Heteropolymetallic compounds containing 1,1′-bis(diphenylphosphino)ferrocene (DPPF) and pyrazolate ligands: synthesis, spectroscopic characterization and reactivity. Crystal and molecular structure of [(DPPF)Pt(az)2] [azH = pyrazole (pzH) or 3,5-dimethylpyrazole] and [(DPPF)Pt(µ-pz)2CdI2]

Abstract

From the interaction between [(DPPF)Pt(az)₂] [DPPF = 1,1′-bis(diphenylphosphino)ferrocene; azH = pyrazole (pzH), 3,5-dimethylpyrazole (3,5-Me₂pzH) or 4-methylpyrazole (4-MepzH)] and several MX₂ acceptors (M = Zn, X = Cl, Br, I or BF₄; M = Cd, X = Cl, Br, I or ClO₄, M = Hg, X = Cl, Br or I; M = Ba, X = I) 16 novel heteropolymetallic compounds were synthesized and characterized by IR, far-IR, ¹H and ³¹P, and in some cases also with ¹¹³Cd, NMR spectroscopy. Heterotrinuclear adducts [(DPPF)Pt(µ-az)₂MX₂] were obtained when X = halide, whereas ionic heteropentanuclear complexes [{(DPPF)Pt(µ₂-az)₂}₂M]²⁺[X]₂^2– were afforded when X is a weak nucleophile (ClO₄ or BF₄). Scrambling of the ligands occurred when the reaction between [(DPPF)Pt(az)₂] and Cu(II)X₂ salts (X = Cl or Br) was carried out in methanol, [(DPPF)PtX₂] being always obtained. X-Ray crystallography confirms the mononuclear structure of [(DPPF)Pt(az)₂] (azH = pyrazole or 3,5-methylpyrazole), in which the Pt atom is in a distorted cis square planar coordination with the two cyclopentadienyl rings in a staggered conformation. In the heterotrinuclear [(DPPF)Pt(µ-pz)₂CdI₂], the cadmium atom is strongly distorted tetrahedral, coordinated by two N-atoms of pyrazolate rings and two iodine atoms.