Synthesis of novel heterotetrametallic (d(6-)d(10)-d(8)) polyalkynyl complexes starting from heterobimetallic chloride-bridged (d(6)-d(8)) compounds

The reaction between the half-sandwich cyclopentadienyl complexes [M(eta (5 )-C5Me5)Cl-2(PEt3)] (M = Rh, Ir) and [cis-M ' (C6F5)(2)(thf)(2)] (M ' = Pt, Pd; thf = tetrahydrofuran) affords the corresponding chloride-bridged hete robinuclear Rh, Ir/ Pt, Pd complexes [(PEt3)(eta (5)-C5Me5)M(mu -Cl)(2)M ' (C6F5)(2)] (1-4). In contrast, similar reactions with the chloro-bridged bi nuclear compounds [{(M(eta (5)-C5Me5)Cl(mu -Cl)}2] (M = Ph, Ir) lead instea d to the unexpected mixed salt complexes {Cp*M(mu -Cl)(3)MCp*}(2)[{(C6F5)(2 )M '(mu -Cl}(2)] (M = Rh, Ir; M ' = Pt, Pd) (5-8) as a result of chloride t ransfer. The structures of [(PEt3)(eta (5)-C5Me5)Rh(mu -Cl)(2)Pt(C6F5)(2) ( 1) and {Cp*Rh(mu -Cl)(3)RhCp*}(2)[{(C6F5)(2)Pd(mu -Cl)}(2)] (6) have been d etermined by X-ray diffraction analyses. The reactivity of the new chloride -bridged heterobinuclear compounds 1-4 towards the alkynylating agents [M " (C drop CR)](n) (M " = Cu, Ag) has also been investigated: a new type of t etranuclear product, [(PEt3)Cp* M(mu -1 kappaC(alpha):eta (2)-C drop CPh)(2 )M " (2)(mu -4 kappaC(alpha):eta -C drop CPh)(2)Pt(C6F5)(2)] (M = Rh, Ir; M " = Cu, Ag) (9-12), was obtained, and fully characterized in the case of c omplex [(PEt3)Cp*Rh(mu -1 kappaC(alpha):eta (2)- C drop CPh)(2)Cu-2(mu -4 k appaC(alpha):eta (2)-C drop CPh)(2)Pt(C6F5)(2)] (9).