Bis(alkylamido)phenylborane Complexes of Zirconium, Hafnium, and Vanadium

Abstract

The coordination chemistry of the bis(tert-butylamido)phenylborane ligand, [(t)BuN-B(Ph)-N(t)Bu](2)(-), is developed. The ligand can be delivered to metals of groups 4 and 5 from its dilithio salt. The reactions of PhB((t)BuNLi)(2), 1, with metal halides of zirconium, hafnium, and vanadium generate complexes of the general formulas ((t)BuN-B(Ph)-N(t)Bu)(2)M(THF) (M = Zr (2), Hf (3)), Li(2)[M((t)BuN-B(Ph)-N(t)Bu)(3)] (M = Zr (4), Hf (5)), and M((t)BuN-B(Ph)-N(t)Bu)(2) (M = V (6)). (1)H and (11)B[(1)H] NMR and single-crystal X-ray analysis show that these amido metal complexes are structurally analogous to amidinates.

Cooperative Bimetallic Reactivity: Hydrogen Activation in Two-Electron Mixed-Valence Compounds

“…Such intermetal redox cooperation in polynuclear metal compounds can potentially be achieved by judicious ligand design. We have explored the coordination chemistry of ligands that stabilize bimetallic centers of formal two-electron mixed valence, M n ···M n +2 . − Dirhodium 35,36 and di-iridium 37,38 complexes bridged by diphosphazane ligands undergo two-electron oxidations at the M n +2 center and two-electron reductions at an M n center. With the metals working in concert, two- and four-electron transformations may be promoted along ground- and excited-state pathways. − Hydrogen production from acidic solutions is a prominent two-electron transformation promoted by these diphosphazane complexes.…”

12 Vanadium, niobium and tantalum

“…10 The diaminophenyl borane Bu t N(Li)B(Ph)N(Li)-Bu t , L, which juxtaposes both p-accepting groups directly adjacent to p-donating groups has been employed in the synthesis of the vanadium(IV) complex [V(L) 2 ]. This tetrahedral molecule was shown to be analogous to the related amidinate complex, and exhibited a well-resolved octet in the frozen solution EPR spectrum from the interaction of the unpaired electron with 51 V. 11 Several low valent vanadium complexes supported by a new class of multidentate b-diketiminato ligand have been synthesised by salt elimination routes; unique V III triflate and V II phosphido complexes were structurally characterised. 12 Reaction between the chelating lithium diamidophosphine Li 2 [npn] (npn ~ArP{CH 2 SiMe 2 NR} 2 ) and [VCl 3 (thf) 3 ] resulted in the clean formation of the dinuclear vanadium(III) complex [{V(m-Cl)(npn)} 2 ], the solid state structure of which was confirmed by X-ray crystallography.…”

4 Boron

“…The reactions of PhB( t BuNLi) 2 , with metal halides of zirconium, hafnium, and vanadium generate complexes of general formulae ( t BuN-BPh-N t Bu) 2 M(THF) (M ~Zr, Hf), Li 2 [M( t BuN-BPh-N t Bu) 3 ] (M ~Zr, Hf), and M( t BuN-BPh-N t Bu) 2 (M ~V). 159 Reaction of bis(amino)phosphane t BuP(NH t Bu) 2 with BH 3 results in a simple Lewis acid Lewis base adduct at the phosphane centre and not the nitrogen consistent with BH 3 being a soft Lewis acid. 160 The thermal decomposition of hindered amine-borane adducts leads to high yields of new monomeric (dialkylamino)boranes R 1 R 2 N-BH 2 (R 1 , R 2 ãlkyl) that are efficient boron sources in the Pd(0) catalyzed borylation reaction that affords monomeric aryl(dialkylamino)boranes R 1 R 2 N-BHR 3 (R 3 ~aryl).…”