STUDY ON THE REACTION OF THE (MU(3)-CPH)CO-3(CO)(9) CLUSTER WITH NAM(CO)(3)(ETA(5)-RCOCP) - SYNTHESIS, CHARACTERIZATION AND CRYSTAL-STRUCTURES OF THE HETERO-NUCLEAR TRIMETAL CARBONYL CLUSTERS (MU(3)-CPH)CO(2)M(CO)(8)(ETA(5)-RCOCP) (M=MO,W, R=H, CH3, C2H5O)

Six mu(3)-benzylidyne trimetal carbonyl clusters (mu(3)-CPh)Co(2)M(CO) (8)(eta(5)-RCOCp) (2a: M=Mo, R=H; 3a: M=Mo, R=CH3; 4a: M = Mo, R = C2H 5O; 2b: M = W, R = H; 3b: M = W, R = CH3; 4b: M = W, R = C2H5O) were o btained by refluxing a solution of the precursor (mu(3)-CPh)Co-3(CO)(9 ) with the metal exchange reagents NaM(CO)(3)(eta(5)-RCOCp) in THF. Th e results show that the electron-withdrawing groups RCO on cyclopentad ienyl affected the activity of the metal exchange reagents NaM(CO)3(et a(5)-RCOCp) and the above reactions were accelerated thermally. The re sults further show that the met al carbonyl unit Co(CO) 3 in the precu rsor PhCCo(3)(CO)9 could be exchanged by organometallic groups M(CO)(2 )(RCOCp). The clusters were characterized by C/H analysis, IR and H-1 NMR, and crystal structure determinations of clusters 3a and 4a. The c rystals of 3a are triclinic with space group <P(1)over bar>, a = 13.63 1(4), b = 14.563(4), c = 14.684(6) Angstrom, alpha = 116.36(2), beta = 106.82(2), gamma = 100.58(2)degrees, V = 2328 Angstrom(3) and Z = 4; final R and Rw = 0.052 and 0.061 for 8552 reflections. The crystals of 4a are monoclinic with space group P2(1)/c, a = 11.356(2), b = 14.030 (2), c = 16.076(3) Angstrom, gamma = 107.19(1)degrees, V = 2446.8(7) A ngstrom(3) and Z = 4; final R and R(w) = 0.048 and 0.057 for 4751 refl ections.