Flat vs. Folded Chelate Rings in cis‐Pt^IIa₂ (a = NH₃, a₂ = en, a₂ = 2, 2′‐bpy) Complexes of Twofold Substituted Diazine Ligands

Abstract

Acid-base and ligating properties of three bis(substituted) pyrazine (pz) and pyrimidine (pym) ligands (pyrazine-2,5-dicarboxylic acid, 2,5-pzdcH2, 2,3-bis(pyridine-2-yl)pyrazine, 2,3-bppz, pyrimidine-4,6-dicarboxylic acid, 4,6-pmdcH 2 ) toward cis-Pt II a 2 (a = NH 3 , a 2 = en, a 2 = 2,2Ј-bpy) have been studied. Combinations of pz-N/pym-N with donor atoms of the substituents lead to 5-membered platinum 1691 chelates, but exclusive N,N-coordination through the pyridyl substituents of 2,3-bppz can lead to a 7-membered platinum chelate with a characteristic L-shape of the resulting cation. It is observed for Pt II (2,2Ј-bpy), yet not for Pt II (en), and is a consequence of differences in sterical interactions between the 2,3-bppz ligand and the coligands of Pt II .

Versatility of copper(II) coordination compounds with 2,3-bis(2-pyridyl)pyrazine mediated by temperature, solvents and anions choice

“…The terminal five-membered chelate (I) (38 hits) [8, as well as bridging bis-bidentate chelate (II) (25 hits) [21,31,[38][39][40][41][42][43][44][45][46][47][48] are the dominant ones for the dpp coordination. The terminal seven-membered bidentate mode (III) (9 hits) [49][50][51][52][53][54], the bidentate/monodentate mode (IV) (14 hits) [29,[55][56][57][58][59][60][61], the bidentate/bis-monodentate mode (V) (1 hit) [55], and the bismonodentate mode (VI) (6 hits) [60][61][62][63][64] are less-common. In copper (II) complexes, most frequently the dpp ligand displays the coordination mode I (15 hits) [8,13,22,24,29,30,35,38,55], whereas the II, IV, and V coordination modes are quite rare: 8 hits for mode II…”

Modulating the MII/Pyrimidine‐4,6‐dicarboxylato System by Metal, Solvent and Temperature Variation

“…The pyrimidine-4,6-dicarboxylic acid (H 2 pmdc) has been, within this class of ligands, unequivocally one of the most useful to create all kinds of metal-organic networks given its great ability to coordinate to different metal centres. [18][19][20][21] Scheme 1 shows all coordination modes exhibited by pmdc, [22,23] among which the predominance of the bis-chelating mode (D-1) stands out due to the strategic disposition of the carboxylate groups. This ligand has shown a marked trend to render oxalate through partial decomposition under hydrothermal condi-tions, a process that was well characterised in the presence of lanthanide(III) ions.…”

Structurally Diverse Polynuclear Copper(I) Complexes Bridged by Pyrimidine–, Pyrazine–, and Triazine–based Ligands with Several 2–Pyridyl Groups

“…Mononuclear bppz complexes of Co(II), Cu(I), Cu(II), Ru(II), Rh(III), Pd(II), Ir(III), Re(I), Pt(II), Pt(IV), and Ln(III) (Ln=Nd, Eu, and Tb) have been reported in coordination mode (ii–a), together with multinuclear and polymeric bppz complexes of Mn(II), Cu(II), Cu(II)/Mo m O n , Re(0), Os(0), Os(I), and Pb(II) containing coordination mode (ii–a). The most likely homometallic dinuclear bppz complexes of Mn(II), Co(II), Ni(II), Cu(II), Ru(II), Re(I), and Pt(II) have been widely known in coordination mode (ii–d), together with multinuclear and polymeric complexes of Cu(I), Cu(II), and Re(0) containing coordination mode (ii–d). Heterometallic dinuclear bppz complexes of Ru(II)/Cu(I), Ru(II)/Pd(II), Ru(II)/Pt(II), Ru(II)/Os(II), Pt(II)/Nd(III), Re(I)/Nd(III), and Re(I)/Gd(III) have also been reported in this coordination mode.…”

“…In contrast, seven–membered bidentate mode (ii–b), bidentate/monodentate (ii–e), bidentate/bis‐monodentate (ii–f), and bis‐monodentate (ii–c) modes are less common types. The limited mononuclear bppz complexes of Pd(II), Pt(II), and Os(0) have been reported in coordination mode (ii–b). Homometallic dinuclear bppz complexes of Cu(II) and Ag(I) as well as Ag(I)–bppz coordination polymers have been known in coordination mode (ii–e), together with polymeric Cu(I)–bppz complex .…”