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

Dalton Transactions Pub Date: 2007-04-23 DOI: 10.1039/B702074K

Abstract

The complexes [Cu(L1)2] 1, [Fe(L1)3] 3 and [Al(L1)3] 4 [L1 = 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)2·3H2O, HL1 and NEt3 giving [Cu6(μ3-OMe)4(μ-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(L1)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 AgNO3 is crucially dependent on the solvent used. The reaction in methanol–acetone gives [Fe(L1)3·AgNO3]∞6, {[Fe2(μ-OMe)2(L1)4·2AgNO3]·CH3C(O)CH3}∞7 and [Fe2(μ-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(μ-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(μ-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.

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