Synthesis and Reactivity of New κ²-[<i>P</i>,<i>N</i>]Pt(II) Complexes of Diisopropylphosphino-Substituted 2-Dimethylaminoindene

Treatment of 1-PiPr2-2-NMe2-indene (1a[H]) with either cis/trans-(SMe2)2PtCl2 or PtCl2 provided (κ2-P,N-2-NMe2-3-PiPr2-indene)PtCl2 (2) in 84% and 55% yield, respectively, while the reaction of 1a[H] with (η4-COD)PtClMe afforded (κ2-P,N-2-NMe2-3-PiPr2-indene)PtClMe (3) in 91% yield. Whereas in the formation of 2 and 3 the ligand precursor 1a[H] undergoes a rearrangement to give a coordinated 2-NMe2-3-PiPr2-indene (1b[H]) ligand, 1a[H] reacted cleanly with 0.5 equiv of [(μ-SMe2)PtMe2]2 to give (κ2-P,N-1a[H])PtMe2 (4a) in 97% yield. The isomerization of 4a to (κ2-P,N-1b[H])PtMe2 (4b) in a THF/iPrOH mixture is rapid and allowed for the isolation of 4b in 99% yield. Heating of 4a in CH2Cl2 resulted in the quantitative formation of 3, while the thermolysis of 4a in toluene in the presence of SMe2 afforded 5, the apparent product of intramolecular C−H activation of an NMe group. The reactivity of 4a with a variety of other two-electron donors, as well as E−H-containing substrates (E = main group fragment), is reported. Although NMR spectroscopic evidence indicated the formation of an intermediate of the type (κ2-P,N-1[H])Pt(SnPh3)(Me), as well as Ph6Sn2, in the reaction of 4a with 10 equiv of Ph3SnH, negligible conversion of Ph3SnH to Ph6Sn2 was obtained when employing 1 mol % 4a as a catalyst. Single-crystal X-ray diffraction data for 2 and 5 are reported.