Search results for "coordination complex"

>3 + 1 = 6 + 2> In Cu(ii) coordination chemistry of 1H-pyrazole aza cryptands

2015

A polyazamacrocycle formed from two tris(2-aminoethyl)amine units connected by 1H-pyrazole units shows unique hexanuclear Cu(ii) complexes by combination of two binuclear Cu(ii) cryptand complexes through pyrazolate moieties belonging to both cryptands. The formation of these dimeric entities has been proven both in solution by potentiometric studies and mass spectroscopy and in the solid state by X-ray diffraction of crystals of three different batches of formulae [Cu6(H-3L)2(H2O)2](TsO)6·22H2O (2), [Cu6(H-3L)2(NO3)2](NO3)4·2H2O (3) and [Cu6(H-3L)2Cl2]Cl4·(C4H5N3O2)2·14.35H2O (4). The hexanuclear unit in 2 and 4 can be viewed like three magnetically independent binuclear complexes with J =…

Molecular-Programmed Self-Assembly of Homo- and Heterometallic Tetranuclear Coordination Compounds: Synthesis, Crystal Structures, and Magnetic Prope…

2009

New homo- and heterobimetallic tetranuclear complexes of formula [Cu4(mpba)(Me4en)4(H2O)4](ClO4)4·3H2O (1), [Cu4(mpba)(Me4en)4(H2O)4](PF6)4·2H2O (2), [Cu4(ppba)(Me4en)4(H2O)4](ClO4)4·2H2O (3), [Cu4(mpba)(dipn)4](ClO4)4·3H2O (4), [Cu4(ppba)(dipn)4](ClO4)4·2H2O (5), and [Cu2Ni2(ppba)(dipn)4(H2O)2](PF6)4 (6) [mpba = N,N′-1,3-phenylenebis(oxamate), ppba = N,N′-1,4-phenylenebis(oxamate), Me4en = N,N,N′,N′-tetramethylethylenediamine, and dipn = dipropylenetriamine] have been synthesized and structurally and magnetically characterized. Complexes 1−6 have been prepared following a molecular-programmed self-assembly method, where a heteropolytopic tetranucleating phenylenedioxamato bridging ligand (…

Cooperative Spin‐Crossover Behaviour in Polymeric 1D Fe II Coordination Compounds: [{Fe(tba) 3 }X 2 ]· n H 2 O

2007

A new family of 1D cooperative spin-crossover polymers with general formula [{Fe(tba)3}X2]·nH2O [tba = N-(4H-1,2,4-triazol-4-yl)benzamide; X = CF3SO3–, n = 2 (1), n = 0 (4); BF4–,n = 3 (2), n = 0 (5); 4-CH3C6H4SO3–, n = 3 (3), n = 0 (6)] has been synthesised and characterised using a series of spectroscopic methods, X-ray powder diffraction, magnetic susceptibility measurements and differential scanning calorimetry. The copper analogue of 1, [{Cu(tba)3}(CF3SO3)2]·3H2O (7), has also been synthesised and its crystal structure solved at 293 K. Compound 7 crystallises in the P space group. The bidentate N-(4H-1,2,4-triazol-4-yl)benzamide ligand bridges the copper ions through the 1,2-nitrogen p…

Synthesis, crystal structure and magnetic properties of an oxalato-bridged Re(IV)Mo(VI) heterobimetallic complex.

2010

The Re(IV)-Mo(VI) compound of formula (PPh(4))(2)[ReCl(4)(μ-ox)MoO(2)Cl(2)] (1) constitutes the first example of a heterodinuclear oxalato-bridged complex in the coordination chemistry of molybdenum.

Crystal‐Structure Studies of Mononuclear Iron(II) Complexes with Two‐Step Spin Crossover: [Fe{5‐NO 2 ‐sal‐N(1,4,7,10)}] Revisited

2013

In the region of the spin transition of spin-crossover (SCO) compounds there coexist molecules in both high-spin (HS) and low-spin (LS) states. In the case of two-step spin transition, theoretical predictions and computer simulations have shown that HS and LS complex molecules should be ordered in the plateau region. Several examples that support this hypothesis are already presented in the literature. Herein, we discuss a mononuclear complex of iron(II) with two-step spin transition in terms of long-range ordering of HS and LS molecules. In such compounds, spin transition is associated with the formation of a superstructure. However, previous studies of the [Fe{5-NO2-sal-N(1,4,7,10)}] [5-N…

Two-Level Self-Organisation of Arrays of [2×2] Grid-Type Tetranuclear Metal Complexes by Hydrogen Bonding

2001

Here we report on the synthesis and characterisation of four new complexes of the [2×2] M4II grid-type (M = Co, Fe, Zn) with oligopyridine-derived ligands. The presence of aminopyrazine and aminopyrimidine moieties at the edge of the ligands potentially enables the formation of infinite hydrogen-bonded multi-grid networks. The ligands were synthesised by subsequent stannylations and Stille-type coupling reactions. The complexes were obtained by self-assembly of the ligand with the metal salt. The single-crystal X-ray structure was determined for the Co complex 7 containing aminopyrimidine as the hydrogen-bonding moiety [P1¯; a = 15.4976(4), b = 18.2114(6), c = 31.9538(10) A, α = 86.9809(13)…

The Synthesis of Quinoline-based Tin Complexes with Pendant Schiff Bases

2019

Isomerism of [64Cu-NOTA-Bn]-labeled radiotracers: separation of two complex isomers and determination of their interconversion energy barrier using i…

2011

The model complex [(64)Cu((S)-p-NH(2)-Bn-NOTA)](-) ([(64)Cu]1) was used to study the isomerism of [(64)Cu-NOTA-Bn]-labeled radiotracers. Two complex isomers [(64)Cu]1a and [(64)Cu]1b, which were formed at a ratio of 1:9 during the complexation of [(64)Cu]Cu(2+) with (S)-p-NH(2)-Bn-NOTA, were separated using ion pair chromatography. To study the interconversion, the nonradioactive complex isomers Cu1a and Cu1b were separated and thermally treated at 90 °C in both ammonium acetate solution and deionized water. A faster interconversion rate was observed for both isomers with lower concentrations of ammonium ions. At the end of reaction, the thermodynamic Cu1a to Cu1b equilibrium ratio was 6:94…

Intramolecular electron transfer between molybdenum and iron mimicking bacterial sulphite dehydrogenase

2014

Diferrocenyl/diferrocenium substituted dioxido molybdenum(VI) complexes [Fe2MoO2] 2(Fc)/[2(FC)]²⁺ mimic the catalytic active site including the redox subunits as well as the catalytic function of bacterial sulphite oxidases.

Teaching Inorganic Photophysics and Photochemistry with Three Ruthenium(II) Polypyridyl Complexes: A Computer-Based Exercise

2015

Among computational methods, DFT (density functional theory) and TD-DFT (time-dependent DFT) are widely used in research to describe, inter alia, the optical properties of transition metal complexes. Inorganic/physical chemistry courses for undergraduate students treat such methods, but quite often only from the theoretical point of view. In the calculation exercise herein described, students are guided step by step through the computational study of the photophysics and photochemistry of polypyridyl Ru(II) d6-metal complexes. In particular, by means of DFT and TD-DFT calculations, they are asked to examine and interpret a set of experimental data describing the absorption, emission, and ph…