Search results for " theoretical"
showing 10 items of 9066 documents
Ligand Noninnocence in Cobalt Dipyrrin–Bisphenols: Spectroscopic, Electrochemical, and Theoretical Insights Indicating an Emerging Analogy with Corro…
2019
Three cobalt dipyrrin-bisphenol (DPPCo) complexes with different meso-aryl groups (pentafluorophenyl, phenyl, and mesityl) were synthesized and characterized based on their electrochemistry and spectroscopic properties in nonaqueous media. Each DPPCo undergoes multiple oxidations and reductions with the potentials, reversibility, and number of processes depending on the specific solution conditions, the specific macrocyclic substituents, and the type and number of axially coordinated ligands on the central cobalt ion. Theoretical calculations of the compounds with different coordination numbers are given in the current study in order to elucidate the cobalt-ion oxidation state and the innoc…
Enhanced Interplay between Host–Guest and Spin-Crossover Properties through the Introduction of an N Heteroatom in 2D Hofmann Clathrates
2021
Controlled modulation of the spin-crossover (SCO) behavior through the sorption-desorption of invited molecules is an extensively exploited topic because of its potential applications in molecular sensing. For this purpose, understanding the mechanisms by which the spin-switching properties are altered by guest molecules is of paramount importance. Here, we show an experimental approach revealing a direct probe of how the interplay between SCO and host-guest chemistry is noticeably activated by chemically tuning the host structure. Thus, the axial ligand 4-phenylpyridine (4-PhPy) in the 2D Hofmann clathrates {Fe(4-PhPy)2[M(CN)4]} (PhPyM; M = Pt, Pd) is replaced by 2,4-bipyridine (2,4-Bipy),…
Combination of magnetic susceptibility and electron paramagnetic resonance to monitor the 1D to 2D solid state transformation in flexible metal-organ…
2012
Two families of coordination polymers, {[M(btix)(2)(OH(2))(2)]·2NO(3)·2H(2)O}(n) [M = Co (1), Zn (2), Co-Zn (3); btix = 1,4-bis(triazol-1-ylmethyl)benzene] and {[M(btix)(2)(NO(3))(2)]}(n) [M = Co (4), Zn (5), Co-Zn (6)], have been synthesized and characterized. The two conformations of the ligand, syn and anti, lead to one-dimensional (1D) cationic chains or two-dimensional (2D) neutral grids. Extrusion of the water molecules of the 1D compounds results in an irreversible transformation into the 2D compounds, which involves a change in conformation of the btix ligands and a rearrangement in the metal environment with cleavage and reformation of covalent bonds. This structural transformation…
Selective Metal–Ligand Bond-Breaking Driven by Weak Intermolecular Interactions: From Metamagnetic Mn(III)-Monomer to Hexacyanoferrate(II)-Bridged Me…
2020
Metal–ligand coordination interactions are usually much stronger than weak intermolecular interactions. Nevertheless, here, we show experimental evidence and theoretical confirmation of a very rare...
Hexanuclear manganese(III) single-molecule magnets based on oxime and azole-type ligands
2019
Abstract Two novel hexanuclear manganese(III) complexes belonging to the Mn6 family of single-molecule magnets (SMMs), of formulae [Mn6(μ3-O)2(H2N-sao)6(bta)2(EtOH)6]·2EtOH·4H2O (1) and [Mn6(μ3-O)2(H2N-sao)6(pta)2(EtOH)6]·4EtOH (2) [H2N-saoH2 = salicylamidoxime, bta = 1,2,3-benzotriazolate anion, pta = 5-phenyl-tetrazolate anion], have been synthesized and characterized structurally and magnetically. Both compounds crystallize in the triclinic system with space group P 1 ¯ (1 and 2). In their crystal packing, adjacent Mn6 complexes are connected through non-coordinating solvent molecules, which are H-bonded to N atoms of azole rings and –NH2 groups of salicylamidoxime ligand. The study of t…
A P-chirogenic β-aminophosphine synthesis by diastereoselective reaction of the α-metallated PAMP–borane complex with benzaldimine
2004
International audience; The diastereoselective synthesis of a P-chirogenic β-aminophosphine ligand with carbon–carbon bond formation of the ethano bridge in a 3:1 ratio via reaction of an α-metallated P-chirogenic phosphine borane with a benzaldimine is described. The diastereoselectivity is attributed to a transition state where the lithium cation chelates the phosphine borane carbanion and the nitrogen of the imine and the attack of the C@N occurs on the face opposite to the P–B bond, due to its interaction with the antibonding P–B bond. The major diastereoisomeric β-aminophosphine borane was then separated and decomplexed into the corresponding β-aminophosphine under neutral conditions a…
Titanocene–gold complexes containing N-heterocyclic carbene ligands inhibit growth of prostate, renal, and colon cancers in vitro
2016
We report on the synthesis, characterization, and stability studies of new titanocene complexes containing a methyl group and a carboxylate ligand (mba = −OC(O)-p-C6H4-S−) bound to gold(I)−N-heterocyclic carbene fragments through the thiolate group: [(η5 -C5H5)2TiMe(μ-mba)Au(NHC)]. The cytotoxicities of the heterometallic compounds along with those of novel monometallic gold−N-heterocyclic carbene precursors [(NHC)Au(mbaH)] have been evaluated against renal, prostate, colon, and breast cancer cell lines. The highest activity and selectivity and a synergistic effect of the resulting heterometallic species was found for the prostate and colon cancer cell lines. The colocalization of both tita…
Recent studies on RR′S·C2B9H11 charge-compensated ligands
2002
Abstract In this paper we report the synthesis of three new carborane derivatives of the series 7,8-R,R′-10-L-7,8-C2B9H9 (R=R′=H, L=SEtPh; R=CH3, R′=H, L=SMe2 and L=SEt2) along with the enhanced characterization of formerly described compounds 7,8-R,R′-10-L-7,8-C2B9H9 (R=R′=H, L=SMe2 (1), L=SEt2 (2) and L=S(CH2)4 (3)). They have been fully characterised using 1H-, 11B- and 13C-NMR spectroscopy. Their bridging proton resonances have been located for the first time. Individual sulfonium substituent contributions have been calculated that have permitted to establish a rule to predict its position in the 1H-NMR spectrum. The crystal structures of 1 and 3 have been resolved for the first time. T…
Solvent effects on the dimensionality of oxamato-bridged manganese(II) compounds
2018
Two new oxamate-containing manganese(II) complexes, [{Mn(H2edpba)(H2O)2}2]n (1) and [Mn(H2edpba)(dmso)2]∙dmso∙CH3COCH3∙H2O (2) (H4edpba = N,N′-ethylenediphenylenebis(oxamic acid) and dmso = dimethylsulfoxide), have been synthesized and the structures of 1 and 2 were characterized by single crystal X-ray diffraction. The structure of 1 consists of neutral honeycomb networks in which each manganese(II) is six-coordinate by one H2edpba2− ligand and two carboxylate–oxygens from two other H2edpba2− ligands building the equatorial plane. Each manganese is connected to its nearest neighbor through two carboxylate(monoprotonated oxamate) bridges in an anti-syn conformation. A dmso solution of singl…
Effects of Remote Ligand Substituents on the Structures, Spectroscopic, and Magnetic Properties of Two-Coordinate Transition-Metal Thiolate Complexes
2018
The first-row transition-metal(II) dithiolates M(SAriPr4)2 [AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2; M = Cr (1), Mn (3), Fe (4), Co (5), Ni (6), and Zn (7)] and Cr(SArMe6)2 [2; ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] and the ligand-transfer reagent (NaSAriPr4)2 (8) are described. In contrast to their M(SAriPr6)2 (M = Cr, Mn, Fe, Co, Ni, and Zn; AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) congeners, which differ from 1 and 3-6 in having p-isopropyl groups on the flanking aryl rings of the terphenyl substituents, compounds 1 and 4-6 display highly bent coordination geometries with S-M-S angles of 109.802(2)° (1), 120.2828(3)° (4), 91.730(3)° (5), and 92.68(2)° (6) as well as relatively close metal-flanking …