Crystal structure of bis[1-(2-hydroxyethyl)-2-methyl-5-nitro- 1H-imidazole-κN3]silver(I) tetrafluoridoborate methanol monosolvate

1-(2-Hydroxyethyl)-2-methyl-5-nitro-1Η-imidazole (metronidazole, MET) is a medication that is used to treat infections by a variety of anaerobic organisms, but there are relatively few reports of the structures of metal compounds that exhibit coordination of metronidazole. We have demonstrated that MET reacts with AgBF4 to give [Ag(MET)2]BF4•CH3OH, in which the AgI cation is coordinated by two MET ligands with a trans arrangement. The structure of [Ag(MET)2]BF4 exhibits some interesting differences from its nitrate counterpart, [Ag(MET)2]NO3 [Fun et al. (2008). Acta Cryst. E64, m668]. For instance, although the two MET ligands of both [Ag(MET)2]BF4 and [Ag(MET)2]NO3 are almost coplanar, the former compound has an anti-like geometry with a molecular inversion center, but the latter has a syn-like arrangement. In the crystal, the BF4− anion is linked by an O—H•••F hydrogen bond to the methanol solvent molecule, which is, in turn, linked to the cation by an O— H•••O hydrogen bond; the components of the structure are linked by O—H•••O hydrogen bonds, forming chains along [001]. One of the MET ligands and the BF4 − anion are disordered over two sets of sites with ratios of refined occupancies 0.501 (17):0.499 (17) and 0.539 (19):0.461 (19), respectively

Structures and Reactivity Patterns of Group 9 Metallocorroles

Group 9 metallocorroles 1-M(PPh_3) and 1-M(py)_2 [M = Co(III), Rh(III), Ir(III); 1 denotes the trianion of 5,10,15-tris-pentafluorophenylcorrole] have been fully characterized by structural, spectroscopic, and electrochemical methods. Crystal structure analyses reveal that average metal−N(pyrrole) bond lengths of the bis-pyridine metal(III) complexes increase from Co (1.886 Å) to Rh (1.957 Å)/Ir (1.963 Å); and the average metal−N(pyridine) bond lengths also increase from Co (1.995 Å) to Rh (2.065 Å)/Ir (2.059 Å). Ligand affinities for 1-M(PPh_3) axial coordination sites increase dramatically in the order 1-Co(PPh_3) < 1-Rh(PPh_3) < 1-Ir(PPh_3). There is a surprising invariance in the M(+/0) reduction potentials within the five- and six-coordinate corrole series, and even between them; the average M(+/0) potential of 1-M(PPh_3) is 0.78 V vs Ag/AgCl in CH_2Cl_2 solution, whereas that of 1-M(py)_2 is 0.70 V under the same conditions. Electronic structures of one-electron-oxidized 1-M(py)_2 complexes have been assigned by analysis of electron paramagnetic resonance spectroscopic measurements: oxidation is corrole-centered for 1-Co(py)_2 (g = 2.008) and 1-Rh(py)_2 (g = 2.003), and metal-centered for 1-Ir(tma)_2 (g_(zz) = 2.489, g_(yy) = 2.010, g_(xx) = 1.884, g_(av) = 2.128) and 1-Ir(py)_2 (g_(zz) = 2.401, g_(yy) = 2.000, g_(xx) = 1.937, g_(av) = 2.113)

Iodinated Aluminum(III) Corroles with Long-Lived Triplet Excited States

The first reported iodination of a corrole leads to selective functionalization of the four C–H bonds on one pole of the macrocycle. An aluminum(III) complex of the tetraiodinated corrole, which exhibits red fluorescence, possesses a long-lived triplet excited state

Coordination of metronidazole to Cu(II): Structural characterization of a mononuclear square-planar compound Joshua H.

The reaction between metronidazole [1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole, MET] and CuCl2•2H2O in methanol solution has allowed isolation of blue crystals of composition Cu(MET)2Cl2•MeOH. These crystals have been shown by X-ray diffraction to consist of mononuclear square-planar trans-Cu(MET)2Cl2 molecules in which the metronidazole ligands are trans to each other, as are the Cl ligands. The structure of this compound is very different from other compounds that have been obtained from the reaction between CuCl2•2H2O and metronidazole, namely [Cu(MET)2(μ-Cl)Cl]2 and [Cu(MET)2(μ-Cl)(OH2)]2[Cl]2, which are dimers featuring bridging chloride ligands

Electronic Structures of Group 9 Metallocorroles with Axial Ammines

The electronic structures of metallocorroles (tpfc)M(NH_3)_2 and (tfc)M(NH_3)_2 (tpfc is the trianion of 5,10,15-(tris)pentafluorophenylcorrole, tfc is the trianion of 5,10,15-trifluorocorrole, and M = Co, Rh, Ir) have been computed using first principles quantum mechanics [B3LYP flavor of Density Functional Theory (DFT) with Poisson−Boltzmann continuum solvation]. The geometry was optimized for both the neutral systems (formal M^(III) oxidation state) and the one-electron oxidized systems (formally M^(IV)). As expected, the M^(III) systems have a closed shell d^6 configuration; for all three metals, the one-electron oxidation was calculated to occur from a ligand-based orbital (highest occupied molecular orbital (HOMO) of B_1 symmetry). The ground state of the formal M^(IV) system has M^(III)-Cπ character, indicating that the metal remains d^6, with the hole in the corrole π system. As a result the calculated M^(IV/III) reduction potentials are quite similar (0.64, 0.67, and 0.56 V vs SCE for M = Ir, Rh and Co, respectively), whereas the differences would have been large for purely metal-based oxidations. Vertically excited states with substantial metal character are well separated from the ground state in one-electron-oxidized cobalt (0.27 eV) and rhodium (0.24 eV) corroles, but become closer in energy in the iridium (0.15 eV) analogues. The exact splittings depend on the chosen functional and basis set combination and vary by ~0.1 eV

Crystal structure of hexa-μ-chlorido-μ4-oxido-tetrakis{[1-(2-hydroxyethyl)-2- methyl-5-nitro-1H-imidazole-κN3]copper(II)} containing short NO2· · ·NO2 contacts

The title tetranuclear copper complex, [Cu4Cl6O(C6H9N3O3)4] or [Cu4Cl6O- (MET)4][MET is 1-(2-hydroxyethyl)-2-methyl-5-nitro-1Η-imidazole or metronidazole], contains a tetrahedral arrangement of copper(II) ions. Each copper atom is also linked to the other three copper atoms in the tetrahedron via bridging chloride ions. A fifth coordination position on each metal atom is occupied by a nitrogen atom of the monodentate MET ligand. The result is a distorted CuCl3NO trigonal–bipyramidal coordination polyhedron with the axial positions occupied by oxygen and nitrogen atoms. The extended structure displays O− H ⋅ ⋅ ⋅O hydrogen bonding, as well as unusual short O⋅ ⋅ ⋅ N interactions [2.775 (4) A ˚ ] between the nitro groups of adjacent clusters that are oriented perpendicular to each other. The scattering contribution of disordered water and methanol solvent molecules was removed using the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9–16] in PLATON [Spek (2009). Acta Cryst. D65, 148–155]

Molecular Redox: Revisiting the Electronic Structures of the Group 9 Metallocorroles

The electronic structures of monocationic tris[(5,10,15-pentafluorophenyl)-corrolato]iridium compounds, [Ir(tpfc)L_2]^+, where L = 4-cyanopyridine [1]^+, pyridine [2]^+, 4-methoxypyridine [3]^+, or 4-(N,N′-dimethylamino)pyridine [4]^+, have been probed by electron paramagnetic resonance (EPR) spectroscopy, Ir L_(3,2)-edge X-ray absorption spectroscopy (XAS), UV/visible (UV–vis) spectroelectrochemistry, and density functional theoretical (DFT) calculations. The data demonstrate that these complexes, which have been previously formulated as either of the limiting cases [Ir^(III)(tpfc^•)L_2]^+ or [Ir^(IV)(tpfc)L_2]^+, are best described as possessing a singly occupied molecular orbital (SOMO) dominated by tpfc with small but significant Ir admixture. EPR g-values and electronic absorption spectra are reproduced well using a simple DFT approach. These quantities depend profoundly upon Ir orbital contribution to the SOMO. To wit, the calculated Ir spin population ranges from 10.6% for [1]^+ to 16.3% for [4]^+, reflecting increased Ir d mixing into the SOMO with increasingly electron-rich axial ligation. This gives rise to experimentally measured g_z values ranging from 2.335 to 2.533, metal-to-ligand charge transfer (MLCT) bands ranging from 14730 and 14330 cm^(–1), and [Ir(tpfc)L_2]^(+/0) reduction potentials ranging from 0.305 to 0.035 V vs Fc^(+/0). In addition, the calculated Ir character in the SOMO tracks with estimated Ir L_(3,2) XAS branching ratios (EBR), reflecting the increasing degree of Ir d orbital character upon proceeding from [1]^+ to [4]^+

Cellular uptake and anticancer activity of carboxylated gallium corroles

We report derivatives of gallium(III) tris(pentafluorophenyl)corrole, 1 [Ga(tpfc)], with either sulfonic (2) or carboxylic acids (3, 4) as macrocyclic ring substituents: the aminocaproate derivative, 3 [Ga(ACtpfc)], demonstrated high cytotoxic activity against all NCI60 cell lines derived from nine tumor types and confirmed very high toxicity against melanoma cells, specifically the LOX IMVI and SK-MEL-28 cell lines. The toxicities of 1, 2, 3, and 4 [Ga(3-ctpfc)] toward prostate (DU-145), melanoma (SK-MEL-28), breast (MDA-MB-231), and ovarian (OVCAR-3) cancer cells revealed a dependence on the ring substituent: IC_(50) values ranged from 4.8 to >200 µM; and they correlated with the rates of uptake, extent of intracellular accumulation, and lipophilicity. Carboxylated corroles 3 and 4, which exhibited about 10-fold lower IC_(50) values (> 3 > 2 >> 1 (intracellular accumulation of gallium corroles was fastest in melanoma cells). We conclude that carboxylated gallium corroles are promising chemotherapeutics with the advantage that they also can be used for tumor imaging