The chemistry of tetraphenylcyclopentadienone complexes of ruthenium and rhodium: the X-ray crystal structure of [Ru{η5-C5Ph4OC(O)CH(OMe)Ph}(CO)2Cl]

Abstract

[Ru(η⁴-C₅Ph₄O)(CO)₃](1) and [{Rh(η⁴-C₅Ph₄O)Cl}₂](2) react with L-(–)-α-methylbenzylamine to give the tetraphenylcyclopentadienone complexes [Ru(η⁴-C₅Ph₄O)(CO)₂{NH₂CH(Me)Ph}] and [Rh(η⁴-C₅Ph₄O)Cl{NH₂CH(Me)Ph}] respectively; trimethylamine N-oxide also reacts with complex (1) to give the amine adduct [Ru(η⁴-C₅Ph₄O)(CO)₂(NMe₃)](5). Complexes (2) and (5) oxidatively add HX to give the corresponding hydroxytetraphenylcyclopentadienyl complexes [{M(η⁵-C₅Ph₄OH)(L)X}_n][M = Ru, L =(CO)₂, X = Cl, OC(O)CF₃, or OC(O)Me, n= 1; M = Rh, X = L = Cl, n= 2]; all these compounds readily reductively eliminate HX, the ease of this reaction increasing in the order of X and M listed. Methyl iodide also oxidatively adds to (5) to give the stable complex [Ru(η⁵-C₅Ph₄OMe)(CO)₂I]. The acyl chlorides RC(O)Cl similarly oxidatively add to complexes (1) and (2) to give the corresponding ester complexes [M{η⁵-C₅Ph₄OC(O)R}(L)Cl}_n][M = Ru, L =(CO)₂, n= 1, R = Me; M = Rh, L = Cl, n= 2, R = Me or (–)CH(OMe)Ph]; the complex [Ru(η⁵-C₅Ph₄OH)(CO)₂Cl] also reacts with RC(O)Cl to give [Ru{η⁵-C₅Ph₄OC(O)R}(CO)₂Cl][R = Me or (–)CH(OMe)Ph (14)]. The X-ray structure of (14) is reported; the crystals are orthorhombic, space group p2₁2₁2₁(no. 19) with a= 24.58(3), b= 14.518(13), c= 9.299(4)Å, and Z= 4. The structure was solved via the heavy-atom method and refined to R= 0.0541 using 1 425 independent reflections. Carbonylation of [{Rh(η⁵-C₅Ph₄OC(O)R*)Cl₂}₂] in the presence of zinc gives [Rh{η⁵-C₅Ph₄OC(O)R*}(CO)₂] and complex (14) undergoes carbonyl substitution with triphenylphosphine to give the two diastereoisomers of [Ru{η⁵-C₅Ph₄OC(O)R*}(CO)(PPh₃)Cl][R*=(–)CH(OMe)Ph]. The use of [Rh{η⁵-C₅Ph₄OC(O)R*}(CO)₂] and [{Rh(η⁵-C₅Ph₄OC(O)R*}Cl₂}₂][R*=(–)CH(OMe)Ph] as asymmetric hydroformylation and hydrogenation catalysts respectively is briefly discussed. I.r., ¹H, ¹³C, and ³¹P n.m.r. spectroscopic data are presented.