Imidazole‐Bridged Tetrameric Group(IV) Heteroleptic Complexes from the Spontaneous Metal‐Ligand Assembly of a Potentially N₄‐Tetradentate Ligand

Abstract

The imidazole-containing N 4 -tetradentate ligand N-(2-(1H-imidazol-2-yl)-3-(pyridin-2-yl)propyl)-2,6-diisopropylaniline (L2 H ) and its N-benzyl-protected variant (L2 Bn ) at the imidazole fragment have been synthesized and fully characterized. Both molecules contain an unresolved C sp3 stereogenic center. The coordination behavior of the newly prepared ligands towards group IV metal ions (M IV = Zr, Hf ) has been examined through multinuclear 1 H and 13 C{ 1 H} NMR spectroscopy and selected single-crystal X-ray structural analyses. The ability of the imidazole fragment to enter the metal coordination sphere as a neutral or a monoanionic system has also been investigated, unveiling quite original coordination modes as well as unexpected molecular architectures. When one N imidazole atom is blocked by a benzyl protecting group (L2 Bn ), the ligand reaction with M IV (NMe 2 ) 4 (M IV = Zr, Hf ) as metal precursor gives rise to discrete monometallic tris(dimethylamido) 5-coordinated [a]

Micelle-modulated reactivity of novel copper(ii) complexes with reduced l-histidine Schiff bases as mimic carboxylesterases

“…Within this MOC structure, imidazole N of the one unit coordinates with the Cu 2+ ion of the next unit, thereby constructs a ring geometry. 47 The four central copper( ii ) possess a symmetric coordination atmosphere, namely a five-coordinate mode due to the involvement of the DMF molecule. Addison tau factors listed in Table S3 (ESI†) show that the central Cu( ii ) cation of 2 adopts a slightly distorted square pyramidal configuration with N 3 O 2 donors.…”

Coordination Polymer of Cobalt (ΙΙ) Nitrate with Imidazole: Synthesis, Properties and Crystal Structure

“…Among the ligands suitable for the synthesis of compounds with the above-mentioned properties, such a ligand likes an imidazole containing two different nitrogen atoms: pyridine and pyrrole. Consequently, imidazole can act as both a chelating and a bridging ligand [6]. In addition, imidazole can participate in the formation of hydrogen bonds through the -N-H groups of imidazole with the counter ion ( 3 NO − ), creating supramolecular assemblies.…”

“…Imidazole ligand molecules are coordinated through the pyridine nitrogen atom N(3) to the Co 2+ ion with an average Co•••N bond distance of 2.1590 Ǻ.In the octahedral complex [Co(L) 6 ](NO 3 ) 2 three trans angles are 180˚ in symmetry, and the remaining angles vary from 88.24(2) to 91.76(2)˚ (Table2). The Co-N bond distance is as follows: a short Co(1)-N(1) bond = 2.1588(6) and a long Co(1)-N(1) bond = 2.1592(2). The chelate cycle of the complex is flat, with an average deviation of 0.0015(2) Ǻ.…”