Synthesis and Structures of an Organometallic Carboxyphosphine, <i>r</i><i>ac</i>-{2-(Diphenylphosphino)ferrocenyl}acetic Acid, Related Compounds, and Palladium(II) Complexes with <i>r</i><i>ac</i>-{2-(Diphenylphosphino)ferrocenyl}acetato or Methyl <i>rac</i>-{2-(Diphenylphosphino)ferrocenyl}acetate and Ortho-Palladated <i>C</i>,<i>N</i>-Chelate Ligands

An organometallic carboxyphosphine, rac-[2-(diphenylphosphino)ferrocenyl]acetic acid (rac-Hpfa*), was synthesized from rac-N,N-dimethyl[2-(diphenylphosphino)ferrocenyl]methylamine by successive alkylation to rac-benzyldimethyl{2-[(diphenylphosphino)ferrocenyl]methyl}ammonium bromide (2*), a replacement of the ammonium group with CN-, and, finally, hydrolysis of the obtained rac-[2-(diphenylphosphino)ferrocenyl]acetonitrile (3*). The acid was further converted to the respective methyl ester 4, phosphine oxide 5*, and phosphine sulfide 6*. The metathesis of the in situ generated salt rac-Kpfa with di-μ-chloro-bis{2-[(dimethylamino)methyl-κN]phenyl-κC1}dipalladium(II) (7) afforded a heterobimetallic complex with the chelating carboxylate pfa--κ2O,P and the cyclometalated C,N-ligand, [SP-4-3]-{2-[(dimethylamino-κN)methyl]phenyl-κC1}{rac-[2-(diphenylphosphino-κP)ferrocenyl]acetato-κO1}palladium(II) (8*), while the cleavage of the chloro bridges in 7 with 4 gave a complex with a P-bonded phosphino ester, [SP-4-4]-chloro{2-[(dimethylamino-κN)methyl]phenyl-κC1}{rac-methyl [2-(diphenylphosphino)ferrocenyl]acetate-κP}palladium(II) (9*). Compound 9 was further converted by reacting with AgClO4 to the cationic bis(chelate) complex [SP-4-3]-{2-[(dimethylamino-κN)methyl]phenyl-κC1}{rac-methyl [2-(diphenylphosphino-κP)ferrocenyl]acetate-κO2}palladium(II) perchlorate (10*). Complex 10 was alternatively obtained by a replacement of acetonitrile ligands in bis(acetonitrile){2-[(dimethylamino)methyl]phenyl-κ2C1,N}palladium(II) perchlorate (11) with 4. (The asterisk indicates that the solid-state structure has been determined by X-ray crystallography.)