Zinc(II) and Nickel(II) Benzoate Complexes from the Use of 1‐methyl‐4,5‐diphenylimidazole

Konstantina A Kounavi,Vassilios Nastopoulos,Manolis J Manos,Spyros P Perlepes,Anastasios J Tasiopoulos

doi:10.1155/2010/178034

Abstract

Two new complexes, [Zn(O2CPh)2(L)2]·2MeOH (1 ·2MeOH) and [Ni2(O2CPh))4(L)2]·2MeCN (2 ·2MeCN), have been synthesized and characterized by X-ray analysis in the course of an ongoing investigation of the MII/X−/L [MII = Co, Ni, Cu, Zn; X− = Cl−, Br−, I−, NCS−, NO3 −, N3 −, PhCO2 −; L = 1-methyl-4,5-diphenylimidazole] reaction system, aiming at understanding and assessing the relative strength and the way in which the intermolecular interactions control the supramolecular organization of these compounds. In the mononuclear complex 1 ·2MeOH, the benzoate ion acts as a monodentate ligand resulting in a distorted tetrahedral N2O2 coordination environment. Complex 2 ·2MeCN exhibits a dinuclear paddle-wheel structure; each NiII has a square pyramidal NiNO4 chromophore with four benzoate oxygens in the basal plane and the pyridine-type nitrogen atom of one ligand L at the apex. The structure of 1 ·2MeOH is stabilized by intramolecular π-π interactions between aromatic rings of adjacent 4,5-diphenylimidazole moieties; it is a feature also evidenced in similar compounds of the type [MX2L2].

Highlights

Imidazole and its derivatives have played a formative role in the development of coordination chemistry [1, 2]
In spite of the enormous scientific literature on metal complexes with simple imidazoles as ligands, there is relatively little known about the coordination and metallosupramolecular chemistry of heavily substituted imidazoles [1]
An investigation has recently been initiated to determine the crystal structures of a designed series of transition metal complexes using heavily substituted imidazole ligands aiming at understanding the relative strength and the way in which these interactions control the noncovalent assembly of molecular building blocks in supramolecular systems [12]

Summary

Introduction

Imidazole and its derivatives have played a formative role in the development of coordination chemistry [1, 2]. Bioinorganic models may lead to compounds which mimic enzyme function and provide new reagents or catalysts for practical application In the latter field, the presence of both donor atoms to metal ions and hydrogen bond donors within imidazoles, combined with the π-excessive character of the 5-membered heterocyclic ring, can lead to intermolecular assembly of metal complexes through ligandligand or ligand-inorganic anion interactions. It is well established nowadays that the most prominent intermolecular interactions responsible for the supramolecular organization of metal complexes are hydrogen bonds and π-π stacking interactions [6,7,8,9,10,11] With this in mind, an investigation has recently been initiated to determine the crystal structures of a designed series of transition metal complexes using heavily substituted imidazole ligands aiming at understanding the relative strength and the way in which these interactions control the noncovalent assembly of molecular building blocks in supramolecular systems [12]. IR data (KBr, cm−1): 3134 (m), 3060 (m), 1626 (s), 1570 (s), 1522 (s), 1492 (w), 1444 (sh), 1418 (s), 1402 (s), 1254 (w), 1202 (m), 1174 (w), 1072 (m), 1024 (m), 978 (m), 922 (w), 842 (w), 786 (m), 776 (sh), 720 (s), 700 (s), 682 (m), 648 (m), 538 (w), 476 (m)

Experimental

Compound Preparation

Results and Discussion

C27 O2 C19 O1

Conclusions