Synthesis of homo- and heterodinuclear metal complexes with dimethylsilylene bridged unsymmetrical bis(cyclopentadienyl) ligand

Abstract

The reaction of the dilithium salt Li 2[Me 2Si(C 5H 4)(C 5Me 4)] ( 2) of Me 2Si(C 5H 5)(C 5HMe 4) ( 1) with [MCl(C 8H 12)] 2 (M=Rh, Ir) and [RhCl(CO) 2] 2 afforded homodinuclear metal complexes [{Me 2Si(η 5-C 5H 4)(η 5-C 5Me 4)}{M(C 8H 12)} 2] (M=Rh: 3; M=Ir: 4) and [{Me 2Si(η 5-C 5H 4)(η 5-C 5Me 4)}Rh 2(CO) 2(μ-CO)] ( 5), respectively. The reaction of 2 with RhCl(CO)(PPh 3) 2 afforded a mononuclear metal complex [{Me 2Si(C 5HMe 4)(η 5-C 5H 4)}Rh(CO)PPh 3] ( 6) leaving the C 5HMe 4 moiety intact. Taking advantage of the difference in reactivity of the two cyclopentadienyl moieties of 2, heterodinuclear complexes were prepared in one pot. Thus, the reaction of 2 with RhCl(CO)(PPh 3) 2, followed by the treatment with [MCl(C 8H 12)] 2 (M=Rh, Ir) afforded a homodinuclear metal complex [Rh(CO)PPh 3{(η 5-C 5H 4)SiMe 2(η 5-C 5Me 4)}Rh(C 8H 12)] ( 7) consisting of two rhodium centers with different ligands and a heterodinuclear metal complex [Rh(CO)(PPh 3){(η 5-C 5H 4)SiMe 2(η 5-C 5Me 4)}Ir(C 8H 12)] ( 8). The successive treatment of 2 with [IrCl(C 8H 12)] 2 and [RhCl(C 8H 12)] 2 provided heterodinuclear metal complex [Ir(C 8H 12){(η 5-C 5H 4)SiMe 2(η 5-C 5Me 4)}Rh(C 8H 12)] ( 9). The reaction of 2 with CoCl(PPh 3) 3 and then with PhCCPh gave a mononuclear cobaltacyclopentadiene complex [{Me 2Si(C 5Me 4H)(η 5-C 5H 4)}Co(CPhCPhCPhCPh)(PPh 3)] ( 10). However, successive treatment of 2 with CoCl(PPh 3) 3, PhCCPh and [MCl(C 8H 12)] 2 in this order afforded heterodinuclear metal complexes [M(C 8H 12){(η 5-C 5H 4)SiMe 2(η 5-C 5Me 4)}Co(η 4-C 4Ph 4)] (M=Rh: 11; M=Ir: 12) in which the cobalt center was connected to the C 5Me 4 moiety. Although the heating of 10 afforded a tetraphenylcyclobutadiene complex [{Me 2Si(C 5Me 4H)(η 5-C 5H 4)}Co(η 4-C 4Ph 4)] ( 13), in which the cobalt center was connected to the C 5H 4 moiety, simple heating of the reaction mixture of 2, CoCl(PPh 3) 3 and PhCCPh resulted in the formation of a tetraphenylcyclobutadiene complex [{Me 2Si(C 5H 5)(η 5-C 5Me 4)}Co(η 4-C 4Ph 4)] ( 14), in which the cobalt center was connected to the C 5Me 4 moiety. The mechanism of the cobalt transfer was suggested based on the electrophilicity of the formal trivalent cobaltacyclopentadiene moiety. In the presence of 1,5-cyclooctadiene, the reaction of 2 with CoCl(PPh 3) 3 provided a mononuclear cobalt cyclooctadiene complex [{Me 2Si(C 5Me 4H)(η 5-C 5H 4)}Co(C 8H 12)] ( 15). The reaction of 15 with n-BuLi followed by the treatment with [MCl(C 8H 12)] 2 (M=Rh, Ir) afforded the heterodinuclear metal complexes of [Co(C 8H 12){(η 5-C 5H 4)SiMe 2(η 5-C 5Me 4)}M(C 8H 12)] (M=Rh: 16; M=Ir: 17). Treatment of 6 with Fe 2(CO) 9 at room temperature afforded a heterodinuclear metal complex [{Me 2Si(C 5HMe 4)(η 5-C 5H 4)}{Rh(PPh 3)(μ-CO) 2Fe(CO) 3}] ( 18) in which the C 5HMe 4 moiety was kept intact. Treatment of dinuclear metal complex 5 with Fe 2(CO) 9 afforded a heterotrinuclear metal complex [{(η 5-C 5H 4)SiMe 2(η 5-C 5Me 4)}{Rh(CO)Rh(μ-CO) 2Fe(CO) 3}] ( 19) having a triangular metal framework. The crystal and molecular structures of 3, 11, 12, 18 and 19 have been determined by single-crystal X-ray diffraction analysis.