From Metallaborane to Borylene Complexes: Syntheses and Structures of Triply Bridged Ruthenium and Tantalum Borylene Complexes |
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| Authors: | K Geetharani Shubhankar Kumar Bose Babu Varghese Dr Sundargopal Ghosh |
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| Institution: | 1. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036 (India), Fax: (+91)?44‐2257‐4202;2. Sophisticated Analytical Instruments Facility, Indian Institute of Technology Madras, Chennai 600 036 (India) |
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| Abstract: | Reaction of 1,2‐(Cp*RuH)2B3H7] ( 1 ; Cp*=η5‐C5Me5) with Mo(CO)3(CH3CN)3] yielded arachno‐(Cp*RuCO)2B2H6] ( 2 ), which exhibits a butterfly structure, reminiscent of 7 sep B4H10. Compound 2 was found to be a very good precursor for the generation of bridged borylene species. Mild pyrolysis of 2 with Fe2(CO)9] yielded a triply bridged heterotrinuclear borylene complex (μ3‐BH)(Cp*RuCO)2(μ‐CO){Fe(CO)3}] ( 3 ) and bis‐borylene complexes {(μ3‐BH)(Cp*Ru)(μ‐CO)}2Fe2(CO)5] ( 4 ) and {(μ3‐BH)(Cp*Ru)Fe(CO)3}2(μ‐CO)] ( 5 ). In a similar fashion, pyrolysis of 2 with Mn2(CO)10] permits the isolation of μ3‐borylene complex (μ3‐BH)(Cp*RuCO)2(μ‐H)(μ‐CO){Mn(CO)3}] ( 6 ). Both compounds 3 and 6 have a trigonal‐pyramidal geometry with the μ3‐BH ligand occupying the apical vertex, whereas 4 and 5 can be viewed as bicapped tetrahedra, with two μ3‐borylene ligands occupying the capping position. The synthesis of tantalum borylene complex (μ3‐BH)(Cp*TaCO)2(μ‐CO){Fe(CO)3}] ( 7 ) was achieved by the reaction of (Cp*Ta)2B4H8(μ‐BH4)] at ambient temperature with Fe2(CO)9]. Compounds 2 – 7 have been isolated in modest yield as yellow to red crystalline solids. All the new compounds have been characterized in solution by mass spectrometry; IR spectroscopy; and 1H, 11B, and 13C NMR spectroscopy and the structural types were unequivocally established by crystallographic analysis of 2 – 6 . |
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| Keywords: | borylenes manganese metallaboranes ruthenium tantalum |
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