Heterometallic Triply‐Bridging <i>Bis‐</i>Borylene Complexes
Ranjit Bag, Sourav Kar, Suvam Saha, Suman Gomosta, Beesam Raghavendra, Thierry Roisnel, Sundargopal Ghosh
Abstract
Abstract Triply‐bridging bis‐ {hydrido(borylene)} and bis‐ borylene species of groups 6, 8 and 9 transition metals are reported. Mild thermolysis of [Fe 2 (CO) 9 ] with an in situ produced intermediate, generated from the low‐temperature reaction of [Cp*WCl 4 ] (Cp*= η 5 ‐C 5 Me 5 ) and [LiBH 4 ⋅THF] afforded triply‐bridging bis ‐{hydrido(borylene)}, [( μ 3 ‐BH) 2 H 2 {Cp*W(CO) 2 } 2 {Fe(CO) 2 }] ( 1 ) and bis ‐borylene, [( μ 3 ‐BH) 2 {Cp*W(CO) 2 } 2 {Fe(CO) 3 }] ( 2 ). The chemical bonding analyses of 1 show that the B−H interactions in bis ‐{hydrido (borylene)} species is stronger as compared to the M−H ones. Frontier molecular orbital analysis shows a significantly larger energy gap between the HOMO‐LUMO for 2 as compared to 1 . In an attempt to synthesize the ruthenium analogue of 1 , a similar reaction has been performed with [Ru 3 (CO) 12 ]. Although we failed to get the bis‐ {hydrido(borylene)} species, the reaction afforded triply‐bridging bis ‐borylene species [( μ 3 ‐BH) 2 {WCp*(CO) 2 } 2 {Ru(CO) 3 }] ( 2′ ), an analogue of 2 . In search for the isolation of bridging bis ‐borylene species of Rh, we have treated [Co 2 (CO) 8 ] with nido ‐[(RhCp*) 2 (B 3 H 7 )], which afforded triply‐bridging bis ‐borylene species [( μ 3 ‐BH) 2 (RhCp*) 2 Co 2 (CO) 4 ( μ ‐CO)] ( 3 ). All the compounds have been characterized by means of single‐crystal X‐ray diffraction study; 1 H, 11 B, 13 C NMR spectroscopy; IR spectroscopy and mass spectrometry.