86421-45-6Relevant articles and documents
Ruthenium(II) complexes of 1-substituted 3,4-dimethylphospholes
Wilkes, Linda M.,Nelson, John H.,McCusker, Lynne B.,Seff, Karl,Mathey, Francois
, p. 2476 - 2485 (2008/10/08)
Several ruthenium(II) complexes of 1-substituted 3,4-dimethylphospholes, (RDMP, R = CH3, n-C4H9, t-C4H9, C6H5, and C6H5CH2) have been prepared and characterized by elemental analyses and infrared and 1H, 13C{1H}, and 31P{1H} NMR spectroscopy. Stable carbonyl complexes of the types cis- and trans-Ru(CO)2(RDMP)2Cl2 and one example of (RDMP)3Ru(CO)Cl2 (R = C6H5) were prepared. In each case, the kinetically formed trans-(RDMP)2Ru(CO)2Cl2 thermally isomerizes smoothly to the thermodynamically stable cis-(RDMP)2Ru(CO)2Cl2. These phospholes are shown to be better donors than PPh3 toward ruthenium(II) as they readily displace PPh3 from (PPh3)4RuCl2 in refluxing hexane to produce cis- and trans-(RDMP)4RuCl2 (R = CH3, n-C4H9, C6H5, and C6H5CH2) in moderate yield. With the sterically more bulky 1-t-C4H9DMP, the pentacoordinate (t-BuDMP)2(PPh3)RuCl2 is obtained under these same conditions. The kinetically 1 formed trans-(RDMP)4RuCl2 complexes only slowly dissociate in solution and undergo both thermal and photochemical isomerization to the thermodynamically stable cis-(RDMP)4RuCl2 with some attendant decomposition. The pentacoordinate (t-BuDMP)2(PPh3)RuCl2 is much more dissociately stable than (PPh3)3RuCl2 and displays phosphorus-phosphorus coupling at room temperature whereas, for (PPh3)3RuCl2, this coupling is not observable above -90°C in CH2Cl2 solutions. The crystal structure of (PhDMP)3Ru(CO)Cl2 has been determined by three-dimensional X-ray diffraction techniques. The molecule crystallizes in the triclinic space group P1 in a unit cell of dimensions a = 13.789 (2) A?, b = 14.752 (3) A?, c - 9.915 (2) A?, α = 98.37 (1)°, β = 111.80 (1)°, γ = 95.08 (1)°, ρcalcd = 1.39 g cm-3, and ρobsd = 1.40 (5) g cm-3 with Z = 2. Refinement converged to R = 0.039 with 4235 independent reflections. Within this molecule, there exist interesting charge-transfer type interactions which seemingly stabilize one particular isomeric configuration. Some of these complexes have been shown to catalyze the hydrogenation of 1-heptene at ambient temperature and pressure at rates comparable to this same catalysis by (Ph3P)3RuCl2.
