Serkan Guney

Different coordination modes of saccharin in the metal complexes with 2-pyridylmethanol: synthesis, spectroscopic, thermal and structural characterization

The reaction of [M(sac)2(H2O)4]/2H2O, where M is Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), and sac is the saccharinate anion, with 2-pyridylmethanol (mpy) result in the formation of the new complexes, which have been characterized by elemental analyses, magnetic measurements, FT-IR spectroscopy, thermal analysis and X-ray diffraction methods. The [Co(sac)2(mpy)2 ]( 3) and [Ni(sac)2(mpy)2 ]( 4) complexes are isomorphous with the triclinic space group the two sac ligands in both 3 and 4 exhibit unusual and non-equivalent coordination. One of them coordinates to the metals through the imino nitrogen atom, while the other is bonded to the metals with the carbonyl oxygen atom behaving as an ambidentate ligand. The [Cu(sac)2(mpy)2 ]( 5) complex is centrosymmetric and crystallizes in orthorhombic space group and both sac ligands in (5) are N coordinated. [Hg2(sac)4(mpy)2 ]( 8) crystallizes in monoclinic space group P 21/n .I n8, the mpy ligands acts as a bridge between the mercury two mercury(II) centres and the complex 8 consists of one-dimensional chains in which dimeric [Hg2(sac)4(mpy)2] units are sequentially bridged by bis-bidentate sac ligands forming a coordination polymer. In all cases, the metal atoms are six-coordinate. The mpy molecules act as a bidentate N - and O-donor ligand in 1/7. Thermal decomposition of the complexes in air results in removal of mpy ligands and formation of stable metal saccharinates as intermediates, which also decompose at higher temperatures to give the corresponding metal oxides. # 2002 Elsevier Science Ltd. All rights reserved.

Different Coordination Modes of Saccharin in the Complexes of Lead(II) with 2-Pyridylmethanol and Pyridine-2, 6-dimethanol — Synthesis, Spectral and Structural Characterization

New lead(II)-saccharin complexes, [Pb(sac)2(pym)] (1) and [Pb(sac)2(pydm)] (2) (sac = saccharinate anion; pym = 2-pyridylmethanol; pydm = pyridine-2, 6-dimethanol) were synthesized and characterized by IR spectroscopy and single crystal X-ray diffractometry. Complex 1 crystallizes in the monoclinic P21/c space group with Z = 4, while the crystals of complex 2 are extremely X-ray sensitive and decompose by the X-ray beam within one day. Pym and pydm act as bi- and tridentate ligands, respectively. Most important feature of the complexes is non-equivalent coordination of the sac ligands to the lead(II) atom. In the complex 1, the sac ligands coordinate to the lead(II) ion in two distinct manners. One sac ligand behaves as a bridge between the lead(II) atoms through its N and carbonyl O atoms, whereas the other sac ligand acts as a bidentate chelating ligand through its N and carbonyl O atoms which is bicoordinating and also bridges the metal atoms to achieve the seven-coordination. The structure is built up of three-dimensional chains formed by the bridging of the PbN3O2 units and also held intermolecular hydrogen bonds. The IR spectra of the complexes were discussed in detail. Unterschiedliche Koordination von Saccharin in den Komplexen von Blei(II) mit 2-Pyridylmethanol und Pyridin-2, 6-dimethanol — Synthese, spektroskopische und strukturelle Charakterisierung Neue Blei(II)-Saccharin-Komplexe, [Pb(sac)2(pym)] (1) und [Pb(sac)2(pydm)] (2) (sac = Saccharinat-Anion; pym = 2-Pyridylmethanol; pydm = Pyridin-2, 6-dimethanol) wurden synthetisiert und durch IR-Spektroskopie und Einkristall-Rontgenanalyse charakterisiert. 1 kristallisiert monoklin, Raumgruppe P21/c mit Z = 4, wahrend die Kristalle von 2 extrem rontgenempfindlich sind und im Rontgenstrahl innerhalb eines Tages zerfallen. Pym und pydm sind zwei- bzw. dreizahnige Liganden. Die wichtigste Besonderheit der Komplexe ist die unterschiedliche Koordination der Saccharinat-Liganden am Bleiatom. Im Komplex 1 koordinieren die Saccharinat-Liganden in zwei unterschiedlichen Weisen. Ein sac-Ligand bildet eine Brucke zwischen den Blei(II)-Atomen uber seine N- und Carbonyl-O-Atome, wahrend der andere sac-Ligand als zweizahniger Chelatligand uber seine N- und Carbonyl-O-Atome die Metallatome zweifach koordiniert und verbruckt, die dadurch Siebenerkoordination erreichen. Die Struktur ist aus dreidimensionalen Ketten aufgebaut durch die Verbruckung der PbN3O2-Einheiten und wird uber zwischenmolekulare Wasserstoffbruckenbindungen zusammengehalten. Die IR-Spektren werden im einzelnen diskutiert.

Bis(2-pyridyl­methanol)­bis­(saccharinato)­zinc(II) and -cadmium(II) at 120 K: three-dimensional structures containing both N-and O-coordinated ambi­dentate saccharinate ligands

The title complexes [M(sac)(2)(mpy)(2)] [sac is saccharinate (C(7)H(4)NO(3)S) and mpy is 2-pyridylmethanol (C(6)H(7)NO)], with M = Zn(II) and Cd(II), are isostructural and consist of neutral molecules. The Zn(II) or Cd(II) cations are octahedrally coordinated by the two neutral mpy and two anionic sac ligands. The mpy ligand acts as a bidentate donor through the amine N and hydroxyl O atoms. The sac ligands exhibit an ambidentate coordination behaviour; one is N-coordinated and the other is O-coordinated within the same coordination octahedron. The crystal packing is determined by C-H...O-type hydrogen bonding, as well as by weak py-py and sac-sac aromatic pi-pi-stacking interactions.

Synthesis, crystal structure, spectroscopic and thermal properties of trans-[Ni(sac)2(aeppz)2] [sac = saccharinate and aeppz = N -(2-aminoethyl)piperazine]

A nickel(II) complex of saccharinate (sac) with N-(2-aminoethyl)piperazine (aeppz), trans-[Ni(sac)2(aeppz)2], has been prepared and characterized by elemental analyses, IR, UV-vis, magnetic measurements and single crystal X-ray diffraction. The compound crystallizes in space group (No. 2). The nickel(II) ion sits on an inversion centre and is octahedrally coordinated by two neutral aeppz and two anionic sac ligands. The aeppz ligand is bidentate (N,N′) chelating, while sac is O-coordinated through the carbonyl O atom. The IR spectrum of [Ni(sac)2(aeppz)2] displays typical absorption bands of bidentate aeppz and O-bonded sac ligands. Under atmospheric conditions, [Ni(sac)2(aeppz)2] is thermally stable up to 220°C, but at higher temperatures, loses two aeppz ligands between 220 and 317°C and two sac ligands in the temperature range 320–528°C, giving NiO as end product.

Synthesis, crystal structure and properties of trans-[Cu(sac)2(en)2] (sac=saccharinato and en=ethylenediamine)

The title complex trans-[Cu(sac)2(en)2] (sac = saccharinato, en = ethylenediamine) has been obtained accidentally by the reaction of piperazine (ppz) with [Cu(sac)2(H2O)4]·2H2O in butanol solution. During the reaction, ppz was presumably decomposed to produce en which then coordinated to copper(II) to yield the title complex. trans-[Cu(sac)2(en)2] has been characterized by elemental analysis, IR, UV-VIS, magnetic measurements and single crystal X-ray diffraction. The compound crystallizes in space group (No. 2) and it consists of neutral units linked by bi- and trifurcated N–H···O hydrogen bonds into chains which are further connected by aromatic π–π stacking interactions forming a three-dimensional supramolecular network. The copper(II) ion in [Cu(sac)2(en)2] sits on a inversion centre and is octahedrally coordinated by two neutral en and two anionic sac ligands. An elongated distorted octahedral geometry along the Cu–Nsac bonds is a consequence of the Jahn–Teller effect. The en ligand acts as a bidentate (N,N′) chelating ligand, while sac is N-coordinated. IR and UV spectra and thermal analysis are in agreement with the crystal structure.

trans-Bis[2-(piperazin-1-yl)­ethan­amine]­bis­(saccharinato)cobalt(II)

In the centrosymmetric title complex, [Co(C7H4NO3S)2(C6H15N3)2], the CoII ion is coordinated by two saccharinate (sac) anions and two neutral 2-piperazin-1-ylethanamine (ppzea) ligands, showing a distorted octahedral coordination. Sac is O-bonded via the carbonyl group, while ppzea acts as an N,N′-bidentate chelating ligand. The molecules are connected by N—H⋯N and N—H⋯O hydrogen bonds, forming a linear chain running parallel to the crystallographic a axis. The compound is isostructural with the reported Ni, Zn, and Cd analogues.

trans-Bis(saccharinato)zinc and -cadmium Complexes with N-(2-Aminoethyl)piperazine: Synthesis, Crystal Structures and IR Spectra

The reactions of N-(2-aminoethyl)piperazine (aeppz) with tetraaqua-bis(saccharinato)zinc(II) and -cadmium(II) in ethanol solution yield the new complexes trans-[Zn(sac)2(aeppz)2] (1), and trans- [Cd(sac)2(aeppz)2] (2) (sac = saccharinate), respectively. The complexes were characterized by elemental analyses, IR spectroscopy and X-ray crystallography. Both complexes 1 and 2 are mononuclear of Ci symmetry. The zinc(II) and cadmium(II) ions are coordinated by two neutral aeppz ligands and two sac anions in an elongated distorted octahedral environment. The aeppz ligand acts as a bidentate N, N’ donor through the central heterocyclic N atom and the N atom of the aminoethyl group, while the sac ligand is O-coordinated via the carbonyl O atom. The packing of the molecules in the crystals in both complexes is consolidated by arene π −π stacking interactions between the sac rings and by intermolecular hydrogen bonds involving the amine groups of aeppz and the sulfonyl oxygen atoms of the sac ligands