Axial ligand substitution and photoisomerization reactions in ruthenium(II) trans mixed-chelate complexes containing the ligands 1,2-phenylenebis(dimethylarsine) and 2,2 '-bipyridine or 1,10-phenanthroline

摘要

The nitrosyl complex in trans-[RuCl(pdma) (bpy) (NO)][PF6](2) (pdma= 1,2-phenylenebis(dimethylarsine), bpy=2,2'-bipyridine) reacts at room temperature with stoichiometric NaN2, followed by an excess of a neutral ligand L-1 in 2-butanone under reflux, to afford high yields of the mono-substituted derivatives trans-[RuCl(pdma) (bpy)L-1]PF6 (L-1 = pyridine (py) 1, triphenylphosphine (PPh3) 2, N-methylimidazole (mim) 3, acetonitrile (MeCN) 4, dimethylsulfoxide (dmso) 5 or pyrazine (pyz) 6). The related compound trans[RuCl(pdma) (phen) (NO)] [PF6](2) (phen = 1,10-phenanthroline) reacts similarly to yield trans-[RuCl(pdma) (phen)L-1]PF6 (L-1 = py 8, PPh3 9, mim 10 or pyz 11). The pyrazine complexes in 6 and 11 react with Mel at room temperature in acetone to afford trans-[RuCl( pdma) (L-L) (mpyz(+)) [PF6](2) (mpyz(+) = N-methylpyrazinium, L-L = bpy 7 or phen 12, respectively). 3 reacts with an excess of a neutral ligand L-2 in the presence of stoichiometric AgCF3CO2 in water/acetone under reflux to afford high yields of the di-substituted derivatives trans-RuCl(pdma) (bpy)mim(L-1)] [PF6](2) (L-2 = mim 13, py 14 or MeCN 15) and 2 reacts similarly with AgCF3CO2 in water/MeCN to give trans-[RuCl(pdma) (bpy)PPh3(MeCN)] [PF6](2) (16). The complexes in 1-16 exhibit intense d(pi)(Ru-II) -->pi*(L-L) and d pi(Ru-II) --> pi*(L-1/L-2) (L-1/L-2, = py, pyz or mpyz(+)) metal-to-ligand charge-transfer absorption bands in the near-UV-visible region and are mildly photosensitive in solution. Solar irradiation leads to isomerization; for example 3 is converted into cis-[RuCl(pdma) (bpy)mim]PF6 (17) over a period of ca. 100 h exposure to diffuse sunlight in acetone. Single crystal X-ray structures have been determined for 1, 2. DMF, 3, 12 . 3MeCN, 14 . DMF and 17. (C) 2000 Elsevier Science Ltd All rights reserved. [References: 28]