Coordination versatility of 1,3-bis[3-(2-pyridyl)pyrazol-1-yl]propane: Co(II) and Ni(II) complexes

Generation and Properties of CoI/NiI Species Stabilized by a Tetradentate Pyridylpyrazole Ligand: Crystal Structures of Dialkyl‐CoIII Complexes

“…[16] Syntheses: The complexes [(L (3) were obtained as described previously. [14] Chemical Reduction of Co II Complexes: The cobalt(II) complexes 1 and 2 were reduced chemically by a similar methodology. 1-2 m solutions of the complexes were purged with N 2 gas (Schlenk-line technique) for 30 min under ice-cold conditions.…”

“…The six-coordination around Co III is provided by four nitrogen atoms [N(1), N(2), N(5), and N(6)] from the ligand L 1 coordinated in a cis-equatorial tetradentate chelating mode and by two methyl groups [C(20) and C (21)] cis to each other. It is interesting to note that in going from parent complex 1, [14] to the dialkyl-Co III complex 4 the ligand has changed its coordination mode from trans to cis tetradentate. This observation reflects the coordination flexibility of L 1 , which is further realized in other two structures (see below).…”

“…The latter complex has bulky and hydrophobic BPh 4 -counterion which makes it and its product more soluble in a nonpolar medium. Due to expected higher solubilityof [(L [a] 113.2°115.0°112.8°2 [a] 110 [14] .…”

“…Notably, the ligand of pertinence to this work 2,2Ј- [propane-1,3-diylbis(1H-pyrazole-1,3-diyl)]dipyridine (L 1 ) contains both soft (pyridine) and hard (pyrazole) donor sites. As a part of our activity in exploring metal-binding properties of pyridylpyrazole ligands [10][11][12][13] we have recently reported [14] the coordination chemistry of the tetradentate ligand L 1 , [15] towards mononuclear Co II and Ni II . Moreover, we have addressed the issue of stereoelectronic preference of Ni II and Cu II ions [16] to assume five-/six-coordinate geometry in their binuclear complexes and stabilized the mixed-valence Ni III ) [12d] as terminal and 3-(2-pyridyl)pyrazolate ion (pypz anion) [17,18] (Figure 1).…”

Bis‐μ‐pyrazolate‐Bridged Dinickel(II) and Dicopper(II) Complexes: An Example of Stereoelectronic Preference of Metal Ions and Stabilization of Mixed‐Valence NiIIINiII Species

“…[1] As part of our continued involvement in the exploration of interesting coordination chemistry of pyridyl/pyrazole-based chelating ligands, [2] we have investigated the magneto-structural properties of a large variety of dinuclear/trinuclear/polymeric complexes with a varied combinations of endogenous/exogenous and solely exogenous bridging ligands (alkoxo/pyrazolato, [3] acetato/pyrazolato, [4] carbonato, [5] diacetato, [4,6] dichloro, [7] dihydroxo, [4,8] monohydroxo, [9] oxo/bis-acetato, [10,11] phenoxo/chloro, [12] phenoxo/hydroxo, [8,13] diphenoxo [14] ).…”