Matrix Isolation and Cryogenic Thin Film Studies of Molecular Complexes of Dimethylzinc with Group V and VI Hydrides

Abstract

Both 1:l and 1:2 molecular complexes of (CH3)2Zn with NH3, PH3, AsH3, H20, H2S, and H2Se have been formed, isolated, and characterized in argon matrices and cryogenic thin films. The reactivity of these systems varied greatly, from very rapid with HIS and H2Se to very slow (and low product yield) for PH3 and AsH3. Infrared spectra of these complexes showed perturbations to a number of vibrational modes of the acid and base subunits, the most sensitive of which was the intense ZnC2 antisymmetric stretch near 600 cm-I. This mode shifted between 8 and 34 cm-1 to the red in the different complexes; the shifts correlated well with the proton affinities of the bases. Cryogenic thin film experiments permitted initial formation and trapping of the 1 : 1 complex, while warming the film led (in some cases) to 1 :2 complex formation and then ultimately dissociation.The dissociation temperature correlated well with the shift of the ZnC2 antisymmetric stretch, suggesting that both are related to the bond strength in the complex.

Infrared Study of the Surface Species Formed by Sequential Chemical Vapor Deposition of Dimethyl Zinc and Ethanethiol on Hydroxylated Alumina Surfaces

“…It is known from earlier work , that the stretching (ν(Zn−Me)), rocking (ρ(Zn−CH 3 )), and the lower-frequency methyl bending modes (δ(CH 3 )) in the infrared spectra of solid methylzinc complexes are sensitive to coordination of different O-, N-, and S-containing ligands to the Zn center. More recent detailed matrix isolation and cryogenic thin-film spectroscopic studies − of the interaction of DMZ with group V and VI alkyls, hydrides, methanol, and methanethiol have been able to distinguish both 1:1 and 1:2 complexes of DMZ with these ligands. Unfortunately, again due to the high-intensity alumina lattice modes below ∼1000 cm -1 , the methyl rocking, and the ν(Zn−C) stretching modes cannot be observed in our transmission infrared experiment.…”

Matrix-Isolation ESR Studies of the Various Isotopomers of the CH3Zn and ZnH Radicals: Comparisons with ab Initio Theoretical Calculations

“…Hauge and co-workers have reported ZnCH 2 and CH 3 ZnH. Ault and Bai have reported argon-matrix studies of the reaction of (CH 3 ) 2 Zn with group-V and group-VI hydrides, with group-V and group-VI alkyls, and with CH 3 OH and CH 3 SH . Greene and co-workers have reported the reaction of excited metal atoms with methane to generate species of the type CH 3 MH, where M = Zn, Cd, or Hg in argon matrixes; the CH 3 ZnH species produced in this study was found to be photostable and did not yield the CH 3 Zn radical when irradiated with the broad-band output of a 500-W medium-pressure Hg lamp.…”

A study of the mechanism of the reaction of trimethylgallium with hydrogen selenide

“…little is known about the participation of any intermediate species that may be created and subsequently destroyed in the growth process. 8 The ability of individual GaMe 3 molecules to form complexes with Lewis bases is well documented 9 and Piocos and Ault have investigated the formation of molecular complexes of trimethylgallium with group V hydrides 10±12 and dimethylzinc with group VI hydrides 13 using matrix isolation and cryogenic thin ®lm techniques. We have published ab initio molecular orbital and density functional theory (DFT) calculations describing the geometries, harmonic frequencies and binding energies of the gallane and GaMe 3 adducts with H 2 Se; 14 the major ®nding being that such species are not expected to be stable intermediates under MOCVD growth conditions.…”