Synthesis and Reactivity of Low-Valent Group 14 Element Compounds

Abstract

The tetravalent germanium and tin compounds of the general formulae Ph*EX3 (Ph* = C6H3Trip-2,6, Trip = C6H2iPr3-2,4,6; E = Sn, X = Cl (1a), Br (1b); E = Ge, X = Cl (2)) are synthesized by reaction of Ph*Li·OEt2 with EX4. The subsequent reaction of 1a,b with LiP(SiMe3)2 leads to Ph*EP(SiMe3)2 (E = Sn (3), Ge (4)) and the diphosphane (Me3Si)2PP(SiMe3)2 by a redox reaction. In an alternative approach 3 and 4 are synthesized by using the corresponding divalent compounds Ph*ECl (E = Ge, Sn) in the reaction with LiP(SiMe3)2. The reactivity of Ph*SnCl is extensively investigated to give with LiP(H)Trip a tin(II)-phosphane derivative Ph*SnP(H)Trip (6) and with Li2PTrip a proposed product [Ph*SnPTrip]– (7) with multiple bonding between tin and phosphorus. The latter feature is confirmed by DFT calculations on a model compound [PhSnPPh]–. The reaction with Li[H2PW(CO)5] gives the oxo-bridged tin compound [Ph*Sn(μ-O)2SnPh*] (8) as the only isolable product. However, the existence of 8 as the bis-hydroxo derivative [Ph*Sn(μ-OH)2SnPh*] (8a) is also possible. The SnIV derivatives Ph*Sn(OSiMe3)2Cl (9) and [Ph*Sn(μ-O)Cl]2 (10) are obtained by the oxidation of Ph*SnCl with bis(trimethylsilyl)peroxide and with Me3NO, respectively. Besides the spectroscopic characterization of the isolated products compounds 1a, 2, 3, 4, 8, and 10 are additionally characterized by X-ray diffraction analysis.