Vanadium complexes bipyridyl

Organometallic compounds apart, oxidation states below - -2 are best represented by complexes with tris-bidentate nitrogen-donor ligands such as 2,2 -bipyridyl. Reduction by LiAlH4 in thf yields tris(bipyridyl) complexes in which the formal oxidation state of vanadium is -1-2 to —1. Magnetic moments are compatible with low-spin configurations of the metal but. 

Carbonyl and other Low Oxidation State Compounds.—Tris-(2,2 -bipyridyl)vana-dium(O) solutions in DMF exhibit three one-electron reduction waves corresponding to VL3 - VL3 (L = 2,2 -bipyridyI) VLJ -> VL " and VLf -VL, and two oxidation waves corresponding to VL3-> VL3 and VLJ ->VL3+ whose half-wave potentials differ by only 0.10 V.342 The difference for the isoelectronic chromium complexes is 0.49 V. An explanation has been offered for the small difference between the vanadium potentials in terms ol the possible diamagnetism of the d4VL3 species arising from a substantial splitting of the l2g orbitals. 

An early claim (332, 334) to have prepared V(bipy)g+ has been revised (431) the compound V(bipy)3l is considered to be a mixture of V(bipy)3 and V(bipy) 3I2. The reaction of V(bipy ) or of Cr(bipy) + with aluminum hydride gives the neutral tris-bipyridyl complexes, but with other dipositive metals Al(bipy)3 is the major product (357). Attempts to prepare bipyridyl and plienanthroline derivatives of hexacarbonylvanadium led to the disproportionation of vanadium(O) (376). 

DNA cleavage as the mechanism by which tumour growth is inhibited is also been suggested for the action of bis(peroxo)vanadium(V) complexes of the general composition [V0(02)2L] (L = o-phenanthroline or bipyridyl) and traced back to the formation of hydroxyl radicals. 

Vanadium(III) complexes, 473 adenine, 475 alcohols, 478 amides, 474, 480 amines, 474 amino acids, 484 ammonia, 474 aqua, 477 arsines, 476 azide, 475 bipyridyl, 475 bromides, 483 carboxylates, 479 catecholates, 478 chlorides, 482 complexones, 485 cyanides, 474,476 (Wethyl sulfoxide, 480 dioxygen, 478 dithiocarbamates, 481 dithiolates, 481 dithiophosphinates, 481 ethers, 478... 

Vanadium(IV) complexes, 487 acetates, 513 acetylacetonates, 504 electrochemistry, 505 ESR spectra, 505 adenine, 568 adipates, 516 alcohols, 502 amines, 489 amino adds, 544 equilibria, 544 ammonia, 489 arsenates, 513 arsenic ligands, 496 arsines, 498 ascorbic add, 502 benzilato, 522 biguanide, 496 binucleating ligands, 561 bipyridyl, 492,494... 

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