Synthesis and magnetic properties comparison of M-Cu(II) and M-VO(II) Schiff base-porphyrazine complexes: what is the mechanism for spin-coupling? Academic Article uri icon

abstract

  • Dimetallic Schiff base-porphyrazine (pz) compounds, denoted 1[M(1); M(2); R], have been prepared, where metal ion M(1) is incorporated into the pz core, and metal ion M(2) is bound to a bis(5-tert-butylsalicylidenimine) chelate built onto two amino nitrogens attached to the pz periphery; R is a solubilizing group (either propyl (Pr) or 3,4,5-trimethoxyphenyl (TMP)) attached to the remaining carbons of the pz periphery. The synthesis of 1[Cu; Cu; R], 1[Cu; VO; R], 1[ClMn; Cu; Pr], and 1[ClMn; VO; Pr] is discussed, the crystal structures of 1[Cu; Cu; TMP] and 1[ClMn; VO; Pr] are presented, and the magnetic properties of these compounds are compared. The pattern of ligand-mediated exchange coupling in these complexes is startling: for the Cu-M(2) complexes 1[Cu; VO; R] and 1[Cu; Cu; R], 2 x 10(2) < or = |J(Cu-VO)/J(Cu-Cu)|; for the ClMn-M(2) complexes 1[ClMn; Cu; Pr] and 1[ClMn; VO; Pr], J(ClMn-VO)/J(ClMn-Cu) approximately 1/3, an inverse ratio from that of the Cu-M(2) complexes, but with lesser discrimination. This coupling pattern is explained in terms of a novel orientation relative to the M(1)-M(2) direction: the "square-planar" Schiff base ligand set of M(2) is rotated in-plane by 45 degrees relative to the effectively coplanar pz ligand set of M(1).

published proceedings

  • J Am Chem Soc

author list (cited authors)

  • Zhao, M., Zhong, C., Stern, C., Barrett, A., & Hoffman, B. M

citation count

  • 50

complete list of authors

  • Zhao, Min||Zhong, Chang||Stern, Charlotte||Barrett, Anthony GM||Hoffman, Brian M

publication date

  • July 2005