Porous coordination networks generated from lanthanum trifluoromethanesulfonate and single/mixed N-oxide spacer linkers

摘要

Three new lanthanum coordination polymers {[La(mu-L)(2)L(H2O)(2)](CF3SO3)(3)}(n) (1), {[La(mu-L')(CF3SO3)(H2O)(2)(mu-L)(0.5)L] (H2O)(3)(CF3SO3)}(n) (2) and {[La(mu-L')(2)(mu-L)](H2O)(1.5)(CF3SO3)}(n) (3) have been prepared by the reaction of La(CF3SO3)(3) with 1,2-bis(4-pyridyl)ethane-N,N'-dioxide (L), or with mixed N-oxide ligands L and L' (HL' = isonicotinic acid N-oxide) in different molar ratios. Single-crystal X-ray analysis showed that 1 possesses a three-dimensional coordination framework connected by L ligands, whereas bridging by both L and L' spacers in different molar ratios results in coordination polymers 2 and 3 that exhibit two- and three-dimensional networks, respectively. Compounds 2 and 3 represent the first metal complexes containing two different N-oxide bridging ligands. Thermogravimetric analysis studies revealed that ligands L and L' are bound differently in compounds 1-3 due to their distinctive coordination modes. (C) 2003 Elsevier Ltd. All rights reserved.