Titanium and zirconium complexes with novel phenoxy-phosphinimine ligands

A series of novel phenoxy-phosphinimine ligands (L): L = 2-(Ph₂PNR), 4, 6-(CMe₃)₂-C₆H₂OH [2, R = SiMe₃; 3, R = Ph] have been prepared in the yield of 65-71%. And bis(phenoxy-phosphinimide) group 4 complexes of the type L₂MCl₂ [4, M = Ti, R = SiMe₃; 5, M = Zr, R = SiMe₃; 6, M = Ti, R = Ph; 7, M = Zr, R = Ph] have been synthesized by the reaction of the ligands with TiCl₄ and ZrCl₄. The structure of complex 7 has been determined by X-ray crystallography. The complexes 4-7 showed inactive to ethylene polymerization in the presence of modified methylaluminoxane (MMAO) and i-Bu₃Al/Ph₃CB(C₆ F₅)₄. These results should be caused by overdoing the steric congestion around central metal.     

Titanium complexes with novel triaryl-substituted phosphinimide ligands: Synthesis, structure and ethylene polymerization behavior

A series of titanium phosphinimide complexes [Ph₂P(2-RO-C₆H₄)]₂TiCl₂ (7, R = CH₃; 8, R = CHMe₂) and [PhP(2-Me₂CHO-C₆H₄)][THF]TiCl₃ (9) have been prepared by reaction of TiCl₄ with the corresponding phosphinimines under dehalosilylation. The structure of complex 9 has been determined by X-ray crystallography, and a solvent molecule THF was found to be coordinated with the central metal and the Ti-O bond was consistent with the normal Ti-O (donor) bond length. The complexes 7 and 8 displayed inactive to ethylene polymerization, and the complex 9 displayed moderate activity in the presence of modified methylaluminoxane (MMAO) or i-Bu₃Al/Ph₃CB(C₆F₅)₄, and this should be partly attributed to coordination of THF with titanium and the steric effect of two iso-propoxyl. And catalytic activity up to 32.2 kg-PE/(mol-Ti h bar) was observed.     

Synthesis of air-stable zwitterionic 2-phosphiniminium-arenesulfonates

Efficient synthetic methodology for preparation of 2-phosphiniminium-5-methylbenzenesulfonate zwitterions is reported. Staudinger reaction between phosphines and n-propyl 2-azido-5-methylbenzenesulfonates followed by sulfonate ester deprotection using pyridinium tetrafluoroborate/pyridine afforded the zwitterions in excellent yields. This new route directly accesses ortho-substituted-arenesulfonate ligands that incorporate a phosphinimine, a strong σ-donor.     

Reactivity of Iminophosphoranes. Formation of the Piperazine Ring

Reaction of 3-azidopropyl methanesulfonate with triphenylphosphine produced the 1,4-bis(triphenyl-phosphino)piperazine 5 by intermolecular cyclization, instead of formation azidine derivatives by an intramolecular pathway. Structural formulation of 5 was achieved by both spectral and X-ray crystal analysis. Hydrolysis of 5 under basic condition gives piperazine, whereas reaction of lithium diphenylphosphide with 5 produced 1,2-bis(diphenyl-phosphino)ethane (dppe) exclusively.     

Synthesis and Structure of Alkali Bis(phosphinimino)methanides

The reaction of CH₂(PPh₂NSiMe₃)₂ with n‐butyllithium or potassium hydride in THF leads, after the recrystallization from toluene or n‐heptane/diglyme, to the corresponding alkali derivatives [Li(THF)][CH(PPh₂NSiMe₃)₂] ( 1 ), K[CH(PPh₂NSiMe₃)₂] ( 2 ), and [K(digylme)][CH(PPh₂NSiMe₃)₂] ( 3 ). Upon coordination to the metal center the ligand forms a six membered metallacycle in which both phosphinimine nitrogen atoms bind to the metal atom.