Properties of trifluoromethylgermanes. Adduct formation and substitution reactions of (CF3)nGeX4-n (n = 2-4) with NH3

Article abstract of DOI:10.1016/0022-328X(91)83280-H

Crystalline adducts of compositions (CF3)4Ge*nRNH2 (R=H: n=2, 3; R=CH3: n= 1, 2) with dissociation vapour pressures at 22 deg C of 70 (R=H) and 75 mbar (R=CH3) have been isolated.From their Raman spectra both NH3 adducts are judged to have a cis-configurated ocahedral coordination at the germanium atom.Reaction of (CF3)3 GeI with NH3 yielded the digermazane <(CF3)3Ge>2NH whereas the cyclic trimers <(CF3)2GeNR>3 (R=H, CH3) were obtained from (CF3)2GeI2 and RNH2.IR spectra show that NH3 and <(CF3)3Ge>2NH undergo equilibration to give (CF3)3GeNH2 in the gas phase, withsimultaneous formation of a solide phase with the composition (CF3)3GeNH2*2NH3.Addition of trimethyl- or triethyl-amine to <(CF3)3Ge>2NH yields solid 1:1 adducts.The vibration spectra of <(CF3)3Ge>2NH, (CF3)3GeNH2 and of the NH3 adducts of (CF3)4Ge and of their deuterated analogues have been analyzed.A Ge-N-Ge bond angle of 130 deg was deduced for <(CF3)3Ge>2NH from model force constant calculations.