Structural and electrochemical studies on trithia macrocyclic complexes of palladium

Geometrical Characteristics and Reactivities of Tetracoordinated Pd Complexes: Mono- and Bidentate Ligands and Charged and Uncharged Ligands

“…[1][2][3][4][5][6][7][8][9][10][11][12] In particular, the reactivities have been investigated by focusing on the geometrical structures (PdL 4 , PdL 5 , PdL 6 ) and the ligand exchange reactions in the solvation system via a ligand-solvent interaction and/or metal-solvent/ligand interaction (e.g., Pd-DNA bases interactions). [1][2][3] In the tetracoordinated Pd(II) complexes, the ground electronic configuration of the central Pd(II) metal is 4d 8 with a partially occupied d-shell as a 3 F state. Since the unoccupied d x 2 -y 2 orbital of the Pd center interacts with the lone pair orbitals of four surrounding ligands, the structural characteristic of Pd(II) complexes has the tendency to form square planar geometry.…”

“…3,4 The binding between the transition metal and macrocyclic ligands containing electronegative atoms are formed with the coordination of the N-and O-atoms (hard σ-donor properties) and the P-and S-atoms (soft σ-donor and π-acceptor properties) on the ligand. [1][2][3][4] The geometrical structures of the macrocyclic Pd complexes are distorted from the π-acceptor property using empty d-orbitals on the P-and Satom. Generally, the Pd(II) complexes have a square-planar Pd(II) center bound to the electronegative atom on ligands.…”

“…4 The distances of the apical (Pd…L) interaction are longer than the values of a Pd-S (Pd-N, Pd-O) bond observed normally. 1,2 That is, the distance (2.92 Å) of the axial (Pd…S) interaction is in excess of the normal bonding range of R (Pd-S) = (2.30~2.50 Å). Meanwhile, the Pd-S distances of the two equatorial thia donors are shorter than those of Pd(II) complexes coordinated with four equatorial thia donors.…”

“…Meanwhile, the Pd-S distances of the two equatorial thia donors are shorter than those of Pd(II) complexes coordinated with four equatorial thia donors. 1,2 Regarding the decrease of the Pd-S distances, it has been known that π-orbital back donation occurs from the Pd(II) ion to the S atom. The characteristics of the microcyclic-metal complexes are electronically controlled by the metal-donor atom interactions rather than by any conformational and configurational constraints of the macrocyclic ligands.…”

Geometrical Characteristics and Atomic Charge Variations of Pd(II) Complexes [Pd(L)Cl2] with an Axial (Pd·O) Interaction

“…The bindings between the transition metals and macrocyclic ligands are formed by the coordination of the N-and O-atoms (hard σ-donor property) and the Satom (soft σ-donor and π-acceptor properties) on the ligand. In the experimental results of Schröder's group, [1][2][3][4][5][6][7] the crystal structures of the Pd(II) complexes have a square-planar Pd(II) center bound to the N-, O-, and S-atom donors. In endo-Pd(II) complexes, an apically long-range (PdÎL) interaction of (R PdÎL ) = 2.952~3.033 Å between Pd(II) and the apical L-atom is formed.…”