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

The reaction of the dilithium salt Li-2[Me2Si(C5H4)(C5Me4)] (2) of Me2Si(C5 H5)(C5HMe4) (1) with [MCl(C8H12)](2) (M = Rh, Ir) and [RhCl(CO)(2)](2) affo rded homodinuclear metal Complexes [{Me2Si(eta (5)-C5H4)} {M(C8H12)}(2)] (M = Rh: 3; M = Ir: 4) and [{Me2Si(eta (C5H4)-C-5)(eta (5)-C5Me4)Rh-2(CO)(2)( mu -CO)] (5), respectively. The reaction of 2 with RhCl(CO)(PPh3)(2) afford ed a mononuclear metal complex [{Me2Si(C5HMe4)(eta (5)-C5H4)}Rh(CO)PPh3] (6 ) leaving the C5HMe4 moiety intact. Taking advantage of the difference in r eactivity of the two cyclopentadienyl moieties of 2, heterodinuclear comple xes were prepared in one pot. Thus, the reaction of 2 with RhCl(CO)(PPh3)(2 ), followed by the treatment with [MCl(C8H12)](2) (M = Rh, Ir) afforded a h omodinuclear metal complex [Rh(CO)PPh3{( eta (5)-C5H4)SiMe2(eta (5)-C5Me4)} Rh(C8H12)] (7) consisting of two rhodium centers with different ligands and a heterodinuclear metal complex [Rh(CO)(PPh3){(eta (5)-C5H4)SiMe2(eta (5)- C5Me4)}Ir(C8H12)] (8). The successive treatment of 2 with [IrCl(C8H12)](2) and [RhCl(C8H12)](2) provided heterodinuclear metal complex [Ir(C8H12){(eta (5)-C5H4)SiMe2(eta (5)-C5Me4)}Rh(C8H12)](2) (9). The reaction of 2 with Co Cl(PPh3)(3) and then with PhC equivalent to CPh gave a mononuclear cobaltac yclopentadiene complex [{Me-2-Si(C5Me4H)(eta (5)-C5H4)}Co(CPh equivalent to CPh-CPh equivalent to CPh)(PPh3)] (10). However, successive treatment of 2 with CoCl(PPh3)(3), PhC = CPh and [MCl(C8H12)](2) in this order afforded h eterodinuclear metal complexes [M(C8H12) {(eta (5)-C5H4)SiMe2(eta (C5Me4)-C -5) Co(eta (4)-C4Ph4)] (M = Rh: 11; M = Ir: 12) in which the cobalt center was connected to the C3Me4 moiety. Although the heating of 10 afforded a te traphenylcyclobutadiene complex [{Me2Si(C5Me4H)(eta (5)-C5H4)}CO(eta (4)-C4 Ph4)] (13), in which the cobalt center was connected to the C5H4 Moiety, si mple heating of the reaction mixture of 2 CoCl(PPh3)(3) and PhC equivalent to CPh resulted in the formation of a tetraphenylcyclobutadiene complex [{M e,Si(C5H5)(eta (5)-C5Me4)} Co(eta (4)-C4Ph4)] (14). in which the cobalt cen ter was connected to the C5Me4 moiety. The mechanism of the cobalt transfer was suggested based on the electrophilicity of the formal trivalent cobalt acyclopentadiene moiety. In the presence of 1,5-cyclooctadiene, the reaction of 2 with COCl(PPh3)(3) provided a mononuclear cobalt cyclooctadiene complex [{Me2Si(C5Me4H)(eta ( 5)-C5H4)}Co(C8H12)] (15). The reaction of 15 with n-BuLi followed by the tr eatment with [MCl(C8H12)](2) (M = Rh, Ir) afforded the heterodinuclear meta l complexes of [Co(C8H12}{(eta (5)- C5H4)SiMe2(eta (5)-C5Me4)}M(C8H12)] (M = Rh: 16; M = Ir: 17). Treatment of 6 with Fe-2(CO)(9) at room temperature afforded a heterodinuclear metal complex [{Me2Si(C5HMe4)(eta (5)-C5H4)} {Rh (PPh3)(mu -Co)(2)Fe(CO)(3)}] (18) in which the C5HMe4 moiety was kept intac t. Treatment of dinuclear metal complex 5 with Fe-2(CO)(9) afforded a heter otrinuclear metal complex [{(eta (5)-C5H4)SiMe2(eta (5)-C5Me4)} {(Rh(CO)Rh( mu -CO)(2)Fe(CO)(3})] (19) having a triangular metal framework. The crystal and molecular structures of 3, 11, 12, 18 and 19 have been determined by s ingle-crystal X-ray diffraction analysis. (C) 2001 Elsevier Science B.V. Al l rights reserved.