The stepwise formation of mixed-metal coordination networks using complexes of 3-cyanoacetylacetonate

The complexes [Cu(L1)2] 1, [Fe(L1) 3] 3 and [Al(L1)3] 4 [L1 = CH 3C(O)C(CN)C(O)CH3] have been prepared for use as metallo-ligands in mixed-metal coordination networks. Surprisingly, the nature of the copper precursor is important in the synthesis of 1, with the reaction between Cu(NO3)2·3H2O, HL1 and NEt3 giving [Cu6(3-OMe)4(-OMe) 2(L1)6] 2 instead of the anticipated 1, which was obtained with CuCl2·2H2O under the same conditions. Compound 1 reacts with AgNO3 to form [Cu(L 1)2·AgNO3]∞ 5, the structure of which contains one-dimensional chains in which Ag+ ions bridge between molecules of 1. These chains are cross-linked into ladders by bridging nitrates. The product obtained from the reaction of 3 and AgNO 3 is crucially dependent on the solvent used. The reaction in methanol-acetone gives [Fe(L1)3·AgNO 3]∞ 6, {[Fe2(-OMe)2(L 1)4·2AgNO3]·CH 3C(O)CH3}∞ 7 and [Fe2(-OMe) 2(L1)4·AgNO3] ∞ 8. Compounds 6 and 8 both have one-dimensional chain structures, whereas 7 has a two-dimensional layer structure. The reaction in methanol gives 6 and 8 as the major products and, in addition, small quantities of {[AgFe2(-OMe)2(L1)4]OH·0. 4H2O]∞ 9. Compound 9 has a three-dimensional structure based on doubly interpenetrated PtS nets. Compounds 7-9 contain Fe2(-OMe)2(L1)4 dimers, but the coordination properties of the dimers differ, with all the cyanides coordinated in 7 and 9 but one uncoordinated in 8. The orientation of the cyanide groups depends on the relative chirality of the iron centres. A transmetallation reaction occurs between 4 and AgNO3 to give [Ag(L1)] ∞ 10, which has a two-dimensional layer structure. Compounds 2, 3 and 5-10 have been characterised by X-ray crystallography. © The Royal Society of Chemistry 2007.