Synthesis and structure of a sodium complex of an aromatic β-diketone and pyrazolylpyridine

Abstract

Reaction of NaH with a THF solution of Eu(BTA)3(pypzH) [BTA = 1-benzoyl-3,3,3-trifluoroacetonate, pypzH = 2-(3-pyrazolyl)pyridine] leads to the formation of the europium-free tetrasodium complex [Na4(pypzH) 2(μ4-BTA)2(μ2-BTA) 2]. Single-crystal X-ray diffraction studies revealed the presence of a centrosymmetric Na+ hybrid tetramer, which fully occupies the contents of the triclinic unit cell. The crystal structure contains two individual Na+ cations, Na(1) and Na(2), which have highly irregular {NaN2O3} and {NaO6} local coordination environments, respectively. One of the key features is the presence of a central {Na4O6} core, which is unprecedented for Na+. Externally to this {Na4O6} cluster pyrazolylpyridine organic molecules are N,N-chelated to Na(1). Even though all of the organic residues contain aromatic rings, the crystal packing of individual centrosymmetric tetrasodium [Na4(pypzH)2(μ4- BTA)2(μ2-BTA)2] molecular moieties is essentially driven through geometrical aspects combined with weak C-H⋯π interactions, rather than the expected a priori π-π interactions. The material also contains classical strong hydrogen bonds, even though these do not directly contribute to the packing driving forces. © 2006 by MDPI.