Search results for " complex"

Helicate Extension as a Route to Molecular Wires

2008

We describe the preparation of a helicate containing four closely spaced, linearly arrayed copper(I) ions. This product may be prepared either directly by mixing copper(I) with a set of precursor amine and aldehyde subcomponents, or indirectly through the dimerization of a dicopper(I) helicate upon addition of 1,2-phenylenediamine. A notable feature of this helicate is that its length is not limited by the lengths of its precursor subcomponents: each of the two ligands wrapped around the four copper(I) centers contains one diamine, two dialdehyde, and two monoamine residues. This work thus paves the way for the preparation of longer oligo- and polymeric structures. DFT calculations and elec…

Synthesis and Coordination Chemistry of Lower Rim Cavitand Ligands

2001

Spin Crossover Phenomenon in Coordination Compounds

2016

Controlling the dimensionality of oxalate-based bimetallic complexes: The ferromagnetic chain {[K(18-crown-6)][Mn(bpy)Cr(ox)3]}∞(18-crown-6=C12H24O6,…

2007

Abstract The bimetallic ferromagnetic chain {[K(18-crown-6)][Mn(bpy)Cr(ox)3]}∞ (1) has been synthesized and characterized. It crystallizes in the orthorhombic chiral space group P212121 [a = 9.0510(2) A, b = 14.4710(3) A, c = 26.8660(8) A, V = 3510.97(1) A3, Z = 2]. Compound 1 is made up by anionic [Mn(bpy)Cr(ox)3]− 1D chains and cationic [K(18-crown-6)]+ complexes. The magnetic exchange within the chain is ferromagnetic [J = +7.8(7) cm−1]. In the solid state, the ferromagnetic chains are well isolated magnetically and no long range magnetic ordering has been observed above 2 K.

Coordination compounds of methazolamide. Synthesis, spectroscopic studies and crystal structures of [M(Methazolamidato)2(py)2(OH2)2] (M  CoII, NiII …

1992

Abstract The synthesis and X-ray crystallographic characterization of three monomeric transition-metal coordination compounds with the ligand methazolamide {[N(4-methyl-2- sulphamoyl-Δ21,3,4-thiodiazolin-5-ylidene)],acetamide} (abbreviated as Hmacm) are described, via [M(macm)2(py)2(OH2)2] [M  Co(1), Ni(2) and Cu(3)]. In all the compounds the metal ion, lying on the centre of symmetry, is surrounded by two sulphonamidato nitrogen atoms and two pyridine nitrogen atoms in equatorial sites and two oxygen water molecules in axial positions. The coordination geometry of the metal is an almost regular octahedron around the cobalt(II) and nickel(II) ions. In contrast, the copper(II) ion has a sig…

Chiral Lanthanocene Derivatives Containing Two Linked Amido−Cyclopentadienyl Ligands:  Heterobimetallic Structure and Lactone Polymerization Activity

1997

Reaction of 2 equiv of dilithium amido−cyclopentadienide Li2(C5R4SiMe2NCH2CH2X) (C5R4 = C5Me4, C5H3tBu; X = OMe, NMe2) with anhydrous LnCl3 (Ln = Y, Lu) gave C2-symmetric complexes of the type Li[Ln(η5:η1-C5R4SiMe2NCH2CH2X)2] containing a heterobimetallic core. The molecular structure of Li[Y(η5:η1-C5Me4SiMe2NCH2CH2OMe)2] was determined by single-crystal X-ray structural analysis, which showed it to exhibit both a pseudotetrahedral yttrium as well as a tetrahedral lithium center. In accordance with a formal 20-electron configuration at the rare earth metal center Ln, the amido-nitrogen atoms are shown to be pyramidalized. In the case of Li[Y(η5:η1-C5H3tBuSiMe2NCH2CH2X)2], mixtures of the tw…

Complexes of organometallic compounds XXXIII. The coordination chemistry of dimethyl and diphenylthallium(III) ith tridentate ligands

1973

Summary Several novel complexes Na[Me 2 TIL] and Na[Ph 2 TIL] (L 2− =dianion tridentate ligands with S, N, and O donor atoms) were synthesized, and investigated by infrared spectroscopy in the solid state, and by electronic and PMR spectroscopy in solution. Suggestions for the configuration of the complex anions are advanced and the nature of species present in solution is discussed.

Refined carotenoid analysis of the major light-harvesting complex of Mantoniella squamata

1997

The major light-harvesting complex (LHC) of the prasinophycean alga Mantoniella squamata is unique compared to other chlorophyll (Chl) a/b-binding LHC with respect to the primary protein structure and the pigmentation. Although the presence of Chl a, Chl b, a Chl c-type pigment and the xanthophylls neoxanthin, violaxanthin and prasinoxanthin was clearly determined, several carotenoids remained unidentified or were described controversially. We re-analysed the carotenoid composition and identified a new set of xanthophylls present in the LHC: uriolide, micromonol, micromonal and dihydrolutein. Additionally, one hydrophobic component was detected, presumably a xanthophyll. The pigment analysi…

Polypeptide sequence of the chlorophyll a/b/c-binding protein of the prasinophycean alga Mantoniella squamata.

1994

The primary structure of the Chla/b/c-binding protein from Mantoniella squamata is determined. This is the first report that protein sequencing reveals one modified amino acid resulting in a LHCP-specific TFA-cleavage site. The comparison of the sequence of Mantoniella with other Chla/b-and Chla/c-binding proteins shows that the modified amino acid is located in a region which is highly conserved in all these proteins. The alignment also reveals that the LHCP of Mantoniella is related to the Chla/b-binding proteins. Finally, possible Chl-binding regions are discussed.

Pigment-pigment interactions and secondary structure of reconstituted algal chlorophyll a/b-binding light-harvesting complexes of Chlorella fusca wit…

1995

Earlier we have shown by in vitro reconstitution experiments that the pigment composition of the chlorophyll alb-binding light-harvesting complex of the green alga Chlorella fusca could be altered in a relatively broad range (Meyer and Wilhelm 1993). In this study we used these reconstituted complexes of different pigment loading to analyze the excitonic interactions between the pigment molecules and the secondary structure by means of circular dichroism spectra in the visible and the far UV spectral regions, respectively. We found that, in contrast to the expectations, the pigment composition and pigment content hardly affected the circular dichroism spectra in the visible spectral region.…