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

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.

Thermolysis of dithiamolybdaborane [(Cp*Mo)2B4H4S2] (Cp* = η5-C5Me5) with [Fe2(CO)9] afforded hypoelectronic eleven vertex cluster [(Cp*Mo)2B4H2S2Fe4(CO)9(μ-CO)], that possess a closo geometry based on tricapped square antiprism. Similarly, reaction of [(Cp*Mo)2B4H4Se2 Fe(CO)2Fe(CO)3] with [Co2(CO)8] yielded eleven vertex dimolybdaheteroborane cluster [(Cp*Mo)2B3H2Se2Co(CO)(μ-CO)3{Fe4(CO)7}], which is isostructural with the sulfur analog (See picture).Figure optionsDownload as PowerPoint slideHighlights
► [(Cp*Mo)2B4H4S2] on reaction with metal carbonyls yielded higher nuclearity clusters.
► 11-vertex hypoelectronic dimolybdaheteroborane clusters has been isolated.
► Geometry of these complexes derived using DSD rearrangement.