A toluene solution of pentamethyldisilanylcyclopentadiene and Mo(CO)6 was heated at reflux for 9 h to yield the dimolybdenum complex [h-Me5Si2C5H4Mo(CO)3]2 (1). 1 Was converted into the title compound (h-Me5Si2C5H4)(CO)2MoYMo(CO)2(C5H4Si2Me5-h) (2) by thermal decarbonylation. 2 Reacted resp. with Ph3P, HCYCH and PhCYCH afforded the addition products: [h-Me5Si2C5H4Mo(CO)2PPh3]2(3), [(h-Me5Si2C5H4)(CO)2Mo]2(m-HCYCH) (4) and [(h-Me5Si2C5H4)(CO)2Mo]2(m-PhCYCH) (5). Their structures were characterized by elemental analyses, IR and 1H NMR spectra. The crystal structure of 4 was determine by x-ray diffraction.

Key words: INFRARED SPECTROPHOTOMETRY, ELEMENTAL ANALYSIS, CRYSTAL STRUCTURE, X-RAY DIFFRACTION ANALYSIS, CYCLOPENTADIENE P, PROTON MAGNETIC RESONANCE SPECTROMETRY, MOLYBDENUM COMPLEX, HEXACARBONYLMOLYBDENUM