J. Iran. Chem. Soc., Vol. 7, No. 4 December 2010, pp.864~874.

Current location: JICS Archive > Vol. 7 > No. 4 > Articles : 11

Very Strong Centrosymmetric [O...H...O]+ and Asymmetric [O-H…O]+ Hydrogen Bonds In a New POM-Based Hybrid Material

M. Pourayoubia,b and A.R. Mahjoubb,*

aDepartment of Chemistry, Ferdowsi University of Mashhad, Mashhad, 91779, Iran
bDepartment of Chemistry, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran

A specific assembly process, driven by coexisting X-H…O hydrogen bonding and X…O short intermolecular contacts (X = C, N, O) is described, in which the pseudo-Keggin polyoxoanion and two types of molecule...cation pairs (with C1 and Ci symmetries) were assembled to the programmed supramolecular architecture. Cooperation of the positive-charge, resonance effect and the O=C…Oterminal intermolecular contact led to the short and strong symmetrical [O…H…O]+ hydrogen bond (O…O = 2.449(13) Å) in one of the molecule…cation pairs [C4H9NO…H…ONC4H9]+ with the H-bonded proton in the center of inversion. The other [C4H9NOH…ONC4H9]+ molecule…cation pair (non-centrosymmetric) was formed through a very strong asymmetric [O.H.O]+ hydrogen bond of 2.431(13) Å in length which was created via the synergistic effect between the minor N-H…O secondary interaction, +CAHB (positive-charge-assisted hydrogen bond) and RAHB (resonance assisted hydrogen bond) mechanisms.

Keywords: Strong hydrogen bond, Crystal structure, Organic/inorganic hybrid, Polyoxometalate

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