Hypercoordinate aryltrialkylsilanes and -stannanes and Their urse in the synthesis of homodinuclear organometallic complexes with a 1,4-phenylene bridge

Abstract

New mono- and dinuclear aryltrialkylsilanes and -stannanes [Me3M{C6H3(CH2NMe2)2-2,6}] (M = Si (5), Sn (6)) and [(Me3M)2-1,4-{C6(CH2NMe2)4-2,3,5,6}] (M = Si (9), Sn (10)) have been prepared from transmetalation reactions of dimeric [Li{C6H3(CH2NMe2)2-2,6}]2 and new polymeric [Li2-1,4-{C6(CH2NMe2)4-2,3,5,6}] with (trimethylsilyl)trifluoromethanesulfonate or trimethyltin chloride. The X-ray crystal structures of dinuclear 9 and 10 have been determined and in the molecular geometries found the central 1,4-phenylene dimetalated aryl ligand system provides bidentate C,N-coordination to silicon in 9 and terdentate pseudofacial N,C,N'-coordination to tin in 10. Reactions of the newly prepared silanes 5 and 9 and stannanes 6 and 10 with diverse palladium(II) and platinum(II) substrates afford organometallic products arising from both aryl and methyl group transfer. For example, the reaction of dinuclear stannane 10 (or dinuclear silane 9) with palladium(II) species gives the bimetallic complex [(PdCl)2-1,4-{C6(CH2NMe2)4-2,3,5,6}] (15), whereas its reaction with [PtCl2(COD)] (COD = cycloocta-1,5-diene) or Me3SnCl gives the ionic tin(IV) species [(Me2Sn)2-1,4-{C6(CH2NMe2)4-2,3,5,6}]2+(X-)2 with X being Cl (18a) or Me3SnCl2 (18b). The X-ray crystal structure of 18b has been determined and the molecular geometry found shows that the central dimetalated aryl ligand system provides terdentate meridional N,C,N'-coordination to both tin centers.