Seven-coordinate molybdenum(II) carbonyl complexes containing two different bidentate ligands (2,2′-bipyridyl and Ph 2PCH 2PPh 2 or Ph 2PCH 2CH 2PPh 2)

Abstract

The complexes MoX 2(CO) 3(bipy) (X=Cl, Br, I) undergo substitution of a single CO ligand by Ph 2PCH 2PPh 2 (dppm) and Ph 2PCH 2CH 2PPh 2 (dppe) to give seven-coordinate complexes MoX 2(CO) 2(bipy)(LL) (X=Cl, Br, I; LL=dppm, dppe). Spontaneous isomerization to [MoX(CO) 2(bipy)(dppm)]X was observed for X=I in dichloromethane at room temperature. However MoCl 2(CO) 2(bipy)(dppm) led to MoCl 2(CO)(bipy)(dppm) by sunlight irradiation. The cationic species [MoX(CO) 2(bipy)(LL)]BPh 4 (X=Cl, Br; LL=dppm and X=Cl, Br, I; LL=dppe) were also prepared by use of NaBPh 4. Reactions of MoX 2(CO) 3(bipy) (X=Cl, Br) with dppe in molar ratios 2/1 (complex/ligand) afforded the slightly soluble compounds formulated as dimers, Mo 2X 4(CO) 4(bipy) 2(μ-dppe). We also report the possibility of preparing MoCl 2(CO) 3(bipy) by direct halogenation of Mo(CO) 4(bipy) at room temperature in dichloromethane.