Nucleophilic and electrophilic reactions of C 5cyclo-polyenes coordinated to the [CpMoL 2] n+ fragment ( n = 1,2; L = 1/2dppe, PMe 3, P(OMe) 3, CO)

Abstract

Reaction of several nucleophiles (R −) with the dications [Cp 2MoL 2] 2+ (L = CO, PMe 3, dppe) produces the cyclopentadiene complexes [CpMo( η 4-C 5H 5R)L 2] + (L = dppe, R = H, CH 3, CH 2CN, CH 2PPh 3, SMe; L = CO, R = H, CH 3, SPh, PMe 3; L = PMe 3, R = H). Excess nucleophiles only produces regio and stereospecific double addition to one Cp ring in the case of H − forming CpMo( η 3-C 5H 7)L 2 (L = CO, PMe 3, dppe). [CpMo( η 4-C 5H 6)L 2] + reacts with LiCuMe 2 to give CpMo( η 3-C 5H 6Me)L 2 (L = dppe, CO) and [Cp′Mo( η 4-C 5H 6)(CO) 2] + reacts with NaSPh and PMe 3 to give Cp′Mo( η 3-C 5H 6SPh)(CO) 2 (Cp′ = Cp, indenyl) and [CpMo( η 3-C 5H 6PMe 3)(CO) 2]BF 4 respectively. The structure of the exclusively formed conformers endo-[CpMo( η 4-C 5H 6)(dppe)]PF 6 and endo-CpMo( η 3-C 5H 7)(dppe) was determined by NMR and X-ray crystallography and analyzed by EHMO calculations. The reverse H − abstractions from [CpMo( η 4-C 5H 6)L 2] + and CpMo( η 3-C 5H 7)L 2 with Ph 3C + are specific in all cases except for CpMo( η 3C 5H 7)(dppe) which gives oxidative decomposition to [Cp 2Mo(dppe)] 2− and [CpMo(dppe) 2] 2+. All the complexes [CpMo( η 4-C 5H 5R)L 2] + and CpMo( η 3-C 5H 7)L 2 (L = CO 1, PMe 3, dppe) as well as their C6 ring congeners [CpMo( η 4-C 6H 8)(CO) 2] + and CpMo( η 3-C 6H 9)(CO) 2 have irreversible cyclovoltammograms. Nucleophilic attacks of Me 3NO/NCMe and PMe 3 to [CpMo( η 4-C 6H 8)(CO) 2] + gave [CpMo( η 4-C 6H 8)(NCMe) 2]BF 4 and [CpMo( η 3-C 6H 8PMe 3)(CO) 2]BF 4 respectively. Both were crystallographically characterized.