Synthesis, structure and electrochemistry of Ph2PCH2PPh2-bridged, heterometallic complexes containing a (η-C5H4Me)Mn(CO)2fragment

Abstract

Heterometallic complexes and clusters were prepared by using the new metallophosphine [Mn(η-C5H4Me)(CO)2(dppm-P)]1 obtained from [Mn(η-C5H4Me)(CO)3] and Ph2PCH2PPh2(dppm). The dark green complexes [(OC)2(η-C5H4Me)M[graphic omitted]dCl2] and [{(η-C5H4Me)[graphic omitted]h(µ-Cl)}2], which contain metal–metal bonds, have been obtained by the reactions of 1 with [PdCl2(NCPh)2] and [{Rh(cod)(µ-Cl)}2](cod = cycloocta-1,5-diene), respectively. Starting from [Pt(cod)2], the trimetallic complex [Pt{(µ-dppm)Mn(η-C5H4Me)(CO)2}2] was formed and a reversible Mn–Pt bond formation has been observed by variable-temperature 31P-{1H} NMR spectroscopy. Reactions of 1 with [PtCl2(NCPh)2], [{Re(CO)3(thf)(µ-Br)}2](thf = tetrahydrofuran), [{RuCl(CO)3(µ-Cl)}2] and [{Ir(cod)(µ-Cl)}2] led in high yields to complexes of the type Mn–dppm–M–dppm–Mn (M = Pt, Re, Ru or Ir) having no metal–metal interaction. With [Mn(η-C5H4Me)(CO)2(thf)], [{Pd(η3C-3H4Me)(µ-Cl)}2] or [AuBr(tht)](tht = tetrahydrothiophene) bimetallic complexes of the type Mn-dppm-M′(M′= Mn, Pd or Au) were obtained again with no metal–metal interaction. Another route to this type of bimetallic complexes consists of the reaction of [(OC)2(η-C5H4Me)M[graphic omitted]dCl2] with two-electron donor ligands such as isocyanides RNC (R = 2,6-xylyl or But), which yielded [(OC)2(η-C5H4Me)Mn(µ-dppm)Pd(CNR)Cl2]. Reaction of the isocyanide complexes with azetidine did not lead to the expected carbene complexes, instead the isocyanide ligand was substituted by azetidine, yielding [(OC)2(η-C5H4Me)Mn(µ-dppm)Pd(NHC3H6)Cl2]. The structures of the xylyl isocyanide and azetidine complexes have been determined by X ray diffraction. Reaction of [(OC)2(η-C5H4Me)Mn(µ-dppm)AuBr] with the metalate K[Fe{Si(OMe)3}(CO)3(PPh3)] gave in high yield the heterotrimetallic chain complex [(OC)2(η-C5H4Me) Mn(µ-dppm)AuFe{Si(OMe)3}(CO)3(PPh3)]. Reaction of 1 with trans-[Pt{W(η-C5H4Me)(CO)3}2(NCPh)2] afforded the cluster [Pt2W2(η-C5H4Me)2(µ3-CO)2(µ-CO)4{(µ-dppm)Mn(η-C5H4Me)(CO)2}2]. An electrochemical study of some of the complexes has provided evidence for possible electronic communication between the metal centres.