E.S.R. spectra and structure of the halogermane radical anions

Abstract

E.S.R. spectra of GeH₃ X ^- (X = Br, I) radical anions consisting of the hyperfine structure from one halogen X and three equivalent hydrogens were observed with γ-irradiated solid solutions of tetramethylsilane (TMS) containing GeH₃ X. The spectra were compared with those assigned to the congeneric radical anions SiH₃ X ^- having structures of trigonal bipyramid. In the latter spectra, hyperfine structures due to one halogen and one hydrogen in the axial positions of SiH₃ X ^- were observed, while splittings due to the other two hydrogens in the equatorial positions were unresolved. Thus, in contrast to the result for SiH₃ X ^-, the presence of the three equivalent hydrogens indicates that the GeH₃ X ^- radical anions have structures of C _3v symmetry. The geometric and electronic structures of GeH₃ X ^- were compared with those of CH₃ --- X ^- adducts formed in acetonitrile and SiH₃ X ^- radical anions generated in TMS.