Quasi-octahedral complexes of pentamethylcyclopentadienyliridium(iii) bearing bis(diphenylphosphinomethyl)phenylphosphine (dpmp)

Abstract

Reaction of [Cp*IrCl₂]₂ (1) with dpmp in the presence of KPF₆ afforded a binuclear complex [Cp*IrCl(dpmp-P¹,P²;P³)IrCl₂Cp*](PF₆) (2) (dpmp = (Ph₂PCH₂)₂PPh). The mononuclear complex [Cp*IrCl(dpmp-P¹,P²)](PF₆) (4) was generated by the reaction of [Cp*IrCl₂(BDMPP)] (BDMPP = PPh{2,6-(MeO)₂C₆H₃}₂) with dpmp in the presence of KPF₆. These mono- and binuclear complexes have four-membered ring structures with a terminal and a central P atom of the dpmp ligand coordinated to an iridium atom as a bidentate ligand. Since there are two chiral centers at the Ir atom and a central P² atom, there are two diastereomers that were characterized by spectrometry. Complexes anti-4 and syn-4 reacted with [Cp*RhCl₂]₂ or [(C₆Me₆)RuCl₂]₂, giving the corresponding mixed-metal complexes, anti- and syn-[Cp*IrCl(dppm-P¹,P²;P³)MCl₂L](PF₆) (6: M = Rh, L = Cp*; 7: M = Ru, L = C₆Me₆). Treatment with AuCl(SC₄H₈) gave tetranuclear complexes, anti- and syn-8 [{Cp*IrCl(dppm-P¹,P²;P³)AuCl}₂](PF₆)₂ bearing an Au–Au bond. Reaction of anti-4 with PtCl₂(cod) generated the trinuclear complex anti-9, anti-[{Cp*IrCl(dppm-P¹,P²;P³)}₂PtCl₂](PF₆)₂. These reactions proceeded stereospecifically. The P,O-chelated complex syn-[Cp*IrCl(BDMPP-P,O)] (syn-10) (BDMPP-P,O = PPh{2,6-(MeO)₂C₆H₃}{2-O-6-(MeO)C₆H₃}₂) reacted with dpmp in the presence of KPF₆, generating the corresponding anti-complex as a main product as well as a small amount of syn-complex, [Cp*Ir(BDMPP-P,O)(dppm-P¹)](PF₆) (11). The reaction proceeded preferentially with inversion. The reaction processes were investigated by PM3 calculation. anti-11 was treated with MCl₂(cod), giving anti-[Cp*Ir(BDMPP-P,O)(dppm-P¹;P²,P³)MCl₂](PF₆) (14: M = Pt; 15: M = Pd), in which the MCl₂ moiety coordinated to the two free P atoms of anti-11. The X-ray analyses of syn-2, anti-2, anti-4, anti-8 and anti-11 were performed.