Reaction of [Mo(CO)6] with Ph2P(CH2)6PPh2(dpph): the synthesis of [Mo(CO)3(dpphn)][dpphn = Ph2P(CH2)2CHCH(CH2)2PPh2] and trans-[Mo2(CO)8(µ-dpph)2] and the crystal structure of the latter

The complex [Mo(CO)3(dpphn)][dpphn = Ph2P(CH2)2CHCH(CH2)2PPh2] was prepared from [Mo(CO)6] and Ph2P(CH2)6PPh2(dpph) in refluxing decahydronaphthalene via a dehydrogenation process. The dpph bridged, bimetallic complex trans-[Mo2(CO)8(µ-dpph)2] was also prepared from the same starting materials, but in refluxing toluene. Crystals of the latter are triclinic, space group P, with a= 11.989(2), b= 13.304(4), c= 16.011(5)A, α= 109.59(2), β= 88.32(2), γ= 109.71(2)°, Z= 1 and R= 0.051 for 3866 observed reflections. The compound has a trans bridged 18-membered ring structure. The trans geometry may be due to the steric effect of the diphenylphosphino groups during the thermolytic substitution reaction. The Mo-P bond lengths are similar, but the Mo–CO bond lengths are significantly different, with the bonds inside the 18-membered ring being shorter than those outside.