1 research outputs found
The First Characterized Coordination Compounds of Macrocyclic Ligands Including Incorporated Tetrazole Rings
The
macrocyclic binuclear tetrazole, 2,2,5,5-tetramethyl-12-oxa-1,6,7,8,16,17,18,19-octaazatricycloÂ[13.2.1.16,9]Ânonadeca-7,9(19),15(18),16-tetraene
(<b>L</b>), reacts with copperÂ(II) chloride or copperÂ(II) tetrafluoroborate
hexahydrate to give complexes [Cu<sub>3</sub>Cl<sub>6</sub>L<sub>2</sub>] (<b>1</b>) or [CuL<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]Â(BF<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O) (<b>2</b>), respectively. According to single crystal X-ray analysis, both
complexes were found to be coordination polymers. In the crystal structure
of complex <b>1</b>, there are neutral linear bibridged trinuclear
units Cu<sub>3</sub>Cl<sub>6</sub>, in which the copper atoms are
linked together by double chlorine bridges. Neighboring Cu<sub>3</sub>Cl<sub>6</sub> units are bonded to each other by two bridging macrocyclic
ligands L due to coordination bonds Cu–N between terminal copper
atoms of Cu<sub>3</sub>Cl<sub>6</sub> units and the tetrazole ring
nitrogen atoms of ligands L to form polymeric chains. In complex <b>2</b>, the copper atom is bonded to three ligands L via the tetrazole
ring nitrogen atoms, and to two water molecules, with formation of
a square-pyramidal coordination of the metal. In this complex, one
of two independent ligands L shows monodentate coordination, whereas
another ligand plays the role of a bridge between two neighboring
copper atoms being responsible for formation of polymeric cationic
chains [CuL<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]<sub><i>n</i></sub><sup>2<i>n</i>+</sup>. A complex system of hydrogen
bonds connects the chains and the anions BF<sub>4</sub><sup>–</sup> into a three-dimensional network. The temperature-dependent magnetic
susceptibility measurements of complex <b>1</b> revealed that
the copperÂ(II) ions were ferromagnetically coupled showing a coupling
constant <i>J</i> of 50 cm<sup>–1</sup>