Chemistry: A European Journal 2015-06-22

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

Mihaela Cibian, Garry S Hanan

Index: Chemistry 21 , 9474-81, (2015)

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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.© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.