New triplet silylenes M–Si–M′–X along with some unusual cyclic forms (M = Li, Na, and K M′ = Be, Mg, and Ca X = F, Cl, and Br)

Authors : Samaneh ASHENAGAR, Mohamad Zaman KASSAEE

Pages : 974-987

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Comparison of 54 M-Si--M ′ ′ -X species is carried out using quantum mechanical ab initio and DFT computations at B3LYP/6-311 + + ++ G**, QCISDinsert ignore into journalissuearticles values(T);/6-311 + + ++ G**, and CCSDinsert ignore into journalissuearticles values(T);/6-311 + + ++ G** levels of theory insert ignore into journalissuearticles values(M = Li, Na, K; M ′ ′ = Be, Mg, Ca, and X = F, Cl, Br);. All triplet species with M = K appear more linear than their corresponding ones with Li and Na. The electronegativity reactivity descriptor for each halogen insert ignore into journalissuearticles values(X = F, Cl, Br); is used as a tool to evaluate the interrelated properties of these silylenes. Stability, assumed as singlet-triplet energy difference insert ignore into journalissuearticles values( Δ E S − T ); ΔES−T); for each series depends on the substituent`s electropositivity, analyzed by applying appropriate isodesmic reactions. Stability of triplet M--Si-M ′ ′ -X silylenes increases as functions of electropositivity of α α -substituents and of β β -substituents. The purpose of the present work was therefore to assess the influence of different di-alkaline metals with different β β -substituents on the singlet--triplet energy gaps.
Keywords : Triplet silylene, electropositivity, energy gaps, and substituent effects, multiplicity