Weak Pd…︁S Interactions in Palladium(II) Complexes with 1,4,7‐Trithiacyclononane as Ligand

Abstract

The remarkable ring-current effect of the [26]porphyrin 7 is presumably due to the flattening effect of the four pyrrole rings; the two cationic centers support this effect somewhat but are not decisive."'] Thus, according to the 'H-NMR criterion, 7b contains a "superaromatic n-electron system." It demonstrates that the limits for aromatic behavior, so far expected to be reached with [26]annulenes, can be exceeded.Apart from the ring-current effect of the [26]porphyrin 7, its strong color intensity also deserves consideration. Thus, the molar extinction coefficient ( E ) of its most intense absorption band at 547nm (909600) is more than twice as large as that for the corresponding Soret band of porphyrins (maximally 400000). In the case of [26]porphyrin 7, the visual effect of the color is increased still further by the fact that its most intense band lies in the middle of the visible range. In contrast, the Soret band of the porphyrins at 400 nm, compared with the longer-wavelength satellite maxima that are smaller by an order of magnitude, contributes little to the depth of color.

Synthesis of mono- and trinuclear palladium(II) complexes via oxidative addition of a bulky hexathioether containing a disulfide bond to palladium(0)

“…On the other hand, the distances between the palladium and the two sulfur atoms at the axial positions (Pd1Á Á ÁS3 and Pd1Á Á ÁS3 * = 3.385(2) Å ) are slightly shorter than the sum of the van der Waals radii of palladium and sulfur atoms (3.43 Å ) [18], suggesting weak interactions between the palladium (Pd1) and the terminal sulfur atoms (S3 and S3 * ) in the crystalline state. Although some cationic species of 6-coordinate palladium(II) complex have been synthesized using crown thioether ligands [19], S-and N-donor macrocyclic ligands [20], and tris (2,4,6-trimethoxyphenyl)phosphine ligands [21], the neutral species are of great rarity [22].…”

Synthesis of an acyclic diselenodithioether ligand tethered with bulky substituents and its application to the synthesis of a distorted octahedral palladium(II) complex

“…2). There are only few reports on the X-ray structural analysis of neutral, 6-coordinate palladium(II) complexes [6,16,17], although some cationic, 6-coordinate complexes of palladium(II) have already been synthesized using crown thioether ligands [1][2][3][4][5], S-and N-donor macrocyclic ligands [18][19][20], and tris(2,4,6-trimethoxyphenyl)phosphine ligands [21].…”

“…Cyclic polythioether (crown thioether) ligands such as 1,4,7-trithiacyclononane (9S3) [1,2], 1,4,7,10,13,16-hexathiacyclooctadecane (18S6) [3], and 1,4,7-trithiacyclodecane (10S3) [4,5], reportedly complexed with a palladium(II) metal to give the corresponding five-or six-coordinate palladium(II) complexes, in which the four sulfur atoms are arranged in a square planar fashion around the palladium(II) atom and the other sulfur atoms weakly coordinate to the palladium(II) atom [Pd · · · S: 2.96-3.27Å] at the axial positions.…”

Gold(III) compounds of 1,4,7-triazacyclononane showing high cytotoxicity against A-549 and HCT-116 tumor cell lines

“…Investigations on metal-H interactions arose from its diversity of binding mode and catalytic function. Many transition metals, such as Pt, Pd, Co and Ni, have been reported to act as hydrogen bond acceptor [23][24][25][26][27][28][29][30][31], but as far as we know, no Au(III)-H short contact has ever been discussed before except for some relevant calculations on Au(0)-H or Au(I)-H [32].…”