Trans. Met. Chem. 2003, 548 (original) (raw)
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Inorganica Chimica Acta, 1998
Metal complexes with varying intramolecular hydrogen bonding networks
Polyhedron, 2013
Alfred Werner described the attributes of the primary and secondary coordination spheres in his development of coordination chemistry. To examine the effects of the secondary coordination sphere on coordination chemistry, a series of tripodal ligands containing differing numbers of hydrogen bond (H-bond) donors were used to examine the effects of H-bonds on Fe(II), Mn(II)acetato, and Mn(III)-OH complexes. The ligands containing varying numbers of urea and amidate donors allowed for systematic changes in the secondary coordination spheres of the complexes. Two of the Fe(II) complexes that were isolated as their Bu 4 N + salts formed dimers in the solidstate as determined by X-ray diffraction methods, which correlates with the number of H-bonds present in the complexes (i.e., dimerization is favored as the number of H-bond donors increases). Electron paramagnetic resonance (EPR) studies suggested that the dimeric structures persist in acetonitrile. The Mn(II) complexes were all isolated as their acetato adducts. Furthermore, the synthesis of a rare Mn(III)-OH complex via dioxygen activation was achieved that contains a single intramolecular H-bond; its physical properties are discussed within the context of other Mn(III)-OH complexes.
Rational Design of Homo and Hetero Hexanuclear Coordination Compounds: Syntheses and Magnetic Properties of [Cu2IIM4II] (M = Cu, Ni) Species and the Crystal Structure of {[Cu(tmen)(H2O)]2[Cu(tmen)]2Cu2L}(ClO4)4 · 2 H2O
European Journal of Inorganic Chemistry, 2000
New homo-and heterometallic hexanuclear complexes of formula {[Cu(tmen)(H 2 O)] 2 [Cu(tmen)] 2 [Cu 2 L](H 2 O)}(ClO 4 ) 4 ⋅ 2 H 2 O [Cu 6 -tmen] {[Cu(pmdien)] 4 [Cu 2 L]}(ClO 4 ) 4 ⋅ 4 H 2 O [Cu 6 -pmdien] and {[Ni(cyclam)] 4 [Cu 2 L]}(ClO 4 ) 4 ⋅ 4 H 2 O [Cu 2 Ni 4 -cyclam] [H 8 L = tetrakis(aminomethylene)methanetetrakis(oxamic acid), tmen = N, N,NЈ, pmdien = N,N,N',N', and cyclam = 1, have been synthesized. The crystal structure of [Cu 6 -tmen] has been determined by single-crystal X-ray diffraction. The structure consists of cationic {[Cu(tmen)(H 2 O)] 2 [Cu(tmen)] 2 -[Cu 2 L](H 2 O)} 4+ hexanuclear units. The hexanuclear cation is made up of two symmetry-related oxamato-bridged trinuclear units connected through the central carbon atom C(6) of the L 8ligand. Variable-temperature magnetic susceptibility [a]
Inorganica Chimica Acta, 2004
Two compounds H[Mn(cyclam)(pyridine-2,6-dicarboxylate) 2 ] Á H 2 O (1) and [Mn III (cyclam)Cl 2 ]ClO 4 (2) (where cyclam ¼ 1,4,8,11tetraazacyclotetradecane) have been synthesized and structurally characterized. The complex 1 crystallizes in the monoclinic space group P 2ð1Þ=c with a ¼ 11:4328ð11Þ, b ¼ 14:4275ð14Þ, c ¼ 8:5782ð9Þ A A, V ¼ 1343:1ð2Þ A A 3 , Z ¼ 2, R ¼ 0:0453. Complex 1 is octahedral in which [Mn(cyclam)] 3þ unit occupies the basal plane having two pyridine-2,6-dicarboxylate anions in the axial positions. Molecular packing of the crystal is dominated by string of molecules along the b-axis. The strings are held together by extensive intermolecular hydrogen bonds involving N-H Á Á Á O, N-H Á Á Á N and O-H Á Á Á O which impart it an infinite 1D chain. Complex 2 on the other hand crystallizes in the space group P 2 1 2 1 2 1 (No. 19) of the orthorhombic system. Mn(III) ions occupy the center of a distorted octahedron and two chloride ions occupy the axial positions. The packing diagram of 2 reveals that the complex is percholrate-bridged hydrogen bonded 1D chain along a-axis. Cyclic voltammogram of complex 1 shows a reduction wave at)0.25 V coupled to an oxidation wave at)0.05 V versus SCE in aqueous solution. The complex 2 is characterized by an irreversible reduction wave at)0.11 V versus SCE and is identical to that observed for [Mn III (cyclam)Cl 2 ]Cl Á 5H 2 O. The magnetic measurements in the temperature range 1.9-300 K have been carried out for complex 1 which exhibits a very weak ferromagnetic interaction at low temperature. Complex 2 shows room temperature magnetic moment value of 4.92 BM consistent with the high spin d 4 electronic configuration.
Hydrogen-Bonded Networks Based on Cobalt(II), Nickel(II), and Zinc(II) Complexes of N,N'-Diethylurea
Bioinorganic Chemistry and Applications, 2010
N,N'-diethylurea (DEU) was employed as a ligand to form the octahedral complexes[M(DEU)6]2+(M=Co, Ni and Zn). Compounds[Co(DEU)6](BF4)2(1),[Co(DEU)6](CIO4)2(2),[Ni(DEU)6](CIO4)2(3), and[Zn(DMU)6](CIO4)2(4) have been prepared from the reactions of DEU and the appropriate hydrated metal(II) salts in EtOH in the presence of 2,2-dimethoxypropane. Crystal structure determinations demonstrate the existence of[M(DEU)6]2+cations andCIO4-(in2–4) orBF4-(in1) counterions. The[M(DEU)6]2+cations in the solid state are stabilized by apseudochelateeffect due to the existence of six strong intracationicN-H⋯O(DEU)hydrogen bonds. The[M(DEU)6]2+cations and counterions self-assemble to form hydrogen-bonded 2D architectures in2–4that conform to thekgd(kagome dual) network, and a 3D hydrogen-bondedrtl(rutile) network in1. The nature of the resulting supramolecular structures is influenced by the nature of the counter-ion. The complexes were also characterized by vibrational spectroscopy (IR).
Journal of Molecular Structure, 2019
Three new coordination complexes [Mn(L1)(m-azide)(azide)] 2 ,4H 2 O (1), [Mn(L1)(fum)] n (2) [L1 ¼ 2methyl-N 1 ,N 2-bis(pyridin-2yl)propane-1,2-diamine, fum ¼ Fumaric acid] and [Co(L2)(azide)] (3) [L2 ¼ 6 phenyl-1,3,5-triazine 2,4-diyl amino(pyridine-2yl)methanol] have been synthesized and X-ray crystallographically characterized. Complex 1, a dinuclear Mn(II) complex is formed by bridging azide ligand and other coordination sites are satisfied by tetradentate ligand L1 and terminal azide ligand. The overall structure is an incomplete supramolecular 3D cage structure, formed by intermolecular p … p interaction of pyridyl ligand and hydrogen bonding. Complex 2 comprised of eight coordinated Mn(II) centre where ligand L1 and fumarate is bridged between the metal centers that leads to a one dimensional chain structure which further extended to a 3D structure by p … p and CeH … p interactions. The overall structure is further stabilized by hydrogen bonding with the guest water molecules. Complex 3, a six coordinated mononuclear Co(II) discrete complex is consist of pentadentate ligand L2 and azide act as a terminal ligand. This Mononuclear complex is connected by p … p, CeH … p interactions and hydrogen bonding which ultimately leads to a supramolecular 2D architecture. All the complexes have been further characterized by elemental analysis, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD) studies.
Inorganic Chemistry Communications, 2013
Six new complexes 1-6 with the common formula [M(NiL) 4 ][M(NCS) 4 ] (M=Mn, Fe, Co, Ni, Cu and Zn for 1, 2, 3, 4, 5 and 6, respectively; the same below) were synthesised and structurally characterised by X-ray single crystal analysis. NiL acts as a complex ligand. L denotes the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7dioxodibenzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Each M(II) centre of the [M(NiL) 4 ] 2+ complex cations in 1-6 adopts a distorted square-antiprism coordination geometry with a O 8 donor set. All the M\O bonds in the six complexes are abnormally long (2.444-2.528 Å). M(II) complexes having such weak coordination environments have not been reported, and eight-coordinate M(II) complexes with all the eight oxygen donor atoms coming from metalloligands have also not been documented. Each M(II) centre of the [M(NCS) 4 ] 2− anions in 1-6 has a distorted tetrahedral coordination environment with a N 4 donor set. Theoretical calculations for the bond dissociation energies (BDEs) of the M\O semi coordinate bonds were performed using density functional theory at B3LYP level. The calculated BDE values are 23.8, 25.5, 20.0, 22.3, 19.8 and 18.2 kcal/mol for 1, 2, 3, 4, 5 and 6, respectively. The BDE values suggest that the long Mn\O bonds in 1 and the long Co\O bonds in 3 are significantly weaker than their significantly shorter counterparts in the formerly reported [Mn(NiL) 2 (NCS) 2 ] and [Co(NiL) 2 (NCS) 2 ], respectively.
Structural Chemistry, 2009
Three new coordination complexes, 2{[Co (L 1 ) 2 ]ClO 4 } Á 0.5CH 3 OH (1), [Mn(L 2 ) 2 ] (2), and [Cu(HL 2 ) (L 2 )]ClO 4 Á 2H 2 O (3) have been synthesized from two tridentate N,N,O-donor hydrazone ligands HL 1 , 2-acetylpyridine-salicyloylhydrazone, and HL 2 , 2-benzoylpyridine-salicyloylhydrazone, respectively and thoroughly characterized by elemental analysis, FT-IR, UV-Vis, electrochemical, and room temperature magnetic susceptibility measurements. Structures of the complexes have been unequivocally established by single crystal X-ray diffraction technique. Structural analysis reveals that 1 consists of two chemically similar but crystallographically independent cationic [Co(L 1 ) 2 ] ? units and 2 consists of a neutral [Mn(L 2 ) 2 ] molecule while 3 consists of a cationic [Cu(HL 2 )(L 2 )] ? unit. Metal ions display distorted octahedral geometry in 1 and 2 while in 3 it shows a distorted square pyramidal geometry. Ligand conformations around the metal ions are stabilized by the presence of intra-ligand hydrogen bonding in all the complexes. Structure of 3 reveals that a perchlorate ion linked to the complex by hydrogen bonding via a water molecule.