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

The diyne-bridged complexes Cp2Mo2(CO)(4)(mu-eta(2)-C14H20) (1) and [Cp2Mo2 (CO)(4)](2)(mu,mu-eta(2),eta(2)-C14H20) (2) have been prepared from the rea ctions of cyclotetradeca-1,8-diyne (C14H20) with Cp2Mo2(CO)(6) in refluxing toluene, or with Cp2Mo2(CO)(4) at 25 degrees C. In contrast, Cp2Mo2(CO)(6) reacts with Ag+ BF4- and C14H20 to yield [CpMo+(CO)(mu,mu-eta(2),eta(2)-C1 4H20)](2)(BF4-)(2) (3-BF4) through redox cleavage of the Mo-Mo bond. An alt ernative method to prepare 3-BF4 is via iodide abstraction of CpMoI(CO)(3) by Ag+BF4- in the presence of C14H20. Compound 3-BF4 reacts with Me3NO in a cetonitrile to afford [CpMo+ (NCMe)(mu,mu-eta(2),eta(2)-C14H20)](2)(BF4-)(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(eta(4)-C- 4(C10H20)) (5). Metathesis of 3-BF4 with Na+BPh4- gives [CpMo+ (CO)(mu,mu-e ta(2),eta(2)-C14H20)](2)(BPh4-)(2) (3-BPh4), the crystal structure of which was determined by X-ray diffraction. (C) 1999 Elsevier Science S.A. All ri ghts reserved.