Chelating diamide complexes of titanium, zirconium and scandium: New polymerization catalysts based on non-Cp ligand environments

The reaction of RHN(CH{dollar}sb2)sb3{dollar}NHR (2.3a,b) (a, R = 2,6-Me{dollar}sb2{dollar}C{dollar}sb6{dollar}H{dollar}sb3{dollar}; b, R = 2,6-{dollar}sp{lcub}rm i{rcub}{dollar}Pr{dollar}sb2{dollar}C{dollar}sb6{dollar}H{dollar}sb3{dollar}) with two equivalents of butyl lithium (BuLi) followed by two equivalents of ClSiMe{dollar}sb3{dollar} yields the silylated diamines R(Me{dollar}sb3{dollar}Si)N(CH{dollar}sb2)sb3{dollar}N(SiMe{dollar}sb3{dollar})R (2.9a,b). The reaction of 2.9a,b with TiCl{dollar}sb4{dollar} yields the dichloride complexes (RN(CH{dollar}sb2)sb3{dollar}NR) TiCl{dollar}sb2{dollar} (2.10a,b) and two equivalents of ClSiMe{dollar}sb3.{dollar} An X-ray study of 2.10b revealed a distorted tetrahedral geometry about titanium with the aryl groups lying perpendicular to the TiN{dollar}sb2{dollar}-plane. Complexes 2.10a,b react with two equivalents of MeMgBr to give the dimethyl derivatives (RN(CH{dollar}sb2)sb3{dollar}NR) TiMe{dollar}sb2{dollar} (2.11a,b). An X-ray study of 2.11a again revealed a distorted tetrahedral geometry about titanium. These titanium dimethyl complexes are active catalyst precursors for the polymerization of {dollar}alpha{dollar}-olefins, when activated with methylaluminoxane (MAO). Equimolar amounts of 2.11a or 2.11b and B(C{dollar}sb6{dollar}F{dollar}sb5)sb3{dollar} catalyze the living polymerization {dollar}alpha{dollar}-olefins. Highly active living systems are obtained when 2.11a is activated with {dollar}{lcub}{dollar}Ph{dollar}sb3{dollar}C{dollar}{rcub}sp+{dollar} (B(C{dollar}sb6{dollar}F{dollar}sb5)sb4rbracksp-.{dollar}; The addition of a pentane solution of complexes 2.11a,b to a pentane solution of B(C{dollar}sb6{dollar}F{dollar}sb5)sb3{dollar} at 23{dollar}spcirc{dollar}C yields an insoluble yellow-orange solid (2.52a,b). Complexes 2.52a,b are catalysts for the living polymerization of 1-hexene at 23{dollar}spcirc{dollar}C. In the absence of monomer, complex 2.52b slowly evolves methane to give a new pentane soluble derivative (RN(CH{dollar}sb2)sb3{dollar}NR) Ti (CH{dollar}sb2{dollar}B(C{dollar}sb6{dollar}F{dollar}sb5)sb2rbrack{dollar} (C{dollar}sb6{dollar}F{dollar}sb5{dollar}) (2.54b). Complex 2.54b is inactive for the polymerization of {dollar}alpha{dollar}-olefins.; The reaction of diamines 2.3b with Zr(NMe{dollar}sb2)sb4{dollar} yields the complex, (RN(CH{dollar}sb2)sb3{dollar}NR) Zr(NMe{dollar}sb2)sb2{dollar} (4.1b), and two equivalents of NHMe{dollar}sb2.{dollar} Compound 4.1b reacts with two equivalents of (Me{dollar}sb2{dollar}NH{dollar}sb2{dollar}) Cl to yield the complex (RN(CH{dollar}sb2)sb3{dollar}NR) ZrCl{dollar}sb2{dollar}(NHMe{dollar}sb2)sb2{dollar} (4.5b) and in the presence of excess pyridine affords the complex (RN(CH{dollar}sb2)sb3{dollar}NR) ZrCl{dollar}sb{lcub}rm 2py2{rcub}{dollar} (4.6b). The base-free dichloride complex (RN(CH{dollar}sb2)sb3{dollar}NR) ZrCl{dollar}sb2{dollar} (4.7b) can be prepared from 4.1b and excess ClSiMe{dollar}sb3.{dollar} The alkylation of compound 4.6b or 4.7b with two equivalents of MeMgBr, two equivalents of PhCH{dollar}sb2{dollar}MgCl, and one equivalent of NaCp(DME) yields the alkyl derivatives (RN(CH{dollar}sb2)sb3{dollar}NR) ZrR{dollar}sb2{dollar} (4.12a, R = Me; 4.13b, R = CH{dollar}sb2{dollar}Ph) and (RN(CH{dollar}sb2)sb3{dollar}NR) Zr({dollar}etasp5{dollar}-C{dollar}sb5{dollar}H{dollar}sb5{dollar})Cl (4.26b), respectively. The reaction of two equivalents of PhMe{dollar}sb2{dollar}CCH{dollar}sb2{dollar}MgCl with complex 4.6b yields the {dollar}etasp2{dollar}-pyridyl complex (RN(CH{dollar}sb2)sb3{dollar}NR) Zr({dollar}etasp2{dollar}-N,C-NC{dollar}sb5{dollar}H{dollar}sb4{dollar})(CH{dollar}sb2{dollar}CMe{dollar}sb2{dollar}Ph) (4.20b). An X-ray study of 4.20b revealed an edge-capped tetrahedral geometry with the pyridyl nitrogen occupying the capping position. The catalyst system 4.12b/MAO polymerizes 1-hexene to a mixture of high po...