A neutral germanium/phosphorus frustrated Lewis pair: Synthesis and reactivity

Abstract A novel germinal germanium/phosphorus frustrated Lewis pair, Cl3GeCH2PtBu2 1, was prepared through the metathesis reaction of tBu2PCH2Li with tetrachlorogermanium. This neutral germanium-based frustrated Lewis pair 1 exhibits higher reactivity toward a series of small molecules. When 1 was treated with an excess amount of tetrachloromethane (2.3equiv) yielding a zwitterionic adduct 2, Cl4GeCH2P(Cl)tBu2. The cycloaddition of dimethyl but-2-ynedioate with 1 was took place smoothly at room temperature, and afforded a zwitterionic cyclic vinyl 3 in good yields. The reaction of 1 with furan-2,5-dione has also been performed giving the corresponding cycloaddition 4 in high yields. The additions of C=Ch (Ch = O, and S) units involving 1-isocyanato-4-methylbenzene and isothiocyanatobenzene with 1 have been also carried out at ambient temperature in which the five-membered GeCPCO(S)-ring products 5a and 5b were furnished, respectively. All these above-mentioned compounds 1-5 were fully characterized by multinuclear NMR spectroscopy, high-resolution mass spectrometry (HRMS), and the structures of 1 and 3 were also determined by single-crystal X-ray diffraction.