NEW VANADIUM COMPLEXES WITH SUBSTITUENT-F REE PHOSPHORUS LIGANDS

The photo-induced reaction of the half-sandwich complex CpV(CO)(4) (1 ) (Cp=eta(5)-C(5)Me(5), pentamethylcyclopentadienyl) with white phosp horus (P-4) in tetrahydrofuran solution at 0 degrees C leads to a mixt ure of carbonyl-containing vanadium-phosphorus compounds such as CpV( CO)(2)(eta(4)P(4)) (2), CPV(CO)(2)(P-n) (3), CP*(CO)V(mu-eta(2), eta( 2)-P-2)(2)V(CO)CP (4) and Cp*(CO)(2)V[mu-eta(4), eta(1)-P-4]V(CO)(3)C p() (5). Complete displacement of the carbonyl ligands in 2-5 by eith er thermolysis or photolysis (with or without P-4) always gives the kn own tripledecker complex CpV(mu-eta(6),eta(6)-P-6)VCp* (6) (O.J. Shwa lb, H. Swarowsky, G. Wolmershauser, W. Kaim and R. Gross, Chem. Ber., 121 (1988) 443) which is considered to be the thermodynamically stable end product in the system CpV(CO)(4)-P-4. According to the X-ray str ucture determination the binuclear complex 5 contains a [CpV(CO)(3)] fragment attached to 3 2. The reaction of 2 with Cr(CO)(5)(thf) gives a mixture of CpV(CO)(2)(eta(4)-P-4)[Cr(CO)(5)] (7) and Cp*V(CO)(2)(et a(4)-P-4)[Cr(CO)(5)](2) (8). The spectroscopic data of the new compoun ds 2-5 are discussed. Carbonyl-free vanadium-phosphorus complexes are obtained by cothermolysis of (CPV)-V-0(CO)(4) (Cp(0)=Cp (9a), Cp' (9b) , Cp(t) (9c)) (Cp=eta(5)-C5H5, cyclopentadienyl; Cp'=eta(5)-C(5)H(4)Me , methylcyclopentadienyl; Cp(t)=eta(5)-C5H4(CMe(3)), tert-butylcyclope ntadienyl) and P-4 in boiling xylene. With the exception of (eta(5)-in denyl)V(CO)(4) (10) as starting material, the reactions result in the formation of both a tripledecker, Cp(0)V(mu-eta(6), eta(6)-P-6)VCp(0)( Cp(0)=Cp (11a), Cp' (11b), Cp(t) (11c)), and a cluster, Cp(4)(0)V(4)(P -3)(2) (Cp(0)=Cp (12a), Cp' (12b), Cp(t) (12c)). In the case of the bu lky indenyl ring ligand, only the tripledecker (eta(5)-indenyl)V(mu-et a(6), eta(6)-P-6)V(eta(5)-indenyl) (11d) could be isolated. An X-ray s tructure analysis carried out for 12a reveals a distorted cubane frame work with vanadium and phosphorus atoms occupying alternating corners. Two P-3 units are arranged perpendicular to the two V-V face diagonal s on opposite faces of the cube.