Complexes of CO₂, COS, and CS₂ with the Super Lewis Acid BH₄⁺ Contrasted with Extremely Weak Complexations with BH₃:  Theoretical Calculations and Experimental Relevance¹

Abstract

Structures and energies of the complexes of CO2, COS, and CS2 with BH4 +, a super Lewis acid (1−4a), were calculated with the density functional theory (DFT) at the B3LYP/6-311+G** level. Each of the complexes 1−4a contains a hypercoordinate boron with a three-center two-electron (3c-2e) bond. Formation of 1−4a from the complexation of CO2, COS, and CS2 with BH4 + was calculated to be exothermic by 26−42 kcal/mol. At the same B3LYP/6-311+G** level calculations indicate that complexation of CO2, COS, and CS2 with neutral BH3 leads only to very weak complexes (1−4c) with relatively long B−O or B−S bonds. The computational results shed new light on related experimental studies of the ready and extremely mild superacid induced ionic hydrogenation of CO2, COS, and CS2 with NaBH4 to methane.

Ab initio /GIAO-MP2-calculated structures and 11 B- 13 C NMR chemical shift relationship in hypercoordinate onium-carbonium dications and isoelectronic onium-boronium cations

“…The structures 1-10a can also be considered as onium-boronium ions. The MP2͞6-311ϩG**-calculated structures of 9a and 10a agree well with the recently reported density functional theory B3LYP͞6-311ϩG**-calculated structures (16). We have also recently reported (17) the structures of 7a and 8a calculated at the MP2͞6-311ϩG** level.…”

Reactions of superelectrophilic BH2+, BCl2+ and AlCl2+ with carbonyl compounds and alkenes1

“…3 In contrast to the reactive methyl cation, the exothermicity of the reactions with BH 2 + was found to be moderate and the energy profiles of the reactions were found to be well defined. 3 Recently we reported 6 the calculated structures of the complexes of CO 2 , COS and CS 2 with superelectrophilic 7 BH 4 + species. BH 4 + can be obtained in the gas phase by reacting BH 2 + and H 2 .…”

“…2,3 Complexations of CO 2 , COS and CS 2 with BH 4 + were calculated to be exothermic in the range of 26-42 kcal/mol. 6 However, similar complexations of CO 2 , COS and CS 2 with neutral BH 3 lead to very weak complexes with long B-O or B-S bonds. It is indicated that the BH 4 + complexes are significantly activated compared with their parents and readily undergo ionic hydrogenation.…”

“…It is indicated that the BH 4 + complexes are significantly activated compared with their parents and readily undergo ionic hydrogenation. 6 Similar to BH 4 + , superelectrophilic BH 2 + also should be significantly more reactive than Lewis acidic BH 3 . In continuation of our work we now report investigation of the reactions of BH 2 + with some carbonyl compounds (formaldehyde, acetaldehyde) and alkenes (ethene, propene) by the density functional theory (DFT) method.…”

Chemisorption of BH3 and BF3 on aluminum nitride nanocluster: quantum-chemical investigations

“…They are drab gases that are famous as substantial reagents in reaction pathway [1,2]. In addition, they are known as significant Lewis acids (because of the electron deficiency of boron atom in their compounds) and general construction blocks for further boron complexes.…”