Heterometallic complexes and clusters with 2-boratanaphthalene ligands

Abstract

The new lithium (2-boratanaphthalene)tricarbonylmolybdates Li[Mo(RBn)(CO)₃] (Bn = η⁵-C₁₀H₉B; R = NiPr₂, Me) have been prepared and used as nucleophilic reagents for the synthesis of metal–metal bonded complexes and clusters. Dinuclear [(iPr₂NBn)(OC)₃Mo–Au(PPh₃)] (7) and trinuclear [Hg{Mo(CO)₃(iPr₂NBn)}₂] (9) and [Ag{Mo(CO)₃(iPr₂NBn)}{Mo(CO)₃[(iPr₂HN)Bn]}] (13) chain complexes have been obtained in which the metalate behaves as an anionic two-electron donor metalloligand. In 13, the other metal carbonyl fragment consists of an N-protonated (2-boratanaphthalene)tricarbonylmolybdenum fragment and acts therefore as a neutral, two-electron donor. In the 58-cluster valence electron planar, triangulated cluster [Mo₂Pd₂(MeBn)₂(CO)₆(PEt₃)₂] (15), the [Mo(MeBn)(CO)₃]⁻ fragment is however best viewed as a four-electron donor metalloligand bridging the Pd–Pd bond. These bonding situations are compared with those observed in complexes prepared from the metalate [MoCp(CO)₃]⁻ (Cp = η⁵-C₅H₅) and this establishes experimentally the isoelectronic and isolobal character of the [Mo(MeBn)(CO)₃]⁻ and [MoCp(CO)₃]⁻ fragments. The crystal structures of complexes 7, 9, 13 and 15 have been determined by X-ray diffraction.