Yusaku Suenaga

Synthesis, crystal structures and magnetic behavior of polymeric lanthanide complexes with benzenehexacarboxylic acid (mellitic acid)

Abstract Three lanthanide complexes with mellitic acid [Ce2{C6(COO)6}(H2O)8]·H2O (1), [Eu2{C6(COO)6}(H2O)8]·H2O (2) and [Yb2{C6(COO)6}(H2O)10]·2H2O (3), have been synthesized and structurally characterized by X-ray crystallography and magnetic properties. The three compounds crystallize in the monoclinic space space P21/n, with unit cell dimensions of: a = 8.627(2), b = 13.218(2), c = 9.650(1) A , β = 95.93(1)° and Z = 2 for 1 ;a = 8.505(2), b = 13.145(1), c=9.536(2) A , β=94.73(2)° and Z=2 for 2 ; a = 8.420(1), b = 9.224(4), c = 16.229(1) A , β = 100.267(9)° and Z = 2 for 3. All three structures consist of an extended network of metal ions, coordinated to mellitate anions and water molecules linked by a complex hydrogen bonding. 1 and 2 are isomorphous with near isostructural [M2{C6(COO)6}(H2O)8] units in which the metal ion is coordinated by four water molecules and five oxygen atoms of the mellitate anions, and each mellitate group involves a tetrakis(bidentate) and bis(unidentate) coordination mode bridging six metal ions forming a three-dimensional framework. In 3 the ytterbium atom is bound with five water molecules and three oxygen atoms of the mellitate anion, and each mellitate moiety bridges four dodecahedral Yb(III) ions yielding a two-dimensional sheet structure. The magnetic susceptibility of 1 and 3 as a function of temperature (5.0–300 K) exhibits a sharp maximum at 6.0 K for both compounds.

An S⋯S contact assembled tetranuclear copper(I) complex with sulfur-rich ligand, 4,5-ethylenedithio-1,3-dithiole-2-thione

Abstract A copper(I) complex with 4,5-ethylenedithio-1,3-dithiole-2-thione (C 5 H 4 S 5 ), [Cu 4 I 4 (C 5 H 4 S 5 ) 4 ] ∞ , was synthesized and the molecular structure and packing were characterized crystallographically. The metal center is a stepped Cu 4 I 4 core coordinated by two ligands C 5 H 4 S 5 in different ways. One is bidentate coordinated through the thiocarbonyl group and the thioether group and the other is monodentate coordinated only through thiocarbonyl group. The Cu 4 I 4 clusters are bridged by bidentate C 5 H 4 S 5 molecules to form one-dimensional polymeric chains along the c -axis, and these chains form a three-dimensional network linked by interchain S⋯S contacts. The shortest S⋯S contact distance is 3.257 (2) A. A crystal of the complex is triclinic with space group P 1 , a=11.350(5) A , b=11.854(3) A , c=9.275(5) A , α=97.32(4)°, β=112.35(4)°, γ=67.67(2)°, V=1067.0(9) A 3 , Z=2, R=0.034, R w =0.051 .

A UNIQUE COORDINATION POLYMER CONSISTING OF TWO PARALLEL C5H4S5 MOLECULES BRIDGING TWO SILVER(I) IONS (C5H4S5=4,5-ETHYLENEDITHIO-1,3-DITHIOLE-2-THIONE )

The silver(I) complex with 4,5-ethylenedithio-1,3-dithiole-2-thione (C 5 H 4 S 5 ), [Ag(C 5 H 4 S 5 ) 2 NO 3 ] ∞ , was synthesized and the molecular structure and packing were characterized crystallographically. The Ag atom is coordinated with four ligands through two thiocarbonyl sulfur atoms (CS) and two thioether sulfur atoms of the six-membered ring (–S–), respectively, forming an extremely distorted tetrahedral geometry. This is the first metal complex of TTF or BEDT–TTF analogs, in which the sulfur atom in a five- or six-membered ring directly coordinates to the silver(I) ion. Two parallel C 5 H 4 S 5 molecules are connected by two Ag(I) ions to give a unique infinite chain. The S⋯S contacts of 3.41 A are very strong between two nearby chains along the b axis, generating a two-dimensional network. The crystal of the complex is monoclinic with space group P 2/ n , a =8.701(1), b =8.955(1), c =11.811(1) A, β =91.438(8)°, V =920.0 A 3 , Z =2, R =0.031, R w =0.045. Although the iodine-doped free ligand is an insulator, the iodine-doped complex is a semiconductor ( σ =3×10 −5 S cm −1 ) at room temperature.

Structure and 1H NMR study of copper(I) complex with ethylene and tetramethylethylenediamine

Abstract A ternary copper(I) complex with ethylene and tetramethylethylenediamine(tmen) has been prepared and the structure characterized by the single crystal X-ray method. The copper atom is coordinated to two nitrogen atoms of tmen and an ethylene molecule in a trigonal-planar arrangement. The CC bond distance of 1.36(1) A is slightly longer than that of the free ethylene (1.335 A). In the 1 H NMR study, chemical shifts of ethylene protons at 5.46 ppm move upfield (4.16 ppm) upon coordination to copper(I). This indicate that the π back donation from copper to the ethylene is rather weak compared with other metal-ethylene systems.

Silver(I) complexes of triazine derivatives having stepped π–π interactions and 2D sheets

Abstract Reactions of silver(I) perchlorate and triflate with the triazine ligands 2,4,6-trimethoxy-1,3,5-triazine (L1) and 2,4,6-triphenyl-1,3,5-triazine (L2) have provided three novel silver complexes: [Ag(L1)2](ClO4) (1), [Ag(L1)2](CF3SO3) (2) and [Ag2(L2)(CF3SO3)2] (3). The crystal structures of these complexes have been determined by single-crystal X-ray diffraction. Each complex exhibits distinct coordination behavior and different frameworks. Complex 1 has a 1D stepped framework in which one crystallographically independent metal center interacts with two L1 molecules and strong π–π interactions between the triazine planes of two L1 molecules exist. On the other hand, complex 2 has a herringbone-like molecular packing in which the triflate ions are arranged between mononuclear complex cations. In complex 3, L2 molecules are suspended between two double chains of silver triflate through the coordination to silver(I) ions to form the 2D sheet network structure. The factors that influence the crystal structure and packing are discussed.

Synthesis and crystal structure of two ternary dicopper(I) complexes having the unsymmetrical coordination arrangement bridged by 1,8-naphthyridine (napy). [Cu2(napy)2(Me2CO)](PF6)2·2Me2CO and [Cu2(napy)2(dppm)(CH3CN)](PF6)2

Abstract Two novel ternary dicopper(I) complexes bridged by 1,8-naphthyridine (napy), [Cu2(napy)2(Me2CO)](PF6)2·2Me2CO (1) and [Cu2(napy)2(dppm)(CH3CN)](PF6)2(2), have been prepared and their structures have been determined crystallographically. Complex 1: space group P2 1 la, a=12.281(4), b=21.154(3), c=13.891(3) A , β=112.74(2)°, Z=4, R=0.079 and R w =0.093 . Complex 2: space group Cc, a=19.572(7), b=13.708(7), c=18.457(3) A , β=108.56(2)°, Z=4, R=0.064 and R w =0.066 . On complex 1 two Cu atoms are doubly bridged by two napy ligands to provide a dinuclear structure, which has a close Cu(I)…Cu(I) separation of 2.533(2)A. Two Cu atoms on 2 are also triply bridged by two napy and one dppm ligands to give a dinuclear structure with a close Cu(I)…Cu(I) separation of 2.607(3) A. On these dicopper(I) complexes the most remarkably structural feature is that the coordination environment around each Cu atom is different: complexes 1 has one linear and one T-shaped copper, and 2 has one distorted trigonal and one distortd tetrahedral copper. It was structurally found that the Cu(I)…Cu(I) separation greatly depends on the coordination arrangement around each Cu atom: the Cu(I)…Cu(I) distance should be longer in the order of the coordination arrangements of [two linear coppers]. one linear and one T-shaped copper, two trigonal coppers, one trigonal and one tetrahedral copper, and two tetrahedral coppers.

1:2 TCNQ/TCNQ−. mixed salts exhibiting ferromagnetic behavior at room temperature

Abstract Ferromagnetic behavior at room temperature was observed in the tetramethylammonium (NMe + 4 ) and cesium (Cs + ) salts of tetracyanoquinodimethane (TCNQ) and its radical anion (TCNQ −. ) in a molecular ratio of 1:2. The saturation magnetizations and coercive forces are 0.79 emu/mol and ≈300 Oe for ( NMe + 4 · TCNQ −. ) · 1 2 TCNQ , and 1.46 emu/mol and ≈100 Oe for ( Cs +. · TCNQ −. ) · 1 2 TCNQ , respectively. In contrast, the 1:1 TCNQ/TCNQ −. mixed tetraethylammonium (NEt 4 + salt, (NEt 4 + ·TCNQ − ·)·TCNQ, exhibited no ferromagnetic behavior at room temperature nor at lower temperatures.

Syntheses and structures of copper(I) and silver(I) coordination polymers with hexakis(methylthio)benzene

Abstract Copper(I) and silver(I) complexes of hexakis(methylthio)-benzene (hmb), [Cu(hmb)]PF6 (1) and [Ag(hmb)]PF6 (2), have been prepared and their molecular structures determined by X-ray crystallography. In 1 the copper ion prefers a tetrahedral coordination geometry comprising four sulfur atoms from two different hmb molecules and giving a linear chain structure of alternating metal cations and organic ligands. The para-position two sulfur atoms of hmb are not coordinated to copper. In 2 silver ion is of similar coordination geometry to copper ion but the shortest S · · · S distance between inter-chain S atoms no coordinated with silver is 3.57 A. Therefore, complex 2 forms two-dimensional network through S · · · S contacts.

Syntheses, structures and properties of palladium (II) complexes with photochromic 4-methoxyazobenzene

Abstract Two palladium (II) complexes with the photochromic ligand 4-methoxyazobenzene (MeOazbH), [Pd(MeOazb) (PhCN) (H2O)] (ClO4) (1) and [Pd(MeOazbH)2Cl2] (2) were prepared and their molecular structures determined by X-ray crystallography. 1: triclinic, P 1 , a=9.684(3), b=11.833(2), c=9.731(3) A , α=102.41(1), s=94.54(3), γ=94.82(2)°, V=1079.7(4) A 3 , Z=2 . 2: triclinic, P 1 , a=9.497(3), b=9.719(4), c=8.226(3) A , α=96.43(4), s=109.24(3), γ=62.13(2)°, V=632.9(4) A 3 , Z=1 . The molecular structure of complex 1 shows a significantly distorted square planar coordination around the Pd atom and the MeOazb group forms a five-membered chelate ring with the metal ion by means a σ-bond at an ortho-carbon atom and the lone pair of the further nitrogen. In complex 2 the palladium atom lies on an inversion center, surrounded in an essentially square planar fashion by the symmetry related two MeOazbH ligands and two chloride ions. In contrast with the ortho-metalation reaction in 1, MeOazbH in 2 acts as a monodenate ligand to bind the metal center via a PdN σ-bond. Electronic spectroscopic studies of the two complexes together with the free ligand were carried out in solution at room temperature and upon irradiation of light; while rigidity imparted to the MeOazb linkage by palladation in 1 inhibits its photochromic reaction, the monodentate-coordinated MeOazbH in 2 shows a trans-cis photoisomerization.

Silver(I) complexes of dibenzo-18-crown-6-ether having cation–π and π–π interactions

Three silver(I) complexes of dibenzo-18-crown-6-ether (DB[18]C6), [Ag(DB[18]C6)(ClO 4 )](THF) ( 1 ), [Ag(DB[18]6)(CF 3 SO 3 )] 2 (acetone) 2 ( 2 ) and [Ag(DB[18]C6)(CF 3 COO)] 2 (AgCF 3 COO) 2 ( 3 ) have been synthesized in different solvents and characterized structurally. In each complex, silver ions prefer an octahedral coordination geometry and form close dinuclear complex with DB[18]C6 based on cation–π interaction in η 2 -fashion. In particular, the coordination unit involving σ bonding at an oxygen group and π–π bonding between two benzene rings is quite unique.