Identification of Hexameric Water and Hybrid Water–Chloride Clusters Intercalated in the Crystal Hosts of (Imidoylamidine)nickel(II) Complexes

Abstract

AbstractTwo structurally related bis(imidoylamidine or 1,3,5‐triazapentadiene)nickel(II) compounds {Ni[HN=C(3‐py)NC(3‐py)=NH]2}·H2O·MeOH (1) and [Ni{HN=C(3‐py)N(H)C(3‐py)=NH}2]Cl2 (2) with symmetrical 3‐pyridyl (3‐py) substituents have been prepared by direct 2‐butanone oxime mediated transformation of 3‐cyanopyridine in the presence of Ni(MeCO2)2·4H2O or NiCl2·2H2O, respectively. Compounds 1 and 2 have been characterized by elemental analyses, IR, 1H and 13C{1H} NMR spectroscopy, and FAB+ mass spectrometry, while their slow recrystallization in air from organic solvents revealed a high affinity for water and resulted in the formation of the derived compounds [Ni{HN=C(3‐py)NC(3‐py)=NH}2]·6H2O (1′) and [Ni{HN=C(3‐py)N(H)0.5C(3‐py)=NH}2]Cl·2H2O (2′). Single‐crystal X‐ray diffraction analyses allowed the identification of discrete hexameric water or hybrid water–chloride clusters hosted by the crystal matrixes of 1′ and 2′, respectively. Both the (H2O)6 and [(H2O)4(Cl)2]2– clusters possess similar geometries and consist of cyclic planar tetranuclear (H2O)4 or [(H2O)2(Cl)2]2– cores with two dangling water molecules. These water associates occupy voids in the crystal cells and display extensive H‐bonding interactions with monomeric nickel–organic units, thus playing a key role in the formation of 3D hydrogen‐bonded supramolecular assemblies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)