Vanadium complexes phosphorus ligands

The second is a polyoxovanadate, [(V06)(RP03)8]+ (R = tBu, OSiMe3), reported by Zubieta et al. [32] and Thom et al. [33] which consists of V05 pyramids and phos-phonate ligands (Fig. 9.12b). The vanadium atoms of the shell are located at the vertices of an octahedron, while the phosphorus atoms are located at the comers of a cube, thus displaying the dual relationship of these polyhedra. In both cases, the host has been shown to complex a chloride ion. 

Oxovanadium(IV) complexes with dithiophosphate ligands have been extensively examined <8,121.161,252,386) x typical ESR spectrum is shown in Fig. 7. In addition to the eight vanadium 1=112 hyperfine lines phosphorus (/ = 1/2) superhyperfine splitting is also observed. The phosphorus superhyper-fine splitting can be considered a bit unusual since the phosphorus is located about 3 A or more away from the metal ion. P and As superhyperfine splitting has been observed in the ESR spectra of ill-defined vanadium phosphine 388) and arsine 389) complexes but in those cases, presumably, direct V-P and V—As interactions occur. ESR parameters have been tabulated for a large number of dithiophosphate 121,252) dithiophosphinate 121.252) complexes. Evaluation 3i) of the fractional 3s character of unpaired electron in dithiophosphate complexes yielded a value of 1.35%. The vanadyl(IV) complexes possess approximate C2V symmetry. The unpaired d electron resides... 

Only three general reviews on vanadium(IV) complexes have been given 355-357 others deal with subnormal magnetic complexes,358 ESR spin probes,354 vanadium(IV) halides,6 optical spectra and phosphorus donor ligands,359 vanadium porphyrins128 and annual reviews for 1979, 1980 and 1981. 

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphorus, arsenic, and antimony compounds, they have nevertheless been employed to a considerable extent as ligands in transition metal complexes. The metals coordinated to the bismuth in these complexes include chromium (72—77), cobalt (78,79), iridium (80), iron (77,81,82), manganese (83,84), molybdenum (72,75—77,85—89), nickel (75,79,90,91), niobium (92), rhodium (93,94), silver (95—97), tungsten (72,75—77,87,89), uranium (98), and vanadium (99). The coordination compounds formed from tertiary bismuthines are less stable than those formed from tertiary phosphines, arsines, or stibines. 

Two vanadium(iv) ethylxanthate complexes have been prepared 440 their e.p.r. parameters are practically identical with those of the corresponding diethyldithio-carbamate complexes and on this basis analogous structures were proposed, i.e. a dodecahedral eight-co-ordinate structure with four bidentate ethylxanthate ligands and a distorted tetrahedral structure with four unidentate ligands. Addition of phosphorus(iii) ligands (L) such as trialkylphosphites to solution of the ethyl xanthate... 

The metal vapor ligand codeposition method has extended the array of such sandwich complexes. A wide range of substituents can be tolerated on the arene ring unusual arene M complexes have been prepared. Elschenbroichmade the interesting compound bis(j7 -phosphabenzene)vanadium, which is less air sensitive than the ligand itself. It turned out that the phosphorus heteroatom has a much stronger influence on the electron affinity of the free arene than of the bound arene. 

These compounds are monomeric and paramagnetic. The magnetic moment of the allylphosphine vanadium(O) derivative equals 1.98 BM at room temperature. The v(C = C) shifts from 1637 cm in the free ligand to 1513 cm in the complex. Reduction by sodium amalgam leads to the anion [V(CO)5L] in which the ligand is coordinated only through the phosphorus atom. 

Palladium complexes with an heterocyclic N-containing ligand have been used in the carbonylation of aromatic nitro compounds with cocatalysts such as cyclopentadienyl halides or oxyhalides of transition metals belonging to group V e.g. CP2VCI) [168], a cyclopentadienyl halide or oxyhalide together with phosphorus oxytrichloride [169], or a 1,3-diketone derivative of vanadium [170], even also in the presenee of phosphorus oxychloride [171]. 

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