Mono complexes vanadium

Trinuclear zinc carboxylate structures of the form MZn2(MeCH=CHC02)6(quinoline)2 have been structurally characterized with M = Mn, Co, Ni, Zn, Cd, Mg, Ca, Sr. Structural variation is observed for the group 2 metals. The remaining complexes all show linear trimers with the central metal atom octahedrally coordinated and linked to each zinc by two bidentate and one mono-dentate carboxylate.377 A basic benzoate octanuclear structure with four vanadium(III) and four zinc atoms has been characterized, [VZnO(benzoate)3(TF[F)]4-2TnF.378... 

Macrocyclic ligands 1,4,7-triazacyclonona-iV-acetate 221 and iV-(2-hydroxybenzyl)-l,4,7-cyclononane 225 have been prepared from l,4,7-triazacyclio[5.2.1.04 10]decane 40 and were subsequently used for the synthesis of a series of mono- and dinuclear complexes of vanadium(rv) and (v) (Scheme 35) <1995ICA(240)217>. 

The -complexes formed between chromium(O), vanadium(O) or other transition metals, and mono- or poly-fluorobenzene show extreme sensitivity to heat and are... 

Mono- and diphenylphosphine also give the corresponding dimeric complexes with vanadium hexacarbonyl. 

HIGH-VALENT MONO- -PENTAMETHYLCYCLO-PENTADIENYL)VANADIUM AND MOLYBDENUM COMPLEXES... 

The Ji-complexes formed between chromium(O), vanadium(O) or other transition metals, and mono- or poly-fluorobenzene show extreme sensitivity to heat and are explosive [1,2], Hexafluorobenzenenickel(O) exploded at 70°C [3], and presence of two or more fluorine substituents leads to unstable, very explosive chromium(O) complexes [1]. Apparently, the aryl fluorine atoms are quite labile, and on decomposition M—F bonds are formed very exothermically. Laboratory workers should be wary of such behaviour in any haloarenemetal Ji-complex of this type [1]. However, in later work, no indications of explosivity, or indeed of any complex formation, were seen [4]. Individually indexed compounds are ... 

A molecular conversion system based on a four-electron transfer to 02 was accomplished in the 02-oxidative polymerization of diphenyl disulfide (Figure 14) [116]. This is the first example of a multielectron mediator that is applied to molecular conversion systems. The multielectron transfer process from the reduced vanadium(III) complex (VOV+) to 02 not only revealed the 02 oxidation mechanism but also provided additional insight into the unique chemistry of vanadium with possible relevance to metal mono-oxygenases. 

Somewhat surprisingly, maltol (2-methyl-3-hydroxy-4-pyrone), an aromatic analogue to a-hydroxy carboxylic acids, shows little inclination toward formation of dimeric complexes. Rather, the chemistry is more in parallel with that of oxalate, and an x-ray structure of the bismaltolato complex [25] shows a cis octahedral coordination similar to that found for the oxalate complex. Under mildly acidic to moderately basic solution, the major complexes are mono- and bisligand derivatives. The corresponding vanadium chemical shifts are -509 and -496 ppm, respectively [25,26], The closely related amines, 2-methyl-3-hydroxy-4-pyridinone and its N-... 

All three oxidation states of vanadium found in living systems form stable complexes with a wide variety of mono- and multidentate ligands. Ions of these three oxidation states form complexes rapidly they are therefore labile. As mentioned on page 142, bimolecular complex formation rate constants for monomeric vanadate species are approximately 104 M V1. Water exchange rate constants are 280s 1 for V3+, and 500s 1 for V02+ at 25 °C52. ... 

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