Organometallic clusters containing oxygen atoms. Preparation, structure, and properties of (.eta.-C5H5)11V13O18(NMe3)2 and (.eta.-C5H5)14V16O24, dimeric derivatives of (.eta.-C5H5)6V6O8

Organometallic Oxides: Preparation and Properties of the Clusters [(η-C5Me5)V(μ3-O)]4and [(η-C5Me5)V]4(μ-O)6by Reductive Aggregation of (η-C5Me5)VCl2(O)

“…Because of the antiferromagnetism of [Cp‘Cr(μ 3 -O)] 4 , we wished to investigate the magnetic behavior of the vanadium analogues [Cp‘V(μ 3 -O)] 4 and of the previously reported [Cp*V] 4 (μ-O) 6 . The neutral [Cp‘Cr(μ 3 -O)] 4 clusters were prepared by mild oxidation of Cp‘ 2 Cr. − , Similar oxidations of Cp‘ 2 V gave a wealth of clusters including [Cp*V] 4 (μ-O) 6 , − but the only indication of [Cp‘V(μ 3 -O)] 4 was the observation of [(C 5 H 5 )VO] 4 in the mass spectrum of the products of the oxidation of Cp 2 V by C 5 H 5 NO . Recently we have been investigating the reductive aggregation of Cp*MCl n (A) complexes as a route to clusters containing the hard ligands nitrogen or oxygen as the A atom. ,, It appeared from their stoichiometries that reduction of Cp*VCl 2 (O) − or [Cp*VCl(μ-O)] 4 ( 3 ) 31 would give [Cp*V(μ 3 -O)] 4 and reduction of [Cp*VCl(O)] 2 (μ-O) 32 would give [Cp*V] 4 (μ-O) 6 .…”

“…23 The neutral [Cp′Cr(µ 3 -O)] 4 clusters were prepared by mild oxidation of Cp′ 2 Cr. [2][3][4]25 Similar oxidations of Cp′ 2 V gave a wealth of clusters including [Cp*V] 4 (µ-O) 6 , [23][24][25][26][27][28] [Cp′V(µ 3 -O)] 4 was the observation of [(C 5 H 5 )VO] 4 in the mass spectrum of the products of the oxidation of Cp 2 V by C 5 H 5 NO. 28 Recently we have been investigating the reductive aggregation of Cp*MCl n (A) complexes as a route to clusters containing the hard ligands nitrogen or oxygen as the A atom.…”

Synthesis and Structure of a Trigonal Monopyramidal Vanadium(III) Complex, [(C6F5NCH2CH2)3N]V, and the Vanadium(IV) Product of Its Oxidation, {[(C6F5NCH2CH2)2N(CH2CH2NHC6F5)]V(O)}2

“…The shorter bond lengths are to be expected in {V(O)[N(SiMe 3 ) 2 ] 2 } 2 as a consequence of four-coordination about V versus five-coordination about V in 2 . Other examples of crystallographically characterized complexes that contain V 2 O 2 cores are known, − but apparently {V(O)[N(SiMe 3 ) 2 ] 2 } 2 is the only other divanadium(IV) species. In a typical divanadium(V) species the V 2 O 2 core is even less symmetric than found in the divanadium(IV) species, although the V−O−V and O−V−O angles are similar to what is found in the divanadium(IV) species.…”

Oxidative decarboxylation-deoxygenation of 3-hydroxy carboxylic acids via vanadium(V) complexes. A new route to tri- and tetrasubstituted olefins

“…', If initial V-OC(0) homolysis were rate-determining, then an electron-withdrawing group on the aryl imido ligand (for example, NO2) should accelerate the overall reaction relative to a donor (X = OCH3).I4 The stereospecificity of the overall process would vary in the opposite direction: substituent groups which destabilize low-valent versus high-valent vanadyl should accelerate diradical collapse relative to stereochemical reorganization of the intermediate.Is Cyclization of the 1,4-metallodiradical intermediate to vanadyl oxygen would give a glycolate which could cleave to give the carbonyl products observed.I6 We (6) (3) was prepared (43%) from 2-methylbutanoic acid and benzaldehyde. This involves formation of a carbon-centered radical via one-electron reduction of V(V) to V(IV) and subsequent decarboxylation."…”

“…For benzaldehyde to be produced in this latter case not only must decarboxylation occur but also a new C-0 bond must be formed. In support of a glycolate intermediate it was noted that benzaldehyde and 2butanone were obtained from 2-ethyl-3-hydroxy-2-methyl-3phenylpropanoic acid (3).6 When imido complexes were used in place of VOCl3, no cleavage occurred, and only olefins were formed.13 If initial V-OC(O) homolysis were rate-determining, then an electron-withdrawing group on the aryl imido ligand (for example, N02) should accelerate the overall reaction relative to a donor (X = OCH3).14 The stereospecificity of the overall process would vary in the opposite direction: substituent groups which destabilize low-valent versus high-valent vanadyl should accelerate diradical collapse relative to stereochemical reorganization of the intermediate.15 Cyclization of the 1,4-metallodiradical intermediate to vanadyl oxygen would give a glycolate which could cleave to give the carbonyl products observed.16 We (6) 2-Ethyl-3-hydroxy-2-methyl-3-phenylpropanoic acid (3) was prepared (43%) from 2-methylbutanoic acid and benzaldehyde. The diastereomers were separated by column chromatography (50:50:1 hexane/ether/acetic acid).…”