ISOLATION OF A POSTULATED INTERMEDIATE IN THE STILLE REACTION - SYNTHESIS OF 2-ARYLAZOARYLPHOSPHONIUM SALTS VIA C-P COUPLING - SYNTHESIS OFACETONE COMPLEXES OF PALLADIUM(II) - CRYSTAL AND MOLECULAR-STRUCTURE OF [PD(C6H4N=NPH-2)(PPH(3))(ACETONE)], [PH(3)P(C6H3(N(2)C(6)H(4)ME-4')-2-ME-5)]CLO4 AND [PD(O,O-ACAC)(PPH(3))(2)]CLO4

PPh(3) and aqueous HClO4 react with an acetone solution of [Pd(C6H4N=N Ph-2) (O, O-acac)] (Hacac = acetylacetone; 1:2:7) 1a or [Pd{C6H3(N = N To)-2,Me-5'}(O,O-acac)] (To = C(6)H(4)Me-4; 1:1:7) 1b to give [Pd(C6H4 N = NPh-2)(PPh(3))(acetone)]ClO4 2a or [Pd{C6H3N = NTo)-2,Me-5'}(PPh(3 )) (acetone)]ClO4 2b, respectively. They also react with a dichloromet hane solution of 1b to afford a mixture of the phosphonium salt [Ph(3) P{C6H3(N(2)To)-2,Me-5}]ClO4 3b and the complex [Pd(O,O-acac)(PPh(3))(2 )]ClO4 4. Compounds 2a, 2b or 4 have also been prepared directly by re acting [Pd(R)(mu-Cl)](2) (R = C6H4N = NPh-2 or C6H3(N = NTo)-2,Me-5')] , PPh(3) and AgClO4 in acetone or [PdCl2(PPh(3))(2)] with NaClO4 . H2O and Tl(acac), respectively. The phosphonium salts [Ph(3)P{C6H4(N(2)Ph )-2}]ClO4 3a or 3b can be prepared by reacting complexes 2a or 2b, res pectively, with PPh(3). The structures of 2a, 3b and 4 have been deter mined by X-ray diffraction methods. Complex 2a crystallizes in the tri clinic space group <P(1)over bar> with Z = 2 in a unit cell of dimensi ons a = 9.588(6), b = 10.966(5), c = 15.464(8) Angstrom, alpha = 95.82 (1), beta = 99.54(1), gamma = 91.21 (1)degrees. Compound 3b crystalliz es in the monoclinic space group P2(1)/n with Z = 4 in a unit cell of dimensions a = 10.523(4), b = 28.102(11), c = 10.028(5) Angstrom, beta = 94.41(1)degrees. Compound 4 crystallizes in the monoclinic space gr oup P2(1) with Z = 4 in a unit cell of dimensions a = 9.763(5), b = 33 .465(9), c = 12.026(5) Angstrom, beta = 103.06(2)degrees. The structur es have been solved from diffractometer data by Patterson and Fourier mehods and refined by full-matrix least squares on the basis of 5539 ( 2a), 1873 (3b) and 6798 (4) observed reflections to R and R(w) values of 0.0584 and 0.0645 (2a), 0.0617 and 0.0642 (3b), 0.0410 and 0.0478 ( 4). In 2a the Pd atom is coordinated in a square planar fashion by the P atom from the PPh(3) ligand, by the O(1) atom from the acetone mole cule, and by the N and C atoms from the chelating C6H4N = NPh-2 ligand . The structure of the phosphonium salt 3b shows the C-P bond coupling of C6H4(N(2)To)-2,Me-5' with PPh(3). The Pd atom in 4 is in a square planar arrangement involving two P atoms from the PPh(3) ligands and t wo O atoms from the chelating acac ligand.