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The crystal structure of the novel hydrated CuII salt, [Cu(L)(H2O)2]Cl2·4H2O (L = 3,14-diethyl-2,6,13,17-tetra­aza­tri­cyclo­[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of the [Cu(L)(H2O)2]2+ cation (completed by crystallographic inversion symmetry), one chloride anion and two lattice water mol­ecules. The copper(II) atom exists in a tetra­gonally distorted octa­hedral environment with the four N atoms of the macrocyclic ligand in equatorial and two O atoms from water mol­ecules in axial positions. The latter exhibit a long axial Cu—O bond length of 2.7866 (16) Å due to the Jahn–Teller distortion. The macrocyclic ring adopts a stable trans-III conformation with typical Cu—N bond lengths of 2.0240 (11) and 2.0441 (3) Å. The complex is stabilized by hydrogen bonds formed between the O atoms of coordinated water mol­ecules and the NH groups as donors, and chloride anions as acceptors. The chloride anions are further connected to the lattice water solvent molecules through O—H⋯Cl hydrogen bonds, giving rise to a three-dimensional network structure. [ABSTRACT FROM AUTHOR]

The crystal structure of the title complex, cis-[Cr(NCS)2(cyclam)]Br (cyclam = 1,4,8,11-tetraazacyclotetradecane, C10H24N4), has been determined from synchrotron X-ray data. The asymmetric unit contains one [Cr(NCS)2(cyclam)]+ cation and one bromide anion. The CrIII ion of the complex cation is coordinated by the four N atoms of the cyclam ligand and by two N-coordinating NCS groups in a cis arrangement, displaying a distorted octahedral coordination sphere. The Cr--N(cyclam) bond lengths are in the range 2.075 (3) to 2.081 (3) Å while the average Cr--N(NCS) bond length is 1.996 (16) Å. The macrocyclic cyclam moiety adopts the most stable cis-V conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the cyclam N--H groups as donor groups, and the bromide anion and the S atom of one of the NCS ligands as acceptor groups. [ABSTRACT FROM AUTHOR]

The crystal structure of the hydrated title salt, C22H48N44+4Cl-4H2O(C22H48N4 =H4L = 3,14-diethyl-2,6,13,17-tetraazoniatricyclo[16.4.0.07,12]docosane), has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at all four amine N atoms. The asymmetric unit comprises one half of the macrocyclic cation (completed by crystallographic inversion symmetry), two chloride anions and two water molecules. The macrocyclic ring of the tetracation adopts an exodentate (3,4,3,4)-D conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the macrocycle N-H groups and water O-H groups as donors, and the O atoms of the water molecules and chloride anions as acceptors, giving rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The structure of the title compound, [CrCl2(C10H24N4)][Cr(HCONH2)2- (C10H24N4)][ZnCl4]2 (C10H24N4 = 1,4,8,11-tetraazacyclotetradecane, cyclam; HCONH2 = formamide, fa), has been determined from synchrotron X-ray data. The asymmetric unit contains two independent halves of the [CrCl2(cyclam)]+ and [Cr(fa)(cyclam)]3+ cations, and one tetrachloridozincate anion. In each complex cation, the CrIII ion is coordinated by the four N atoms of the cyclam ligand in the equatorial plane and two Cl ligands or two O-bonded formamide molecules in a trans axial arrangement, displaying a distorted octahedral geometry with crystallographic inversion symmetry. The Cr-- N(cyclam) bond lengths are in the range 2.061 (2) to 2.074 (2) A ° , while the Cr--Cl and Cr--O(fa) bond distances are 2.3194 (7) and 1.9953 (19) A ° , respectively. The macrocyclic cyclam moieties adopt the centrosymmetric trans-III conformation with six- and five-membered chelate rings in chair and gauche conformations. The crystal structure is stabilized by intermolecular hydrogen bonds involving the NH or CH groups of cyclam and the NH2 group of coordinated formamide as donors, and Cl atoms of the ZnCl4 2- anion as acceptors. [ABSTRACT FROM AUTHOR]

The crystal structure of title compound, (C14H36N4)[CrO3Cl]2Cl2, has been determined by synchrotron radiation X-ray crystallography at 220 K. The macrocyclic cation lies across a crystallographic inversion center and hence the asymmetric unit contains one half of the organic cation, one chlorochromate anion and one chloride anion. Both the Cl- anion and chlorochromate Cl atom are involved in hydrogen bonding. In the crystal, hydrogen bonds involving the 1,4,8,11-tetramethyl-1,4,8,11-tetraazoniacyclotetradecane (TMC) N--H groups and C--H groups as donor groups and three O atoms of the chlorochromate and the chloride anion as acceptor groups link the components, giving rise to a threedimensional network. [ABSTRACT FROM AUTHOR]

The crystal structure of title salt, C14H36N44+·2ClO4-·2Cl-, has been determined using synchrotron radiation at 220-K. The structure determination reveals that protonation has occurred at all four amine N atoms. The asymmetric unit contains one half-cation (completed by crystallographic inversion symmetry), one perchlorate anion and one chloride anion. A distortion of the perchlorate anion is due to its involvement in hydrogen-bonding interactions with the cations. The crystal structure is consolidated by intermolecular hydrogen bonds involving the 1,4,8,11-tetramethyl-1,4,8,11-tetraazoniacyclotetradecane N-H and C-H groups as donor groups, and the O atoms of the perchlorate and chloride anion as acceptor groups, giving rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The structure of the title compound, [Cr(tacn)2]2[ZnCl4]3·H2O (tacn is 1,4,7-tri­aza­cyclo­nonane; C6H15N3), has been determined from synchrotron X-ray data. Each CrIII cation is coordinated by the six N atoms from the two tacn ligands, displaying a distorted octa­hedral geometry. Three distorted tetra­hedral [ZnCl4]2− anions and one lattice water mol­ecule lie outside this coordination sphere. The Cr—N bond lengths are in the range 2.0621 (11) to 2.0851 (12) Å, while the mean inner N—Cr—N bond angle is 82.51 (5)°. The crystal packing is stabilized by hydrogen-bonding inter­actions with the N—H groups of the tacn ligands and the water O—H groups acting as donors, and the O atoms of the water mol­ecules and Cl atoms of the [ZnCl4]2− anions as acceptors. Overall these contacts lead to the formation of a three-dimensional network. [ABSTRACT FROM AUTHOR]

The crystal structure of the title salt, C20H44N4 4+4Cr-4H2O, has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at all four amine N atoms. The asymmetric unit contains one half-cation (completed by crystallographic inversion symmetry), two chloride anions and two water molecules. There are two molecules in the unit cell. The Cl- anions and hydrate molecules are involved in hydrogen bonding. The crystal structure is stabilized by intermolecular hydrogen bonds involving the macrocycle N--H groups and water O--H groups as donors and the O atoms of the water molecules and the Cl- anions as acceptors, giving rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, [Ag(C24H46N6O2)](NO3)2 [C24H46N6O2 is (5,16-dimethyl-2,6,13,17-tetra­aza­tri­cyclo­[16.4.0.07,12]docosane-2,13-di­yl)diacetamide, L], consists of one independent half of the [Ag(C24H46N6O2)]2+ cation and one nitrate anion. The Ag atom, lying on an inversion centre, has a square-planar geometry and the complex adopts a stable trans-III conformation. Inter­estingly, the two O atoms of the pendant acetamide groups are not coordinated to the AgII ion. The longer distance of 2.227 (2) Å for Ag—N(tertiary) compared to 2.134 (2) Å for Ag—N(secondary) may be due to the effects of the attached acetamide group on the tertiary N atom. Two nitrate anions are very weakly bound to the AgII ion in the axial sites and are further connected to the ligand of the cation by N—H⋯O hydrogen bonds. The crystal packing is stabilized by hydrogen-bonding inter­actions among the N—H donor groups of the macrocycle and its actetamide substituents, and the O atoms of the nitrate anions and of an acetamide group as the acceptor atoms. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the hydrated title salt, (C10H28N4)[Cr2O7]2⋅H2O [C10H28N4 = H4(cyclam) = 1,4,8,11-tetraazoniacyclotetradecane], contains two half-cations (both completed by crystallographic inversion symmetry), two dichromate anions and one water molecule. The two [CrO7]2- anions exhibit a nearly staggered conformation, with bridging angles of 133.37 (11) and 136.28 (12)°. The distortions of the dichromate anions are due to their participation in hydrogen-bonding interactions with the water molecule and the cations. Intermolecular hydrogen bonds involving the cyclam N--H groups and water O--H groups as donor groups, and the O atoms of the dichromate anions as acceptor groups give rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, [Cr(C2O4)(C10H24N4)]2[Cr2O7]·-8H2O (C10H24N4 = 1,4,8,11-tetraazacyclotetradecane, cyclam; C2O4 = oxalate, ox) contains one [Cr(ox)(cyclam)]+ cation, one half of a dichromate anion that lies about an inversion centre so that the bridging O atom is equally disordered over two positions, and four water molecules. The terminal O atoms of the dichromate anion are also disordered over two positions with a refined occupancy ratio 0.586 (6):0.414 (6). The CrIII ion is coordinated by the four N atoms of the cyclam ligand and one bidentate oxalato ligand in a cis arrangement, resulting in a distorted octahedral geometry. The Cr--N(cyclam) bond lengths are in the range 2.069 (2)-2.086 (2) Å, while the average Cr--O(ox) bond length is 1.936 Å. The macrocyclic cyclam moiety adopts the cis-V conformation. The dichromate anion has a staggered conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the cyclam N--H groups and water O--H groups as donors, and the O atoms of oxalate ligand, water molecules and the Cr2O72- anion as acceptors, giving rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The structure of the title compound, C21H40N4·2H2O, has been determined from synchrotron X-ray radiation data. The asymmetric unit comprises one 12-membered macropolycycle and two lattice water molecules. The macropolycycle contains two cyclohexane rings and one 1,3-diazacyclohexane ring, all in chair conformations. The C--N and C--C bond lengths are in the ranges 1.4526 (16)-1.4786 (17) and 1.517 (2)-1.5414 (17) Å, respectively. One intramolecular N--H⋯N hydrogen bond helps to stabilize the molecular conformation while medium-strength intermolecular N--H⋯O, O--H⋯N and O--H⋯O hydrogen bonds involving the lattice water molecules connect the components into a three-dimensional network. [ABSTRACT FROM AUTHOR]

The structure of the title hybrid compound, (C6H16N2)[CrO4], has been determined from synchrotron data. The organic cation adopts a chair conformation. The inorganic CrO42- anion is slightly distorted owing to its involvement in N--H⋯O hydrogen-bonding interactions with neighbouring trans-cyclohexane-1,2-diammonium cations, whereby the two Cr--O bonds to the O atoms acting as acceptor atoms for two hydrogen bonds are slightly longer than the other two Cr--O bonds for which only one acceptor interaction per O atom is observed. In the crystal, cations and anions are packed into layers parallel to (001), held together through the aforementioned N--H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the asymmetric unit of the title compound, [CrCl2(C10H24N4)][Cr(C2O4)- (C10H24N4)](ClO4)2 (C10H24N4 = 1,4,8,11-tetraazacyclotetradecane, cyclam; C2O4 = oxalate, ox), there are two independent halves of the [CrCl2(cyclam)]+ and [Cr(ox)(cyclam)]+ cations, and one perchlorate anion. In the complex cations, which are completed by application of twofold rotation symmetry, the CrIII ions are coordinated by the four N atoms of a cyclam ligand, and by two chloride ions or one oxalate bidentate ligand in a cis arrangement, displaying an overall distorted octahedral coordination environment. The Cr--N(cyclam) bond lengths are in the range of 2.075 (5) to 2.096 (4) Å while the Cr--Cl and Cr--O(ox) bond lengths are 2.3358 (14) and 1.956 (4) Å, respectively. Both cyclam moieties adopt the cis-V conformation. The slightly distorted tetrahedral ClO4- anion remains outside the coordination sphere. The supramolecular architecture includes N--H...O and N--H...Cl hydrogen bonding between cyclam NH donor groups, O atoms of the oxalate ligand or ClO4- anions and one Cl ligand as acceptors, leading to a three-dimensional network structure. [ABSTRACT FROM AUTHOR]

The structure of the title compound, [(NH4)0.8K0.2][Cr(C5H7NO4)2] (C5H7NO4 is methyliminodiacetate; mida), has been determined from synchrotron data. The CrIII atom is located on a centre of symmetry and is coordinated by two N atoms and four O atoms of two facially arranged tridentate mida ligands, displaying a slightly distorted octahedral coordination environment. The Cr-N and mean Cr-O bond lengths are 2.0792 (14) and 1.958 (14) Å, respectively. The cation site is located on a twofold rotation axis and shows occupational disorder, being occupied by ammonium and potassium cations in a 0.8:0.2 ratio. In the crystal, intermolecular hydrogen bonds involving the N-H groups of the ammonium cation as donor and the two non-coordinating O atoms of the carboxylate group as acceptor groups consolidate the three-dimensional packing. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title complex salt, [Cr(C10H24N4)(NH3)2][ZnCl4]Cl•H2O, is comprised of four halves of the CrIII complex cations (the counterparts being generated by application of inversion symmetry), two tetrachloridozincate anions, two chloride anions and two water molecules. Each CrIII ion is coordinated by the four N atoms of the cyclam (1,4,8,11-tetraazacyclotetradecane) ligand in the equatorial plane and by two N atoms of ammine ligands in axial positions, displaying an overall distorted octahedral coordination environment. The Cr--N(cyclam) bond lengths range from 2.0501 (15) to 2.0615 (15) Å, while the Cr--(NH3) bond lengths range from 2.0976 (13) to 2.1062 (13) Å. The macrocyclic cyclam moieties adopt the trans-III conformation with six- and five-membered chelate rings in chair and gauche conformations. The [ZnCl4]2- anions have a slightly distorted tetrahedral shape. In the crystal, the Cl- anions link the complex cations, as well as the solvent water molecules, through N--H⋯Cl and O--H⋯Cl hydrogen-bonding inter-actions. The supramolecular set-up also includes N--H⋯Cl, C--H⋯Cl, N--H⋯O and O--H⋯Cl hydrogen bonding between N--H or C--H groups of cyclam, ammine N--H and water O--H donor groups, and O atoms of the water molecules, Cl- anions or Cl atoms of the [ZnCl4]2- anions as acceptors, leading to a three-dimensional network structure. [ABSTRACT FROM AUTHOR]

The structure of the title complex, [CrCl2(2,3,2-tet)]ClO4 (2,3,2-tet is 1,4,8,11-tetraazaundecane, C7H20N4), has been determined from synchrotron data. The CrIII ion is coordinated by the four N atoms of the 1,4,8,11-tetraazaundecane ligand in the equatorial plane and two chloride ions in an axial arrangement, displaying a slightly distorted octahedral coordination environment. The two H atoms of the secondary amines are grouped on the same side of the equatorial N4 plane (meso-RS conformation). The Cr-N bond lengths range from 2.069 (2) to 2.084 (2) Å, while the mean Cr-Cl bond length is 2.325 (2) Å. The crystal structure is stabilized by intermolecular hydrogen-bonding interactions between the primary and secondary amine groups of the 2,3,2-tet ligands, the Cl ligands and the O atoms of the perchlorate counter-anion, forming corrugated layers parallel to (010). [ABSTRACT FROM AUTHOR]

The crystal structure of trans-[Cr(en)2Br2]ClO4 (en = 1,2-ethanediamine) has been determined by a single-crystal X-ray diffraction study at 150 K. The complex crystallizes in the space group $$ P\overline{1} $$ of the triclinic system with two mononuclear formula units in a cell of dimensions a = 6.853(4), b = 8.109(5), c = 12.475(8) Å, α = 81.006(10)° , β = 77.005(10)° and γ = 74.981(10)°. The Cr atom is in a slightly distorted octahedral environment, coordinated by four nitrogen atoms of two en ligands and two bromine atoms in trans axial positions. The mean Cr–N(en) and Cr–Br bond lengths are 2.079(3) and 2.4743(10)Å, respectively. The five-membered rings are in stable gauche conformations with N1–Cr1–N2 and N3–Cr2–N4 angles of 82.81(11)° and 83.67(11)°, respectively. The crystal packing is stabilized by a network of N–H···O and N–H···Br hydrogen bonds. The infrared and electronic absorption spectra are consistent with the results of X-ray crystallography. The spectroscopic properties of the title complex are in good agreement with the result of X-ray crystallography, which shows that the chromium atom is in an octahedral environment, coordinated by two bidentate 1,2-ethanediamine ligands and two bromine atoms in trans positions.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract  In the title compound, [Cu(C34H52N4)](ClO4)2, the Cu(II) ion has a square-planar coordination somewhat distorted towards tetrahedral geometry. The macrocyclic ligand adopts a less stable trans-I (RSRS) configuration. The two benzyl groups and two secondary amine H atoms are oriented towards the same side of the macrocyclic plane. The two six-membered rings are in slightly distorted chair and unsymmetrical twist-boat forms while both five-membered chelate rings are in the gauche conformation. The longer distances (2.050(4) and 2.035(4) Å) of Cu–N(tertiary) compared to 2.017(4) and 1.990(4) Å for Cu–N(secondary) may be due to the steric effects of the attached two benzyl groups on the tertiary N atoms. The crystal structure is stabilized by hydrogen bonds between secondary NH groups and O atoms of perchlorate counter-ions. Graphical Abstract  In the title compound, [Cu(C34H52N4)](ClO4)2, the Cu(II) ion has a square-planar coordination somewhat distorted towards tetrahedral geometry. The macrocyclic ligand adopts a trans-I configuration. The benzyl groups and secondary amine H atoms are oriented towards the same side of the macrocyclic plane. [ABSTRACT FROM AUTHOR]

In the title compound, [Cu(NO3)2(C20H40N4)]·3H2O, the Cu atom lies on a crystallographic inversion centre and has a distorted octahedral geometry, with four N atoms of the macrocyclic ligand in the equatorial positions and two O atoms of the axial nitrate ligands. The long axial Cu—O bond of 2.746 (2) Å may result from the Jahn-Teller effect. The macrocyclic ligand adopts the most stable trans-III configuration with the two six-membered rings in chair form and two five-membered rings in a gauche form. [ABSTRACT FROM AUTHOR]

In the title compound, [Cr(ONO)2(cyclam)]NO2 (cyclam is 1,4,8,11-tetraazacyclotetradecane, C10H24N2), the complex cation is located on a twofold symmetry axis. The central Cr atom has a distorted octahedral coordination, involving two Cr-O bonds, with the monodentate nitrite O atoms adopting a cis configuration, and four Cr-N bonds. The mean Cr-N and Cr-O distances are 2.0895 (14) and 1.9698 (14) Å. [ABSTRACT FROM AUTHOR]

Studies the geometrical structures of chromium complexes. Evidence of two crystallographically independent chromium complex moieties; Existence of a strong hydrogen-bonding interaction between the atoms.; Conformational isomers of the chromium complex cation.

The crystal structure of the title salt, C20H42N42+·2ClO4−, has been determined using synchrotron radiation at 220 (2) K. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms. The asymmetric unit comprises one half of the organic dication, which lies about a center of inversion, and one perchlorate anion. The macrocyclic dication adopts the most stable endodentate trans-III conformation. The crystal structure is stabilized by intra­molecular N—H...N, and inter­molecular N—H...O and C–H...O hydrogen bonds involving the macrocycle N—H and C—H groups as donors and the O atoms of perchlorate anions as acceptors, giving rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, Ag[Cr(C11H14N2O8)]·3H2O, contains one [Cr(1,3-pdta)]- anion [1,3-pdta is (propane-1,3-diyldinitrilo)tetraacetate], one Ag+ cation and three water molecules. The Cr3+ ion is coordinated to the four O and two N atoms of the 1,3-pdta ligand, displaying a distorted octahedral geometry. The mean Cr--N and Cr--O bond lengths are 2.0727 (17) and 1.9608 (15) Å, respectively. The conformations of the chelate rings were found to be envelope for the glycinates and twist-boat for the six-membered diamine (T) ring. The Ag+ cation is surrounded by six O atoms from three noncoordinated carbonyl O atoms of neighbouring 1,3-pdta groups and three water molecules. The crystal structure is stabilized by intermolecular hydrogen bonding involving the water O--H group as donor and the carboxyl O atom as acceptor. [ABSTRACT FROM AUTHOR]

A novel metal complex, [Cu(Lb)](NO3)2 [Lb = 2,13-dibenzyl-5,16-diethyl-2,6,13,17-tetraazatricyclo(16.4.0.07,12)docosane], was synthesized and characterized by single-crystal X-ray diffraction as well as other spectroscopic techniques. Structural analysis revealed that the copper(II) ion has an approximately square planar arrangement with stable trans -III configuration of the macrocyclic ligand. The Cu-N(tertiary) distance (2.0860 (14) Å) is greater than the Cu-N(secondary) distance (2.0229 (15) Å), which may be attributed to the steric effect of the benzyl group attached to the tertiary N atom. The nitrate anion and complex cation are linked by hydrogen bonds and weak Cu...O interactions. The metal complex showed strong blue luminescence when excited in the 355-391 nm region, and both blue as well as green emissions when excited in the 438-460 nm range. [ABSTRACT FROM AUTHOR]

The structure of the title compound, [CrCl2(tn)2]2[Cr2O7] (tn = propane-1,3-diamine; C3H10N2), has been determined from synchrotron data. The asymmetric unit contains one CrIII complex cation and half a [Cr2O7]2- anion. In the complex cation, the CrIII ion is coordinated by the four N atoms of two propane-1,3-diamine (tn) ligands in the equatorial plane and by two Cl atoms in a trans configuration, displaying a distorted octahedral coordination sphere. The two six-membered rings in the complex cation have an anti chair-chair conformation with respect to each other. The mean Cr-N(tn) and Cr-Cl bond lengths are 2.09 (1) and 2.320 (2) Å, respectively. The slightly bent dichromate anion is disordered over two sets of sites (occupancy ratio = 0.7:0.3) and has a staggered conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the NH2 groups of the tn ligands as donors and the O atoms of the [Cr2O7]2- anion and chlorido ligands as acceptors. [ABSTRACT FROM AUTHOR]

In the title compound, [Cu(ClO4)2(C20H40N4)], the CuII ion has a tetragonally distorted octahedral environment, with the four N atoms of the macrocyclic ligand in equatorial positions and the O atoms of two perchlorate groups in axial positions. The CuII ion is situated on an inversion centre. The macrocyclic ligand adopts its most stable trans-III conformation. The long axial Cu—O bond is the result of the Jahn–Teller effect. The crystal structure is stabilized by intramolecular hydrogen bonds between secondary N—H and the O atoms of the perchlorate groups. [ABSTRACT FROM AUTHOR]

The mol­ecule of the title compound, 2,13-dibenzyl-5,16-dimethyl-2,6,13,17-tetra­azatricyclo­[16.4.01,18.07,12]docosane, C34H52N4, is centrosymmetric. The 14-membered macrocycle adopts the stable trans-III ( RRSS) configuration, with one benzyl group above and the other below the macrocycle mean plane. The crystal structure is stabilized by N—H⋯N hydrogen bonds. There is no inter­molecular π–π inter­action between benzyl planes, which are almost 6Å apart. [ABSTRACT FROM AUTHOR]

The structure of the title salt, [CrCl(C10H8N2)2(H2O)][ZnCl4], has been determined from synchrotron data. The CrIII ion is coordinated by four N atoms from two 2,2'-bipyridine (bipy) ligands, one O atom from a water molecule and a chloride anion in a cis arrangement, displaying a distorted octahedral geometry. The tetrahedral [ZnCl4]2- anion is slightly distorted owing to its involvement in O-H···Cl hydrogen bonding with the coordinating water molecule. The Cr-N(bipy) bond lengths are in the range 2.0485 (13)-2.0632 (12) Å , while the Cr-Cl and Cr-OH2) bond lengths are 2.2732 (6) and 1.9876 (12) Å, respectively. In the crystal, molecules are stacked along the a axis. [ABSTRACT FROM AUTHOR]

Two diastereoisomers of cyclo(Pro-Tyr) have been synthesized simultaneously. The crystal structures and conformations of both cyclo(L-Pro-L-Tyr) and a racemic mixture of cyclo(D-Pro-L-Tyr) and cyclo(L-Pro-DTyr), abbreviated as rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr), have been determined by a single-crystal X-ray diffraction study at low temperature. The crystals of rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr) belong to orthorhombic space group Pna21 with a = 10.755 (1), b = 12.699 (1), c = 9.600 (1) Å and Z = 4. The tyrosine side chain is folded towards the diketopiperazine (DKP) ring. The DKP ring adopts a twist boat conformation with pseudo symmetry C2v. The pyrrolidine ring has an envelope conformation with the N5, C4, C7 and C8 atoms in a plane. The crystal of rac-cyclo(D-Pro-L-Tyr/L-Pro-D-Tyr) is stabilized by hydrogen bonds between amide N2-H2 and carbonyl oxygen O2 in the neighbor. The hydroxyl group of tyrosine residue is also hydrogen bonded to the oxygen of the carbonyl group of the DKP ring in the next molecule. The spectroscopic properties of both isomers are also described. [ABSTRACT FROM AUTHOR]

The crystal structure of the new double CuII complex salt, [Cu(L)(H2O)2][Cu(L)]Br4·2H2O (L = 3,14-diethyl-2,6,13,17-tetra­aza­tri­cyclo­[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of a [Cu(L)(H2O)2]2+ cation, one half of a [Cu(L)]2+ cation (both completed by crystallographic inversion symmetry), two bromide anions and one water solvent mol­ecule. The CuII atom in the first complex exists in a tetra­gonally distorted octa­hedral environment with the four N atoms of the macrocyclic ligand in equatorial and two aqua ligands in axial positions, whereas the CuII atom in the second complex exists in a square-planar environment defined by the four nitro­gen atoms of the macrocyclic ligand. The two macrocyclic rings adopt the most stable trans-III configuration with normal Cu—N bond lengths from 2.016 (3) to 2.055 (3) Å and an axial Cu—O bond length of 2.658 (4) Å. The crystal structure is stabilized by inter­molecular hydrogen bonds involving the macrocycle N—H or C—H groups and the O—H groups of water mol­ecules as donor groups, and the O atoms of water mol­ecules and bromide anions as acceptor groups, giving rise to a one-dimensional network extending parallel to [100]. [ABSTRACT FROM AUTHOR]

The crystal structure of title salt, C22H46N42+·2NO3−·2H2O, has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms. The asymmetric unit contains half a centrosymmetric dication, one nitrate anion and one water mol­ecule. The mol­ecular dication, C22H46N42+, together with the nitrate anion and hydrate water mol­ecule are involved in an extensive range of hydrogen bonds. The mol­ecule is stabilized, as is the conformation of the dication, by forming inter­molecular N—H⋯O, O—H⋯O, together with intra­molecular N—H⋯N hydrogen bonds. [ABSTRACT FROM AUTHOR]

The structure of the complex salt, cis-[Cr(NCS)2(cyclam)]2[Cr2O7]·H2O (cyclam = 1,4,8,11-tetraazacyclotetradecane, C10H24N4), has been determined from synchrotron data. The asymmetric unit comprises of one [Cr(NCS)2(cyclam)]+ cation, one half of a Cr2O72- anion (completed by inversion symmetry) and one half of a water molecule (completed by twofold rotation symmetry). The CrIII ion is coordinated by the four cyclam N atoms and by two N atoms of cis-arranged thiocyanate anions, displaying a distorted octahedral coordination sphere. The Cr-N(cyclam) bond lengths are in the range 2.080 (2) to 2.097 (2) Å while the average Cr-N(NCS) bond length is 1.985 (4) Å . The macrocyclic cyclam moiety adopts the cis-V conformation. The bridging O atom of the dichromate anion is disordered around an inversion centre, leading to a bending of the Cr-O-Cr bridging angle [157.7 (3)°]; the anion has a staggered conformation. The crystal structure is stabilized by intermolecular hydrogen bonds involving the cyclam N-H groups and water O-H groups as donor groups, and the O atoms of the Cr2O72- anion and water molecules as acceptor groups, giving rise to a three-dimensional network. [ABSTRACT FROM AUTHOR]

The article reports the synthesis, crystal structure and spectroscopic properties of the trans-anti [CR(Me,2tn)2(OH)(H2O)]-CIO4)2 to elucidate the influence of O-donor ligands occupying the axial positions and counter anion. It shows that chromium atom is in a distorted octahedral environment coordinated by 2 biidetate, 2,2-dimethyl-1,3-propanediamine ligands and 2 O atoms of hydroxy group and water molecule in trans position.

The aim of the present study is to explore the possibility of utilizing loess for the adsorption of total phosphorous (T-P) and total nitrogen (T-N) in water. Batch adsorption studies were performed to evaluate the influences of various factors like initial concentration, contact time and temperature on the adsorption of T-P and T-N. The adsorption data showed that loess is not effective for the adsorption of T-N. However, loess exhibited much higher adsorption capacity for T-P. At concentration of 1.0 mg L-1, approximately 97% of T-P adsorption was achieved by loess. The equilibrium data were fitted well to the Langmuir isotherm model. The pseudo-second-order kinetic model appeared to be the better-fitting model because it has higher R² compared with the pseudo-first-order and intra-particle kinetic model. The theoretical adsorption equilibrium qe,cal from pseudo-second-order kinetic model was relatively similar to the experimental adsorption equilibrium qe,exp. The thermodynamic parameters such as free energy ρG, the enthalpy ρH and the entropy ρS were also calculated. [ABSTRACT FROM AUTHOR]