Nickel Complexes and Cobalt Coordination Polymers with Organochalcogen (S, Se) Ligands Bearing an <i>N</i>‐Methylimidazole Moiety: Syntheses, Structures, and Properties

Abstract

Abstract The organochalcogen ligands (S, Se) derived from 3‐methylimidazole‐2‐thione/selone groups mbit ( 2a ), mbis ( 2b ), ebit ( 2c ), and ebis ( 2d ) [mbit = 1,1′‐methylenebis(1,3‐dihydro‐3‐methyl‐2 H ‐imidazole‐2‐thione), mbis = 1,1′‐methylenebis(1,3‐dihydro‐3‐methyl‐2 H ‐imidazole‐2‐selone), ebit = 1,1′‐(1,2‐ethanediyl)bis(1,3‐dihydro‐3‐methyl‐1 H ‐imidazole‐2‐thione), ebis = 1,1′‐(1,2‐ethanediyl)bis(1,3‐dihydro‐3‐methyl‐1 H ‐imidazole‐2‐selone)] were synthesized and characterized. Mononuclear Ni II complexes NiBr 2 mbit ( 3a ), NiBr 2 mbis ( 3b ), NiBr 2 ebit ( 3c ), and NiBr 2 ebis ( 3d ) were obtained by the reactions of Ni(PPh 3 ) 2 Br 2 with 2a , 2b , 2c , and 2d , respectively. However, when the corresponding ligands 2a , 2b , 2c , and 2d were treated with CoCl 2 in thf solution Co II 1D coordination polymers (CoCl 2 mbit) n ( 4a ), (CoCl 2 mbis) n ( 4b ), (CoCl 2 ebit) n ( 4c ), and (CoCl 2 ebis) n ( 4d ) were obtained. All compounds were fully characterized by IR spectroscopy and elemental analysis. The crystal structures of 2c , 3a , 3b , 3c , 4a , 4b , and 4c were determined by X‐ray crystallography. The local geometry around the nickel atom in complexes 3a – c was distorted tetrahedron with coordinated S(Se) and two Br atoms, and the organochalcogen ligands form an eight‐ or a nine‐membered ring with the nickel atom included. The cobalt atom coordination polymers 4a and 4b coexist as left‐handed and right‐handed helical chains, but 4c formed a zigzag chain with a CH 3 CN solvent molecule taken up in the channel structure. After activation with methylaluminoxane (MAO), the nickel complexes exhibited high activities for addition polymerization of norbornene (1.42 × 10 8 g PNBmol –1 Nih –1 for 3a ). The effects of the Al/Ni ratio, reaction temperature, and reaction time to norbornene polymerization were also investigated.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2008)