Structures,energetics, and isomerism of [Be,C,O,S]: Stability of triply bonded sulfur

Multiply bonded sulfur has continued to attract attention both experimentally and theoretically. Triply sulfur‐bonded compounds are still rare, due to either the lack of suitable generation precursors or the conversion instability toward doubly sulfur‐bonded structures. A detailed computational study was performed on the structures and stability of various [Be,C,O,S] isomers at the coupled cluster singles doubles (triple excitations) (CCSD(T))/aug‐cc‐pVTZ//B3LYP/6‐311+G(d)+ZPVE level to predict intrinsically stable isomers with triply bonded sulfur. The molecular orbital, bond distance, and harmonic vibrational frequency analysis were carried out at aug‐cc‐pVTZ‐B3LYP, M06‐2X, and CCSD(T) levels to investigate the bonding nature of linear structures. It was shown that two low‐lying isomers are linear SBeCO 01 (0.0 kcal/mol) and SBeOC 02 (15.7 kcal/mol), both of which possess the SBe triple bonding. The Lewis acid–base association of SBe + CO can barrierlessly form 01 and 02, with the former more abundant, while the insertion reaction of SCO + Be might generate more 02 than 01 via photochemical processes. By contrast, formation of the SC‐bearing isomer SCBeO 04 (39.4 kcal/mol) seems unlikely due to its higher energy and less kinetic competition than that of 01 and 02, via either simple association or insertion reactions. The new stable isomers SBeCO 01 and SBeOC 02 add to the number of SBe triply bonded species. Their unique structures and varied branching ratios under association and insertion processes deserve future experimental study. © 2013 Wiley Periodicals, Inc.