Search results for "coordination complex"

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…

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.

Bis(oxalato)chromium(III) complexes: Versatile tectons in designing heterometallic coordination compounds

2011

Abstract The mononuclear oxalato-containing chromium(III) complexes of general formula [Cr(AA)(C2O4)2]− (AA = α-diimine type ligand) are able to produce a large variety of heterometallic complexes by acting as ligands towards either fully solvated metal ions or preformed cationic complexes with available coordination sites. This review focuses on the structural diversity of the polynuclear complexes (oligonuclear and coordination polymers) which are generated by the bis(oxalato)chromate(III) species, with a special emphasis to their magnetic properties.

Superchiral Pd 3 L 6 Coordination Complex and Its Reversible Structural Conversion into Pd 3 L 3 Cl 6 Metallocycles

2015

Large, non-symmetrical, inherently chiral bispyridyl ligand L derived from natural ursodeoxycholic bile acid was used for square-planar coordination of tetravalent Pd(II) , yielding the cationic single enantiomer of superchiral coordination complex 1 Pd3 L6 containing 60 well-defined chiral centers in its flower-like structure. Complex 1 can readily be transformed by addition of chloride into a smaller enantiomerically pure cyclic trimer 2 Pd3 L3 Cl6 containing 30 chiral centers. This transformation is reversible and can be restored by the addition of silver cations. Furthermore, a mixture of two constitutional isomers of trimer, 2 and 2', and dimer, 3 and 3', can be obtained directly from …

Cooperative High-Temperature Spin Crossover Accompanied by a Highly Anisotropic Structural Distortion

2016

Spin transitions are a spectacular example of molecular switching that can provoke extreme electronic and structural reorganizations in coordination compounds. A new 3D cyanoheterometallic framework, [Fe(pz)(Au(CN)2)2], has been synthesized in which a highly cooperative spin crossover has been observed at 367 and 349 K in heating and cooling modes, respectively. Mössbauer spectroscopy revealed a complete transition between the diamagnetic and paramagnetic states of the iron centres. The low-spin-to-high-spin transition induced a drastic structural distortion involving a large one-directional expansion (ca. 10.6%) and contraction (ca. 9.6%) of the lattice. Negative thermal expansion along th…

Sn<sup>IV</sup> and Zr<sup>IV</sup> Compounds of a <i>C</i>&l…

2017

This contribution describes the synthesis and structural characterization of a triaminoguanidinium (TAG)-based ligand [H6(OMe)3Limin]BF4 (1) containing imine bonds (Limin) and its reduction with a dimethylamino borane complex to the corresponding amine compound (Lamin)[H9(OMe)3Lamin]OTs (2). In solution, both ligands are C3-symmetric but crystal structures show the great influence of the reduction on the molecular structure. We show that the planar imine ligand is converted to a highly flexible compound which has nine potential coordination sites, three phenoxy and six amine donors, for binding metal ions. First solid state structures of 1:1 (metal:ligand) coordination compounds with SnIV a…

Synthesis, Protonation and Cu II Complexes of Two Novel Isomeric Pentaazacyclophane Ligands: Potentiometric, DFT, Kinetic and AMP Recognition Studies

2008

The synthesis and coordination chemistry of two novel ligands, 2,6,9,12,16-pentaaza[17]metacyclophane (L1) and 2,6,9,12,16-pentaaza[17]paracyclophane (L2), is described. Potentiometric studies indicate that L1 and L2 form a variety of mononuclear complexes the stability constants of which reveal a change in the denticity of the ligand when moving from L1 to L2, a behaviour that can be qualitatively explained by the inability of the paracyclophanes to simultaneously use both benzylic nitrogen atoms for coordination to a single metal centre. In contrast, the formation of dinuclear hydroxylated complexes is more favoured for the paraL2 ligand. DFT calculations have been carried out to compare …