Pyridine‐Based Oligonitriles as Pincer Ligands for Palladium(II), Copper(II), Cobalt(II), and Nickel(II) Ions

Abstract

Nucleophilic ring opening of the 1-oxa-3,5-diazinium salts 2 and 3 by propylamine furnishes the new polydentate, branched, pincer-type ligands 4 and 5, respectively, in 34 and 57 % yield. The 1-oxa-3,5-diazinium salts 2 and 3 were prepared from pyridine-2,6-dicarbonyl dichloride (1) by treatment with dimethylcyanamide and diisopropylcyanamide in the presence of antimony pentachloride and tin tetrachloride, respectively. The structure of 4, which is characterised by a strongly twisted N-acyloligonitrile arm, was determined by X-ray crystallography. The ligand 4, with its short and long arms, forms chelate complexes 4 -·Pd(OAc) + and 4·CuCl 2 when treated with palladium(II) acetate and copper(II) chloride, respectively. 4 -·Pd(OAc) + shows remarkable catalytic

Multivalent 1‐Oxa‐3,5,7‐triazahepta‐1,3,5‐trienes: Synthesis, Structural Properties and Metal Coordination

“…The solid‐state structure of the octahedral complex 6·Ni(NO 3 ) 2 shows many similarities with other pyridine‐based pincer complexes reported recently from our laboratory:3 here, the ligand 6 acts in a pentadentate fashion, while one solvent molecule (methanol) occupies the sixth coordination site (Figure 10).…”

“…These oligomers offer oxygen and nitrogen lone pairs as potential binding sites for metal complexation 1,2. In particular, branched pyridine‐based pincer ligands (Scheme ) have found applications as powerful ligands for the complexation of various transition metal ions 3. Such novel pincer‐type ligands are thermally, moisture‐ as well as air‐stable, and their palladium complexes display high catalytic activity, e.g.…”

Synthesis of Binucleating Macrocycles and Their Nickel(II) Hydroxo- and Cyano-Bridged Complexes with Divalent Ions: Anatomical Variation of Ligand Features

“…The Ni II site is six coordinate with trans DMF ligands (O–Ni–O = 177.7(2)°) and bond lengths (2.14–2.15 Å) ca. 0.10–0.15 Å longer than in (paramagnetic) [Ni(DMF) 6 ] 2+ (Ni–O = 2.04–2.06 Å) , and various cationic pincer complexes (unreported magnetism). − In 28 this distance decreases to 2.052(4) Å in the absence of a trans ligand . All Ni II –OH complexes in DMF solution show 1 H NMR spectra indicative of diamagnetism and weak or nil out-of-plane coordination.…”

Pincer-type bis(carbene)-derived complexes of nickel(II): Synthesis, structure, and catalytic activity

“…Various types (e.g., PCP-, NCN-, CNC-) of pincer complexes of transition metals have been reported to date; among them, palladium-pincer complexes have been widely investigated and employed as catalysts for cross-coupling reactions [10][11][12][13][14][15]. Much less attention has been paid to the nickel-pincer complexes [16][17][18][19][20][21][22], although the use of nickel catalysts instead of palladium catalysts sometimes offers advantages, such as cost effectiveness and distinct catalytic abilities [23][24][25][26][27][28][29][30][31][32][33]. In this regard, we recently reported the synthesis of a CNC-type pincer complex of nickel 1 (Fig.…”