Formation and structure of penta- and hexa-coordinate cobalt (II)-methyl isocyanide complexes in Y-type zeolites

Abstract

The penta- and hexa-coordinate low-spin cobalt(II)–methyl isocyanide complexes were formed in a zeolite framework. A comparison of the e.p.r. data of the cobalt(II)–methyl isocyanide complexes in the zeolite and in other matrices suggests that the symmetries of the complexes were essentially C_4v and D_4h with the unpaired electron in a d_z² orbital and that the extent of the 4s participation decreases on changing from the five- to the six-fold coordination. The superhyperfine structure due to labelled CH₃N¹³C indicated that in the cobalt(II) complexes the unpaired electron must be mainly localized in the d_z² orbital of the Co²⁺ ions and the carbon atoms in the fifth and sixth coordination sites.