SYNTHESIS OF OSMIUM(VI) NEOPENTYL, NEOPENTYLIDENE, AND NEOPENTYLIDYNE COMPLEXES

[PPh4]2[OsO2Cl4] reacts with excess dineopentylzinc in dichloromethane at room temperature to yield purple-brown, water- and air-stable OsO2(CH2-t-Bu)2. OsO2(CH2-t-Bu)2 reacts with 2 equiv of Ta(CH2-t-Bu)(CH2-t-Bu)3 in pentane at -40-degrees-C to yield insoluble [Ta(O)(CH2-t-Bu)3]x and what is proposed to be pseudotetrahedral, thermally unstable Os(CH-t-Bu)2(CH2-t-Bu)2. Os(CH-t-Bu)2(CH2-t-Bu)2 reacts with pyridinium triflate in the presence of excess pyridine to form Os-(C-t-Bu)(CH2-t-BU)2(py)2(O3SCF3), which when treated with LiN(SiMe3)2, NaC5H5, Na[CpCo(P(O)(OEt)2)3], or NaHB(pz)3 in THF yields neopentylidyne complexes of the type Os(C-t-Bu)(CH2-t-Bu)2(L) (L = N(SiMe3)2, eta5-C5H5, CpCo[P(O)(OEt)2]3, HB(PZ)3).