Vanadium Organometallics☆

Lorber, C.

doi:10.1016/b978-0-12-409547-2.11558-6

Cited by 3 publications

(5 citation statements)

References 624 publications

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“…[33][34][35][36][37][38] The octahedral geometry around the vanadium center is slightly distorted and the tripodal nitrogen V-N2 distance of 2.3877(17) Å is significantly longer than the sidearm N1-V bond of 2.2261(17) Å as the result of a trans effect of the oxido group. The vanadium-oxido distance is comparable to those in known structures, [39,40] with V-O6 = 1.5904( 15) Å [1.567(1) Å for cis-1], whereas the vanadium-carboxylate V-O distance is rather short [V-O3 = 1.9649( 15) Å]. The phenolato groups of the [ONNO] framework fold in towards the (dimethylamino)ethyl sidearm, and the angle between the two planes of the aromatic rings is approximately 156°.…”

Section: Resultssupporting

confidence: 71%

Cytotoxic Vanadium Complexes of Branched [ONNO]‐Type Diamine Bis(phenolato) Ligands

et al. 2017

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Vanadium complexes are attractive potential alternatives to platinum-based anticancer drugs. Two vanadium(V) complexes, based on a common chelating tetradentate diaminobis(phenolato) ligand featuring a branched connectivity but differing in their labile ligands, were synthesized and characterized. Whereas the isopropoxido complex was obtained as a mixture of cis and trans isomers with regard to the orientation of the labile group vs. the amine sidearm, the salicylato-containing complex was obtained as a single trans isomer. X-ray

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Section: Resultssupporting

confidence: 71%

Cytotoxic Vanadium Complexes of Branched [ONNO]‐Type Diamine Bis(phenolato) Ligands

et al. 2017

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“…Dianionic imido ligands have been employed also with group 5 metals; for these metals in the +5 oxidation state, the isolobal analogy with group 4 metallocenes is reached with a monoanionic supporting ligand in addition to the dianionic imido ligand. In particular, the imido function has proven to stabilize alkyl groups in both V(IV) and V(V) complexes . The use of imido ligands in V(V) chemistry is well documented .…”

Section: Introductionmentioning

confidence: 93%

“…The use of imido ligands in V(V) chemistry is well documented . Great improvement in this field was achieved by Gibson, who reported the first example of an (imido)vanadium complex, that is CpV(N-4-Me-C 6 H 4 )Cl 2 , to be used as catalysts for the polymerization of olefins, , and Nomura, who developed several examples of V(V) complexes of the type V(NAr)Cl 2 (L) containing both 2,6-disubstituted aryl–imido ligands (NAr) and anionic ancillary donor ligands (L) such as aryloxo, ,, imidazolin-2-iminato and imidazolidin-2-iminato, N -heterocyclic carbenes, 2-(2′-benz-imidazolyl)pyridine, and chelated (2-anilidomethyl)pyridine, and (anilido)methylimine ligands . Many of such vanadium(V) complexes, in combination with aluminum alkyls, proved to be highly active in the (co)polymerization of ethylene, giving high molecular weight (co)polymers, with the exception of those complexes containing chelated ligands that proved to be highly efficient catalysts for ethylene dimerization .…”

Section: Introductionmentioning

confidence: 99%

“…In particular, the imido function has proven to stabilize alkyl groups in both V(IV) and V(V) complexes. 9 The use of imido ligands in V(V) chemistry is well documented. 10 Great improvement in this field was achieved by Gibson, who reported the first example of an (imido)vanadium complex, that is CpV(N-4-Me-C 6 H 4 )Cl 2 , to be used as catalysts for the polymerization of olefins, 5b,c and Nomura, who developed several examples of V(V) complexes of the type V(NAr)Cl 2 (L) containing both 2,6-disubstituted aryl−imido ligands (NAr) and anionic ancillary donor ligands (L) such as aryloxo, 9,11c,e imidazolin-2-iminato and imidazolidin-2-iminato, 11d N-heterocyclic carbenes, 11b 2-(2′-benz-imidazolyl)pyridine, 11a and chelated (2-anilidomethyl)pyridine, 12a and (anilido)methylimine ligands.…”

Section: ■ Introductionmentioning

confidence: 99%

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Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

et al. 2018

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The synthesis and the characterization of a series of phosphine adducts of (imido)vanadium(IV) dichloride complexes of the type V(NR)Cl 2 (PMe 2 Ph) 2 [R = 2,6-Cl 2 -Ph (1), 2,6-i Pr 2 -Ph (2), and t Bu (3)] and V( N t Bu)Cl 2 (PMe 3 ) 2 (3′) are reported. The solid-state structures of 1 and 3′ were determined by X-ray crystallography. The complexes present a geometry around the metal center between a distorted trigonal-bipyramid and a square pyramid, with an almost linear N−V−C bond. Complexes 1−3 were evaluated as catalyst precursors for the polymerization of ethylene and ethylene copolymerization with various cyclic olefins (i.e., norbornene, dicyclopentadiene, 5-ethylidene-2-norbornene, and 5-vinyl-2-norbornene). In combination with Et 2 AlCl (500 equiv to V) and Cl 3 CCO 2 Et (ETA, 10 equiv to V), 1−3 are versatile and promising catalysts for the synthesis of high molecular weight linear poly(ethylene)s and alternating copolymers with efficient comonomer incorporation, unimodal molecular weight distributions, and uniform composition under mild conditions. Differences in the homo-and copolymerization of ethylene regarding the activity, stability over temperature, reactivity toward the target comonomers, and (co)polymer chain growth were investigated to probe the effects of imido ligand substitution. The introduction of more electron-donating groups led to an increase in polymers molecular weight and provided increased stability over temperature to the catalysts, particularly for 3. Both of these effects are likely because the tert-butyl imido moiety in 3 strengthens the V−N bond, thus improving the stability of the active intermediate. The steric shielding of the tert-butyl group may also contribute to inhibit the associative chain transfer. Control over the molecular weight of the resultant copolymers proved to be possible also by varying the ETA loading. ETA acts as a reoxidant, restarting the catalytic cycle, but it behaves also like a chain transfer agent and to a different extent strongly depending on the type of imido ligand.

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“…For example, indenyl- or fluorenyl functionalized bi- or tridentate NHC ligands were employed to avoid unwanted dissociation of the ligand. 8 NHC coordinated vanadium complexes in oxidation states +I, 0 or −I are hitherto unknown.…”

Section: Introductionmentioning

confidence: 99%

N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of vanadium(iii) and vanadium(v)

et al. 2022

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Vanadium Organometallics☆

Cited by 3 publications

References 624 publications

Cytotoxic Vanadium Complexes of Branched [ONNO]‐Type Diamine Bis(phenolato) Ligands

Cytotoxic Vanadium Complexes of Branched [ONNO]‐Type Diamine Bis(phenolato) Ligands

Homo- and Co-Polymerization of Ethylene with Cyclic Olefins Catalyzed by Phosphine Adducts of (Imido)vanadium(IV) Complexes

N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of vanadium(iii) and vanadium(v)

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