Trithia-diborinane and Bis(bridging-boryl) Complexes of Ruthenium Derived from a [BH(SCHS)] Ion.

The field of diborinane is sparsely explored area, and not many compounds are structurally characterized. The room-temperature reaction of [{Cp*RuCl(μ-Cl)}] (Cp* = η-CMe) with Na[BH(SCHS)] yielded ruthenium dithioformato [{Cp*Ru(μ,η-SCHS)}], 1, and 1-thioformyl-2,6-tetrahydro-1,3,5-trithia-2,6-diborinane complex, [(Cp*Ru){(η-SCHS)CHS(BH)}], 2. To investigate the reaction pathway for the formation of 2, we carried out the reaction of [(BH)(CHS)], 3, with 1 that yielded compound 2. To the best of our knowledge, it appears that compound 2 is the first example of a ruthenium diborinane complex where the central six-membered ring [CBS] adopts the chair conformation. Furthermore, room temperature reaction of 1 with [BH·thf] resulted in the isolation of agostic-bis(σ-borate) complex, [Cp*Ru(μ-H)BH(S-CH═S)], 4. Thermolysis of 4 with trace amount of tellurium powder led to formation of bis(bridging-boryl) complex, [{Cp*Ru(μ,η-HBSCH)}], 5, via dimerization of 4 followed by dehydrogenation. Compound 5 can be considered as a bis(bridging-boryl) species, in which the boryl units are connected to two ruthenium atoms. Theoretical studies and chemical bonding analyses demonstrate the reason for exceptional reactivity and stability of these complexes.