The monomeric homoleptic Pt(0) complex [Pt(GaCp*)4] (1) has been synthesized by reaction of [Pt(COD)2] with GaCp* in hexane. The monomeric homoleptic Pd(0) complexes [Pd(GaCp*)4] (2) and [Pd{InC(SiMe3)3}4] (3) are accessible by reaction of [Pd(tmeda)(CH3)2] with GaCp* and [InC(SiMe3)3], respectively. These reactions were shown to proceed via methyl group transfer from palladium to indium or gallium, respectively. Complexes 1 and 2 can be used as building blocks for the synthesis of dinuclear cluster compounds. Thus, reaction of [Pt(COD)2] with 1 or 2 and subsequent addition of GaCp* yields [Pt2(GaCp*)2(μ2-GaCp*)3] (4a) and [PtPd(GaCp*)(μ2-GaCp*)3] (5a). Intermediates of this dimerization reactions, i.e., [Pt2(GaCp*)(μ2-GaCp*)3(η2-COD)] (4b) and [PtPd(GaCp*)(μ2-GaCp*)3(η2-COD)] (5b), were isolated and characterized by means of variable-temperature NMR spectroscopy.

Herein we describe the first phosphine-substituted transition metal complexes with terminal coordinated Cp*E ligands (E ) Al, Ga; Cp* ) pentamethylcyclopentadienyl). The reaction of [(dcpe)Pt(H)(CH 2 t-Bu)] (dcpe ) bis(dicyclohexylphosphino)ethane) with Cp*E yields the tetrahedrally coordinated complexes [(dcpe)Pt(AlCp*) 2 ] (1) and [(dcpe)Pt(GaCp*) 2 ] (2), respectively. Quantum-chemical DFT calculations on the model complexes [(dhpe)Pt-(AlCp) 2 ] (1M) and [(dhpe)Pt(GaCp) 2 ] (2M; dhpe ) diphosphinoethane) verify rather weak Pt-E bonds for both complexes. A comparison with the complexes [M(ER) 4 ] and [(CO) n M-ER] shows that Cp*E represents a moderate σ-donor/π-acceptor and that the bond strength is strongly influenced by the ancillary ligands at the transition metal center; in particular, (CO) n M fragments give more polar bonds than phosphine-substituted metal centers such as L 2 Pt.

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Two new triynes, C6Me3-1,3,5-[CH2O(p-C6H4)C⋮CH]3 (3) and C6Me3-1,3,5-[CH2O(p-C6H4)PhC(OH)C⋮CH]3 (5), have been prepared and used for the facile synthesis of several tris(vinylideneruthenium) and tris(allenylideneruthenium) complexes via metal-mediated activation and tautomerization or isomerization and dehydration of the alkyne moieties, respectively. Complexes C6Me3-1,3,5-{[CH2O(p-C6H4)CHCRu(dppe)2Cl]BF4}3 (6) and C6Me3-1,3,5-{[CH2O(p-C6H4)PhCCCRu(dppe)2Cl]BF4}3 (8) were obtained by activation of 3 and 5 by [RuCl(dppe)2]BF4. C6Me3-1,3,5-[CH2O(p-C6H4)CHCRu(PCy3)2Cl2]3 (7) and C6Me3-1,3,5-{[CH2O(p-C6H4)PhCCCRu(PCy3)(p-cymene)Cl]OTf}3 (9) resulted from the reaction of 3 with [RuCl2(p-cymene)]2/2PCy3 and of 5 with [RuCl(PCy3)(p-cymene)]OTf.