Reactivity of diphenylphosphino enolato ligands in ruthenium(II) complexes and related processes involving easy cleavage of a phosphorus-carbon bond in functionalized phosphine ligands

The migration of a phenyl group from phosphorus to the coordinated ruthenium center in complexes (eta(6)-arene)[eta(2)-Ph(2)PC(R)=C(R')O]RuCl, 2 [arene = 1,3,5-Me(3)C(6)H(3) or C(6)Me(6); R = H or Me; R' = Bu(t)], occurs in methanol at reflux. The reaction is favored by the addition of KOAc and affords selectively the stable phosphinito enolato derivatives (eta(6)-arene)[eta(2)-Ph(MeO)PC(R)=C(R')O]RuPh. In contrast, the reaction of complexes 2 with methanol and K2CO3 preserves the functional ligand and affords selectively the hydride derivatives (eta(6)-arene)[eta(2)-Ph(2)PC(R)=C(R')O]RuH, The cleavage of the ruthenium-chlorine bond in complexes 2 is also the preliminary step involved in the coupling process of functional phosphino enolato ligands with 1-alkynes HC=CR ''. The reaction results in the formation of complexes {(eta(6)-arene)Ru[eta(3)-CH=C(R '')C(R)(PPh(2))C(R')=O]}(PF6) R' = H or Me, R' = Bu(t) or Ph, R '' = H, Me, Ph, p-MeC(6)H(4), or SiMe(3)], the isomerization of which into complexes {(eta(6)-arene)Ru[eta(3)-CH(PPh(2))C(R '')=C(R)C(R')=O]}(PF6), [R' = Bu(t), R '' = H, Me, Ph, or p-MeC(6)H(4), occurs only when R = H, The isomerization consists of an intramolecular [1,3]-migration of a phosphorus-carbon bond and is catalyzed by the fluoride anion. When R '' = H, a subsequent cleavage of the ruthenium-carbon bond foreshadows the formation of (eta(6)-C(6)Me(6))[eta(1)-Ph(2)-PCH2CH=CHC(=O)Bu(t)]RuCl2, 11. Thus, starting from the precursor (eta(6)-C(6)Me(6))[eta(1)-Ph(2)-PCH2C(=O)Bu(t)]RuCl2, the process achieves formally an insertion of ethyne into the starting functionalized phosphorus-carbon bond. The scarcely isolable complexes {(eta(6)-arene)Ru[eta(3)-C(=CH2)C(R)(PPh(2))C(R')=O]Ru}(PF6) (R = H or Me, R' = But or Ph] reveal an easy cleavage of the functionalized phosphorus-carbon bond. This cleavage is the preliminary step involved in the formation of metallafuran complexes {(eta(6)-arene)(Ph(2)PX)Ru[eta(2)-C(CH3)=CRC(R')=O]}(PF6) [X = Cl or F, R = H or Me, R' = Bu(t) or Ph], which implies also the capture of a halide anion by phosphorus in a transient intermediate.