Synthesis of tetrahedral heteronuclear MoCoFe(μ3-E) (E = S, Se) clusters via isolobal displacement and functional transformation reactions.: The crystal molecular structure of η5-MeCOC5H4MoCoFe(μ3-se)(CO)8

The dppe-bridged Mo-Mo singly-bonded dimers (mu-dPPe)(eta(5)-RC5H4)(2)Mo-2(CO)(4) (dppe =Ph2PCH2CH2PPh2; 1a, R=H; 1b, R = MeCO; 1c, R=MeO2C) prepared by reaction of Mo-Mo triply-bonded dimers (eta(5)-RC5H4)(2)(CO)(2)Mo-2(CO)(4) and dppe, reacted with mu(3)-Se cluster Co2Fe(mu(3)-Se)(CO)(9) to give single clusters eta(5)-RC5H4MoCoFe(mu(3)-Se)(CO)(8) (2a, R=H; 2b, R=MeCO; 2c, R=MeO2C), whereas the disodium salt [(mu-dppe)(eta(5)-MeO2CC5H4)(2)Mo-2(CO)(4)]Na-2 (3) prepared by reaction of 1c and 1% Na/Hg, reacted with mu(3)-S cluster Co2Fe(mu(3)-S)(CO)(9) to afford single cluster eta(5)-MeO2CC5H4MoCoFe(mu(3)-S)(CO)(8) (4) and double cluster (mu-dppe)[(eta(5)-MeO2CC5H4MoCoFe(mu(3)-S) (5). Further treatment of 2b with NaBH4 gave a single cluster containing hydroxyl group eta(5)-MeCH(OH)C5H4MoCoFe(mu(3)-Se)(CO)(8) (6), which reacted with Et3OBF4 to give single cluster eta(5)-MeCH(OEt)C5H4MoCoFe(mu(3)-Se)(CO)(8) (7) and double cluster [eta(5)-C5H4CH-(Me)O(Me)CHC5H4-eta(5)][MoCoFe(mu(3)-Se)(CO)(3)](2) (8) both containing ether functionality. All the new clusters have been characterized by elemental analysis and spectroscopic methods, as well as by X-ray diffraction analysis for cluster 2b. (C) 1998 Elsevier Science Ltd. All rights reserved.