Preparation of cyclopentadienyl molybdenum clusters linked by a cyclotetradeca-1,8-diyne ligand

Abstract

The diyne-bridged complexes Cp 2Mo 2(CO) 4(μ-η 2-C 14H 20) ( 1) and [Cp 2Mo 2(CO) 4] 2(μ,μ-η 2,η 2-C 14H 20) ( 2) have been prepared from the reactions of cyclotetradeca-1,8-diyne (C 14H 20) with Cp 2Mo 2(CO) 6 in refluxing toluene, or with Cp 2Mo 2(CO) 4 at 25°C. In contrast, Cp 2Mo 2(CO) 6 reacts with Ag +BF 4 − and C 14H 20 to yield [CpMo +(CO)(μ,μ-η 2,η 2-C 14H 20)] 2(BF 4 −) 2 ( 3-BF4) through redox cleavage of the MoMo bond. An alternative method to prepare 3-BF4 is via iodide abstraction of CpMoI(CO) 3 by Ag +BF 4 − in the presence of C 14H 20. Compound 3-BF4 reacts with Me 3NO in acetonitrile to afford [CpMo +(NCMe)(μ,μ-η 2,η 2-C 14H 20)] 2(BF 4 −) 2 ( 4-BF4). An alkynealkyne coupling reaction is achieved by treating 3-BF4 with PPN +Cl − to yield the cyclobutadienophane complex CpMo(CO)Cl(η 4-C 4(C 10H 20)) ( 5). Metathesis of 3-BF4 with Na +BPh 4 − gives [CpMo +(CO)(μ,μ-η 2,η 2-C 14H 20)] 2(BPh 4 −) 2 ( 3-BPh4), the crystal structure of which was determined by X-ray diffraction.