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1.  Zinc(II) and Nickel(II) Benzoate Complexes from the Use of 1-methyl-4,5-diphenylimidazole 
Two new complexes, [Zn(O2CPh)2(L)2]·2MeOH (1·2MeOH) and [Ni2(O2CPh))4(L)2]·2MeCN (2·2MeCN), have been synthesized and characterized by X-ray analysis in the course of an ongoing investigation of the MII/X−/L [MII = Co, Ni, Cu, Zn; X− = Cl−, Br−, I−, NCS−, NO3−, N3−, PhCO2−; L = 1-methyl-4,5-diphenylimidazole] reaction system, aiming at understanding and assessing the relative strength and the way in which the intermolecular interactions control the supramolecular organization of these compounds. In the mononuclear complex 1·2MeOH, the benzoate ion acts as a monodentate ligand resulting in a distorted tetrahedral N2O2 coordination environment. Complex 2·2MeCN exhibits a dinuclear paddle-wheel structure; each NiII has a square pyramidal NiNO4 chromophore with four benzoate oxygens in the basal plane and the pyridine-type nitrogen atom of one ligand L at the apex. The structure of 1·2MeOH is stabilized by intramolecular π-π interactions between aromatic rings of adjacent 4,5-diphenylimidazole moieties; it is a feature also evidenced in similar compounds of the type [MX2L2].
PMCID: PMC2927736  PMID: 20811497
2.  catena-Poly[[(tetra­aqua­cadmium)-μ-4,4′-bipyridine-κ2 N:N′] 4-hy­droxy-3-sulfonato­benzoate monohydrate] 
The two independent CdII atoms in the polymeric title compound, [Cd(C10H8N2)(H2O)4](C7H4O6S)·H2O, lie on twofold rotation axes, and each is coordinated by four water mol­ecules and the N atoms of two 4,4′-bipyridine mol­ecules in an octa­hedral geometry. Bridging gives rise to chains along [101] and [-101]. The 4-hy­droxy-3-sulfonato­benzoate dianions are not connected to the CdII atoms, but form hydrogen bonds to the coordinated water mol­ecules as well as the lattice water mol­ecule, generating a three-dimensional network.
PMCID: PMC3379062  PMID: 22719283
3.  catena-Poly[[di-μ-chlorido-bis­{[6-methoxy-2-(4-methyl­phenyl­iminio­methyl)phenolato-κ2 O,O′]cadmium(II)}]-di-μ2-thio­cyanato-κ2 N:S;κ2 S:N] 
The asymmetric unit of the title compound, [Cd2Cl2(NCS)2(C15H15NO2)2]n, contains the Schiff base 2-[(4-methyl­phenyl­imino)meth­yl]-6-methoxy­phenol (HL) ligand, one thio­cyanate and one chloride ligand coordinated to a cadmium centre. The cadmium centers are linked to each other via two thio­cyanate and two chloride bridges alternately, resulting in centrosymmetric zigzag chains running parallel to the a axis. The CdII coordination environment contains two Cl atoms, one thio­cyanate (SCN) S atom, one isothio­cyanate (NCS) N atom and two O atoms from the HL ligand. The Schiff base ligand is in the trans conformation.
PMCID: PMC2959993  PMID: 21581192
4.  Biapenem Inactivation by B2 Metallo β-Lactamases: Energy Landscape of the Post-Hydrolysis Reactions 
PLoS ONE  2012;7(1):e30079.
The first line of defense by bacteria against β-lactam antibiotics is the expression of β-lactamases, which cleave the amide bond of the β-lactam ring. In the reaction of biapenem inactivation by B2 metallo β-lactamases (MβLs), after the β-lactam ring is opened, the carboxyl group generated by the hydrolytic process and the hydroxyethyl group (common to all carbapenems) rotate around the C5–C6 bond, assuming a new position that allows a proton transfer from the hydroxyethyl group to C2, and a nucleophilic attack on C3 by the oxygen atom of the same side-chain. This process leads to the formation of a bicyclic compound, as originally observed in the X-ray structure of the metallo β-lactamase CphA in complex with product.
Methodology/Principal Findings
QM/MM and metadynamics simulations of the post-hydrolysis steps in solution and in the enzyme reveal that while the rotation of the hydroxyethyl group can occur in solution or in the enzyme active site, formation of the bicyclic compound occurs primarily in solution, after which the final product binds back to the enzyme. The calculations also suggest that the rotation and cyclization steps can occur at a rate comparable to that observed experimentally for the enzymatic inactivation of biapenem only if the hydrolysis reaction leaves the N4 nitrogen of the β-lactam ring unprotonated.
The calculations support the existence of a common mechanism (in which ionized N4 is the leaving group) for carbapenems hydrolysis in all MβLs, and suggest a possible revision of mechanisms for B2 MβLs in which the cleavage of the β-lactam ring is associated with or immediately followed by protonation of N4. The study also indicates that the bicyclic derivative of biapenem has significant affinity for B2 MβLs, and that it may be possible to obtain clinically effective inhibitors of these enzymes by modification of this lead compound.
PMCID: PMC3260057  PMID: 22272276
5.  catena-Poly[[bis­(2-meth­oxy­aniline-κN)cadmium]-di-μ-thio­cyanato-κ2 N:S;κ2 S:N] 
The structure of the title compound, [Cd(NCS)2(C7H9NO)2]n, consists of cadmium–thio­cyanate layers parallel to the ab plane. Pairs of CdII ions are bridged by two end-to-end inversely bridging μ-NCS-N:S thio­cyanate groups, forming a two-dimensional network with the remaining two trans positions of the octa­hedrally coordinated CdII ions occupied by the N atoms of two neutral 2-meth­oxy­aniline ligands. The crystal structure is stabilized by intra­layer N—H⋯S hydrogen bonds.
PMCID: PMC3647823  PMID: 23723789
6.  catena-Poly[bis­(sulfamethoxazolium) [[trichloridocadmate(II)]-μ-chlorido] monohydrate] 
In the title compound, {(C10H12N3O3S)2[CdCl4]·H2O}n, the CdII atom is five-coordinate with a distorted trigonal–bipyramidal geometry formed by chloride ions. The Cd atom and two of the Cl atoms lie on a mirror plane. The cation is protonated on the amino group N atom; it is not coordinated to cadmium, but is hydrogen bonded to the chlorido ligands. Each water mol­ecule bridges two chlorido ligands, generating ring motifs along the –Cd—Cl—Cd– chains. The isoxazole unit and the amide groups are linked through a pair of N—H⋯N hydrogen bonds. The crystal structure is stabilized by N—H⋯O, O—H⋯Cl, C—H⋯N, N—H⋯Cl and C—H⋯O hydrogen bonds.
PMCID: PMC2915166  PMID: 21200590
7.  catena-Poly[[aqua­(1,10-phenanthroline)cadmium(II)]-μ-benzene-1,4-di­carboxyl­ato] 
The title compound, [Cd(C8H4O4)(C12H8N2)(H2O)]n, is a new coordination polymer of benzene-1,4-dicarboxyl­ate with cadmium(II) and 1,10-phenanthroline. The CdII ion is coordinated by two N atoms from the 1,10-phenanthroline mol­ecule, three O atoms from two crystallographically independent benzene-1,4-dicarboxyl­ate ligands and the O atom of a coordinated water mol­ecule, forming a heavily distorted octa­hedron. The 1,10-phenanthroline ligand is approximately planar within 0.073 (4) Å. The two different benzene-1,4-dicarboxyl­ate ligands each coordinate to two CdII ions in bidentate and monodentate modes, forming an infinite zigzag chain. Adjacent chains are packed tightly by strong π–π inter­actions [centroid–centroid distances = 3.851 (2) and 3.859 (2) Å] between the aromatic rings of the benzene-1,4-dicarboxyl­ate ligand and the 1,10-phenanthroline of a neighboring chain, forming a sheet parallel to (011). Different sheets are linked together via O—H⋯O hydrogen bonds between the coordinated water mol­ecules and the O atoms of the carboxyl­ate groups, forming a three-dimensional network.
PMCID: PMC2967922  PMID: 21581553
8.  catena-Poly[[bis­(pyridine-κN)cadmium]-di-μ2-thio­cyanato-κ2 N:S;κ2 S:N] 
The asymmetric unit of the title compound, [Cd(NCS)2(C5H5N)2]n, consists of two crystallographically independent CdII cations, four thio­cyanato anions and four pyridine ligands. The CdII atoms are each coordinated by four N atoms from two pyridine ligands and two thio­cyanato anions, each in a mutually cis orientation, and by two S atoms from two adjacent thio­cyanato anions within a slightly distorted octa­hedral coordination environment. The CdII atoms are μ-1,3-bridged via the thio­cyanato anions into polymeric chains parallel to [001]. The CdII⋯CdII intra­chain separations range between 5.9688 (6) and 6.0195 (6) Å, whereas the shortest CdII⋯CdII inter­chain separations are 7.8272 (7) and 8.6312 (6) Å.
PMCID: PMC3099960  PMID: 21753993
9.  catena-Poly[[(1,10-phenanthroline)cadmium(II)]-μ-2-(1,3-benzimidazol-2-ylsulfan­yl)acetato-κ3 N 1,O:N 3] 
In title compound, [Cd(C9H6N2O2S)(C12H8N2)]n, the CdII atom is in a distorted tetra­gonal-pyramidal environment, coordinated by one chelating 1,10-phenanthroline ligand, one chelating 2-(1,3-benzimidazol-2-ylsulfan­yl)acetate (bia) ligand bound through one N atom and one O atom of the carboxyl group, and one N atom from a second bia ligand. Each bia ligand acts as bridge between CdII ions, forming one-dimensional coordination polymers along [010], with a shortest Cd⋯Cd distance of 4.27 (2) Å.
PMCID: PMC2967880  PMID: 21581506
10.  catena-Poly[[aqua­bis­(3-chloro­benzoato-κ2 O,O′)cadmium]-μ-N,N-di­ethyl­nico­tin­amide-κ2 N 1:O] 
In the crystal of the title CdII polymeric complex, [Cd(C7H4ClO2)2(C10H14N2O)(H2O)]n, the CdII cation is chelated by two chloro­benzoate anions and coordinated by two N,N-di­­ethyl­nicotinamide (DENA) ligands and one water mol­ecule in a distorted NO6 penta­gonal–bipyramidal geometry. The CdII cations are bridged by the pyridine N atom and carbonyl O atom of the DENA ligand to form a polymeric chain running along the b axis. Inter­molecular O—H⋯O hydrogen bonds between coordinating water mol­ecules and carboxyl­ate groups link adjacent chains into layers parallel to the bc plane. π–π contacts between benzene rings [shortest centroid–centroid distance = 3.912 (2) Å] further stabilizes the crystal structure. In the mol­ecule, weak C—H⋯O hydrogen bonds occur between the pyridine ring and carboxyl­ate groups; the dihedral angles between the carboxyl­ate groups and adjacent benzene rings are 4.6 (3) and 12.8 (3)°, while the benzene rings are oriented at a dihedral angle of 1.89 (13)°.
PMCID: PMC3793697  PMID: 24109284
11.  catena-Poly[[bis­(1-ethyl-1H-imidazole-κN 3)cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN 3)cadmium]-di-μ-chlorido-[(1-ethyl-1H-imidazole-κN 3)cadmium]-di-μ-chlorido-[bis­(1-ethyl-1H-imidazole-κN 3)cadmium]] 
The asymmetric unit of the crystal structure of the title compound, [Cd2Cl4(C5H8N2)3]n, contains two CdII cations, three 1-ethyl-1H-imidazole ligands, and four Cl− anions. The two CdII atoms have quite different coordination environments: one is octa­hedrally coordinated by four Cl atoms and two N atoms from two 1-ethyl-1H-imidazole ligands, and the second is in a severely distorted fivefold coordination by four Cl atoms and one N atom from a 1-ethyl-1H-imidazole ligand. Adjacent CdII cations are inter­connected alternately by pairs of chloride bridges, generating an infinite step-like chain along the a axis. One ethyl group of the 1-ethyl-1H-imidazole ligand is disordered over two sets of sites with a 0.668 (13):0.332 (13) site-occupancy ratio.
PMCID: PMC3238745  PMID: 22199622
12.  catena-Poly[(dichloridocadmium)-di-μ-chlorido-[bis­(morpholinium-κO)cadmium]-di-μ-chlorido] 
In the title compound, [Cd2Cl6(C4H10NO)2]n, the coordination geometry of each CdII ion is distorted octa­hedral, but with quite different coordination environments. One CdII atom is coordinated by four Cl atoms and two O atoms from two morpholinium ligands, while the other is coordinated by six Cl atoms. Adjacent CdII atoms are inter­connected alternately by paired chloride bridges, generating a chain parallel to the a axis. Inter­chain N—H⋯Cl inter­actions form a two-dimensional network.
PMCID: PMC3212201  PMID: 22090903
13.  catena-Poly[di-μ1,1-azido-(1,10-phenanthroline)cadmium(II)] 
The asymmetric unit of the title CdII compound, [Cd(N3)2(C12H8N2)]n, contains a CdII atom, located on a twofold axis passing through the middle of the phenanthroline mol­ecule, one azide ion and half of a 1,10-phenanthroline mol­ecule. The CdII atom exhibits a distorted octa­hedral coordin­ation including one chelating 1,10-phenanthroline ligand and four azide ligands. The crystal structure features chains along the c direction in which azide groups doubly bridge two adjacent CdII atoms in an end-on (EO) mode. Inter­chain π–π stacking inter­actions, with centroid–centroid separations of 3.408 (2) Å between the central aromatic rings of 1,10-phenanthroline mol­ecules, lead to a supra­molecular sheet parallel to the bc plane.
PMCID: PMC3006842  PMID: 21587693
14.  A new polymorph of catena-poly[[tri­aqua­cadmium(II)]-μ2-pyrazine-2,3-dicarboxyl­ato] 
The title complex, [Cd(C6H2N2O4)(H2O)3]n, is a new monoclinic polymorph. The ortho­rhom­bic form has previously been reported [Ma et al. (2006 ▶). Acta Cryst. E62, m2528–m2529]. The Cd—N and Cd—O bond lengths range from 2.265 (3) to 2.333 (3) Å; a weak Cd—O inter­action is also present, the inter­atomic distance being 2.658 (4) Å. The CdII ions, which have a distorted penta­gonal-bipyramidal geometry, are bridged by pyrazine-2,3-dicarboxyl­ato ligands, forming a zigzag chain structure. The chains are connected by O—H⋯O hydrogen bonds into a three-dimensional framework.
PMCID: PMC2977175  PMID: 21583415
15.  catena-Poly[[trans-bis­(cyclo­hexane-1,2-diamine-κ2 N,N)cadmium]-μ-iodido-(diiodidocadmium)-μ-iodido] 
In the title compound, [Cd2I4(C6H14N2)2]n, there are two independent CdII ions. One CdII ion is coordinated in a slightly distorted octa­hedral coordination environment by four N atoms from two cyclo­hexane-1,2-diamine ligands and two iodido ligands. The other CdII ion is coordinated by four iodido ligands in a slightly distorted tetra­hedral coordination environment. Two of the iodido ligands act as bridging ligands connecting CdII ions and forming a one-dimensional polymer along [010]. In the crystal, N—H⋯I hydrogen bonds connect the one-dimensional structure into a two-dimensional framework parallel to (001).
PMCID: PMC3393164  PMID: 22807732
16.  catena-Poly[[[aqua­(1,10-phenan­throline)cadmium(II)]-μ-benzene-1,4-dicarboxyl­ato] benzene-1,4-dicarboxylic acid hemisolvate] 
A new cadmium(II) coordination polymer, {[Cd(C8H4O4)(C12H8N2)(H2O)]·0.5C8H6O4}n, has been synthesized under hydro­thermal conditions. The asymmetric unit contains one CdII atom, one benzene-1,4-dicarboxyl­ate anion, one 1,10-phenanthroline ligand, one coordinated water mol­ecule and half of an uncoordinated benzene-1,4-dicaboxylic acid solvent mol­ecule. The CdII atom is in the centre of a monocapped distorted octa­hedron made up of four O atoms of two chelating benzene-1,4-dicarboxyl­ate anions, one water O atom and two 1,10-phenanthroline N atoms. The metal centres are connected via bis-chelating benzene-1,4-dicarboxyl­ate anions into a zigzag chain structure along [001]. These chains are further connected by O—H⋯O hydrogen bonds between the water mol­ecules and adjacent carboxyl­ate O atoms. Additional O—H⋯O hydrogen bonding between the uncoordinated benzene-1,4-dicaboxylic acid mol­ecules along [010] consolidates the structure.
PMCID: PMC2968137  PMID: 21581788
17.  catena-Poly[lead(II)-[μ-2,4-diamino-6-(piperidin-1-yl)pyrimidine N-oxide-κ2 O:O]di-μ-iodido] 
The N-oxide O atom of the minoxidil unit in the 1/1 adduct with lead(II) iodide, [PbI2(C9H15N5O)]n, bridges two PbII atoms, as do each of the I atoms. The bridging inter­actions give rise to a linear chain motif that propagates along the a axis of the ortho­rhom­bic unit cell. The coordination sphere around the six-coordinate PbII atom is a distorted ψ-monocapped octa­hedron in which the stereochemically active lone pair caps one of the faces defined by the O and I atoms forming the longer Pb—O or Pb—I bonds. The PbII atom lies on a mirror plane; the mirror plane is perpendicular to the pyrimidine ring and it bis­ects the piperidine ring. The aromatic ring is disordered about the mirror plane with respect to the 1-nitro­gen and 5-carbon atoms.
PMCID: PMC2969437  PMID: 21582686
18.  catena-Poly[[(8-amino­quinoline-κ2 N,N′)cadmium]-di-μ-thio­cyanato-κ2 N:S;κ2 S:N-[(8-amino­quinoline-κ2 N,N′)cadmium]-di-μ-chlorido] 
In the title compound, [CdCl(NCS)(C9H8N2)]n, the CdII atom is in a distorted octa­hedral coordination environment defined by two chloride anions, two N atoms from an 8-amino­quinoline ligand, one N atom from one thio­cyanate anion and one S atom from a symmetry-related thio­cyanate anion. Two CdII atoms are bridged by two chloride anions, forming an inversion-related Cd2Cl2 unit; these units are further linked through thio­cyanate anions, leading to a chain structure extending parallel to [010]. Weak π–π stacking inter­actions with centroid–centroid distances of 3.430 (4) Å and an inter­planar separation of 3.390 (3) Å between the pyridine and benzene rings link the chains into a two-dimensional network parallel to (10). Weak inter­molecular C—H⋯Cl hydrogen-bonding inter­actions help to consolidate the crystal packing.
PMCID: PMC3254276  PMID: 22259334
19.  catena-Poly[(di­aqua­cadmium)-μ-iminodi­acetato-κ4 O,N,O′:O′′] 
In the title compound, [Cd(C4H5NO4)(H2O)2]n, the CdII atom exhibits a distorted octa­hedral coordination geometry, defined by one N atom and three O atoms from two iminodi­acetate (IDA) ligands and two water molecules. The tridentate IDA ligand additionally bridges via one of its carboxylate O atoms to another CdII atom, thus forming a zigzag chain along [001]. A three-dimensional network is completed by inter­molecular O—H⋯O and N—H⋯O hydrogen bonds.
PMCID: PMC3772440  PMID: 24046583
20.  catena-Poly[[tetra­aqua­cadmium]-μ-5,5′-(1,4-phenyl­ene)di(tetra­zol-2-ido)-κ2 N 2:N 2′] 
In the title compound, [Cd(C8H4N8)(H2O)4]n, 5,5′-(1,4-phenyl­ene)di(tetra­zol-2-ide) (L) ligands bridge CdII atoms into polymeric chains along [201]. The CdII atom is situated on an inversion centre and is coordinated by two N atoms from two L ligands and by four water O atoms in a distorted octa­hedral geometry. In the L ligand, the benzene ring resides on an inversion centre and the tetra­zole rings are twisted from its plane by 22.3 (1)°. An extensive hydrogen-bonding network formed by classical O—H⋯N and O—H⋯O inter­actions consolidates the crystal packing, linking the poymeric chains into a three-dimensional structure.
PMCID: PMC3647818  PMID: 23723784
21.  catena-Poly[[[aqua­(pyrazino[2,3-f][1,10]phenanthroline)cadium(II)]-μ-4,4′-ethyl­enedibenzoato] N,N-dimethyl­formamide hemisolvate] 
In the title compound, [Cd(C16H10O4)(C14H8N4)(H2O)]·0.5C3H7NO, the CdII atom is six-coordinated by two N atoms from one pyrazino[2,3-f][1,10]phenanthroline ligand, three carboxyl­ate O atoms from two different 4,4′-ethyl­enedibenzoate ligands, and one water mol­ecule in a distorted octa­hedral environment. The two 4,4′-ethyl­enedibenzoate dianions are located on inversion centres bridging two neighboring CdII centres. O—H⋯O hydrogen-bonding inter­actions further stabilize the crystal structure. The DMF molecule is equally disordered about a center of inversion.
PMCID: PMC2977101  PMID: 21583341
22.  catena-Poly[[bis­(nitrato-κO)cadmium]bis­[μ-1,3-bis­[(1H-1,2,4-triazol-1-yl)meth­yl]benzene-κ2 N 4:N 4′]] 
In the title compound, [Cd(NO3)2(C12H12N6)2]n, the CdII cation is located on an inversion center and is six-coordinated by four N atoms from four 1,3-bis­[(1H-1,2,4-triazol-1-yl)meth­yl]benzene (L) ligands and two O atoms from two nitrate anions in a slightly distorted octa­hedral geometry. The ligands link different CdII ions into a ribbon-like structure along [001]. Two O atoms of the nitrate anion are disordered over two sets of sites with site occupancies of 0.575 (8) and 0.425 (8).
PMCID: PMC3379191  PMID: 22719389
23.  catena-Poly[[bis­(nitrato-κO)cadmium]bis­[μ-1,4-bis­(pyridin-3-yl­meth­oxy)benzene-κ2 N:N′]] 
In the title compound, [Cd(NO3)2(C18H16N2O2)2]n, the six-coordinated CdII ion is located on an inversion center and has a distorted octa­hedral environment defined by four N atoms from four 1,4-bis­(pyridin-3-ylmeth­oxy)benzene ligands and two O atoms from two nitrate anions. The ligands link the CdII ions into a ribbon-like structure running along [201]. One O atom of the nitrate anion is disordered over two positions with site-occupancy factors of 0.59 (2) and 0.41 (2).
PMCID: PMC3200741  PMID: 22064823
24.  catena-Poly[[{N,N-dimethyl-N′-[1-(pyridin-2-yl)ethyl­idene]ethane-1,2-diamine-κ3 N,N′,N′′}(thio­cyanato-κN)cadmium]-μ-thio­cyanato-κ2 S:N] 
In the title compound, [Cd(NCS)2(C11H17N3)]n, the CdII atom is octa­hedrally coordinated by the N,N′,N′′-tridentate Schiff base ligand and one terminal thio­cyanate N atom. Two trans-N:S-bridging thio­cyanates complete the N5S donor set around the Cd atom. In the crystal, adjacent CdII ions are linked by the thio­cyanate N:S-bridges into polymeric chains along the c axis.
PMCID: PMC3099776  PMID: 21753992
25.  catena-Poly[[[[2-(2-pyridyl-κN)-1H-benzimidazole-κN 3]copper(II)]-μ-l-methio­ninato-κ3 N,O:O′] perchlorate] 
The structure of the title compound, {[Cu(C5H10NO2S)(C12H9N3)]ClO4}n, has ortho­rhom­bic symmetry. The chain structure is constructed from square-pyramidally coordinated CuII atoms linked through l-methio­nate ligands. The chains propagate along the a-axis direction and are linked to perchlorate anions via N—H⋯O hydrogen bonds.
PMCID: PMC3089275  PMID: 21754350

Results 1-25 (369529)