Hydrazonide titanium derivatives: Synthesis, characterization and catalytic activity in olefin polymerization. Molecular structure of [Ti(η 5-C 5H 4SiMe 3)Cl(μ-N 2CPh 2)] 2

Abstract

Reaction of the mixed dicyclopentadienyl titanium compound Ti(η 5-C 5Me 5)(C 5H 5)Cl 2 with LiN(H)NCPh 2, in toluene at −78 °C, gives the hydrazonide(1−) derivatives (‘metalloazine’) Ti(η 5-C 5Me 5)(C 5H 5)Cl[N(H)NCPh 2] and Ti(η 5-C 5Me 5)(C 5H 5)[N(H)NCPh 2] 2 in high yield. The titanium trichloro compound Ti[η 5-C 5H 4(SiMe 2Cl)]Cl 3 reacts with hydrazone [H 2NNCPh 2] in the presence of one equivalent of NEt 3 to afford the hydrazonide(1−) compound Ti[η 5-C 5H 4(SiMe 2Cl)]Cl 2[N(H)NCPh 2)], while in the presence of two equivalents of NEt 3 the cyclopentadienyl-amido derivative Ti[η 5-C 5H 4(SiMe 2η 1-NNCPh 2)]Cl 2 is obtained. Mono-hydrazonide(1−) compounds Ti(CpR)Cl 2[N(H)NCPh 2)] [CpR=η 5-C 5Me 5, η 5-C 5H 4(SiMe 3)] were synthesized by treatment of the corresponding monocyclopentadienyl trichloro derivatives Ti(CpR)Cl 3 with hydrazone in the presence of one equivalent of NEt 3. The dinuclear complex [Ti(η 5-C 5H 4SiMe 3)Cl(μ-N 2CPh 2)] 2 has been prepared by reaction of Ti(η 5-C 5H 4SiMe 3)Cl 2[N(H)NCPh 2)] with NEt 3 in toluene and alternatively by reaction of Ti(η 5-C 5H 4SiMe 3)Cl 3 with hydrazone and two equivalents of NEt 3. The molecular structure of [Ti(η 5-C 5H 4SiMe 3)Cl(μ-N 2CPh 2)] 2 was determined by single-crystal X-ray diffraction methods and contains two [Ti(η 5-C 5H 4SiMe 3)Cl] units bridged by two hydrazonide(2−) ligands which form a symmetrical ‘Ti 2(NN) 2’ core. These hydrazonide compounds have been activated with MAO and are suited to olefin polymerization.