Metal‐Stabilized [B 8 H 8 ] 2− Derivatives with Dodecahedral Structure in the Solid and Solution States: [(Cp 2 MBH 3 ) 2 B 8 H 6 ] (Cp=η 5 ‐C 5 H 5 ; M=Zr (1‐Zr) and Hf (1‐Hf)).

Kar, Sourav ; Bairagi, Subhash ; Joshi, Gaurav ; Jemmis, Eluvathingal D. ; Ghosh, Sundargopal (2021) Metal‐Stabilized [B 8 H 8 ] 2− Derivatives with Dodecahedral Structure in the Solid and Solution States: [(Cp 2 MBH 3 ) 2 B 8 H 6 ] (Cp=η 5 ‐C 5 H 5 ; M=Zr (1‐Zr) and Hf (1‐Hf)). Chemistry - A European Journal . ISSN 0947-6539

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Official URL: http://doi.org/10.1002/chem.202102832

Related URL: http://dx.doi.org/10.1002/chem.202102832

Abstract

Despite the synthesis and structural characterization of closo-hydroborate dianions, [BnHn]2− (n=6–12) more than 50 years ago, some ambiguity remains about the structure of [B8H8]2−. Although the solid-state structure of [B8H8]2− was established by single-crystal X-ray studies in 1969, fast rearrangements in solution at accessible temperatures prevented its detailed characterization. We therefore stabilized a derivative of [B8H8]2− by using Cp2MBH3 and structurally characterized two new octaborane analogues, [(Cp2MBH3)2B8H6] (Cp=η5-C5H5; M=Zr (1-Zr) and Hf (1-Hf)), so that the dynamics of the B8 skeleton were arrested. The solid-state structures of both 1-Zr and 1-Hf comprise a dodecahedron core protected by {Cp2MBH3} moieties on both sides of the cluster. Spectroscopic characterization (11B NMR) validates the intactness of the B8 dodecahedron core in solution as well. Theoretical calculations establish that the two exo-{Cp2MBH3} fragments provide structural and electronic structural stability to the B8 core and its intact dodecahedral dianionic nature. Furthermore, we propose isodesmic equations for the formation of higher analogues of the Bn core (n>8) guarded by different group 4 transition metals. Our analysis suggests that, as we move to higher polyhedra (n>10), the formation becomes unfavourable irrespective of metal.

Item Type:Article
Source:Copyright of this article belongs to John Wiley & Sons, Inc.
ID Code:123766
Deposited On:13 Oct 2021 07:12
Last Modified:13 Oct 2021 07:12

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