摘要:

IntroductionNumerous recent investigations in the area of crystal engineering have been directed to the designed synthesis of infinite networks of various structural topologies. Many interesting metal–organic coordination networks have been made by employing supramolecular ideas such as the self-assembly of coordination complexes facilitated by covalent linkages provided by suitable bridging ligands.1Such an approach has resulted in the synthesis of one-, two-, and three-dimensional (1-, 2- and 3-D) coordination polymers, including the ones said to display pillared layered structures.2In addition, there have been studies on non-covalently formed supramolecular solids.2d,3–7Most often, intermolecular hydrogen bonds link molecular entities to generate ordered network solids.1a,7The inherent lack of robustnessin hydrogen-bonded networks can be counterbalanced by raising the number and strength of hydrogen bonds.8Examples of 3-D networks formed by utilising these ideas include covalent 1-D chains supramolecularly linked in the other two directions,9covalent 2-D layers interconnected by hydrogen bonds,10supramolecular 2-D networks connected to one another by π–π stacking interactions,11as well as networks formed by hydrogen bond links between hydrogen-bonded sheets.12In these systems, metal complexes themselves provide both covalent and non-covalent links, although free solvent and/or other molecules present in the crystal lattice may also be involved.11We have been interested in the study of metal–organic coordination solids formed between transition metal ions and ligands based on suitably substituted pyridines such as 4-cyanopyridine (4-CNpy) and 4-pyridinecarboxylic acid (4-CO2Hpy). Although both of them may act as bridging ligands to form polymeric coordination compounds,13our studies indicate that, in general, these ligands prefer to coordinate through their pyridyl-N atoms.14Thus they retain parts of their hydrogen bonding functionalities even after complexation, and as such, intermolecular contacts between complexes formed by these substituted pyridine ligands may be expected to yield supramolecular solids. Herein we describe the crystal structure of [Ni(H2O)4(4-CNpy)2](BPh4)2·2(4-CNpy)·4H2O (1) exhibiting an extensive range of hydrogen bonding interactions to form a novel 3-D network structure.

ISSN:1466-8033    

DOI:10.1039/b200333c

出版商:RSC    

年代:2002

数据来源: RSC