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

Two structurally related bis(imidoylamidine or 1,3,5‐triazapentadiene)nickel(II) compounds {Ni[HN=C(3‐py)NC(3‐py)=NH] 2 } · H 2 O · MeOH ( 1 ) and [Ni{HN=C(3‐py)N(H)C(3‐py)=NH} 2 ]Cl 2 ( 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(MeCO 2 ) 2 · 4H 2 O or NiCl 2 · 2H 2 O, respectively. Compounds 1 and 2 have been characterized by elemental analyses, IR, 1 H and 13 C{ 1 H} 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 ] · 6H 2 O ( 1′ ) and [Ni{HN=C(3‐py)N(H) 0.5 C(3‐py)=NH} 2 ]Cl · 2H 2 O ( 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 (H 2 O) 6 and [(H 2 O) 4 (Cl) 2 ] 2– clusters possess similar geometries and consist of cyclic planar tetranuclear (H 2 O) 4 or [(H 2 O) 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)