KINETIC AND THERMODYNAMIC PRODUCTS IN THE REACTION OF [RUCL2(CO)2]N WITH PYRIDINECARBALDIMINE LIGANDS AND THE CRYSTAL-STRUCTURE OF TRANS-CL2RU(CO)2(N-(PYRID-2-YLMETHOXYMETHYL)(3-ISOPROPOXYPROPYL)AMINE)

The reaction of pyridinecarbaldehyde with the appropriate amines H2NR (R = CH2CH2OCH3, CH2CH2CH2OCH(CH3)2) yielded the new pyridinecarbaldimine ligands CH3OCH2CH2-Pyca (b) and iPrOCH2CH2CH2-Pyca (c), respectively. The reaction of n equiv of R-Pyca ligand (iPr-Pyca = a) with the polymer [RuCl2(CO)2]n led to the formation of monomeric ruthenium(II) complexes of composition Ru(CO)2Cl2(R-Pyca). The stereochemistry of these complexes could be controlled by altering the reaction conditions; i.e., in dichloromethane at ambient temperature the kinetic product trans-Cl2Ru(CO)2(R-Pyca) (1) is formed in 75-95% yield. Heating the kinetic product for 80 h in xylene or starting the reaction of the ligand with [RuCl2(CO)2]n in toluene at reflux temperature gave the thermodynamic cis-product (2) in high yields (90-95%). In the reaction of [RuI2(CO)2]n with the corresponding ligands only one isomer was formed: trans-12Ru(CO)2(R-Pyca) (3). If the reaction of c with the polymer was carried out in methanol at room temperature, trans-Cl2Ru(CO)2(N-(pyrid-2-ylmethoxymethyl)(3-isopropoxypropyl)amine) (4c) was obtained, in which a methanol molecule has added to the imine function of the ligand. The X-ray structure determination of the yellow crystals of 4c(Cl5H22N2O4CI2Ru) was carried out. Crystal data for 4c: monoclinic, space group P2(1)/c (No. 14) with a = 8.213(1) angstrom, b = 12.952(4) angstrom, c = 18.009(4) angstrom, beta =95.80(1)-degrees, V = 1905.8(8) angstrom3, and Z = 4. A special feature of the complex is the intramolecular N-H...O bridge, formed between the amine hydrogen and the ether oxygen of the ligand. The methanolysis is acid catalyzed. The reaction of a or b with [RuCl2(CO)2]n in methanol led to new, unidentified products, whose NMR and IR data showed that no methanolysis had taken place.