Oxidation reaction of [{Cu(Hpz)₂Cl}₂](Hpz = pyrazole): synthesis of the trinuclear copper(II) hydroxo complexes [Cu₃(OH)(pz)₃(Hpz)₂Cl₂]·solv (solv = H₂O or tetrahydrofuran). Formation, magnetic properties, and X-ray crystal structure of [Cu₃(OH)(pz)₃(py)₂Cl₂]·py (py = pyridine)

Abstract

The trinuclear copper(i1) complexes [Cu,(OH) (pz),( Hpz),CI,]~solv (Hpz = pyrazole, pz = pyrazolate anion, solv = H, O or tetrahydrofuran) have been obtained by oxidation reactions of [{Cu( Hpz),CI},]. When treated with pyridine(py), both Cu" derivatives gave the related compound [Cu,(OH) ( P Z ) ~-(py),CI,]*py, which has been characterized by a single-crystal X-ray structure analysis. Crystals are orthorhombic, space group Pnma (no. 62), a = 19.883(3), b = 15.063(3), c =9.495(2) A, Z = 4, R = 0.035 and R' = 0.041 for 1 472 absorption corrected reflections having I > 30(/). * p-Chloro-1 : ~~' ~/ -c h ~o r o -~~C / -p , -h y d r o x o -~~~-t r i -~-p y r a z o ~a t o -1 : ~KN'N';

Coordination Versatility of Pyrazole‐Based Ligands towards High‐Nuclearity Transition‐Metal and Rare‐Earth Clusters

“…In some cases, compounds of higher nuclearity, or polymers that retain the trinuclear structure are obtained. [56][57][58][59]61] Trinuclear copper(II) compounds with two types of bridging ligands, such as hydroxide and chloride ligands for [Cu 3 (µ 3 -OH)(µ-Cl)Cl(L1a) 3 -(HL1a) 2 ], [73] and oxide and perchlorate ligands for [Cu 3 (µ 3 -O)(ClO 4 )(L1a) 3 (HL1a) 3 ]·CH 3 OH, [74] were also reported. [68] Apparently, the introduction of substit-uents at the 4-position of the aromatic ring does not affect the formation of trinuclear copper(II) complexes.…”

“…Generally, a decrease in the magnitude of the antiferromagnetic exchange interaction is observed when the Cu-µ 3 -Y-Cu angle decreases (Y -= OH -), and ferromagnetic interactions become operative when the Cu-µ 3 -Y-Cu angle is approximately 80°(Y -= Cl -, Br -). [69,73] This common phenomenon can be described by the presence of antisymmetric exchange between the copper(II) ions in view of the magnetic susceptibility and EPR studies. [57] In some of the O(R)-centred copper(II) triangles, small values of magnetic susceptibility (values lower than those expected for a S T = 1/2) at low temperature are found.…”

Structure, spectroscopic, and magnetic properties of copper(II) dinuclear complex with μ-hydroxo and μ-pyrazolato bridges

“…Although there are many examples of binuclear copper(II) complexes with one bridging pyrazolate group and alcoholate or phenolate as another bridging group, [3][4][5][6][7][8][9] discrete binuclear copper(II) complexes with both pyrazolate and hydroxide bridges are unknown. It is worth to notice that cyclic trinuclear compounds with l 3 -OH [10,11] were described.…”

“…The geometry of the ligand implies the formation of polynuclear [M(pz) 2 ] n [1,2] and low-molecular weight di- [3][4][5][6][7][8][9], tri- [10,11], and tetranuclear [12][13][14] complexes with copper(II). Although there are many examples of binuclear copper(II) complexes with one bridging pyrazolate group and alcoholate or phenolate as another bridging group, [3][4][5][6][7][8][9] discrete binuclear copper(II) complexes with both pyrazolate and hydroxide bridges are unknown.…”

Antiferromagnetic Coupling in the Cyclic Octanuclear Compound [Cu(II)(μ-3,5-dimethylpyrazolate)(μ-OH)] and Its Analogue [Cu(II)(μ-pyrazolate)(μ-OH)]

“…The heterocyclic ligand coordination is supported by a strong and sharp band at 330 cm\, assigned to the (M-N) vibrational mode. The IR data for the OH group indicate its existence as a bridging ligand (12)(13)(14)(15).…”