Preparation and characterization of diarylphosphazene and diarylphosphinohydrazide complexes of titanium, tungsten and ruthenium and phosphorylketimido complexes of rhenium

Abstract

Reaction of the proligand Ph₂PN(SiMe₃)₂ (L¹) with WCl₆ gives the oligomeric phosphazene complex [WCl₄(NPPh₂)]_n, 1 and subsequent reaction with PMe₂Ph or NBu₄Cl gives [WCl₄(NPPh₂)(PMe₂Ph)] (2) or [WCl₅(NPPh₂)][NBu₄] (3), respectively. DF calculations on [WCl₅(NPPh₂)][NBu₄] show a WN double bond (1.756 Å) and a P–N bond distance of 1.701 Å, which combined with the geometry about the P atom suggests, there is no P–N multiple bonding. Reaction of L¹ with [ReOX₃(PPh₃)₂] in MeCN (X = Cl or Br) gives [ReX₂(NC(CH₃)P(O)Ph₂)(MeCN)(PPh₃)] (X = Cl, 4, X = Br, 5) which contains the new phosphorylketimido ligand. It is bound to the rhenium centre with a virtually linear Re–N–C arrangement (Re–N–C angle = 176.6°. when X = Cl) and there is multiple bonding between Re and N (Re–N = 1.809(7) Å when X = Cl). The proligand Ph₂PNHNMe₂ (L²H) reacts with [(C₅H₅)TiCl₃] to give [(C₅H₅)TiCl₂(Me₂NNPPh₂)] (6). An X-ray crystal structure of the complex shows the ligand (L²) is bound by both nitrogen atoms. Reaction of the proligands Ph₂PNHNR₂ [R₂ = Me₂ (L²H), –(CH₂CH₂)₂NCH₃ (L³H), (CH₂CH₂)₂CH₂ (L⁴H)] with [{RuCl(µ-Cl)(η⁶-p-MeC₆H₄ⁱPr)}₂] gave [RuCl₂(η⁶-p-MeC₆H₄ⁱPr)(L)] {L = L²H (7), L³H (8), L⁴H (9)}. The X-ray crystal structures of 7–9 confirmed that the phosphinohydrazine ligand is neutral and bound via the phosphorus only. Reaction of complexes 7–9 with AgBF₄ resulted in chloride ion abstraction and the formation of the cationic species [RuCl(η⁶-p-MeC₆H₄ⁱPr)(L)]⁺BF₄⁻ {(L = L²H (10), L³H (11), L⁴H (12)}. Finally, reaction of complex 6 with [{RuCl(µ-Cl)(η⁶-p-MeC₆H₄ⁱPr)}₂] gave the binuclear species [(η⁶-p-MeC₆H₄ⁱPr)Cl₂Ru(µ²,η³-Ph₂PNNMe₂)TiCl₂(C₅H₅)], 13.