A Study on Fe^II, Zn^II and Cu^II Complexes with Novel Tridentate Bis(pyrazolyl)methane Ligands

Abstract

The ligand class of tridentate bis(pyrazolyl)methanes was extended via the syntheses of HC(3,5‐EtPz)2Py. This ligand is the first of its kind with a homogeneous 3,5‐functionalization with large substituents. On the basis of 3,5‐functionalized ligands we were able to synthesize 15 novel complexes with FeII, ZnII, and CuII salts. Herein we present an extensive coordination chemistry study, that focuses on the influences of different metals, ligands, and counterions on the coordination mode and on the spin state in case of FeII complexes.

Synthesis of Bis(benzotriazol-1-yl)methane Derivatives by Cobalt-Catalyzed Formation of C-C Bonds

“…The disposition of the three rings is in such a way that the nitrogen atoms (if present) are as far as they can, in an anti-or pseudo trans conformation. A similar way occurs in bis(benzotriazol-1-yl)methane [51] and also in some pyrazolyl compounds such as bis(pyrazolyl)bipyridinylmethane [52], but quite different disposition was found in 2-[bis(3,5-diphenyl-1H-pyrazol-1-yl)methyl]pyridine [53] or in bis(benzotriazol-1-yl)methanethione [54], where the two nitrogen atoms in 2-position in both rings are pointing to each other. Figure 4 shows as both benzotriazolyl rings are in opposite direction, one of them with the benzene ring to the right and the other to the left.…”

Interplay of Spin Crossover and Coordination-Induced Spin State Switch for Iron Bis(pyrazolyl)methanes in Solution

“…77 Two ligands coordinate with both N-donors of the bipyridinyl unit and one pyrazolyl unit toward the iron ion while one pyrazolyl unit of each ligand remains uncoordinated. A series of examples for homoleptic iron compounds featuring the bis(pyrazolyl)methane, 44,48,78,79 tris(pyrazolyl)borate, 80 and -methane 81 ligand family for weakly coordinating counterions are known. Thereby also an equimolar stoichiometry of ligand and metal salt leads to compounds with the stoichiometry 2:1 containing a ligand and metal center.…”

“…42,43 To achieve this goal, bis(pyrazolyl)methanes with an additional third larger N-donor were investigated (Scheme 1). 44 This strategy involves the design of a tetradentate (instead of tridentate) N-donor system: the bis(pyrazolyl)bipyridinylmethane ligand (Scheme 1, right). 45 Here we present iron bis(pyrazolyl)bipyridinylmethane complexes with fundamentally different properties in solid state and solution.…”

“…To enable facile catalytic applications of the tris- or bis­(pyrazolyl)­methane complexes, we aimed to install an unsaturated coordination sphere at the metal center. , To achieve this goal, bis­(pyrazolyl)­methanes with an additional third larger N-donor were investigated (Scheme ). This strategy involves the design of a tetradentate (instead of tridentate) N-donor system: the bis­(pyrazolyl)­bipyridinylmethane ligand (Scheme , right) …”

Physicochemical Insight into Coordination Systems Obtained from Copper(II) Bromoacetate and 1,10-Phenanthroline

“…As a specific example, a copper cation can create classical coordination compounds with the c.n. from 2 [ 6 ] to 8 [ 7 ], and with over a dozen of covalently bonded atoms for copper clusters [ 8 ]. For c.n.…”