Magnetic properties of diruthenium(II,III) carboxylate compounds. Crystal structures of Ru2Cl(mu-O2CCH=CHCH=CHMe)(4) and Ru2Cl(mu-O2CCH2OMe)(4)

The reaction of Ru2Cl(mu-O2CMe)(4) with 2,4-hexadienoic and 2-methoxyacetic acids affords the compounds Ru2Cl(mu-O2CR)(4) [R=CH=CHCH=CHCH3 (1), CH2OMe (2)]. The structures of both complexes have been determined by X-ray cryst allography. 1 crystallizes in the triclinic space group P-1 with a = 9.264( 1) Angstrom, b = 12.661(8) Angstrom, c = 12.839(5) Angstrom, alpha = 106.09 (3)degrees, beta = 77.89(2)degrees, gamma = 97.73(3)degrees, and Z = 2. 2 c rystallizes in the nonstandard monoclinic space group P2(1)/c with a = 12.1 32(4) Angstrom, b = 11.570(2) Angstrom, c = 13.674(2) Angstrom, beta = 91.1 8(2)degrees, and Z = 4. Complexes 1 and 2 show [Ru-2(mu-O2CR)(4)](+) units linked by chloride ions, giving zigzag chains with Ru-Cl-Ru angles of 119.4 3(4)degrees and 110.11(7) Angstrom respectively. The Ru-Ru bond distances a re 2.2857(9) Angstrom (1) and 2.290(1) Angstrom (2). A magnetic study, in t he 2-300 K temperature range, of the new compounds and the previously descr ibed Ru2Cl(mu-O2CR)(4) [R = CHMe2 (3), CMe3 (4), C4H4N (5)] is described. T he polymeric complexes 1 and 2 and the nonpolymeric 3-5 show a large zero-f ield splitting which varies from 53.9 to 68.1 cm(-1). These complexes also show a weak, but not negligible, through-space intermolecular antiferromagn etic coupling not observed in the previous magnetic studies carried out on these types of compounds.