Ever since the founding work of Alfred Stock on borane chemistry, synthesis and characterization of polyhedral boranes have gained significant interest because of their unique structures, multi-centre
bonding features and three-dimensional aromaticity.[1] However, many boranes are experimentally unknown due to their instability. Many of these boranes are stabilized utilizing the coordination sphere of transition metals. For example, the solid-state structure of [B8H8]
2- was established by single-crystal X-ray studies in 1969; however, the fast rearrangements in solution at accessible temperatures prevented its detailed characterization.[2] We have stabilized a derivative of dodecahedral [B8H8]2-in solid and solution state by using Cp2MBH3 and structurally characterized octaborane analogues, [(Cp2MBH3)2B8H6] (Cp = η5-C5H5; M = Zr and Hf).[3] Further, we have synthesized the first-ever titanium supported planar hexagonal
borane [B6H6] ring, a structural analogue of benzene. Also, triborane and tetraborane are very rare. We have synthesized triborane and tetraborane analogues in the coordination sphere of tantalum from the reaction of [Cp*TaCl4] with four equivalents of Li[BH3(EPh)] (E = S or Se).[4] Furthermore, we have developed a novel route towards the synthesis of a series of cubane type clusters by using simple
chalcogenatoborate sources and investigated their intriguing structural and bonding features by means of DFT studies.
References:
[1] (a) A. Stock, in Hydrides of Boron and Silicon, Cornell University Press, Ithaca, NY, 1933. (b) J. D. Kennedy, Prog. Inorg.
Chem., 1986, 36, 211. (c) W. L. Lipscomb, in Boron Hydrides, Benjamin, New York, 1963. (d) S. Kar, S. Ghosh, Borane
Polyhedra beyond Icosahedron, in Structure and Bonding, Ed. D. M. P. Mingos; Springer, Berlin, Heidelberg, 2021,
https://doi.org/10.1007/430_2021_85. (e) S. Kar, A. N. Pradhan, S. Ghosh, Polyhedral Metallaboranes and
Metallacarboranes, in Comprehensive Organometallic Chemistry IV, Ed. K. Meyer, D. O’Hare, G. Parkin, S. Aldridge;
Elsevier, 2022.
[2] (a) F. Klanberg, D. R. Eaton, L. J. Guggenberger, E. L. Muetterties, Inorg. Chem. 1967, 6, 1271. (b) L. J. Guggenberger,
Inorg. Chem. 1969, 8, 2771.
[3] S. Kar, S. Bairagi, G. Joshi, E. D. Jemmis, S. Ghosh, Chem. Eur. J. 2021, 27, 15634.
[4] S. Kar, S. Bairagi, K. Kar, T. Roisnel, V. Dorcet, S. Ghosh, Eur. J. Inorg. Chem. 2021, 4443.
[5] (a) S. Kar, K. Saha, K. Bakthabachalam, V. Dorcet, S. Ghosh, Inorg. Chem. 2018, 57, 10896. (b) S. Kar, S. Bairagi, K. Saha,
B. Raghavendra, S. Ghosh, Dalton Trans. 2019, 48, 4203.