Reactions of (Me3SiCH2)2AsSiMe3 with Gallium Halides. Crystal Structure and Dynamic NMR Study of the Dimer {[(Me,SiCH2)2As]2GaBrj2
Publication
, Journal Article
Purdy, AP; Wells, RL; McPhail, AT; Pitt, CG
Published in: Organometallics
(Me3SiCH2)2AsSiMe3reacted with the gallium halides GaBr3, MeGaCl2, and PhGaCl2to produce the (arsino)gallanes [(Me3SiCH2)2AsGaBr2]3, {[(Me3SiCH2)2As]2GaBr}2, [(Me3SiCH2)2AsGaMeCl]n(n = 2, 3), and [(Me3SiCH2)2AsGaClPh]„ (n = 2, 3), which were characterized by elemental analysis (C and H),1H and13C NMR spectroscopy, and cryoscopic molecular weight determinations. A single-crystal X-ray diffraction study of {[(Me3SiCH2)2As]2GaBrj2was carried out. Crystal data are as follows: triclinic, space group PI, a = 11.892 (2) A, b = 12.492 (2) A, c = 11.515 (1) A, a = 98.24 (1)°, β= 113.57 (1)°, y = 84.21 (1)°, V = 1549.9 A3, Z = 1. The centrosymmetric, dimeric molecule crystallizes in the trans configuration, with unequal endocyclic Ga-As distances [2.513 (1) A and 2.521 (1) A] and very significantly different bond angles [84.37 (1)° and 95.63 (2)°, respectively, at Ga and As] in the planar (Ga-As)2ring. The Ga-exo-As distance of 2.437 (1) A is the shortest yet measured in an organogallium-arsenic compound. A18C(12H) dynamic NMR study of {[(Me3SiCH2)2As]2GaBr}2revealed that both an interchange of the (Me3SiCH2)2As groups [AH* = 18.7 ± 0.3 kcal/mol; AS* = 4.5 ± 1.0 cal/(mol K)] and a trans-cis isomerization [AH* = 17.4 ± 0.7 kcal/mol; AS* = -2.2 ± 2.1 cal/(mol K)] take place. © 1987, American Chemical Society. All rights reserved.
