Abstract: | Reaction of MoCo(CO)5(PPh3)2(η5-C5H5)] (1) with diphenylacetylene in tetrahydrofuran at 50 °C yielded two heterobimetallic compounds, MoCo(CO)4.(PPh3){μ-PhC ? CPh}(η5-C5H5)] (4) and MoCo(CO)5{μ-PhC ? CPh} (η5-C5H5)] (5). However, an unexpected product, Co(CO)2(μ-CO)(μ:η2,η4-C4Ph4)Co(CO)2(PPh3) (6), was observed while attempting to grow the crystals for structural determination of 4. The X-ray crystal structure of 6 was determined: triclinic, $ {\rm P}\bar 1 $ , a = 11.654(2) Å, b = 12.864(2) Å, c = 13.854(2) Å, α = 89.67(2)°, β = 86.00(2)°, γ= 83.33(2)°, V = 2057.9(6) Å3 Z=2. In 6, two cobalt fragments are at apical and basal positions of the pseudo-pentagonal pyramidal structure, respectively. The electron count for the apical cobalt fragments is 20, which is rather unusual. It is believed that 6 was formed after the fragmentation and recombination of the fragmented species of 4. |