Preparation of a nitrate-coordinated copper(ii) complex of 2-(pyrazol-3-yl)-6-(pyrazolate)pyridine as an efficient catalyst for methyl methacrylate polymerization

Abstract

Treatment of [CuCl(2)(bppyH(2))] (1, bppyH(2) = 2,6-di(1H-pyrazol-3-yl)pyridine) with 2 equiv. of AgNO(3) in DMF gave rise to a binuclear Cu(II) complex [Cu(2)(bppyH)(2)(NO(3))(2)] (bppyH = 2-(pyrazol-3-yl)-6-(pyrazolate)pyridine) (2). Complex 2 was characterized by elemental analysis, IR and single crystal X-ray diffraction. Complex 2 has a dimeric structure in which the two Cu(ii) centers are bridged by a couple of the in situ-generated bppyH(-) anions. Each Cu(II) center is further coordinated by one O atom of a NO(3)(-) anion and three N atoms of one bppyH(-) anion. Complex 2 exhibited a higher catalytic activity in the polymerization of methyl methacrylate (MMA) than the precursor complex 1. Even though the ratio of catalyst to MMA was raised up to 1 : 1500, the PDI for 2 (reaction time was fixed at 4 h) is 1.63 and the conversion is up to 72%. The effects of solvent, reaction temperature and the ratio of MMA to catalyst were also investigated.

Five‐coordinate dinuclar cobalt (II), copper (II), zinc (II) and cadmium (II) complexes with 4‐bromo‐N‐(2‐pyridinylmethylene)benzenamine: Synthesis, characterisation and methyl methacrylate polymerization

“…Similarly, Cu (II) complexes with ligand N ‐(2‐furanylmethyl)‐ N ‐(1–3,5‐dimethyl‐1H‐pyrazolylmethyl)‐ N ‐(phenylmethyl) amines yielded syndiotactic PMMA ( rr = 0.78) with only 30% conversion. Copper (II) complex of 2‐(pyrazol‐3‐yl)‐6‐(pyrazolate) pyridine and related ligand reported catalyzed MMA polymerization with moderate activity and syndiotacticity. Compared with our previous Co complexes with N , N ‐bis(1‐pyrazolyl)methyl the current Co complex exhibited better activity and stereoselectivity and yielded PMMA with high molecular weight.…”

Reactivity of an Unusual Divalent Chromium Aggregate Supported by a Multifunctional Bis(pyrazolate) Pincer Ligand

“…While we have been unable to grow single crystals of [CrL] 2 , we use the structural precedent of dimeric [Cu(HL)(NO 3 )] 2 , where the entire Cu 2 (HL) 2 unit is coplanar, with nitrates binding perpendicular to that plane, to propose the form shown in Figure for [CrL] 2 . This leaves four coordinate Cr(II) spatially accessible to attack perpendicular to the molecular plane, although the d z ² SOMO at each metal may inhibit such attack.…”

New Bis-Pyrazole-Bis-Acetate Based Coordination Complexes: Influence of Counter-Anions and Metal Ions on the Supramolecular Structures

“…(1) The ligand L is an N-heterocyclic tridentate pyrazolyl pyridine compound capable of forming various coordination modes, and ligating topology with transition metal ions [21]. (2) This type of pyridine ligand having pyrazolyl groups at the second and sixth position, possesses a wide range of interesting chemical and/or physical properties, such as catalytic [22,23], electrochemical [24], magnetic and photophysical properties [25]. (3) Many coordination complexes containing both Lewis base donors and Lewis acid acceptors in the same ligand [26] such as 2,6-bis (pyrazolyl) pyridine have been reported [23][24][25][26][27] according to the Hard-Soft acid base theory [28].…”