Copper(I) Coordination Chemistry of (Pyridylmethyl)amide Ligands

Copper(I) chloro complexes were synthesized with a family of ligands, HLR [HLR = N-(2-pyridylmethyl)acetamide,
R = null; 2-phenyl-N-(2-pyridylmethyl)acetamide, R = Ph; 2,2-dimethyl-N-(2-pyridylmethyl)propionamide, R = Me3;
2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide, R = Ph3)]. Five complexes were synthesized from the respective
ligand and cuprous chloride:  [Cu(HL)Cl]n (1), [Cu2(HL)4Cl2] (2), [Cu2(HLPh)2(CH3CN)2Cl2] (3), [Cu2(HLPh3)2Cl2] (4),
and [Cu(HLMe3)2Cl] (5). X-ray crystal structures reveal that for all complexes the ligands coordinate to the Cu in a
monodentate fashion, and inter- or intramolecular hydrogen-bonding interactions formed between the amide NH
group and either amide CO or chloro groups stabilize these complexes in the solid state and strongly influence
the structures formed. Complexes 1−5 display a range of structural motifs, depending on the size of the ligand
substituent groups, hydrogen bonding, and the stoichiometry of the starting materials, including a one-dimensional
coordination polymer chain (1) and binuclear (2−4) or mononuclear (5) structures.