Makoto Tadokoro

Hydrogen bonded 2,2′-biimidazolate transition metal complexes as a tool of crystal engineering

Abstract In the field of crystal engineering, many attempts have been made to control the molecular arrangements in crystal by simultaneous use of coordination bonds of a transition metal ion and complementary intermolecular hydrogen bonds. We obtained the first crystal structure of the hydrogen bonded metal complex of 2,2′-biimidazolate monoanion ligand Hbim − with Cu(II) as a neutral dimer metal complex. The hydrogen-bonded dimer structure indicates that the Hbim − ligand controls the crystal structure using not only the coordination to a transition metal ion as a bidentate chelate but simultaneously the formation of complementary intermolecular hydrogen bonds. We also found that the Hbim − ligand gave [Ni(Hbim) 3 ] − as a new building block for hydrogen-bonded self-assembling networks by one-pot synthesis to mix Ni(II) ion, counter cation and the ligand. The networks form zero-dimensional, one-dimensional, two-dimensional, and three-dimensional structures depending upon the kind of counter cations.

Cation-Dependent Formation of Superstructures by One-Pot Self-Organization of Hydrogen-Bonded Nickel Complexes

Four different types of molecular arrangements can be formed by one-pot synthesis, depending on the type of counter cation used, when a new anionic tris(biimidazolato)nickel(II) complex is used to form a network held together by hydrogen bonds. The connections occur through biimidazolate ligands, which can act as hydrogen bond donor as well as acceptor (see scheme).

Syntheses and crystal structures of oxovanadium(IV) complexes with N,N′-ethylenebis(amino acids)

Abstract The oxovanadium(IV) complexes with N,N′-ethylenebis(amino acids) ([VO(XeX)(H2O)], where X=A ((S)-Ala), V ((S)-Val) and P ((S)-Pro)) are synthesized and characterized by X-ray analyses and IR spectra. The crystal structure analyses reveal that the geometry around the vanadium cation of each complex is distorted octahedral and is coordinated by a water molecule and the tetradentate N,N′-ethylenebis(amino acidate) anion with Δ-cis-α configuration, in which the water oxygen atom occupies equatorial coordination position and one of the two secondary or tertiary nitrogen atoms of each tetradendate ligand is bound trans to the vanadyl oxo moiety. The compilation of bond lengths for present and previous VO complexes containing nitrogen and oxygen donating ligands shows that the tertiary amine groups of PeP ligand elongate Vue5f8N bonds. Comparison of the sum of the bond angles of three five-membered rings (one ethylenediamine ring and two amino acidate rings) indicates that the ring strain is mostly concentrated in the ethylenediamine ring and the strain of amino acidate ring lying in the equatorial plane of V(IV) ion is more pronounced than that in another amino acidate ring. The IR observations of the present complexes are well consistent with the crystallographic studies of them.

Preparation of Nanoporous Molecular Based-Solid Produced by Tris-2,2′-Biimidazolate CoIii Complexes

Abstract The [CoIII(Hbim)3] (1) (Hbim = 2,2′-biimidazolate monoanion) is synthesized and its crystal structure is characterized by X-ray crystal analysis. (Crystal data: monoclinic, C2/m (No. 12), FW = 970.71, a = 17.144(5) A, b = 30.341(6) A, c = 16.422(5) A, β = 104.38(2)°, V = 8274(3) A3,Z = 8) The crystal structure comprises assemblies of two-dimensional honeycomb sheet structures built up by alternate arrangements of Δ and Δ binary optical isomers of the building block 1 The two-dimensional sheets are formed by complementary intermolecular hydrogen bonds of Hbim− ligands containing the building block 1. Interestingly, two-dimensional sheets is stacked along c axis to form the microporous crystal with large channels.

Wasserstoffbrückenbindungs‐induzierte Selbstassoziation eines anionischen Nickelkomplexes zu Überstrukturen, deren Art vom Gegenkation abhängt

Vier verschiedenartige supramolekulare Anordnungen konnen in einer Eintopfsynthese – je nach Art der vorhandenen Gegenionen – durch intermolekulare Vernetzung eines neuen anionischen Tris(biimidazolato)nickel(II)-Komplexes uber Wasserstoffbruckenbindungen entstehen. Die Verknupfung erfolgt uber die Biimidazolatliganden, die sowohl als H-Bruckendonor wie auch als -acceptor fungieren (siehe Schema).

Na+ ion-specific binding and extraction by lipophilic armed cyclens via octadentate encapsulation

1,4,7,10-Tetraazacyclododecane derivatives having ester- and amide-functionalized sidearms predominantly extracted Na + ion from an aqueous mixture of Li + , Na + and K + ions into a CH 2 Cl 2 via specific octadentate complexation.

Reaction of [Ru3(CO)12] with 2-(chloromethyl)pyridine, syntheses of pyrid-2-ylacetyl ruthenium(II) complexes and crystal structure of [RuCl(C5H4N-2-CH2CO)(CO)(PPh3)2]

Abstract The cycloruthenated pyrid-2-ylacetyl complex [[RuCl(C 5 H 4 N-2-CH in2 CO)(CO) 2 ] 2 ] ( 1 ) was obtained by reaction of [Ru 3 (CO) 12 ] with an excess of 2-(chloromethyl)pyridine in refluxing toluene. Subsequent reaction of 1 with two equivalents of triphenylphosphine in refluxing benzene afforded the bis(phosphine) derivative [RuCl(C 5 H 4 N-2-CH 2 CO)(CO)(PPh 3 ) 2 ] ( 2 ). X-ray analysis of 2 shows that the complex is monomeric with the ruthenium atom coordinated by ring nitrogen and acyl carbon atoms from the cycloruthenated pyrid-2-ylacetyl group, cis chlorine and carbonyl carbon atoms, and trans phosphorus atoms, to form a distorted octahedral geometry.

Molecular Architectures Based on Hydrogen Bond and Coordination Bond Toward New Functionality

Abstract we report the design of new molecular building blocks with hydrogen-bonding sites and the production of a variety of molecular architectures by hydrogen-bonds and coordination bonds. We selected the ligands, such as biimidazole, pterine, lumazine, and glyoxime which have chelating ability to a metal element and multi-hydrogen-bonding sites.

Novel Oligoimidazoles for Hydrogen-bonded Charge-Transfer Complexes

4,4-Biimidazole and two kinds of quaterimidazoles were designed and firstly synthesized, aiming at constructing the charge-transfer complexes with the intermolecular hydrogen-bonding interaction. The one-dimensional hydrogen-bonded structure of 4,4-biimidazole containing protonated 4,4-biimidazole was confirmed by the crystal structural analysis. TCNQ complexes of the oligoimidazoles exhibited a semiconductive behavior with high conductivity. oligoimidazole hydrogen-bonding charge-transfer complexes hydrogen-bonded ligands assembled metal complexes

Structure and Magnetic Characterization of Binuclear Nickel(Ii) Compound with Bridging 2,2′-Biimidazolate Dianion

Abstract As novel molecule-based magnetic materials based on metal coordination polymers bridged by bim2-, [(Ni-cyclam)2(bim)](ClO4)2 (1) (bim2- = dideprotonated 2,2′-biimidazolate dianion) was synthesized and the crystal structure was characterized by X-ray crystal analysis. (Crystal data: orthorhombic, Pbca (No. 61), a = 16.677(2) A, b.= 16.447(5) A, c = 13.212(1) A, V = 3623(1) A3, Z = 4) The magnetic susceptibility measurements of the dinuclear nickel (II) complex (1) in the crystalline state showed the weak antiferromagnetic property (J= − 4.6 cm−1), which was also sujested by the ESR mesurements.