Monofluoride Bridged, Binuclear Metallacycles of First Row Transition Metals Supported by Third Generation Bis(1-pyrazolyl)methane Ligands: Unusual Magnetic Properties

Abstract

The reaction of M(BF(4))(2).xH(2)O, where M is Fe, Co, Cu, and Zn, and the ditopic, bis(pyrazolyl)methane ligand m-[CH(pz)(2)](2)C(6)H(4), L(m), where pz is a pyrazolyl ring, yields the monofluoride bridged, binuclear [M(2)(mu-F)(mu-L(m))(2)](BF(4))(3) complexes. In contrast, a similar reaction of L(m) with Ni(BF(4))(2).6H(2)O yields dibridged [Ni(2)(mu-F)(2)(mu-L(m))(2)](BF(4))(2). The solid state structures of seven [M(2)(mu-F)(mu-L(m))(2)](BF(4))(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. NMR results indicate that [Zn(2)(mu-F)(mu-L(m))(2)](BF(4))(3) retains its dimeric structure in solution. The [Ni(2)(mu-F)(2)(mu-L(m))(2)](BF(4))(2) complex has a dibridging fluoride structure that has a six-coordination environment about each nickel(II) ion. In the solid state, the [Fe(2)(mu-F)(mu-L(m))(2)](BF(4))(3) and [Co(2)(mu-F)(mu-L(m))(2)](BF(4))(3) complexes 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 [Cu(2)(mu-F)(mu-L(m))(2)](BF(4))(3) are diamagnetic between 5 and 400 K, thus showing strong antiferromagnetic exchange interactions of -600 cm(-1) or more negative. Mossbauer spectra indicate that [Fe(2)(mu-F)(mu-L(m))(2)](BF(4))(3) exhibits no long-range magnetic order between 4.2 and 295 K and isomer shifts that are consistent with the presence of five-coordinate, high-spin iron(II).

Phelan–McDermid Syndrome and SHANK3: Implications for Treatment

“…The first clinical trial in PMS studied the effect of intranasal insulin, which has been implicated in synaptic plasticity and memory processing in neuronal models [77], and has improved declarative memory in patients with Alzheimer's disease [78]. Six patients received 0.5-1.5 IU/ kg/day 3 times daily for 12 months, resulting in beneficial effects on cognitive functioning and motor development without adverse effects on glucose levels or hemoglobin A1c levels [77].…”

Physical and structural properties of [Cu(BOT1)Cl]Cl, a fluorescent imaging probe for HNO

“…A strictly linear bridging mode of the fluoride atom in dinuclear copper(II) complexes has been previously encountered [36,37]. Taken together, the structures of [Cu(BOT1)Cl] + and [Cu 2 (BOT1) 2 (μ-F)] 3+ demonstrate the flexibility of the BOT1 ligand.…”

Synthesis, structure and properties of one 2-D Ag(I) complex based on trinuclear silver(I) cluster and arene-linked bis(pyrazolyl)methane ligand

“…More recently, the Smith group successfully employed the "third generation" poly (pyrazolyl)methane ligands which are specifically functionalized at the non-coordinating "back" position to have an insight into the substances with uncommon solid state supramolecular architectures [6]. These third-generation bis-and tri (pyrazolyl) methane compounds have shown outstanding potential for the formation of substances with unusual solid state supramolecular architectures [7].…”

“…More recently, the Smith group successfully employed the "third generation" poly (pyrazolyl)methane ligands which are specifically functionalized at the non-coordinating "back" position to have an insight into the substances with uncommon solid state supramolecular architectures [6]. These third-generation bis-and tri (pyrazolyl) methane compounds have shown outstanding potential for the formation of substances with unusual solid state supramolecular architectures [7].In order to delve into the key roles in directing the final supramolecular structure, we start our work by choosing linear arenelinked p-bis[bis(1-pyrazolyl)methyl]benzene ligand [8], because this third-generation bis (pyrazolyl) ligand has not only rigid backbones but also flexible bis (pyrazolyl)methane units. Theoretically, the multiple coordination sites of ligands can form the structures of higher dimensions and the high symmetry of ligands may result in new structures [9].…”