Coordination Chemistry of Acrylamide. 6 Synthesis and Coordination Compounds of N‐Pyrazolylpropanamide – a Versatile Acrylamide‐derived Ligand

Abstract

The syntheses, spectroscopy and single crystal X-ray structures of the multifunctional acrylamide-derived ligand N-pyrazolylpropanamide (ϭ L) (1), and its complexes [L 2 CuCl 2 ] (2) and [L 4 Co 3 Cl 6 ] (3) with copper(II) and cobalt(II) chlorides, respectively, are described. The ligand 1 is easily obtained in one step by the reaction of pyrazole with acrylamide in a 1:1 molar ratio in the presence of trimethylbenzylammonium hydroxide as a basic catalyst. The reaction of CuCl 2 · 2H 2 O with 1 in a 1:2 metal salt:ligand molar ratio in ethanol/-triethylorthoformate solution gave coordination compound 2. The crystal structure of 2 contains two sevenmembered chelate rings formed by two nitrogen atoms of the pyrazolyl groups and two weakly coordinated carbonyl oxygen atoms Materials. Acrylamide, pyrazole, trimethylbenzylammonium hydroxide (Triton B, 40 % in methanol), copper(II)chloride dihydrate, cobalt(II)chloride hexahydrate, triethylorthoformate (for dehydration), acetonitrile (99 %) and absolute ethanol were all obtained from commercial suppliers and used as received.Physical Methods. Microanalyses of the compounds were performed using a Leco CHNS 923 apparatus. Melting points were

N‐Pyrazolylpropanamide – a Versatile Ligand for the Construction of Supramolecular Hydrogen‐Bonded Frameworks

“…Currently there is a considerable interest in the use of multifunctional ligands containing substituted pyrazole groups because of their potential applications in catalysis and their ability to form complexes that mimic structural and catalytic functions in metalloproteins. [1] As part of our continuing interest in the coordination chemistry of acrylamide [2] and acrylamidebased ligands we have earlier synthesized and characterized an acrylamide-derived pyrazole ligand, N-pyrazolylpropanamide (1 = L), [3] and its complexes L 2 CuCl 2 and L 4 Co 3 Cl 6 with copper(II) and cobalt(II) chlorides, respectively. Both complexes contain the ligand in a seven-membered ring chelating fashion.…”

RuCl2(PPh3)2(N‐ppa) – A Hydrogen‐Bridged Ruthenium(II) Complex of N‐Pyrazolylpropanamide

“…This is in the range of about 1650–1660 cm –1 observed in other metal complexes of the N ‐ppa ligand in which the amide oxygen is coordinated. This shift to lower wave numbers has been attributed to a decrease in the C=O bond strength upon coordination to a metal ion 3,4. Compound 1 is insoluble in common non‐coordinating solvents and in coordinating solvents the N‐ppa ligand often appears to be displaced.…”

“…The bond angles and distances within the coordinated N ‐ppa are unremarkable. As with other complexes of the N ‐ppa ligand,3,4 intermolecular hydrogen bonding occurs. The crystal structure consists of dimers formed by N–H ··· Cl hydrogen bonds from an amide hydrogen on one molecule with a chloride on a second (Figure 2).…”

“…Solvents were dried using an Innovative Technology, Inc, solvent purification system. N ‐Pyrazolypropanamide3 and RuCl 2 (PPh 3 ) 3 11 were prepared using published procedures. Microanalysis was performed by Galbraith Laboratories, Inc, Knoxville, TN, USA.…”

“…Currently there is a considerable interest in the use of multifunctional ligands containing substituted pyrazole groups because of their potential applications in catalysis and their ability to form complexes that mimic structural and catalytic functions in metalloproteins 1. As part of our continuing interest in the coordination chemistry of acrylamide2 and acrylamide‐based ligands we have earlier synthesized and characterized an acrylamide‐derived pyrazole ligand, N ‐pyrazolylpropanamide (= N‐ ppa),3 and its complexes ( N ‐ppa) 2 CuCl 2 and ( N ‐ppa) 4 Co 3 Cl 6 with copper(II) and cobalt(II) chlorides, respectively. Both complexes contain the ligand in a seven‐membered ring chelating fashion.…”