Structural characterization of the trans -equatorial isomer of (aqua)(ethylenediamine- N , N , N ′-tripropionato)chromium(III) trihydrate,[Cr(edtrp)(H2O)] · 3H2O

The structure of trans-equatorial [Cr(edtrp)(H2O)] · 3H2O (edtrp3− is the anion of ethylenediamine-N,N,N′-tripropionic acid) was determined by single crystal X-ray diffraction. The chromium(III) ion is surrounded octahedrally by the two nitrogen and three oxygen atoms of the quinquedentate edtrp3−, forming a five-membered diamine ring and the three six-membered β-propionato chelate rings. The remaining coordination position is occupied by the H2O ligand. The crystal structure conformation is compared to the result of recent molecular mechanics analysis. The ring strain of R and G chelate rings was found to be in agreement with the previously proposed mechanisms for the C—N bond cleavage and recombinatio

Supplementary data for article: Perić, M.; Niketic, S.; Zlatar, M.; Gruden-Pavlović, M.; Grubišić, S. DFT and MM Description of the Structure and Magnetic Properties of Manganese Complexes with X-Phenylcyanamido Bridging Ligand. Monatshefte Fur Chemie 2011, 142 (6), 585–592. https://doi.org/10.1007/s00706-011-0502-x

Supplementary material for: [https://doi.org/10.1007/s00706-011-0502-x]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1340

Derivation of a new set of force field parameters for ammine complexes of chromium(III) containing halogenido ligands: modeling of the trans-influence of halogenido ligands

An approach to model the trans-influence using partial atomic charges derived from the molecular electrostatic potential by means of the restrained electrostatic potential (RESP) fitting method is exemplified on a series of halogenido-ammine octahedral chromium(III) complexes. RESP charges incorporated in the present vibrationally optimized consistent force field account for second-order phenomena, improve the modeling and assignment of skeletal vibrations, and reproduce the trends in frequency shifts along the F, Cl, Br, I series. In addition, a supplementary statistical analysis is given for the Cr-halogen bonds in the crystal structures from the CSD

Supplementary data for article: Perić, M.; Niketic, S.; Zlatar, M.; Gruden-Pavlović, M.; Grubišić, S. DFT and MM Description of the Structure and Magnetic Properties of Manganese Complexes with X-Phenylcyanamido Bridging Ligand. Monatshefte Fur Chemie 2011, 142 (6), 585–592. https://doi.org/10.1007/s00706-011-0502-x

Supplementary material for: [https://doi.org/10.1007/s00706-011-0502-x]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1340

Ligand field regulation of manganese redox potential in MnSODs

Ligand field analysis (in the AOM formalism) of Mn(ll, lll) in seven Mn SOD structures reported in the Brookhaven PDB show non-negligible differences in d-orbital energies. The results are equally affected by the azimuthal deformations of the coordination polyhedron, as well as by the orientations of the His imidazole rings with respect to the Mn-N bonds or of the Asp C700 fragment with resepct to the Mn-O bond, since both N and O ligators are behaving as anisotropic pi acceptors and donors, respectively. The orbital energies were used to gauge the ability of manganese to gain or loose an electron in an attempt to predict changes in the redox potential and to correlate these predictions with the data on the kinetics of dismutation recations. The resuls are used to explain our recent observation that E. coli Mn SOD exposed to nitric oxide (NO) in vitro catalyzes its dismutation

Atomic partial charges for mixed chloroammine chromium(III) complexes fitted to the molecular electrostatic potential

Using the RESP procedure partial atomic charges for six isomers of a series of octahedral complexes [Cr(NH3)(6-x)(Cl)(x)]((3-x)+) (x = 0, 1, 2, 3) were least-square fitted to the molecular electrostatic potential (MEP) derived from quantum mechanical (QM) calculations with different HF basis sets. The resulting charges are self-consistent, they match MEPs, QM dipole and quadrupole moments, and they reflect fine electronic effects in the coordination sphere (viz. trans and cis influence) offering a possibility to explicitly incorporate some of these electronic features in a molecular mechanics (MM) treatment. RESP derived partial atomic charges (together with other nonobservable quantities, such as atomic dipole moments, and atomic polarizabilities) could thus be parametrized on the basis of a multibody model, which is a prerequisite for any nonadditive MM approach

Molecular mechanics study of nickel(ii) octaethylporphyrin adsorbed on graphite (0001)

The effects of adsorption on the graphite(0001) surface on the nonplanar distortions of nickel(II) octaethylporphyrin were studied by molecular mechanics (MM) approach. Using the Consistent Force Field (CFF) program with previously developed parameters for metalloporphyrins and supplemented to treat intermolecular interactions geometry optimizations were carried out for 43 conformations of 28 distinct conformers of nickel(II)octaethylporphyrin. The stable energy-minimized conformers were stereochemically characterized, analyzed by the Normal-coordinate Structural Decomposition (NSD) method and compared with the available theoretical and experimental data for the isolated nickel(II)octaethylporphyrin structures

Structural analysis of conformational flexibility in (aqua)(propanediamine-<b><i>N</i></b>,<b><i>N</i></b> '-diacetato-<b><i>N</i></b>-propionato)chromium(III) dihydrate. Crystal structure of <b><i>cis</i></b>-polar, <b><i>trans</i></b>(H₂O,O⁵)-[Cr(1,3-pddap)(H₂O)]<b>·</b>2H₂O

The quinquedentate complex trans(H₂O,O⁵)-[Cr(1,3-pddap)(H₂O)] · 2H₂O (where 1,3-pddap is the 1,3-propanediamine-N,N '-diacetate-N-3-propionate ion) was prepared and its structure established by X-ray diffraction method. It crystallizes in the orthorhombic space group Pna2₁, a = 17.290(2), b = 10.821(2), c = 7.872(1) Å, Z = 4. The metal atom is surrounded octahedrally with two nitrogen and three oxygen donors of (1,3-pddap)³⁻, forming two six-membered and two five-membered metal chelate rings, and with one water molecule occupying the trans position with respect to the oxygen of the axial glycinate ring. Conformational analysis of the five geometrical isomers of [Cr(1,3-pddap)(H₂O)], performed with the Consistent Force Field (CFF) program and recently developed edta force field, revealed that the global minimum is indeed the trans(H₂O,O⁵) isomer with the geometry in a very good agreement with the crystallographic structure. General patterns for the conformational preferences of edta-type complexes of trivalent first-row transition metals are exposed and discussed

Conformational analysis of edta-type rhodium(III) complexes with mixed five- and six-membered chelate rings. Structural analysis of conformational flexibility in rhodium(III) complexes containing 1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate ligand

Conformational analysis of the three possible geometrical isomers: trans(O5), trans(O5O6) and trans(O6) of the sexidentate [Rh(1,3-pddadp)]- complex, and of the 10 possible isomers: four cis-equatorial, four cis-polar and two trans-equatorial of the quinquedentate [Rh(1,3-pddadp)Cl]2- complex was performed using the consistent force field (CFF) method, with the parameters developed previously for edta-type complexes of chromium(III) and supplemented with new parameters for rhodium(III). The force field is of maximally diagonal type. The energy-minimized structure of the cis-polar,trans(Cl,O5) isomer, having the same absolute configuration at the nitrogen atoms and 5-6-6 ring system in the G plane, represents the global minimum for the quinquedentate [Rh(1,3-pddadp)Cl]2- species. In the case of sexidentate [Rh(1,3-pddadp)]- complex the lowest energy conformer corresponds to the trans(O5O6) configuration. CFF calculations reproduced very well all crystallographically characterized structures: trans(O5)-[Rh(1,3-pddadp)]-, trans(O5O6)-[Rh(1,3-pddadp)]- and cis-polar,trans(Cl,O5)-[Rh(1,3-pddadp)Cl]2-. Comparison of the present molecular mechanics results with those for the analogous complexes revealed some general patterns for the conformational preferences of edta-type complexes. © 2006 Elsevier B.V. All rights reserved