Self-assembly of 2:2 metallomacrocyclic complexes of NiII and PdII with 3,3,3′,3′-tetraalkyl-1,1′-isophthaloylbis(thioureas).: Crystal and molecular structures of cis-[Pd(L2-S,O)]2 and the adducts of the corresponding NiII complexes:: [Ni(L1-S,O)(pyridine)2]2 and [Ni(L1-S,O)(4-dimethylaminopyridine)2]2

The bipodal ligands 3,3,3 ' ,3 ' -tetraethyl-1,1 ' -isophthaloylbis(thiourea). H2L1, and 3,3,3 ' ,3 ' -tetra(n-butyl)-1,1 ' -isophthaloyl-bis(thiourea), H2L2, react with Ni(II) and Pd(II) to form exclusively 2:2 metallomacrocyclic cis-[Pd(L-2-S,O)](2) and cis-[Ni(L-1-S,O)](2) complexes in high yields. Purple-brown cis-[Ni(L-1-S,O)](2) readily form green adducts cis-[Ni(L-1-S,O)(X)(2)](2) (X is pyridine or 4-dimethylaminopyridine), in which two X molecules are axially bound to each Ni(II) atom. Thermogravimetric analysis of these adducts shows that cis-[Ni(L-1-S,O)(X)(2)](2) revert back to the planar ris [Ni(L-1-S,O)](2) complexes on heating. The crystal structures of 3,3,3 ' ,3 ' -tetraethyl-1,1 ' -isophthaloylbis(thiourea), cis-[Pd(L-2-S,O)](2). cis-[Ni(L-1-S,O)(pyridine)(2)](2) and cis-[Ni(L-1-S,O)(4-dimethylamino-pyridine)(2)](2) are reported. (C) 2001 Elsevier Science B.V. All rights reserved.