chloroform decompose the complex. The infrared spectrum shows a sharp v(Ni—H) band at 1916 cm-1 (KBr disk and Nujol mull). The high-field H nmr spectrum in benzene solution has a triplet (1 2 1) at t34.6 (TMS) with JpH 73.5 Hz. The splitting is caused by the coupling of the hydride proton with two equivalent 31P nuclei. This is consistent with a trans square-planar configuration. 

Under syn gas pressure the rhodium acac precursors were converted to the catalytically active hydride complexes HRh(CO)2(L-L). The complexes are generally assmned to have a trigonal bipyramidal structure and two isomeric structures of these complexes are possible, containing the diphosphite coordinated in a bisequatorial (ee) or an equatorial-apical (ea) fashion. The structure of the complexes can be elucidated by (high pressure) IR and NMR data (Table 3). In the carbonyl region of the infrared spectrum the vibrations of the ee and ea complex can be easily distinguished. The ee complexes typically show absorptions around 20 15 and 2075 cm [24, 26,... 

Infrared spectroscopy has assisted in the determination of the structure of certain complex inorganic molecules, uch as the metal carbonyls, inter-halogen compounds, boron hydrides, and nitrogen oxides. The practice used has been to compare the observed spectrum with the spectrum expected for an assumed model on the basis... 

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