Preparative, carbon-13 and phosphorus-31 nuclear magnetic resonance studies on dicarbonyl complexes of ruthenium(II) and ruthenium(I) containing tertiary mono-t-butyl- or di-t-butyl-phosphines
Abstract
Some new complexes of the types cis-[RuCl2(CO)2(PR2But)2](trans-phosphines but COs and Cls cis)(R = Me, Et, Prn, Bun, Ph, or p-tolyl), cis-[RuCl2(CO)2(PRBut2)2](R = Me or Prn), and trans-[RuCl2(CO)2(PR2But)2](R = Et, Prn, or Bun) are described. 31P N.m.r. data for these and other dicarbonylruthenium–tertiary phosphine complexes are given. There is a linear correlation between the chemical shift of the free phosphine, δfree, and the co-ordination shift, Δ, on complexation for the complexes trans-[RuCl2(CO)2L2]. This linear relationship does not apply to the complexes cis-[RuCl2(CO)2L2], possibly because of conformational effects. The 13C n.m.r. spectra have been recorded for a number of the complexes cis-[RuCl2(CO)2L2] and a linear relationship between the 13C chemical shift of the carbonyl and the force constant for the C–O stretching vibration is reported. Treatment of cis-[RuCl2(CO)2(PPrn2But)2] with KOH in 2-methoxyethanol gives [RuHCl(CO)2(PPrn2But)2]. The benzenediazonium cation is shown to insert into the ruthenium–hydrogen bond of [RuHCl(CO)2(PPrn2But)2] to produce the phenyldi-imide complex [RuCl(NHNPh)(CO)2(PPrn2But)2]BF4. Binuclear ruthenium(I) complexes [RuX(CO)2L]2[X = Cl, Br, I, or OAc; L = Pbut2Ph or PBut2(p-tolyl)] with a ruthenium–ruthenium bond and a bent bridging system are also described. For X = Cl, phosphorus–phosphorus nuclear spin–spin coupling of ca. 80 Hz is transmitted through the ruthenium–ruthenium bond. The bridging system in [RuCl(CO)2L]2 is cleaved by Cl2 to give [Ru2Cl4(CO)4L2], which undergo bridge-splitting reactions to give mononuclear complexes [RuCl2(CO)2QL](Q = pyridine or PMe2Ph) or easy reduction back to [RuCl(CO)2L]2. I.r., 1H, and 31P n.m.r. data are given and discussed.