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

Abstract

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(0) compound cannot be further oxidised, but the macrocycle reacts with CpV(CO)₄ thermally or photolytically to produce cis-[(η²-12[ane]P₃Et₃)V(η⁵-Cp)(CO)₂] (3). The diamagnetic compounds have been characterised by IR and multinuclear (¹H, ¹³C, ³¹P and ⁵¹V) NMR spectroscopy.