Synthesis, characterization and structures of copper(II) and cobalt(II) complexes involving N 3 S-coordinated tetradentate ligand and azide/ thiocyanate/ nitrite ion

Synthesis, structures, and catalytic efficiency in ring opening polymerization of rac-lactide with tridentate vs. bidentate cobalt(ii), zinc(ii), and cadmium(ii) complexes containing N-substituted N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amine ligands

“…These values compare favorably to the corresponding ones reported for other complexes in the literature. 65 In the spectra of the complexes, the absorption bands due to the stretching of aromatic C C and C–H bonds were observed to shift to higher wavenumbers with respect to the corresponding free ligands. Similarly, the complexes' absorption bands due to the stretching of sp 3 and sp 2 C–H and C C bonds appeared at the expected wavenumbers, based on literature data.…”

Five-Coordinated Geometries from Molecular Structures to Solutions in Copper(II) Complexes Generated from Polydentate-N-Donor Ligands and Pseudohalides

“…In general, TBP structures are dominating in the solid state when the central Cu 2+ ion is coordinated to tripod tetradentate ligands containing only five-membered chelate rings ( Table 1 and Table 3 : 3 , 4 , 20 – 22 , 36 , 37 , 39 – 41 , 54 , 56 – 60 ) [ 8 , 27 , 28 , 29 , 41 , 52 , 53 , 54 ]. Also, the tendency for stabilization of SP geometry is enhanced ( 18 , 30 – 32 , 47 – 50 ) [ 23 , 30 , 43 , 48 , 56 , 57 ] as the chelate ring sizes are increased to six-membered through insertion of CH 2 group(s) into the ethylenic tripod arms. Interestingly, this analysis was proved to be universal in other five-coordinated complex ions such [Cu(tren)(NH 3 )] 2+ , [Cu(Me 3 tren)(NCCH 3 )] 2+ , [Cu(TPA)(H 2 O)] 2+ and [Cu(233)(NH 3 )] 2+ (233 = N -(2-aminoethyl)- N , N -bis(3-aminopropyl)amine), where the first three complexes were displaying distorted TBP geometry, whereas the latter one exhibits distorted SP geometry [ 55 , 70 , 71 , 72 ].…”

“…This was attributed to the high ability of the pseudohalide ions to act as bridging ligands in a variety of bonding modes and mediating the magnetic interaction between Cu 2+ centers [ 17 , 18 , 19 , 20 ], where efficient magnetic transmitting was found in case of the azide bridging compounds [ 17 , 19 , 20 ]. However, mononuclear pseudohalido-Cu(II) complexes are known to be formed too [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ] and are very stable in aqueous and common organic solvents [ 27 , 28 ]. The Cu(II) centers in these compounds display variable geometries ranging from four—(square planar and tetrahedral) to six—(octahedral) as well as five-coordinated species.…”

Spectroscopic, EPR, X-ray structural, and DFT studies of the complex compound of N4-donor ligand with copper(II)

“…1. The gII and gI values are 2.1294 and 2.0506, respectively indicating a five-coordinate SP geometry around the metal center [29]. The 'Tau Descriptor', τ, for five-coordinate compounds [30], calculated by the program PLATON [31], is 0.07 for 1 (extreme forms: τ = 0.00 for Square Pyramidal, SP, and 1.00 for a…”