Synthesis of Two Isomeric Ferrocene Phosphanylcarboxylic Acids and their Pd-II Complexes with and without Auxiliary ortho-Metalated C, E-Ligands (E = N and S)
Abstract
Two homologous ferrocene phosphanylcarboxylic acids, viz., 1'-[(diphenylphosphanyl) methyl] ferrocene-1-carboxylic acid (HL1) and [1'-(diphenylphosphanyl) ferrocenyl] acetic acid (HL2), were synthesized and studied as ligands in Pd-II complexes. The addition of these hybrid donors to [PdCl2(MeCN)(2)] led to the bis-phosphane complexes trans-[PdCl2(HL1-kappa P)(2)] and trans-[PdCl2(HL2-kappa P)(2)].
In contrast, the reactions of HL1 and HL2 with the Pd-II acetylacetonate (acac) complexes [(L-YC)Pd(acac)], where L-YC = 2-[(dimethylamino-.N) methyl] phenyl-kappa C-1 (L-NC) and 2-[(methylthio-kappa S) methyl] phenyl-kappa C-1 (L-SC), proceeded under proton transfer and replacement of the acac ligand, giving rise to O, P-bridged phosphanylcarboxylate dimers [(LPd)-Pd-YC(mu(P,O)-L-1)](2) and molecular chelates [(LPd)-Pd-YC(L-2-kappa O-2,P)](2), respectively. The analogous reactions involving 1'-(diphenylphosphanyl)-1-ferrocenecarboxylic acid (Hdpf) provided the macrocyclic tetramer [(LPd)-Pd-NC(mu(P,O)-dpf)](4) and the dimer [(LPd)-Pd-SC(mu(P,O)-dpf)](2).
The reactions of HL1 with [Pd(acac)2] only led to an ill-defined, insoluble material, whereas those with HL2 produced a separable mixture of the bis-chelate complexes trans-[Pd(L-2-kappa O-2,P)(2)], cis[Pd(L-2-kappa O-2,P)(2)], and [Pd(acac)(L-2-kappa O-2,P)].