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Kronenether haben Zuwachs bekommen! Neben den Kronenether‐Sandwichkomplexen 1 existieren topologisch äquivalente Metallakronenethersandwichkomplexe 2. Diese entstehen in einer Eintopfreaktion durch Selbstorganisation und wurden in einem Fall durch eine röntgenographische Kristallstrukturanalyse zweifelsfrei charakterisiert.magnified image
Kronenether haben Zuwachs bekommen! Neben den Kronenether‐Sandwichkomplexen 1 existieren topologisch äquivalente Metallakronenethersandwichkomplexe 2. Diese entstehen in einer Eintopfreaktion durch Selbstorganisation und wurden in einem Fall durch eine röntgenographische Kristallstrukturanalyse zweifelsfrei charakterisiert.magnified image
For some time we have been working in the field of cage compounds such as [NH,c Fe,Li] (l), originating by the spontaneous self-assembly of preprogrammed bis(bidentate) bridging ligands and suitable metal ions.1'B21 A notable feature of these tetranuclear adamantanoid endoreceptor complexes is their topological equivalence to cryptates (2) .Iz1 [~I We were convinced that the analogy perceived between 1 and 2 is not a special case, but that the use of properly tailored ligands should give access to other metallatopomers. In order to test this hypothesis we treated dialkyl ketipinates 4a,bf5] or tetraketone 4d6' with copper(r1) chloride and aqueous ammonia or potassium hydroxide in methanol, obtaining dark green crystals in each case. The microanalytical data and FAB-MS spectra (FAB = fast atom bombardment) gave initial indications that the products were hexanuclear copper chelate compounds (5) of the general composition [MOH(Cu,L:),].6HOR2, constituting host guest systems topologically equivalent to well-known organocrown ether sandwich complexes 3 [for example, KI(benzo[l5]crown-5),] .I7] In principle, the composition of a coronate is dependent on the cavity diameter of the host. Correspondence between the size of host and guest leads to complexes with 1 : 1 stoichiometry, whereas "oversize" cations result in sandwich complexes with 2: 1 stoichiometry.
Reaction of a solution of copper(I1) acetate in methanol with ethyl (aminomethy1ene)cyanoacetate derivatives 10 (H2L4) or 13 (H2L5) yields the corresponding 1D-coordination polymers 11 ([CuL41m) and 14 ([CuL51m), respectively. The products are insoluble in non-coordinating solvents and thermally highly stable. The structures of 11 and 14 have been established by X-ray diffraction. The one-dimensional coordination polymers 11 and 14 have different geometries, depending on the lateral group of the ligands.In the context of our research interests in organized entities, we reported on the formation of the neutral coordination polymers 3D-1, 2D-2, and helical 1D-3[2-41. They are generated by spontaneous self-organization[5] from the tridentate ligands 4-6 and copper(I1) acetate via the coordinatively unsaturated bidentate building blocks 7-9. In order to contribute additional material to the chemistry of the organic solid state, we applied our strategy for the development of coordination polymers 1-3 to hexadentate ethyl (aminomethy1ene)cyanoacetate derivatives 10 and 13 as chelate ligands. Having basically been studied by Jager, however with different objectivesL61, these ligands were supposed to provide coordination polymers of variable architectures. The ligands 10 and 13 structurally closely resemble tetrazolyl enol4 or the pyrrolinyl enols 5 and 6. In contrast to 4-6, the two [N,O] donor units in 10 and 13 are connected by a lateral group [lo: -(C6Ht0)-, 13: -(CH2),-]. The alkyl chains exert a crucial influence on the geometry of the chelates and thus on the ensuing coordination polymers 11 and 14. Results and DiscussionThe product obtained by the reaction of copper(I1) acetate with diethyl trans-1,2-cyclohexanediylbis(aminornethylene)bis(cyanocetate) (10) (H2L4) is almost completely insoluble in non-coordinating solvents and is thermally highly stable. According to the microanalysis, the general composition of product 11 corresponds to [CuL4],.X-Ray structure analyses of the copper(I1) complexes 1 and 2 clearly prove the presence of well-ordered infinite three-and two-dimensional architecture~ [~~~]. The formation of the coordination polymers 3D-1 and 2D-2 is understandable, if one assumes initial deprotonation of 4 and 5, which provides planar copper(I1) chelates 7 and 8 as intermediates. Chelates 7 and 8 may be considered as bidentate monomeric building blocks that require coordinative saturation. Basically, this can be achieved by intermolecular linkage of equatorial CN groups to the free axial positions
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