2,2′-dipyridylamine complexes of rhenium(V)

Abstract

The reactivity of oxorhenium(V) precursors with the potentially N,N-donor ligand 2,2 0 -dipyridylamine (dpa) has been investigated. Reaction of a two-fold molar excess of dpa with trans-[ReO(OEt)Cl 2 (PPh 3 ) 2 ] in ethanol led to the isolation of [ReOCl 2 (OEt)(dpa)] (1). Spectroscopic measurements indicate that dpa is coordinated as a bidentate in the equatorial plane cis to the oxo group, with the ethoxide in the trans position. Treatment of trans-[ReOCl 3 (PPh 3 ) 2 ] with a tenfold molar excess of dpa in ethanol at reflux yielded the trans-dioxo complex [ReO 2 (dpa) 2 ]Cl (2), but with a twofold molar excess (-O)[{ReOCl 2 (dpa)} 2 ] (3a) was isolated. The latter reaction with (n-Bu 4 N)[ReOCl 4 ] as starting material in ethanol at room temperature led to a dark green product, also with the formulation (-O)[{ReOCl 2 (dpa)} 2 ] (3b). These compounds were characterised by common spectroscopic techniques, and the crystal structures of 2 Á 3H 2 O, 3a and 3b Á 2DMSO were determined. The structure of 3b presents a nearly linear O¼Re-O-Re¼O group, with the two [ReOCl 2 (dpa)] halves of the dimer rotated by 180.0 about the Re-O-Re fragment away from an eclipsed conformation. In 3a, the two halves are only rotated by 61.4 .

Surfactant–cobalt(III) complexes: Synthesis, critical micelle concentration (CMC) determination, DNA binding, antimicrobial and cytotoxicity studies

“…This shift can be explained on the basis of the fact that the nitrogen atoms of phenanthroline ligands donate a pair of electrons each to the central cobalt metal, forming a coordinate covalent bond [32]. Besides, it is also confirmed by the shift of m (C-N) of phenanthroline from about 1670 cm À1 in the free ligand to 1628 cm À1 after coordination [33]. The spectra of bipyridine complexes in general are less complicated than those of the phen complexes.…”

Surfactant-Ruthenium(II) Complexes: Synthesis, Characterization, DNA Binding, Anticancer and Antimicrobial Activity

“…The bands for free phenanthroline at (C-H) 856, 738 cm -1 , was shifted to 816 and 720 cm -1 in the surfactant-ruthenium(II) complexes as nitrogen atoms of phenanthroline ligands donate a pair of electrons each to the central ruthenium metal, resulting in the formation of a coordinate covalent bond [36]. Moreover, the shift of (C-N) of phenanthroline from about 1670 cm -1 in the free ligand to 1651 cm -1 and 1647 cm -1 after coordination gives a confirmation [37]. The bands for perchlorate at 1090 and 625 cm -1 belong to an ionic species and stressing that this counterion is not involved in the ruthenium-ligand coordination [38].…”

Studies on the synthesis, characterization, human serum albumin binding and biological activity of single chain surfactant–cobalt(III) complexes

“…This shift can be explained by the fact that nitrogen atoms of the phen ligand donate a pair of electrons to the center cobalt forming a coordinate bond. Also band δ (C–N) of phen was shifted from 1670 cm −1 in the free ligand to 1626 cm −1 after coordination . In complex 1 , the IR spectra of the free bpy ligand at 1414, 1446, 1460 and 1566 cm −1 were shifted to a higher frequency upon coordination and observed at 1443, 1469, 1588 and 1609 cm −1 .…”