Hexagonal Planar [B<sub>6</sub>H<sub>6</sub>] within a [B<sub>6</sub>H<sub>12</sub>] Borate Complex: Structure and Bonding of [(Cp*Ti)<sub>2</sub>(μ‐ɳ<sup>6</sup> : ɳ<sup>6</sup>‐B<sub>6</sub>H<sub>6</sub>)(μ‐H)<sub>6</sub>]
Sourav Kar, Subhash Bairagi, Anagha Haridas, Gaurav Joshi, Eluvathingal D. Jemmis, Sundargopal Ghosh
Abstract
Abstract Isolation of planar [B 6 H 6 ] is a long‐awaited goal in boron chemistry. Several attempts in the past to stabilize [B 6 H 6 ] were unsuccessful due to the domination of polyhedral geometries. Herein, we report the synthesis of a triple‐decker sandwich complex of titanium [(Cp*Ti) 2 (μ‐η 6 : η 6 ‐B 6 H 6 )(μ‐H) 6 ] ( 1 ), which features the first‐ever experimentally achieved nearly planar six‐membered [B 6 H 6 ] ring, albeit within a [B 6 H 12 ] borate. The small deviation from planarity is a direct consequence of the predicted structural pattern of the middle ring in 24 Valence Electron Count (VEC) triple‐decker complexes. The large ring size of [B 6 H 6 ] in 1 brings the metal–metal distance into the bonding range. However, significant electron delocalization from the M−M bonding orbital to the bridging hydrogen and B−B skeleton in the middle decreases its bond strength.