[Pd(HL)Cl₂] and [PdL₂], where HLis 2-(3-Pyrazolyl)pyridine

β‐Protic Pyrazole and N‐Heterocyclic Carbene Complexes: Synthesis, Properties, and Metal–Ligand Cooperative Bifunctional Catalysis

“…Among chelating protic pyrazole ligands, the N-N chelate derivatives such as pyridylpyrazoles are most extensively studied. [10] Representative examples (8-10) of square-planar, [11][12][13][14][15][16][17][18] octahedral, [19] and half-sandwichtype [20,21] pyridylpyrazole complexes are shown here. In addition, a number of osmium, iridium, and platinum complexes bearing the deprotonated pyridylpyrazolato ligands have been synthesized, motivated by their luminescent properties.…”

“…The hydrogen bonds in the solid state are delicately influenced by the ligand substituents and crystal packing. The square-planar complex 8 a forms an infinite chain structure along with a crystallographic 2 1 axis through an intermolecular NH···Cl hydrogen bond, [11] while the phenyl derivative 8 c forms a centrosymmetric dimer containing two NH···Cl hydrogen bonds. [12] Both complexes have a close intramolecular NH···Cl contact around 3.0 , which may be ascribed to a hydrogen bond or the rigid fivemembered chelate structure or both.…”

2-(1H-Pyrazol-3-yl)pyridinium chloride monohydrate

“…For related structures with 2-(3-pyrazolyl)pyridine or its derivatives, see: Coelho et al (2006Coelho et al ( , 2007; Fleming et al (1998); Jones et al (1997); Lam et al (1997); Leita et al (2004); Li (2007); Liu et al (2006); Mokuolu et al (2007); ; Hu, Wang et al (2006); Hu et al (2008); Huo et al (2006); Ward, Fleming et al (1998); Ward, Mann et al (1998). For detailed background to the role of hydrogen bonds in the supramolecular organization of organic crystals, see: Nangia & Desiraju (1998).…”

“…In recent years, molecules derived from 2-(3-pyrazolyl)pyridine have been very much explored in coordination chemistry as N,N-chelating moieties, N,N-bridging (the two N-atoms from the pyrazolyl aromatic ring), or even a combination of these two coordination modes, in conjunction with other ligands to produce functional complexes which, ultimately, may find applications in catalysis or as photoluminescent devices. Indeed, a search in the literature and in the Cambridge Structural Database (CSD, Version of November 2008 with three updates; Allen, 2002) reveals a plethora of transition metal complexes: Ag + (Li, 2007), Cd 2+ (Hu et al, 2008;Liu et al, 2006;Hu, Wang et al, 2006;Huo et al, 2006), Cu 2+ Fleming et al, 1998;Mokuolu et al, 2007), Cu + (Lam et al, 1997), Fe 2+ (Leita et al, 2004), Fe 3+ (Jones et al, 1997), In 3+ (Ward, Mann et al, 1998), Pd 2+ (Ward, Fleming et al, 1998), Ru 2+ (Lam et al, 1997), Zn 2+ (Hu et al, 2008).…”

Dichlorotetrakis[3-(4-pyridyl)-1H-pyrazole]cobalt(II) acetonitrile tetrasolvate: an infinite hydrogen-bonded network, in an instant

“…We have extensively studied the structural and photophysical properties of metal complexes with the scorpionate ligand hydrotris[3-(2-pyridyl)pyrazol-1-yl]borate (Tp 2py ) (Davies, Adams, Pope et al, 2005;Davies et al, 2004;Beeby et al, 2002;Ward et al, 2001;Jones, Amoroso et al, 1997;Amoroso et al, 1994). The potentially tridentate ligand 3-(2-pyridyl)pyrazole (2pypz), a precursor to (Tp 2py ), has also proven to be of interest, with a range of coordination modes being displayed depending on whether the pyrazole unit is neutral or deprotonated (Ward, Fleming et al, 1998;Ward, Mann et al, 1998;. Accordingly, we have prepared the isomeric ligand 3-(4pyridyl)pyrazole (4pypz) (Adams et al, 2005), which can no longer act as a chelate but in principle can act as a bridging ligand whose coordination mode will again depend on whether the pyrazole unit is deprotonated.…”