SYNTHESIS, CHARACTERIZATION, AND CRYSTAL-STRUCTURES OF MONOMERIC AND DIMERIC PALLADIUM(II) AMIDE COMPLEXES

Addition of KN(R)Ph to trans-(PMe3)2Pd(R')I (R = H, Me; R' = Ph, Me) results in the formation of the monomeric anilide complexes trans-(PMe3)2Pd(R')N(R)Ph in good yield. A single-crystal X-ray diffraction study of trans-(PMe3)2Pd(Ph)N(H)Ph (1) reveals that it crystallizes in the space group P1BAR with a = 8.423(3) angstrom, b = 10.768(4) angstrom, c = 12.565 angstrom, alpha = 68.81(3)-degrees, beta = 71.90(3)-degrees, gamma = 87.65(3)-degrees, V = 1006.7(7) angstrom 3, and Z = 2. There is no evidence for significant interaction between the N lone pair and the metal center, though a shortened N-C distance (1.32(2) angstrom) may indicate interaction between the N lone pair and the phenyl ring. Thermolysis of 1 at 90-degrees-C in the solid state results in loss of PMe3 and formation of the dimeric complex [(PMe3)Pd(Ph)(mu-NHPh)]2 (9), which was also characterized with a single-crystal X-ray structure study. Compound 9 crystallizes in the space group P1BAR with a = 6.805(1) angstrom, b = 12.186(2) angstrom, c = 18.943(3) angstrom, alpha = 89.56(1)-degrees, beta = 85.17(1)-degrees gamma = 85.17(1)-degrees, gamma = 87.67(1)-degrees, V = 1564.0(4) angstrom 3, and Z = 2. The PMe3 groups are anti with respect to the Pd-Pd vector, while the phenyl groups of the anilides are anti with respect to the Pd2N2P2C2 coordination plane. In solution at 25-degrees-C, 9 undergoes an isomerization equilibrium to form two new isomers. Spectroscopic data suggest that these two new isomers are consistent with syn PMe3 groups and syn anilide groups. Prolonged heating (110-degrees-C, 12 h) of 9 results in reductive elimination of diphenylamine.