Properties of CH bonds in cobalt, tin and zinc alkyl compounds
This thesis describes the results of a detailed vibrational study on a series of mainly methyl, but also certain ethyl containing organometallic compounds. The primary objective of the work is to show that 'isolated CD' frequencies, vis CD measured from a CH2D group, can be used to provide predictions of CH bond parameters (CH bond length (roCH), HCH bond angle (αHCH) etc.) equally as well as 'isolated CH' frequencies, visCH measured from a CHD2 group. From a review of spectroscopic data in the literature it is apparent that visCD, can be linearly related to visCH. The 98% correlation coefficient for the visCD versus visCH plot illustrates the existence of a workable linear relationship. Clearly the existence of such a relationship seems to suggest that the isotopic substitution CH2D removes Fermi and other resonance effects almost as well as the CHD2 isotopic substitution. Moreover, correcting the visCD frequency for the effects of anharmonicity using a variable R correction factor with a maximum variation 0.5% from 1.011 gives a much improved fit. Making use of existing linear correlations between visCH and fundamental CH bond parameters (roCH and αHCH), it has been shown that the determination of the visCD frequency can be used to provide useful predictions of roCH and αHCH. All this can be achieved without the need for deuteration of ligand CH sites, even in complex systems, previously necessary in the determination of visCH frequencies. The CH/CD stretching regions for a series of eight methylpyridinatocobaloxime isotopomers have been studied, frequencies assigned and the geometry of the methyl group determined.