Octakis(trimethylsilylmethyl)dioxotetramolybdenum. A novel tetranuclear compound with two localized metalmetal triple bonds

1,2-Mo2Br2(CH2SiMe3)4 reacts with water (two equivalents) in hexane solution in the presence of HNPri2 (four equivalents) to give the dark red crystalline compound Mo4O2(CH2SiMe3)8 which has been characterized by single crystal X-ray crystallography in the solid-state and by NMR spectroscopy in solution. Two ethane-like OC2MoMoC2O units are held together by the agency of a pair of oxo bridges: Mo–Mo=2.20(1) Å (ave), MoO=1.89(1) Å (ave), MoC=2.11(2) Å (ave), MoMoC=101(1)° (ave), MoMoO=105(1)° (ave) and MoOMo=133(1)° (ave).