Pyrazolate-supported Cr(μ-O) cores; homovalent Cr and mixed-valent CrCr

• Published in: Chemical communications (Cambridge, England) England), 2024-11, Vol.6 (95), p.14117-1412
• Main Authors: López-Plá, Jessica M, Obies, Mohammed, Zahariou, Georgia, Pissas, Michael, Sanakis, Yiannis, McGrady, John E, Raptis, Raphael G
• Format: Article
• ISSN: 1359-7345; 1364-548X
• DOI: 10.1039/d4cc05161k

The thermally assisted reaction of Cr(NO 3 ) 3 ·9H 2 O, 4-Cl-pzH, and Et 3 N yielded electrochemically active trinuclear Cr III -oxo-pyrazolate complexes with formula (Ph 4 P) 2 [Cr 3 (μ 3 -O)(μ-4-Cl-pz) 6 X 3 ], X = Cl ( 1 ) and Br ( 2 ). Magnetic susceptibility measurements and EPR spectroscopy show that 1 has an antiferromagnetically coupled Cr 3 O-core with an S = 1/2 ground state and isotropic exchange of J = −12.7 cm −1 . ( H ex = −2 JS 1 S 2 ). Cyclic voltammetry reveals a facile reversible oxidation to the formally Cr III 2 Cr IV analogue of 1 . The UV-Vis-NIR spectra of Cr III 3 and Cr III 2 Cr IV species have been assigned with the help of DFT calculations. The thermally assisted reaction of Cr(NO 3 ) 3 ·9H 2 O, 4-Cl-pzH, and Et 3 N yielded electrochemically active trinuclear Cr III -oxo-pyrazolate complexes with formula (Ph 4 P) 2 [Cr 3 (μ 3 -O)(μ-4-Cl-pz) 6 X 3 ], X = Cl ( 1 ) and Br ( 2 ).