title: Paramagnetic precursors for supramolecular assemblies: selective syntheses, crystal structures, and electrochemical and magnetic properties of Ru2(O2CMe)4-n(formamidinate)nCl complexes, n = 1-4.
abstract: Reactions of Ru(2)(O(2)CMe)(4)Cl with two formamidines, HDXyl(2,6)F = N,N'-di(2,6-xylyl)formamidine and HDAniF = N,N'-di(p-anisyl)formamidine, have been investigated with the idea of synthesizing compounds with a mixed set of ligands having different labilities to be used as precursors of paramagnetic, higher-order assemblies. Depending on the formamidine and the reaction conditions, several Ru(2)(5+) compounds of the type Ru(2)(O(2)CMe)(4)(-)(n)(DArF)(n)Cl (DArF = anion of an N,N'-diarylformamidine) have been isolated. With the bulky formamidine HXyl(2,6)F, the compounds Ru(2)(O(2)CMe)(3)(DXyl(2,6)F)Cl (1) and trans-Ru(2)(O(2)CMe)(2)(DXyl(2,6)F)(2)Cl (2) were obtained. From reactions with appropriate amounts of HDAniF in THF and in the presence of NEt(3) and LiCl, complexes of the general type Ru(2)(O(2)CMe)(4)(-)(n)(DArF)(n)Cl (n = 1-4) were selectively obtained. For n = 2, only the cis isomer was obtained. The choice of solvent in reactions of Ru(2)(O(2)CMe)(4)Cl and HDAniF is of great importance. Toluene favored the formation of the fully substituted Ru(2)(5+) complex Ru(2)(DAniF)(4)Cl (3), whereas MeOH resulted in a disproportionation reaction that gave the edge-sharing bioctahedral Ru(3+)Ru(3+) complex [trans-Ru(2)(mu-OMe)(2)(mu-O(2)CMe)(2)(HDAniF)(4)]Cl(2) (6) and the Ru(2)(4+) complex Ru(2)(DAniF)(4) (7). Complexes 6 and 7 with an Ru(2)(6+) and Ru(2)(4+) core, respectively, are diamagnetic, whereas all Ru(2)(5+) complexes are paramagnetic with sigma(2)pi(4)delta(2)(pi*delta*)(3) ground-state electronic configurations and large zero-field splitting contributions. All compounds show rich and complex electrochemical behavior.
authors.affiliation: Department of Chemistry and Laboratory for Molecular Structure and Bonding, P.O. Box 30012, Texas A&M University, College Station, Texas 77842-3012, USA.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Angaridis
authors.forename: F Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Murillo
authors.forename: Dino
authors.initials: D
authors.lastname: Villagrán
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wang