For complexes of iron(III) 2, cobalt(II) 3, nickel(II) 4, copper(II) 5 and zinc(II) 7, the NO3 group services served as bidentate ligand
. The nitrate group thus possessed three non-degenerate modes of vibrations (, a and s) at 1548-1541, 1387-1375 and 1304-1302 cm-1.
Preliminary structure-activity relationships have been established, studying diverse parameters such as (i) the coordination geometry of the metal complex (square planar versus octahedral, etc.), (ii) the nature of the bidentate ligands
and occasionally of the moieties in its periphery, (iii) the effect of the counteranions, and (iv) the total charge and size of the complex.
In summary (BROM-ANIS), (BROM-DMB) and (BROM-MB) behave as bidentate ligands
via N-imine donor atom and amine nitrogen atom (attached with cyclohexyl ring of ligand) in complexes (1a)-(1c), (2a)-(2c) and (3a)-(3c) but (BROM-HB) and (BROM-o-VANI) behave as tridentate ligands via phenolic-O, imine-N and amine-N donor atoms in complexes (4a)-(4c) and (5a)-(5c).
Most of them had bipyridine as bidentate ligand
. In this study, 4-(4-bromophenyl)-[2,2'-bipyridine]-6-carboxylic acid was synthesized.
We find that bidentate ligands
of synthesized complexes show a considerable downfield shift of protons after complexation with titanium.
[SB.sup.1], [SB.sup.2] & [SB.sup.3] ligands behave as a monodentate ligand via N imine donor atom in 1-9, but behaves as bidentate ligand
via anionic O atom & imine N atoms in 10-18.
[Et.sub.2]Cit and [Ca.sup.2+] were coordinated to form a 1: 1 complex, and O atoms in -COOH and C-O-C of [Et.sub.2]Cit were coordinated with [Ca.sup.2+] in bidentate ligand
. [Et.sub.2]Cit was able to coordinate with [Ca.sup.2+], and its release capacity of [Ca.sup.2+] was stronger than that of [Et.sub.2]Cit.
In the synthesised complex [Cr(Nor)(Bipy)[Cl.sub.2]] Cl x 2[CH.sub.3]OH, Nor behaves as a bidentate ligand
and is coordinated to Cr (III) through pyridone oxygen and one of the carboxylate oxygen atoms.
Thio- carbohydrazide H2NNHC(S)NHNH2 (abbreviated here as tch), the next higher homologue of thiosemi- carbazide, typically acts as a neutral bidentate ligand
coordinating to a metal through the sulfur atom and one of the terminal nitrogen atoms, forming five- membered chelate rings .
Additionally, for palladium catalysts based on regular bidentate ligands
(e.g., BINAP (I) ) and monodentate ligands (e.g., oligo-aryl phosphine (II) and oligo-arylphosphonites (III) ) (Figure 1), several different models of solvation and mono- and biscomplexation should be evaluated [23, 33-36].
Larionov, "Two modifications of the mixed-ligand complex ZnPhen[(i-[C.sub.3][H.sub.7]OC[S.sub.2]).sub.2] with monodentate and bidentate ligands
i-[C.sub.3][H.sub.7]OC[S.sup.-.sub.2]," Journal of Structural Chemistry, vol.