Synthesis and Characterization of Polynuclear Chain and Tetranuclear Complexes of Mixed-Valent Ruthenium(II,III) Pivalate with N,N'-Didentate Ligands

摘要

Polymeric chain complexes,[Ru_2(piv)_4(pyz)]_n(BF_4)_n centre dot 3nH_2O (1),[Ru_2(piv)_4(4,4'-bpy)]_n(BF_4)_n centre dot nH_2O (2),[Ru_2(piv)_4(dabco)]_n(BF_4)_ncentre dot2nH_2O (3),[Ru_2(piv)_4(phz)]_n(BF_4)_n (4),and [Ru2(piv)_4(H_2O)_2(tmpyz)]_n(BF_4)_ncentre dotnCH_2Cl_2 (6),(Hpiv = pivalic acid,pyz = pyrazine,4,4'-bpy = 4,4'-bipyridine,dabco = l,4-diazabicyclo[2.2.2]octane,phz = phenazine,and tmpyz = tetramethylpyrazine),were synthesized and characterized by elementary analyses,infrared and electronic spectroscopies,and variable-temperature magnetic susceptibilities (4.5-300 K).A tetranuclear complex,[{Ru_2(piv)_4(H_2O)}_2(phz)](BF_4)_2 (5),was also synthesized,and a "dimer of dimers" structure was confirmed by an X-ray structure analysis.The crystal structure of 6 shows that [Ru_2(piv)_4(H_2O)_2]~+ units are linked by hydrogen bonds with tmpyz molecules,giving zigzag chains with Rul-O5...Nl angle of 108.1(2)~o.A red-shift of the delta~*/pi~*(Ru_2) -> sigma~*(Ru-O),and delta(Ru_2) -> delta~*(Ru_2) transition bands of the Ru~(II,III)_2 core was observed in polymeric chain adducts 1-4.All of the present complexes show a very weak antiferromagnetic interaction between the dinuclear units with a considerable zero-field splitting parameter.