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

Abstract

[VCl3(THF)3] offers a convenient entrance point into the chemistry of carbene stabilized V(III) complexes. Herein we report the paramagnetic mono- and biscarbene complexes [VCl3(cAACMe)] 1, [VCl3(cAACMe)(THF)] 1(thf), [VCl3(IMes)] 2, [{VCl2(IiPrMe)(µ-Cl)}2]...

N-Heterocyclic carbene and cyclic (alkyl)(amino)carbene ligated half-sandwich complexes of chromium(ii) and chromium(i)

“…The Cr1–C1 bond length of 2.0767(19) Å is significantly shorter compared to [(η 5 -C 5 Me 5 )Cr(IMe Me )Cl] 8 (2.1204(33) Å), but in the range typically observed in NHC chromium complexes (see Table 1). 14 c ,16 Complex 13 is closely related to the nitrogen ligated Cr( i ) complexes [(η 5 -C 5 Me 5 )Cr(IiPr Me )(N 2 ) 2 ] reported by Xi and coworkers lately. 37,46 Half-sandwich complexes [(η 5 -C 5 H 5 )M(NHC)(CO) 2/3 ] of the higher congeners (M = Mo, W) are known and the reactivity of these complexes is thoroughly investigated.…”

“…Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany. E-mail: u.radius@uni-wuerzburg.de mium complexes substituted with di-and polydentate NHC ligands is rather rich 11g,14 and due to our earlier interests in 3d transition metal complexes of monodentate NHCs (metal = Ti, 15 V, 16 W 17 (5d), Fe, 18 Co, 19 Ni, 20 Cu 21 ) and cAACs [15][16][17]22 we focus herein on monodentate NHC ligated chromium complexes.…”

“…Compared to the rich chemistry of group 6 carbene complexes in oxidation state zero in general, the chemistry of intermediate and high oxidation state NHC half-sandwich complexes of chromium is still in its infancy. As the field of chromium complexes substituted with di- and polydentate NHC ligands is rather rich 11 g ,14 and due to our earlier interests in 3d transition metal complexes of monodentate NHCs (metal = Ti, 15 V, 16 W 17 (5d), Fe, 18 Co, 19 Ni, 20 Cu 21 ) and cAACs 15–17,22 we focus herein on monodentate NHC ligated chromium complexes.…”

Co(iii) complexes of the pentadentate NHC ligand PY4Im: carbene-induced trans influences and the non-disappearing 13C NMR peak

“…It should also be noted that, like cobalt, vanadium is a monoisotopic element, with the quadrupolar 51 V nucleus having I = −7/2, and it might therefore be expected that broadening of the carbene 13 C signal should be observed in vanadium carbene complexes. Indeed, in none of the 21 structurally characterised V(V) complexes containing imidazole-based carbene ligands is the 13 C chemical shift of the carbene carbon reported, [29][30][31][32][33][34][35][36][37][38][39] this being attributed in cases where it was addressed, to broadening by the quadrupolar V nucleus. Thus, the 59 Co nucleus seems to be unusual as to the observation of the 13 C NMR signal of a coordinated carbene carbon, and this will be investigated for other Co(III) carbene complexes.…”

N-heterocyclic carbene and cyclic (alkyl)(amino)carbene complexes of molybdenum(iv) and tungsten(iv)

“…1 c–n ,2 a ,6 Compared to the substantial body of this work, the organometallic chemistry of NHCs and related molecules as ligands in complexes of early to middle transition metals in their high or even highest oxidation states is much less explored. 7…”