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Nitrate Ligands (nitrate + ligand)

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Chemistry100%

Selected Abstracts

Transition metal complexes with thiosemicarbazide-based ligands.

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2002
XLIV.
The title complex, [Cu(NO3)(C10H14N4O2S)(H2O)](NO3), is the first metal complex with a Schiff base derived from iso­thio­semicarbazide and pyridoxal (pyridoxal is 3-hydroxy-5-­hydroxy­methyl-2-methyl­pyridine-4-carbox­aldehyde). The CuII environment is a square pyramid, the equatorial plane of which is formed by the tridentate ONN -coordinated iso­thio­semicarbazone and one water mol­ecule, while the nitrate ligand is in the apical position. The existence of numerous strong intermolecular hydrogen bonds, and weak C,H,O and C,H,, interactions, leads to a three-dimensional supramolecular structure. [source]

Solid-State and Solution Structure of Lanthanide(III) Complexes with a Flexible Py-N6 Macrocyclic Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2009
Cristina Núñez
Abstract Lanthanide complexes of a hexaaza macrocyclic ligand containing a pyridine head unit (L) were synthesized (Ln = La,Lu, except Pm). The solid-state structures of the corresponding La, Ce, Pr, Nd, and Lu complexes were determined by single-crystal X-ray crystallography, and they reveal the presence of three different mononuclear complexes with three different conformations of the macrocycle and coordination environments around the metal ions. In all complexes the lanthanide ion is coordinated in an endomacrocyclic manner to the six nitrogen donor atoms of the ligand. In the La, Ce, and Pr complexes the metal ions show a 12-coordinate mononuclear environment in which 3 nitrate anions coordinate in a bidentate fashion. However, in the Nd analogue the metal ion displays a 10-coordinated environment with the coordination of 2 bidentate nitrate groups, whereas Lu shows a 9-coordinate environment interacting with 2 nitrate ligands, one of them acting as bidentate and the second one coordinating in a monodentate fashion. The 1H and 13C NMR spectra of the complexes recorded in CD3CN suggest that the complexes adopt in solution a similar structure to that observed for the Nd complex in the solid state. The [Ln(L)(NO3)3] and [Ln(L)(NO3)2]+ complexes were characterized by density functional theory (DFT) calculations (B3LYP model). The structures obtained from these calculations for La, Ce, Pr, and Nd are in good agreement with the experimental solid-state structures. The relative stabilities of the [Ln(L)(NO3)2]+ complexes with respect to the [Ln(L)(NO3)3] ones (Ln = La, Nd, Gd, Ho, or Lu) were studied both in vacuo and in acetonitrile solution (PCM model) at the same computational level. Our calculations indicate that in solution the [Ln(L)(NO3)2]+ species is the most stable one along the whole lanthanide series, in agreement with the NMR spectroscopic data.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Receptor versus Counterion: Capability of N,N, -Bis(2-aminobenzyl)-diazacrowns for Giving Endo- and/or Exocyclic Coordination of ZnII

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2007
Lea Vaiana
Abstract The structure of ZnII complexes with receptors L1 and L2[L1 = N,N, -bis(2-aminobenzyl)-1,10-diaza-15-crown-5 and L2 = N,N, -bis(2-aminobenzyl)-4,13-diaza-18-crown-6] was studied both in the solid state and in acetonitrile solution. Both receptors form mononuclear ZnII complexes in this solvent, while no evidence for the formation of dinuclear complexes was obtained. This is in contrast with previous investigations that demonstrated the formation of dinuclear complexes of L2 with first-row transition metals such as NiII, CoII and CuII. Compounds of formula [Zn(L1)](ClO4)2 (1), [Zn(L1)](NO3)2·2CH3CN (2), [Zn(L2)](ClO4)2 (3) and [Zn(L2)(NO3)2] (4) were isolated and structurally characterised by X-ray diffraction analyses. L1 forms seven-coordinate ZnII complexes in the presence of both nitrate and perchlorate anions, as a consequence of the good fit between the macrocyclic cavity and the ionic radius of the metal ion. The ZnII ion is deeply buried into the receptor cavity and the anions are forced to remain out of the metal coordination sphere. The cation [Zn(L1)]2+ present in 1 and 2 is one of the very few examples of seven-coordinate Zn complexes. Receptor L2 provides a very rare example of a macrocyclic receptor allowing endocyclic and exocyclic coordination on the same guest cation, depending on the nature of the anion present. Thus, in 3 the ZnII ion is endocyclically coordinated, placed inside the crown hole coordinated to four donor atoms of the ligand in a distorted tetrahedral environment, whereas in 4, the presence of a strongly coordinating anion such as nitrate results in an exocyclic coordination of ZnII, which is directly bound only to the two primarily amine groups of L2 and two nitrate ligands. Spectrophotometric titrations of [Zn(L2)]2+ with tetrabutylammonium nitrate in acetonitrile solution demonstrate the stepwise formation of 1:1 and 1:2 adducts with this anion in acetonitrile solution. The [Zn(L1)]2+, [Zn(L2)]2+ and [Zn(L2)(NO3)2] systems were characterised by means of DFT calculations (B3LYP model). The calculated geometries show an excellent agreement with the experimental structures obtained from X-ray diffraction analyses. Calculated binding energies of the macrocyclic ligands to ZnII are also consistent with the experimental data.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Coordination and hydrogen-bonding assemblies in hybrid reaction products between 5,10,15,20-tetra-4-pyridylporphyrin and dysprosium trinitrate hexahydrate

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010
Sophia Lipstman
Reactions of the title free-base porphyrin compound (TPyP) with dysprosium trinitrate hexahydrate in different crystallization environments yielded two solid products, viz. [,-5,15-bis(pyridin-1-ium-4-yl)-10,20-di-4-pyridylporphyrin]bis[aquatetranitratodysprosium(III)] benzene solvate, [Dy2(NO3)8(C40H28N8)(H2O)2]·C6H6, (I), and 5,10,15,20-tetrakis(pyridin-1-ium-4-yl)porphyrin pentaaquadinitratodysprosate(III) pentanitrate diethanol solvate dihydrate, (C40H30N8)[Dy(NO3)2(H2O)5](NO3)5·2C2H6O·2H2O, (II). Compound (I) represents a 2:1 metal,porphyrin coordinated complex, which lies across a centre of inversion. Two trans -related pyridyl groups are involved in Dy coordination. The two other pyridyl substituents are protonated and involved in intermolecular hydrogen bonding along with the metal-coordinated water and nitrate ligands. Compound (II) represents an extended hydrogen-bonded assembly between the tetrakis(pyridin-1-ium-4-yl)porphyrin tetracation, the [Dy(NO3)2(H2O)5]+ cation and the free nitrate ions, as well as the ethanol and water solvent molecules. This report provides the first structural characterization of the exocyclic dysprosium complex with tetrapyridylporphyrin. It also demonstrates that charge balance can be readily achieved by protonation of the peripheral pyridyl functions, which then enhances their capacity in hydrogen bonding as H-atom donors rather than H-atom acceptors. [source]

cis -Bis(di­methyl sulfoxide- S)­dinitrato­palladium(II) and cis -dinitratobis(1,4-oxathiane- S)­palladium(II)

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2001
Maria H. Johansson
The Pd atom in each of the two title compounds, [Pd(NO3)2(C2H6OS)2], (I), and [Pd(NO3)2(C4H8OS)2], (II), coordinates two O atoms from two nitrate ligands and two S atoms from di­methyl sulfoxide (dmso) and thio­xane (systematic name: 1,4-oxathiane) ligands in a pseudo-square-planar cis -geometry. In the dmso complex, the distances to palladium are Pd,O 2.067,(2) and 2.072,(2),Å, and Pd,S 2.2307,(11) and 2.2530,(8),Å. The corresponding distances in the thio­xane complex are Pd,O 2.053,(3) and 2.076,(2),Å, and Pd,S 2.2595,(9) and 2.2627,(11),Å. Both compounds may be regarded as dimers with an inversion centre, where one of the coordinating nitrate O atoms in one mol­ecule also interacts with the Pd atom in the adjacent mol­ecule, with Pd,O distances of 2.849,(9) and 3.31,(3),Å in (I) and (II), respectively. [source]

Configurations of Nickel,Cyclam Antiviral Complexes and Protein Recognition

CHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2007
Tina M. Hunter
Abstract Nickel(II),xylylbicyclam is a potent anti-HIV agent and binds strongly to the CXCR4 co-receptor. We have investigated configurational equilibria of NiII,cyclam derivatives, since these are important for receptor recognition. Crystallographic studies show that both trans and cis configurations are readily formed: [Ni(cyclam)(OAc)2],H2O adopts the trans -III configuration with axial monodentate acetates, as does [Ni(benzylcyclam)(NO3)2] with axial nitrate ligands, whereas [Ni(benzylcyclam)(OAc)](OAc),2,H2O has an unusual folded cis -V configuration with NiII coordination to bidentate acetate. UV/Vis and NMR studies show that the octahedral trans -III configuration slowly converts to square-planar trans -I in aqueous solution. For NiII,xylylbicyclam, a mixture of cis -V and trans -I configurations was detected in solution. X-ray diffraction studies showed that crystals of lysozyme soaked in NiII,cyclam or NiII2,xylylbicyclam contain two major binding sites, one involving NiII coordination to Asp101 and hydrophobic interactions between the cyclam ring and Trp62 and Trp63, and the second hydrophobic interactions with Trp123. For NiII,cyclam bound to Asp101, the cis -V configuration predominates. [source]