Weakening the Interchain Interactions in One Dimensional Cobalt(II) Coordination Polymers by Preventing Intermolecular Hydrogen Bonding.

The reaction of Co(NCS) 2 with N -methylaniline leads to the formation of [Co(NCS) 2 ( N -methylaniline) 2 ] n ( 1 ), in which the cobalt(II) cations are octahedrally coordinated and linked into linear chains by pairs of thiocyanate anions. In contrast to [Co(NCS) 2 (aniline) 2 ] n ( 2 ) reported recently, in which the Co(NCS) 2 chains are linked by strong interchain N-H···S hydrogen bonding, such interactions are absent in 1 . Computational studies reveal that the cobalt(II) ions in compound 1 show an easy-axis anisotropy that is lower than in 2 , but with the direction of the easy axis being similar in both compounds. The high magnetic anisotropy is also confirmed by magnetic and FD-FT THz-EPR spectroscopy, which yield a consistent g z value. These investigations prove that the intrachain interactions in 1 are slightly higher than in 2 . Magnetic measurements reveal that the critical temperature for magnetic ordering in 1 is significantly lower than in 2 , which indicates that the elimination of the hydrogen bonds leads to a weakening of the interchain interactions. This is finally proven by FD-FT THz-EPR experiments, which show that the interchain interaction energy in the N -methylaniline compound 1 is nine-fold smaller than in the aniline compound 2 .