SYNTHESIS AND CHARACTERIZATION OF MONONUCLEAR PYRAZOLYL COMPLEXES OF PALLADIUM(II) AND PLATINUM(II) - CRYSTAL-STRUCTURES OF [NBU4][M(C6F5)2(PYRAZOLE)(PYRAZOLATO)] (M = PD, PT)

Pyrazolyl complexes of the types [MR2(HX)2] (M = Pd, R = C6F5, HX = pyrazole (Hpz) (1), 3,5-dimethylpyrazole (Hdmpz) (2); M = Pd, R = C6CI5, HX = Hpz (3), Hdmpz (4); M = Pt, R = C6F5, HX = Hpz (5), Hdmpz (6); M = Pt, R = C6Cl5, HX = Hdmpz (7)) and [NBu4][M(C6F5)2Cl(Hpz)] (M = Pd (8), Pt (9)) have been prepared by reaction of cis-[MR2(PhCN)2] and [NBu4]2[{M(C6F5)2(mu-Cl)}2], respectively, with HX (1:2 mole ratio). Deprotonation by NBu4OH of complexes 1, 3, and 5, and 6 leads to the formation of the pyrazole-pyrazolato complexes [NBU4] [MR2X(HX)] (M = Pd, X = pz, R = C6F5 (10), C6Cl5 (11); M = Pt, R = C6F5, X = pz (12), dmpz (13); M = Pt, R = CrC15, X = pz (14)). The IR and NMR data for complexes 10-14 show that both pyrazolyl ligands are identical, and the X-ray structure determinations of 10 and 12 have established the existence of a intramolecular hydrogen bond between the two pyrazolyl rings, the coordination at palladium and platinum being essentially square planar. The structures are isomorphous, and both compounds are tetragonal, space group P4(3)2(1)2. Crystal data for 10: a = b = 17.022 (2) angstrom, c = 12.466 (3) angstrom, Z = 4, 2146 reflections, R = 0.045. Crystal data for 12: a = b = 17.088 (2) angstrom, c = 12.466 (4) angstrom, Z = 4, 2540 reflections, R = 0.029.