Synthesis and room temperature single crystal EPR studies of a dinickel complex having an Ni2(μ-phenoxide)2 2+ unit supported by a macrocyclic ligand environment [Ni2(L)2(OClO3)2] [L = 2-[(4-methyl-pyridin-2-ylimino)-methyl]-phenol]

Abstract

A bimetallic nickel(II) complex with the ligand Hsalamp (2-[(4-methylpyridin-2-ylimino)-methyl]-phenol), having the molecular formula, Ni 2 C 26 H 22 N 4 O 10 Cl 2 , is synthesized and characterized by elemental, UV-Vis, IR and EPR studies. The IR spectrum confirms the presence of coordinated perchlorate ion and the UV-Vis. spectrum substantiates that the geometry around the metal ion is distorted square pyramidal. In the solvent methanol, the complex undergoes dissociation indicating the nature of the complex to be 1 : 2 electrolyte. The single crystal EPR studies indicate that the zero-field splitting is not large and the spectra can be observed even at room temperature, not so common for a nickel(II) ion. The spin Hamiltonian parameters calculated from single crystal rotations are: g-2⋅377, 2⋅219, 2⋅071 and D-9⋅7, 4⋅2 and-13⋅9 mT. Optical and electron paramagnetic spectral data have been used to obtain the parameters Dq, B and C.

Preparation, Structural characterization and DNA binding/cleavage affinity of new bioactive nano‐sized metal (II/IV) complexes with oxazon‐Schiff's base ligand

“…The electronic absorption spectra (Figure ) of the free oxazon‐Schiff's base ligand and its Mn (II) (Figure a), Co (II) (Figure b), Ni (II) (Figure c), Cu (II) (Figure d), Zn (II) and Pt (IV) complexes were studied in DMSO solution. The electronic spectrum of the free oxazon‐Schiff's base ligand HL in Nujol mull showed absorption bands at 39,682–25,380 cm −1 regions which are attributed to n → π* and π → π* transitions involving molecular orbital of the oxazin ring, a broad shoulder at approximately 23,094 cm −1 were observed which is attributed to an n (oxygen) → π* transition of the dipolar Zwitter ionic structure or keto‐amine tautomer of the free oxazon‐Schiff's base ligand HL . In the electronic spectra of metal chelates, a new band appears in 24,812 cm −1 , which may be due to ligand‐to‐metal charge transfer transitions .…”

“…The electronic spectrum of the free oxazon‐Schiff's base ligand HL in Nujol mull showed absorption bands at 39,682–25,380 cm −1 regions which are attributed to n → π* and π → π* transitions involving molecular orbital of the oxazin ring, a broad shoulder at approximately 23,094 cm −1 were observed which is attributed to an n (oxygen) → π* transition of the dipolar Zwitter ionic structure or keto‐amine tautomer of the free oxazon‐Schiff's base ligand HL . In the electronic spectra of metal chelates, a new band appears in 24,812 cm −1 , which may be due to ligand‐to‐metal charge transfer transitions . The electronic spectrum of the Mn (II) complex (Figure a) exhibits at room temperature in DMSO solution shows four bands at 17, 984 cm −1 ( ε = 29 L mole −1 cm −1 ), 22,476 cm −1 ( ε = 35 L mole −1 cm −1 ), 28,287 cm −1 ( ε = 64 L mole −1 cm −1 ) and 36,971 cm −1 ( ε = 140 L mole −1 cm −1 ), which may be assigned to the transitions: 6 A 1 g → 4 T 1 g (4G), 6 A 1 g → 4 Eg, 4 A 1 g (4G) (10B + 5C), 6 A 1 g → 4 Eg (4D) (17B + 5C) and 6 A 1 g → 4 T 1 g (4P) (7B + 7C), respectively.…”

“…The electronic spectrum of the Mn (II) complex (Figure a) exhibits at room temperature in DMSO solution shows four bands at 17, 984 cm −1 ( ε = 29 L mole −1 cm −1 ), 22,476 cm −1 ( ε = 35 L mole −1 cm −1 ), 28,287 cm −1 ( ε = 64 L mole −1 cm −1 ) and 36,971 cm −1 ( ε = 140 L mole −1 cm −1 ), which may be assigned to the transitions: 6 A 1 g → 4 T 1 g (4G), 6 A 1 g → 4 Eg, 4 A 1 g (4G) (10B + 5C), 6 A 1 g → 4 Eg (4D) (17B + 5C) and 6 A 1 g → 4 T 1 g (4P) (7B + 7C), respectively. These bands are characteristic for six coordinate octahedral Mn (II) hybrid . Racah parameters (B and C), Dq and β were calculated from the second and third transitions because these transitions are free from the crystal field splitting and depend on B and C parameters.…”

DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

“…The characteristic out-of-plane hydrogen bending modes of free phen observed at 851 and 735 cm −1 and for bipy at 848, 740 cm −1 were shifted to 849, 722 cm −1 for 1 , 841, 731 cm −1 for 2 , 849, 720 cm −1 for 5, and 830, 30 cm −1 for 6 upon metal complexation [34]. The peaks around 1112, 1104, and 1034 cm −1 ( ν (ClO 4 )) confirm the presence of a coordinated perchlorate ion [35, 36]. A strong ν (C–O) band observed in the range between 1105 and 1135 cm −1 indicates the presence of oxine moiety in the complexes coordinated through its nitrogen and oxygen atoms as mononegative bidentate ligand [37–40].…”

Synthesis of a One-Dimensional Coordination Polymer of Nickel(II) Complex with a β-Oxodithioester Ligand

“…, respectively, in an octahedral environment around the nickel ion [24][25][26][27][28], due to the coordination of two bipyridyl molecules.…”