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

The complexes [Cu( L-1)(2)] 1, [Fe(L-1)(3)] 3 and [Al(L-1)(3)] 4 [L-1 = CH3C(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)center dot 3H(2)O, HL1 and NEt3 giving [Cu-6(mu(3)-OMe)(4)(mu-OMe)(2)(L-1)(6)] 2 instead of the anticipated 1, which was obtained with CuCl2 center dot 2H(2)O under the same conditions. Compound 1 reacts with AgNO3 to form [Cu(L-1)(2)center dot AgNO3](infinity) 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 AgNO3 is crucially dependent on the solvent used. The reaction in methanol-acetone gives [Fe(L-1)(3)center dot AgNO3](infinity) 6, {[Fe-2(mu-OMe)(2)(L-1)(4)center dot 2AgNO(3)]center dot CH3C(O)CH3}infinity 7 and [Fe-2(mu-OMe)(2)(L-1)(4)center dot AgNO3]infinity 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(mu-OMe)(2)(L-1)(4)]OH center dot 0.4H(2)O]infinity 9. Compound 9 has a three-dimensional structure based on doubly interpenetrated PtS nets. Compounds 7-9 contain Fe-2(mu-OMe)(2)(L-1)(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(L-1)]infinity 10, which has a two-dimensional layer structure. Compounds 2, 3 and 5-10 have been characterised by X-ray crystallography.