Exchange Coupling of Transition-Metal Ions through Hydrogen Bonding:  A Theoretical Investigation

Abstract

Density functional calculations for full structures of dimers of Cu(II) complexes linked via O-H...O hydrogen bonds provide exchange-coupling constants that are in excellent agreement with experimentally reported values. Magneto-structural correlations between the exchange-coupling constant and the O...O distance or the separation between the coordination planes of the two monomers are analyzed. The calculations support the orbital models usually employed in qualitative interpretations of magneto-structural correlations, showing excellent correlations between the calculated coupling constants and the square of the orbital gap or of the overlap between the two magnetic orbitals. The orbital gap responsible for the antiferromagnetic coupling is seen to result from direct through-space overlap between the oxygen atoms of the two monomers, whereas the hydrogen bonds play an essentially structural role by holding these oxygen atoms in close proximity.

Strong Magnetic Interactions through Weak Bonding Interactions in Organometallic Radicals: Combined Experimental and Theoretical Study

“…The large spin polarization of the doubly occupied orbitals gives considerably different a and b orbitals, resulting in a total spin density with small contributions on the carbon atoms. Hence, the two empty b orbitals corresponding to the SOMOs (called UMSOs; [52] see Figure 6b) provide a better picture of the spin density distribution than the equivalent a occupied orbitals. This effect is not always as dramatic as shown for the [ www.chemeurj.org the differences between a and b orbitals are smaller (see Figure S1, Supporting Information).…”

Evidence for Hydrogen‐Bond‐Mediated Exchange Coupling in an Aqua‐Bridged CuII Dimer: Synthesis, Magnetic Study and Correlation with Density Functional Calculations

“…All hydrogen atoms were positioned geometrically and allowed to ride on their parent atoms with isotropic displacement parameters fixed at 1.2-times U eq of their parent atoms. C 24 (4); [29] largest difference peak/hole: 0.844/-1.478 e Å -3 . CCDC-279057 (1) contains the supplementary crystallographic data for this paper.…”

“…[22] Different intermediate values have also been reported, [23] as well as density functional calculations on these dimers. [24] For compound 1, the relatively weak exchange interaction is essentially due to the fact that the two basal planes of the copper geometry are not coplanar. This reduces the overlap of the magnetic orbitals, which causes decreased interactions between the two coppers centres.…”

A New Basic Motif in Cyanometallate Coordination Polymers: Structure and Magnetic Behavior of M(μ‐OH2)2[Au(CN)2]2(M=Cu, Ni)

“…[46] Water molecules are known to mediate both ferro-and antiferromagnetic interactions through hydrogen bonding between different spin carriers, including copper(II), [47] nitronylnitroxide radicals, [48] chromiumA C H T U N G T R E N N U N G (III), [49] and mixed nickel(II)-radical systems. [50] The [Au(CN) 2 ] À unit has been observed to medi- www.chemeurj.org ate magnetic interactions between several first-row transition metals at low temperature.…”