Low valent carbonylvanadium complexes of the triphosphorus macrocycle 12[ane]P3Et3

The triphosphorus macrocycle 1,5,9-triethyl-1,5,9-triphosphacyclododecane, 12[ane]P3Et3, reacts with [V(CO)6] under photolytic conditions to produce fac-[(12[ane]P3Et3)V(CO)3] (1) which has been isolated as its Et4N salt. This can be oxidised to the neutral 17 electron complex fac-(12[ane]P3Et3)V(CO)3 (2), which has been characterised by EPR spectroscopy. Density functional calculations support the spectroscopic observations and give insight into the bonding. The V() compound cannot be further oxidised, but the macrocycle reacts with CpV(CO)4 thermally or photolytically to produce cis-[(η-12[ane]P3Et3)V(η -Cp)(CO)2] (3). The diamagnetic compounds have been characterised by IR and multinuclear (H, C, P and V) NMR spectroscopy.