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 theeuropium-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 containstwo 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 thepresence 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). Eventhough all of the organic residues contain aromatic rings, the crystal packing of individualcentrosymmetric tetrasodium [Na4(pypzH)2(μ4-BTA)2(μ2-BTA)2] molecular moieties isessentially driven through geometrical aspects combined with weak C–H···π interactions,rather than the expected a priori π-π interactions. The material also contains classicalstrong hydrogen bonds, even though these do not directly contribute to the packingdriving forces.

Keywords

• Sodium
• bridging ligands
• N ligands
• O ligands
• coordination modes
• aggregation