Reactivity of cationic molybdenum(II) complexes. Part 3. Synthesis of methoxide and carbomethoxide derivatives of -pentamethylcyclopentadienyl–molybdenum(II) and the crystal structure determination of the oxidation product trans-[{Mo(-C5Me5)(O)2}2(µ-O)]

The complex [Mo(CO)3(η-C5Me5){P(OMe)3}]BF4 (1) reacts in methanol solution with Na(OMe) to give a mixture of cis- and trans-[Mo(CO)2(η-C5Me5){P(OMe)3}(CO2Me)](3). Compound (3) decarbonylates at room temperature in various solvents giving a mixture of cis- and trans-[Mo(CO)2(η-C5Me5){P(OMe)3}(OMe)] (4). The complex [Mo(CO)3(η-C5Me5)] BF4 (2) reacts in methanol solution with Na(OMe) affording the insoluble complex [{Mo(CO)2(η-C5Me5)(OMe)}n] (5) which is monomerized by reaction with P(OMe)3 in refluxing tetrahydrofuran (thf); trans-(4) is the main product of this reaction. Oxidation of a thf suspension of [{Mo(CO)2(η-C5Me5)(OMe)}n] by oxygen gives the Mo(VI) derivative [{Mo(η-C5Me5)(O)2}2(µ-O)] (6), together with unidentified products. The X-ray crystal structure of (6) has been established: (6) is monoclinic, space group P21/a, a= 17.677(6), b= 9.248(1), c= 21.272(6)Å, β= 101.68(2)°, Z= 6.