• Rongala Ramalakshmi

      Articles written in Journal of Chemical Sciences

    • Dimetallaheteroborane clusters containing group 16 elements: A combined experimental and theoretical study

      Kiran Kumarvarma Chakrahari Rongala Ramalakshmi Dudekula Sharmila Sundargopal Ghosh

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      Recently we described the synthesis and structural characterization of various dimetallaherteroborane clusters, namely nido-[(CpMo)2B4ECl$_x$H$_{6−x}$], 1-3; (1: E = S, x = 0; 2: E = Se, x = 0; 3: E = Te, x = 1). A combined theoretical and experimental study was also performed, which demonstrated that the clusters 1-3 with their open face are excellent precursors for cluster growth reaction. In this investigation process on the reactivity of dimetallaheteroboranes with metal carbonyls, in addition to [(CpMo)2B4H6EFe(CO)3] (4: E = S, 6: E = Te) reported earlier, reaction of 2 with [Fe2(CO)9] yielded mixed-metallaselenaborane [(CpMo)2B4H6SeFe(CO)3], 5 in good yield. The quantum chemical calculation using DFT method has been carried out to probe the bonding, NMR chemical shifts and electronic properties of dimolybdaheteroborane clusters 4-6.

    • Reactivity of [Cp*Mo(CO)₃Me] with chalcogenated borohydrides Li[BH₂E₃] and Li[BH₃EFc] (Cp* = (ŋ⁵-C₅Me₅); E = S, Se or Te; Fc = (C₅H₅-Fe-C₅H₄))


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      Reactivity of [Cp*Mo(CO)₃Me], 1 with various chalcogenide ligands such as Li[BH₂E₃] andLi[BH₃EFc]] (E = S, Se or Te; Fc = (C₅H₅-Fe-C₅H&#8324)) has been described. Room temperature reaction of 1 with Li[BH₂E₃] (E = S and Se) yielded metal chalcogenide complexes [Cp*Mo(CO)₂(ŋ2-S₂CCH3)], 2 and [Cp*Mo(CO)₂(ŋ1-SeC₂H₅)], 3. In compound 2, {Cp*Mo(CO)2} fragment adopts a four-legged piano-stool geometry with a η2-dithioacetate moiety. In contrast, treatment of 1 with Li[BH3(EFc)] (E = S, Se or Te; Fc = C₅H₅-Fe-C₅H₄) yielded borate complexes [Cp*Mo(CO)₂(μ-H)(μ-EFc)BH₂], 4-6 in moderate yields. Compounds 4-6 are too unstable and gradual conversion to [{Cp*Mo(CO)₂}₂(μ-H)(μ-EFc] (7: E = S; 8: Se) and [{Cp*Mo(CO)₂}₂(μ-TeFc)₂], 9 happened by subsequent release of BH₃. All the compounds have been characterized by mass spectrometry, IR, multinuclear NMR spectroscopy and structures were unequivocally established by crystallographic analysis for compounds 2, 3 and 7.

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