Investigations of LiP(SiMe2CH2SiMe3)-PtBu2, the Surprising Byproduct in the Metalation of (Me3Si)2P-PtBu2

During the metalation reaction of (Me3Si)(2)P-PtBu2 with nBuLi, a byproduct with the sum formula Li(thf)(n)P(SiMe2CH2SiMe3)-PtBu2 (2, n = 2.7-1) was detected. The formation of the unexpected substituent SiMe2CH2SiMe3 was investigated, a possible reaction mechanism based on DFT calculations established, and the compound synthesized following an independent route. Compound 2 eliminated thf in vacuo to yield the dimeric [Li(thf)P(SiMe2CH2SiMe3)-PtBu2](2) (2a). Exchange of thf with tmeda [Me2N(CH2)(2)NMe2] in 2 led to the solvent-separated ion pair [Li(tmeda)(2)](+)[(SiMe2CH2SiMe3)P-PtBu2](-) (4). The solid-state structures of 2a, 4, and the contact ion pair Li(thf)(tmeda)P(SiMe2CH2SiMe3)-PtBu2 (5) were determined by single-crystal X-ray diffraction analysis. Extensive variable-temperature multinuclear NMR studies were carried out to elucidate the structures of these compounds in solution and to compare them with the solid-state structures.