Facile hydrosilylation of norbornadiene by silanes R3SiH and R2SiH2 with molybdenum catalysts

Photochemically activated Mo(CO)₆] and Mo(CO)₄(η⁴-nbd)] have been demonstrated to be very effective catalysts for hydrosilylation of norbornadiene (nbd) by tertiary (Et₃SiH, Cl₃SiH) and secondary (Et₂SiH₂ and Ph₂SiH₂) silanes to give 5-silyl-2-norbornene, which under the same reaction conditions transform in ring-opening metathesis polymerization (ROMP) to unsaturated polymers and to a double hydrosilylation product, 2,6-bis(silyl)norbornane. The yield of a particular reaction depends very strongly on the kind of silane involved. The reaction products were identified by means of chromatography (GC–MS) and ¹H and ¹³C NMR spectroscopy. In photochemical reaction of Mo(CO)₄(η⁴-nbd)] and Ph₂SiH₂ in cyclohexane-d₁₂, η²-coordination of the SiH bond to the molybdenum atom is supported by ¹H NMR spectroscopy due to the detection of two equal-intensity doublets with ²J_HH = 5.4 Hz at δ 6.12 and −5.86 ppm.