Transition Metal Silyl Complexes. 62. Platinum Dimethyl Complexes with Hemilabile P,N-Chelating Ligands: Synthesis, Structure, and Reactions with Iodotrimethylsilane and 1,2-Bis(dimethylsilyl)benzene

Reaction of (η4-2,5-norbornadiene)dimethylplatinum(II) with (2-diphenylphosphinoethyl)dimethylamine, (3-diphenylphosphinopropyl)dimethylamine, 2-diphenylphosphino-N,N-dimethylaniline, or (o-diphenylphosphinobenzyl)dimethylamine resulted in the formation of
the corresponding dimethyl platinum complexes containing the P,N-chelating ligands, while
reaction with (diphenylphosphinomethyl)dimethylamine gave only the bis(phosphine)
complex. Reaction of the P,N-chelated dimethyl complexes with iodotrimethylsilane stereoselectively gave the corresponding methyl iodo complexes in which only the methyl group
trans to the phosphorus atom was exchanged. Reaction with 1,2-bis(dimethylsilyl)benzene
yielded cyclic bis(silyl) complexes. Analogous experiments with (dppe)PtMe2 revealed that
the P,N-chelated complexes exhibit a considerably higher reactivity than the bis(phosphine)
complex. The most interesting feature in the solid-state structures of [(κ2-P,N)-Ph2PC2H4NMe2]PtMe2, trans-[(κ2-P,N)-Ph2PC6H4-2-CH2NMe2]Pt(I)Me, and [(κ2-P,N)-Ph2PC6H4-2-NMe2]Pt[o-(Me2Si)2C6H4] is the very long Pt−N distances (221.0(7), 223.3(6), and 236.8(5)
pm, respectively), showing that the nitrogen atom of the P,N-chelating ligand is only weakly
bonded. The Pt−C and Pt−Si distances trans to nitrogen are much shorter (203.7(9), 230.4(2) pm) than those trans to phosphorus (206.9(8), 237.2(2) pm).