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Synthesis and Characterization of Free and Coordinated 1,2,3-Tripnictolide Anions

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posted on 08.04.2013, 00:00 by Robert S. P. Turbervill, Andrew R. Jupp, Phillip S. B. McCullough, Doruk Ergöçmen, Jose M. Goicoechea
We have investigated the chemical reactivity of heptaatomic anionic clusters of the group 15 elements ([E7]3–/[HE7]2–, E = P, As) toward the symmetric and asymmetrically substituted alkynes diphenylacetylene and phenylacetylene. The results reported herein, alongside a previous report on the reactivity of such clusters toward acetylene, describe a versatile route by which to access otherwise elusive 1,2,3-tripnictolide anions of the general formula [E3C2RR′] (R = R′ = H, E = P (1), As (2); R = R′ = C6H5, E = P (3) As (4); R = H, R′ = C6H5, E = P (5), As (6)). These species can be isolated as [K­(18-crown-6)]+ or [K­(2,2,2-crypt)]+ salts. All anions were characterized by multielement NMR spectroscopy and electrospray mass spectrometry. In addition, single-crystal X-ray diffraction structures of the novel species [K­(18-crown-6)­(THF)2]­[3], [K­(2,2,2-crypt)]­[4xTHF (x = 0, 0.5), and [K­(18-crown-6)­THF]­[6] were also obtained. The chemical reactivity of these group 15 cyclopentadienyl analogues has been explored in a series of ligand displacement reactions with Mo­(CO)3(L)3 (L = CO, CH3CN) to yield the complex anions [(η5-E3C2H2)­Mo­(CO)3] (E = P (7), As (8)), [{η5-E3C2(C6H5)2}­Mo­(CO)3] (E = P (9), As (10)), and [{η5-E3C2H­(C6H5)}­Mo­(CO)3] (E = P (11), As (12)).