| Popis: |
It is shown by X-ray structural studies that the bisamide ligands N,N′-p-xylylenebisacetamide (PXBA, I), N,N′-trans-1,4-cyclohexylaminebisacetamide (1,4-CHBA, II) and N,N′-trans-1,4-cyclohexylaminebis-n-butyramide (1,4-CHBB, III) form polymeric network structures with lanthanide(III) nitrates. In the compound Er2(PXBA)3(NO3)6 (1) the erbium atoms are nine-coordinate and are linked by PXBA bridges to form sheets of contiguous 78-membered metallacyclic rings. In Ce(1,4-CHBA)2(NO3)3 (2) the cerium atoms are ten-coordinate and the 1,4-CHBA ligands bridge adjacent cerium centres to form sheets of contiguous 44-membered rings with (4,4) topology and with a very compact stacking of the adjacent sheets. In Nd(1,4-CHBB)2(NO3)3 (3) the neodymium atoms are eight-coordinate with the 1,4-CHBB ligands also bridging adjacent neodymium centres to form sheets of contiguous 44-membered rings with (4,4) topology, but with a pronounced ‘square-wave’ corrugation and crest-in-trough sheet stacking. |
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