Benzyl and platinum derivatives of organogermanes

Abstract

The work described in this thesis is conveniently divided into three parts. PART A. Benzyl Derivatives of Germanium. Tetrabenzylgermane is cleaved by lithium in 1,2-dimethoxyethane to give moderate yields of tribenzylgermyl-lithium, but some dibenzyl-gerrnyl-dilithium is also produced. The germyl-lithium reagent does not attack the solvent at 0 , but at reflux temperature in the presence of an excess of lithium a progressive series of reactions takes place giving (PhCH(_2))(_3)GeMe, (PhCH(_2))(_2)GeMe(_2) and PhCH(_2)GeMe(_3). Many reactions of tribenzylgermyl-lithium are similar to those of other organolithium reagents. The reaction between tribenzylgermane and lithium is not selective. Both Ge-H and Ge-CH(_2)Ph bonds are cleaved, and this lack of selectivity is also shown by hexabenzyldigermane. Similar complications are evident in the reaction between butyl-lithium and tribenzylgermane. Both hydrogen-metal exchange to give (PhCH(_2))(_3)GeLi, and nucleophilic attack of Bu(^-) with displacement of either H(^-) or PhCH(_2)(^-) occurs. PART B. Triphenylgermylplatinum Complexes. Triphenylgermyl-lithium reacts with the complexes cis or trans (R(_3)P)(_2)PtCl(_2) [R = Et, n-Pr] to give (R(_3)P)(_2)Pt(GePh(_3))(_2). The iodide (R(_3)P)(_2)PtI(_2) reacts with triphenylgermyl-lithium partly by halogen-metal exchange, however, giving the lithio platinum derivatives (R(_3)P)(_2)Pt(Li) I and (R(_3)P)(_2)Pt(Li)GePh(_3). The complexes (R(_3)P)(_2) Pt(GePh(_3))(_2) are stable to air and water but decompose at 150 with cleavage of Ge-Pt, Ge-C and P-C bonds. Iodine, HCl, MeI, NgI(_2), C(_2)H(_4)Br(_2), PhLi and LiAlH(_4) all cleave both Ge-Pt bonds, and in some cases at least the reaction probably proceeds via platinum(IV) intermediates. Hydrogenolysis of one Ge-Pt bond takes place under extremely mild conditions, and this may also proceed via oxidation to a Pt(IV) complex. Stable alkoxy-platinum complexes, (R(_3)P)(_2)Pt(OR')GePh(_3), were produced by the action of alcohols on the intermediate (R(_3)P)(_2)Pt(I)GePh(_3). PART C. Infrared Spectra. Characteristic infrared frequencies are given for 90 organogermanes, including alkyls, aryls, hydrides, deuterides, halides and oxides, with the main object of assisting characterisation of similar compounds. Germanium-carbon stretching frequencies for trans and gauche forms of n-butylgermanes have been observed.