Synthesis and Characterization of Vanadium(V)−Phosphinimide Complexes

Abstract

Synthetic routes to vanadium(V)-phosphinimide derivatives are addressed. Initial synthetic efforts afforded the known compound formulated as VCl(2)(NPPh(3))(3) which was crystallographically determined to be the salt [VCl(NPPh(3))(3)]Cl (1). Reactions of the vanadium-imide precursors VCl(3)(NAr) (Ar = Ph, C(6)H(3)-2,6-iPr(2)) with R(3)PNSiMe(3) (R = Ph, iPr, tBu) afforded VCl(2)(NPh)(NPPh(3)) (4), VCl(2)(NPh)(NPiPr(3)) (5), VCl(2)(NPh)(NPtBu(3)) (6), VCl(2)(NC(6)H(3)-2,6-iPr(2))(NPPh(3)) (7), VCl(2)(NC(6)H(3)-2,6-iPr(2))(NPiPr(3)) (8), and VCl(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (9) in yields ranging from 72% to 84%. Subsequent alkylation or arylation reactions resulted in VMe(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (10), VPh(2)(NPh)(NPtBu(3)) (11), VPh(2)(NC(6)H(3)-2,6-iPr(2))(NPiPr(3)) (12), and VPh(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (13) while substitution reactions with Li[N(SiMe(3))(2)] and Li[SBn] gave VCl(N(SiMe(3))(2))(NPh)(NPtBu(3)) (14) and V(SBn)(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (15) in yields ranging from 40% to 49% yield. Polarization of the N-P phosphinimide bond and V-N multiple bond character are evidenced by crystallographic data.

Homoleptic Imidophosphorane Stabilization of Tetravalent Cerium

“…They differ from siloxides in their degree of zwitterionic character and the energy and radial extent of the donor atom (N 2p vs O 2p; Scheme A). In contrast to the few previous studies of imidophosphorane chemistry employing alkyl or aryl substituents, − dialkylamide substituents (piperidine in this case) amplify this zwitterionic character by stabilizing the P cationic character and terminal nitrogen N 2– character (Scheme A). Spectroscopic, reactivity, and theoretical studies of homoleptic trivalent and tetravalent complexes of cerium supported by the tris­(piperidinyl)­imidophosphorane ligand, [NP­(pip) 3 ] − [pip = piperidinyl, a six-membered ring, N­(C 5 H 10 )], indicate that covalent interactions between the metal and ligand govern the most significant stabilization of tetravalent cerium observed to date. , The binding of a potassium ion in the inner coordination sphere of the trivalent complex contributes significantly to the thermodynamic driving force for complex oxidation.…”

12 Vanadium, niobium and tantalum

“…Salt elimination reactions were used to prepare the V V dialkyl, amido and dithioether complexes [VMe 2 (NAr)(NPR 3 )], [VCl{N(SiMe 3 ) 2 }(NAr)-(NPR 3 )], and [V(SBn) 2 (NAr)(NPR 3 )], respectively. 15 The interest in vanadium complexes as catalysts for alkene polymerisation has prompted the synthesis of V(oxo) complexes that are supported by a multidentate aminophenolate ligand (ONNO). The protonolysis reaction between [VO(OPr i ) 3 ] and H 2 (ONNO) resulted in two isomers of the octahedral V V complex [VO(OPr i )-(ONNO)]; the solution structures were determined using multinuclear NMR techniques, while X-ray crystal structure determinations confirmed the ligand arrangements.…”

Titanium ferrocenyl-phosphinimide complexes

“…Indeed, these systems have proved to be highly active olefin polymerization catalysts under commercial conditions. 26- 28 Our progress over the issuing years target an understanding of the structure-activity relationship, [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] and the mechanisms of deactivation 44-49 of phosphinimide-catalyst systems has been recently reviewed.…”