The cis-structure rule for planar four-coordinated sulfur-containing chelate compounds of transition metals

Quantum-chemical model for the formation of the coordination mode structure of Be(II), Ni(II), Pd(II), Pt(II), and Hg(II) bis(chelate) complexes with polydentate azomethine ligands

“…The complexes of transition d 8 metals (Ni 2+ , Pd 2+ , and Pt 2+ ) are characterized by the polyvariant configurations (cis and trans planar and pseudo tet rahedral) of the coordination mode MN 2 Y 2 (Y = O, S), depending primarily on the nature of the central metal atom, the choice of ligating donor atoms, and struc tural regularities of the ligands. The transition from the O containing (Y = O) to S containing (Y = S) complexes is accompanied by basic changes in the configuration of the coordination mode MN 2 Y 2 and related properties of the complexes [1][2][3][4][5][6]. Therefore, complexes based on bifunctional donor systems capa ble of accomplishing one of two variants of the coordi nation mode MN 2 O 2 (a) or MN 2 S 2 (b), depending on the metal atom, are of special interest.…”

“…Considerable attention is given to experimental studies of the molecular structures and spectral, mag netic, and other physical properties of chelate com plexes of transition and nontransition metals with Schiff bases (coordination modes MN 2 Y 2 (Y = O, S)) [1][2][3][4]. The complexes of transition d 8 metals (Ni 2+ , Pd 2+ , and Pt 2+ ) are characterized by the polyvariant configurations (cis and trans planar and pseudo tet rahedral) of the coordination mode MN 2 Y 2 (Y = O, S), depending primarily on the nature of the central metal atom, the choice of ligating donor atoms, and struc tural regularities of the ligands.…”

“…In the classification series of Pearson's chemical hardness, Ni 2+ is assigned to an intermediate type of Lewis acids capable of manifest ing the properties of both hard and soft acids [7][8][9]. In addition, as the above considered Pd(II) and Pt(II) complexes, the nickel complex is polyvariant by both the composition (MN 2 O 2 or MN 2 S 2 ) and configura tion (pseudo tetrahedral, trans and cis planar) of the coordination mode [1][2][3][4]. Taking this into account, we performed calculations (Tables 2 and 5) for the pseudo tetrahedral configuration corresponding to the triplet electron state and for the trans and cis planar configurations corresponding to the singlet electron state of the a(MN 2 O 2 ) and b(MN 2 S 2 ) isomers of com plex I (M = Ni(II)).…”

New Metal Chelates with Sterically Hindered Azo Ligands: Synthesis and Physicochemical Properties

“…Metal chelates with azo ligands have been for a long time in the focus of the researchers' attention [1][2][3][4][5]. This is explained by both their wide practical and theoretical application in coordination chemistry.…”

“…This is explained by the fact that due to the ambidentate nature of the azo group [8], both nitrogens have identical donor properties and can equally participate in coordination. Therefore, both five-and six-membered chelate cycles can form and simultaneously occur in one molecule, which was established by X-ray diffraction method [2,9]. Moreover, it was shown that in addition to the isomeric transformations in type A metal chelates, the cis -trans -isomerism can also take place [10].…”