Preparation, NOESY characterisation and structure of [Ni(N3-macrocycle)(hp)]ClO4: the first crystallographic characterised mononuclear nickel complex containing the 2-pyridonate (hp) ligand

2-Pyridonates: a versatile ligand platform in 3d transition metal coordination chemistry and catalysis

“…The first example of a mononuclear nickel pyridonate complex was structurally characterized by López et al in 1998 (Scheme 11, top). 72 The distorted square-pyramidal cation 25 , containing a κ- N , O -bound 2-pyridonate and the tripodal co-ligand 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene, was characterized by 1 H NMR spectroscopy (paramagnetic shifts, in acetone-d 6 ), and pyridonate resonances were assigned by NOESY. Jones et al reported the synthesis of the related quinolinate complex 26 supported by tris(3,5-dimethylpyrazolylborate) and documented its catalytic activity in the acceptorless dehydrogenation of alcohols.…”

Divergent Solution and Solid-State Structures of Mono- and Dinuclear Nickel(II) Pyridone Complexes

“…4,16,17 While great focus has been given to Ni−pyridone complexes of high nuclearity, comparatively less attention has been paid to the synthetic control of mononuclear Ni−pyridone complexes. Seven monomeric Ni−pyridone complexes have been reported in the literature (excluding families of closely related compounds), and it is notable that all of these structures contain either polydentate supporting ligandssuch as scorpionate 19 or triazacyclododecane 20 or a pyridone ligand that is, itself, polydentate. 21−23 These polydentate ligands block coordination sites at the nickel center, thus hindering pyridone ligands from achieving high nuclearity.…”

“…For example, Winpenny and co-workers leveraged the propensity for nickel to form polynuclear oxo-bridged clusters in the presence of 2-pyridone ligands to synthesize so-called “metal cages” to study the relationship between the structure and magnetic properties of metal and metal oxide materials, , with application in data storage using single-molecule magnets. ,, While great focus has been given to Ni–pyridone complexes of high nuclearity, comparatively less attention has been paid to the synthetic control of mononuclear Ni–pyridone complexes. Seven monomeric Ni–pyridone complexes have been reported in the literature (excluding families of closely related compounds), and it is notable that all of these structures contain either polydentate supporting ligandssuch as scorpionate or triazacyclododecaneor a pyridone ligand that is, itself, polydentate. − These polydentate ligands block coordination sites at the nickel center, thus hindering pyridone ligands from achieving high nuclearity. It has also been observed that the formation of lower-nuclearity Ni–pyridone complexes is favored when the reaction and crystallization are performed in polar solvents such as methanol, ethanol, and acetonitrile …”

Structural Diversity of Nickel and Manganese Chloride Complexes with Pyridin-2-One

“…A curious feature of some nickel complexes is the chelate coordination of three chp − in [Ni(chp 3 ] 2− , a counterion to cationic polynuclear nickel clusters [26,27]. The chelate coordination of hp − is accomplished in a mononuclear nickel complex with a N 3 -macrocycle [28]. Interestingly, the 1,3-bridging coordination of hp − or its derivatives has not been adopted by manganese or nickel complexes, although complexes of some other 3d metals-copper or chromium-include this type of bonding (2)(3)(4)7).In contrast to hp − anions-stabilizing high-nuclearity metal cages-are the Hph, Hchp, or Hmhp complexes, mostly mono-or di-nuclear species, if no additional bridging ligands are included.…”