Hypercoordinate Aryltrialkylsilanes and -stannanes and Their Use in the Synthesis of Homodinuclear Organometallic Complexes with a 1,4-Phenylene Bridge

New mono- and dinuclear aryltrialkylsilanes and -stannanes [Me 3 M{C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}] (M = Si ( 5 ), Sn ( 6 )) and [(Me 3 M) 2 -1,4-{C 6 (CH 2 NMe 2 ) 4 -2,3,5,6}] (M = Si ( 9 ), Sn ( 10 )) have been prepared from transmetalation reactions of dimeric [Li{C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}] 2 and new polymeric [Li 2 -1,4-{C 6 (CH 2 NMe 2 ) 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-{C 6 (CH 2 NMe 2 ) 4 -2,3,5,6}] ( 15 ), whereas its reaction with [PtCl 2 (COD)] (COD = cycloocta-1,5-diene) or Me 3 SnCl gives the ionic tin(IV) species [(Me 2 Sn) 2 -1,4-{C 6 (CH 2 NMe 2 ) 4 -2,3,5,6}] 2+ (X - ) 2 with X being Cl ( 18a ) or Me 3 SnCl 2 ( 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.