Synthesis and characterization of novel eleven-vertex dimetallaheteroborane clusters containing Heavier group 16 elements

Abstract

The thermolysis of [(Cp*Mo)₂B₄H₄S₂], 1 with [Fe₂(CO)₉] yielded eleven vertex dimolybdathiaborane cluster [(Cp*Mo)₂B₄H₂S₂Fe₄(CO)₉(μ-CO)], 2 together with cubane-type [(Cp*Mo)₂(μ₃-S)₂B₂H(μ-H){Fe(CO)₂}₂Fe(CO)₃], 3 and a fused cluster [(Cp*Mo)₂B₄H₄S₂ Fe₂(CO)₅], 4. In a similar fashion, thermolysis of [(Cp*Mo)₂B₄H₄Se₂], 5 with [Fe₂(CO)₉] yielded tetracapped pentagonal bipyramidal [(Cp*Mo)₂B₃H₃Se₂{Fe(CO) ₂}₂{Fe(CO)₃}₂], 6, and an incomplete cubane-type cluster [(Cp*Mo)₂BH(μ₃-Se)₂Fe₂(CO)₇], 7. In parallel with the formation of 6 and 7, clusters [(Cp*Mo)₂(μ₃-Se)₂B₂H(μ-H){Fe(CO) ₂}₂Fe(CO)₃], 8 and [(Cp*Mo)₂B₄ H₄Se₂Fe₂(CO)₅], 9 were obtained albeit in low isolated yields. Cluster 6 exhibits tetracapped pentagonal bipyramidal geometry, having 98 cluster valence electrons, appropriate for its geometric structure. The thermolysis of 9 in presence of [Co₂(CO)₈] led to the isolation of [(Cp*Mo)₂B₃H₂Se₂Co(CO)(μ-CO)₃{Fe₄(CO)₇}], 10. The structure analysis shows that both of the clusters 2 and 10 are based on 11-vertex closo-cage geometry and the core geometry of them can be derived from tricapped square antiprism by performing diamond-square-diamond (dsd) rearrangement. All new metallaheteroborane compounds have been fully characterized by various spectroscopic techniques and elemental analyses and the geometric structures were unequivocally established by crystallographic analysis of 2, 6, 7 and 10.