Long bipyridyl-type linking ligands containing an intervening cyclohexyl fragment and their cadmium coordination polymers: [formula omitted] and [formula omitted] ( Ln = ( n-py)–CH [dbnd]N–C 6H 10–N [dbnd]CH–( n-py); n = 4, 3, 2)

Abstract

We prepared three isomeric bipyridyl-type ligands ( L n = ( n-py)–CH N–C 6H 10–N CH–( n-py); n = 2–4). Two cadmium coordination polymers, [ Cd L 1.5 4 ( NO 3 ) 2 ] · ( CH 2 Cl 2 ) ( 1) and [ Cd L 1.5 3 ( NO 3 ) 2 ] ( 2), were prepared from cadmium nitrate and ligands L 4 and L 3, respectively. The N⋯N separations between the two terminal pyridyl groups in the free ligands L 4, L 3, and L 2 are 15.798(6), 15.036(4), and 12.417(5) Å, respectively. The 2-D α-arsenic-type polymer 1, which contains CH 2Cl 2 guest molecules, has two distinct N⋯N separations of 15.706(10) Å and 14.479(9) Å and a large 102-membered cyclohexane-like ring unit. The 1-D stair-like polymer 2 has also two distinct N⋯N separations and a 60-membered ring unit. The various lengths of the observed N⋯N separations are due to the ring flip of the intervening cyclohexyl fragment in the ligands.