Geometry and Spin Change at the Heart of a Cobalt(II) Complex: A Special Case of Solvatomorphism

Abstract

Structural analysis and spectroscopic methods revealed a special case of solvatomorphism: hydrogen-bonding-induced geometry and spin change within a same N,O-(bis)chelate of cobalt(II). Solid-state structures are presented for both the tetrahedral and the solvated square-planar forms of the complex. Magnetic-moment measurements and ESR spectroscopy confirmed the high-spin state of the tetrahedral form (μeff =4.7 μB ) and the low-spin state of the square-planar solvatomorph. Specific hydrogen-bonding interactions between the solvent molecules and the complex chelate ring (O1⋅⋅⋅H-CHCl2 (d=2.26 Å, D=3.24 Å, θ=173°); O2⋅⋅⋅H-CHCl2 (d=2.22 Å, D=3.19 Å, θ=165°)) play a pivotal role in biasing the system toward the low-spin ground state.

Cobalt Catalysts for Alkene Hydrosilylation under Aerobic Conditions without Dry Solvents or Additives

“…The observed g value ( g = 2.09) is consistent with a low spin homoleptic complex [Co(tpy) 2 ] 2+ , but not with the heteroleptic complexes, 1b or 2b , which are expected to be S = 3/2 species. However, cobalt(II) species with S = 3/2 could be EPR silent . Then, quantitative EPR was employing in order to measure the formation of homoleptic species with both precursors.…”

Electro‐ and Photocatalytic Generation of H2 Using a Distinctive CoII “PN3P” Pincer Supported Complex with Water or Saturated Saline as a Hydrogen Source

“…[40] Importantly,amajority of these complexes requiret he presenceo fa cids as the sourceo fh ydrogen in order to electrocatalytically produce H 2 in polar organic solvents. [50][51][52][53] Single crystalso f1 were obtained from CH 2 Cl 2 and X-ray diffraction analysisr evealed two independentm olecules in the structure with distorted square-based pyramidal geometry at Co and with nearly identical bondingp arameters as shown in Scheme 1( Figure S1, Table S2, S3). [8,11,[41][42][43] Cobalt-basedelectrocatalysts that use watero rm ixed organic/water solutions as the hydrogen sourceoperate in the voltage range of À1.5 to À2.0 Vvs.…”

“…[50][51][52][53] Single crystalso f1 were obtained from CH 2 Cl 2 and X-ray diffraction analysisr evealed two independentm olecules in the structure with distorted square-based pyramidal geometry at Co and with nearly identical bondingp arameters as shown in Scheme 1( Figure S1, Table S2, S3). The targeted molecular formula was supported by microanalysis and ar oom temperature magneticm oment of 2.4 m B ,w hich indicatedap aramagnetic low spin Co II center.…”

Two Consecutive Magneto-Structural Gas-Solid Transformations with Single-Crystal Retention in Non-Porous Molecular Materials

“…Indeed, magnetic materials with structures unequivocally characterized by single-crystal diffraction after ac hemical reaction are tremendously valuable for understanding the mechanism of the transformation and the magnetostructural correlations,but are extremely scarce. [13,[19][20][21][22][23][24][25][26][27][28] Here we present fort he first time at wo-consecutive guest inclusion-release process occurring with retention of longrange order that is accompanied by modification in the magnetic behavior.T he first process involves ap olymeric-to-molecular materialt ransformation,w hereast he second process encompasses the reformation of ac oordinationp olymer,a se videnced by X-ray single-crystal diffraction.…”