Novel lanthanide coordination polymers with a flexible disulfoxide ligand, 1,2-bis(ethylsulfinyl)ethane: Structures, stereochemistry, and the influences of counteranions on the framework formations

The reactions of meso-1,2-bis(ethylsulfinyl)ethane (meso-L) with Ln(ClO4)(3) [Ln(NO3)(3) or Ln(NCS)(3)] in MeOH and CHCl3 gave a series of new lanthanide coordination polymers, {[Ln(mu-meso-L)(rac-L)(2)(CH3OH)(2)](ClO4)(3)}(n) [Ln: La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), and Yb (7)], [Yb(mu-meso-L)(1.5)(NO3)(3)](n) (8), and [La(mu-meso-L)(2.5)(NCS)(3)](n) (9). All the structures were established by single-crystal X-ray diffraction. Complexes 1-7 are isostructural with infinite single mu-chain structure, in which the L ligands take two kinds of coordination modes: bidentate chelating and bis-monodentate bridging. Six sulfur atoms of the sulfoxide groups around each Ln(III) center adopt alternatively the same R or S configuration in the chain. In addition, the configuration change of partial ligands occurred from the meso to the rac form when reacting with Ln(ClO4)(3). To our knowledge, this is the first example of disulfoxide complexes with two kinds of coordination modes and three kinds of configurations (R,R, S,S, and R,S) occurring simultaneously in the same complex. 8 exhibits single-double bridging chain structure, in which dinuclear macrometallacycles formed through bridging two Yb-III by two meso-L ligands are further linked by another meso-L ligand. In 9 each La-III ion is linked to five other La-III ions by five meso-L ligands to form a 5-connected 2-D (3/4,5) network containing two types of macrometallacyclic arrays: quadrilateral and triangle grids. The structural differences among 1-7, 8, and 9 show that counteranions play important roles in the framework formation of such coordination polymers. In addition, the luminescent properties of 3 and 5 were also investigated.