Date of Award

1-1-2009

Document Type

Campus Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Daniel L. Reger

Abstract

A new phenylene-linked multitopic family of bis(pyrazolyl)methane ligands, (C6H6-n[CH2OCH2CH(pz)2]2)n, where pz is a pyrazolyl ring, has been synthesized by the general reaction of (pz)2CHCH2OH with NaH, followed by the addition of C6H6-n[CH2Br]n. The silver(I) complexes of ligand o-C6H4[CH2OCH2CH(pz)2]2 form coordination polymer. The two other ditopic ligands, which have meta- and para-oriented "arms" (-CH2OCH2CH(pz)2), were treated with Ag(I) salts and recrystallized from acetone or acetonitrile to give nine silver(I) complexes, in which the four pyrazolyl rings of the ligand chelate a single silver(I) cation in a distorted tetrahedral environment forming unusually sized mononuclear metallacycles. The silver(I) complexes of the tetratopic and hexatopic ligands form double, mononuclear metallacycles, a new structural form. In the silver complexes of the tetratopic ligand, the double, mononuclear metallacycles are formed by two pairs of para-oriented arms chelating two silver ions on opposite sides of the central arene ring. The silver complexes of the hexatopic ligand also form double, mononuclear metallacycles; however, one metallacycle is formed by para-oriented arms and the other metallacycle is formed by meta-oriented arms. The remaining two arms link these metallacyles into coordination polymers.

The more rigid, ditopic, bis(pyrazolyl)methane ligand m-[CH(pz)2]2C6H4, Lm, yields the monofluoride bridged, binuclear [M2(μ-F)(μ-Lm)2](BF4)3 complexes when treated with M(BF4)2*xH2O, where M is Fe, Co, Cu, and Zn. In contrast, a similar reaction of Lm with Ni(BF4)2*6H2O yields dibridged [Ni2(μ-F)2(μ-Lm)2](BF4)2. The solid state structures

of seven [M2(μ-F)(μ-Lm)2](BF4)3 complexes show that the divalent metal ion is in a five-coordinate, trigonal bipyramidal, coordination environment with either a linear or nearly linear M-F-M bridging arrangement. In the solid state, the [Fe2(μ-F)(μ-Lm)2](BF4)3 and [Co2(μ-F)(μ-Lm)2](BF4)3complexes show weak intramolecular antiferromagnetic exchange coupling between the two metal(II) ions with J values of -10.4 and -0.67 cm-1, respectively; there is no observed long-range magnetic order. Three different solvates of [Cu2(μ-F)(μ-Lm)2](BF4)3 are diamagnetic between 5 and 400 K, thus showing strong antiferromagnetic exchange interactions of -600 cm-1 or more negative.

Because of unusually large J value in [Cu2(μ-F)(μ-Lm)2](BF4)3, the complexes [Cu2(μ-Cl)(μ-Lm)2](BF4)3, [Cu2(μ-Cl)(μ-Lm)2](ClO4)3, [Cu2(μ-OH)(μ-Lm)2](ClO4)3, and [Cu2(μ-Br)(μ-Lm)2](BF4)3 were synthesized. The solid state structures of the [Cu2(μ-Cl)(μ-Lm)2]3+ complexes show that the divalent copper ion is in a five-coordinate, trigonal bipyramidal, coordination environment with most of the monochloro bridges in a linear arrangement. The [Cu2(μ-OH)(μ-Lm)2]3+ complexes have a bent hydroxo bridge and a distorted square pyramidal coordination environment. In the solid state, all of these complexes are diamagnetic up to 350 K, which is indicative of very strong antiferromagnetic exchange interactions. nylene-linked multitopic family of bis(pyrazolyl)methane ligands, m-[CH(pz)2]2C6H4, Lm, yields the monofluoride bridged, binuclear [M2(μ-F)(μ-Lm)2](BF4)3 complexes when treated with M(BF4)2*xH2O, where M is Fe, Co, Cu, and Zn. In contrast, a similar reaction of Lm with Ni(BF4)2*6H2O yields dibridged [Ni2(μ-F)2(μ-Lm)2](BF4)2. The solid state structures

of seven [M2(μ-F)(μ-Lm)2](BF4)3 complexes show that the divalent metal ion is in a five-coordinate, trigonal bipyramidal, coordination environment with either a linear or nearly linear M-F-M bridging arrangement. In the solid state, the [Fe2(μ-F)(μ-Lm)2](BF4)3 and [Co2(μ-F)(μ-Lm)2](BF4)3complexes show weak intramolecular antiferromagnetic exchange coupling between the two metal(II) ions with J values of -10.4 and -0.67 cm-1, respectively; there is no observed long-range magnetic order. Three different solvates of [Cu2(μ-F)(μ-Lm)2](BF4)3 are diamagnetic between 5 and 400 K, thus showing strong antiferromagnetic exchange interactions of -600 cm-1 or more negative.

Because of unusually large J value in [Cu2(μ-F)(μ-Lm)2](BF4)3, the complexes [Cu2(μ-Cl)(μ-Lm)2](BF4)3, [Cu2(μ-Cl)(μ-Lm)2](ClO4)3, [Cu2(μ-OH)(μ-Lm)2](ClO4)3, and [Cu2(μ-Br)(μ-Lm)2](BF4)3 were synthesized. The solid state structures of the [Cu2(μ-Cl)(μ-Lm)2]3+ complexes show that the divalent copper ion is in a five-coordinate, trigonal bipyramidal, coordination environment with most of the monochloro bridges in a linear arrangement. The [Cu2(μ-OH)(μ-Lm)2]3+ complexes have a bent hydroxo bridge and a distorted square pyramidal coordination environment. In the solid state, all of these complexes are diamagnetic up to 350 K, which is indicative of very strong antiferromagnetic exchange interactions.

Share

COinS