Copper(II) and Nickel(II) Complexes of two Nitrogen‐Functionalized N‐Salicylidene Carbonic Acid Hydrazides: Molecular and Supramolecular Architectures

• Published in: Zeitschrift für anorganische und allgemeine Chemie
• Main Authors: Roth, Arne, Buchholz, Axel, Gärtner, Martin, Malassa, Astrid, Görls, Helmar, Vaughan, Gavin, Plass, Winfried
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2007
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1002/zaac.200700249; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fzaac.200700249; https://onlinelibrary.wiley.com/doi/pdf/10.1002/zaac.200700249

Abstract Copper(II) and nickel(II) complexes with the new Schiff‐base ligands N ‐salicylidene‐3‐(2‐pyridyl)‐propionic acid hydrazide (H 2 salhypyp) and the newly synthesized N ‐Salicylidene‐3‐(1‐benzylimidazol‐2‐yl)‐propionic acid hydrazide (H 2 salhyimp) have been synthesized and structurally characterized. The crystal structure analysis of the metal complexes reveals two fundamentally different structural motifs. Cationic di‐ μ ‐phenolate‐bridged dimers are observed for the complexes with the H 2 salhypyp ligand, [{Cu(H 2 salhypyp)(MeOH)(ClO 4 )} 2 ](ClO 4 ) 2 ( 1 ) and [{Ni(H 2 salhypyp)Cl(MeOH)} 2 ]Cl 2 (MeOH) 2 ( 2 ), whereas neutral dimeric units aggregated via the side chain nitrogen donors are observed for the complexes with the H 2 salhyimp ligand, [{Ni(salhyimp)} 2 ](H 2 O) 4 ( 4 ) and [{Cu(salhyimp)} 2 ](MeOH) 4 ( 3 ). The formation of either motif depends on the charge of the ligand species and consequently on the pH‐value of the reaction solution. For the complexes 1 and 2 extensive hydrogen‐bonding networks are observed which involve the perchlorate (N–H···O–Cl) and chloride anions (N–H···Cl), respectively. The M 2 O 2 core unit of complexes 1 and 2 facilitates the formation of intramolecular M–(Me)O–H···X–M hydrogen‐bonding interactions $\rm (X = ClO^{-}_{4}, Cl^{-})$ . The copper complex 3 exhibits an unusual one‐dimensional coordination polymer which is linked through the axial coordination of phenolate oxygen atoms of adjacent dimeric units. Complex 4 exhibits a layered structure with each layer composed of hydrophobic π‐stacks of the dimeric complex units which are interlaced by hydrogen‐bonded chains of water molecules. The supramolecular structures of 3 and 4 are governed by π‐π‐stacking interactions. For 4 additional CH/π interactions are found within and between individual sheets of the layered structure.