Pyrazine-mediated antiferromagnetic intermolecular exchange in mixed-valent diruthenium tetracarboxylates

F. D. CUKIERNIK; A. M.GIROUD-GODQUIN; P. MALDIVI; J. C. MARCHON

INORGANICA CHIMICA ACTA

Elsevier

Año: 1994 vol. 215 p. 203 - 207

0020-1693

Two mixed-valent diruthenium tetracarboxylates [Rue2-(AcO)4(H2O)2]BPh4 (1) [Ru2(AcO)4(pz)]BPh4 (2) AcO = acetate, BPh4 = tetraphenylborate PZ = pyrazine), were synthesized and characterized by elemental analysis, IR and UV---Vis spectroscopies, magnetic susceptibility measurements between 6 320 K. The magnetic behaviour of 1 can be understood in terms of non-interacting spin 3/2 dimers undergoing a large (c. 72 cm−1) zero-field splitting, whereas an intermolecular antiferromagnetic interaction (c. −2 cm−1) in addition to a large zero-field splitting (c. 63 cm−1), is required to account for the data for 2.