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Synthesis of mono- and geminal dimetalated carbanions of bis(phenylsulfonyl) methane using alkali metal bases and structural comparisons with lithiated bis(phenylsulfonyl)imides

MacDougall, D J and Kennedy, A R and Noll, B C and Henderson, K W (2005) Synthesis of mono- and geminal dimetalated carbanions of bis(phenylsulfonyl) methane using alkali metal bases and structural comparisons with lithiated bis(phenylsulfonyl)imides. Dalton Transactions (12). pp. 2084-2091. ISSN 1472-7773

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Abstract

The alpha,alpha'-stabilized carbanion complexes [(PhSO2)(2)CHLi center dot THF] 1, [(PhSO2)(2)CHNa center dot THF] 2 and [(PhSO2)(2)CHK] 3 were prepared by the direct deprotonation of bis(phenylsulfonyl) methane I in THF with one molar equivalent of MeLi, BuNa and BnK respectively. The geminal dianionic complexes [(PhSO2)(2)CLi2 center dot THF] 4, [(PhSO2)(2)CNa2 center dot 0.55THF] 5 and [(PhSO2)(2)CK2] 6 were similarly prepared by the reaction of I with two molar equivalents of MeLi, BuNa and BnK respectively in THF. NMR and MS solution studies of 1 - 3 are consistent with the formation of charge-separated species in DMSO media. Solutions studies of 4 - 6, in conjunction with trapping experiments, indicate that the dianions deprotonate DMSO and regenerate the monoanions 1 - 3. Crystallographic analysis of 1 revealed a 1D chain polymer in which the metal centers are chelated by the bis( sulfonyl) ligands and connect to neighboring units through Li-O(S) interactions. An unexpected feature of 1 is that the polymeric chains are homochiral, since the chelating ligands of the backbone adopt the same relative configuration. Also, the phenyl substituents of each chelate in 1 are oriented in a cisoid manner. The sodium derivative 2 adopts a related solid-state structure, where enantiomeric pairs of chains combine to give a 1D ribbon motif. The lithium bis( phenylsulfonyl) imides [(PhSO2)(2)NLi center dot THF] 9 and [(PhSO2)(2)NLi center dot Pyr(2)] 10 were also prepared and structurally characterized. In the solid state 9 has a similar connectivity to that found for 1 but with heterochiral chains. In comparison, the more highly solvated complex 10 forms a 1D polymeric arrangement without chelation of the ligands and with the phenyl substituents oriented in a transoid fashion.