4 . 5 H 2 O , ( Him / imidazole , 5 MeImH / 5 - methylimidazole and 2 , 2 ? - bipy / 2 , 2 ? - bipyridine )

N -tert -butyliminodiacetic acid (H2TEBIDA, compound 1) has been prepared and characterised by thermogravimetric analysis, FT-IR and NMR spectra, and X-ray crystallography (final R1 /0.04). The zwitterion H2TEBIDA 9 is intra -stabilised by a hydrogen bond, and H-bonded chains of zwitterions form supramolecular 2D bilayers with tert -Bu groups towards the external faces. Compounds [Cu(TEBIDA)(H2O)2] (2), {[Cu(TEBIDA)(Him)] /2H2O}n (3) {[Cu(TEBIDA)(5MeHim)] /H2O}n (4) [Cu(TEBIDA)(bipy)] /4.5H2O (5) were also obtained and studied by thermal, (FT-IR, reflectance and ESR) spectral, magnetic and X-ray diffraction methods. Compound 2 has a molecular structure and TEBIDA with mer -NO2 tridentate conformation in contrast with that reported for {[Cu(IDA)(H2O)2]}n (polymeric chains, elongated octahedral Cu(II) coordination and fac -NO / O(apical) IDA conformation). Compounds 3 and 4 form zig /zag polymeric chains and follow all structural co-relations reported for complexes with equimolar Cu(II)/iminodiacetato (IDA)/N -heterocyclic donor ratio (Cu(II) coordination type 4 /1, mer -NO2 TEBIDA conformation and N(Him-like) donor in trans to the Cu /IDA-like bond). However, compound 5 has an unexpected fac O2 /N(apical) TEBIDA conformation, with the aqua ligand (instead of one N -heterocyclic donor) in the trans -site of the Cu / N(IDA-like) bond, in contrast with structural co-relations for complexes with Cu/(IDA or IDA-like)/N -heterocyclic donor ratio 1/1/ 2 and closely related compounds (fac -NO /O(apical) IDA-like conformation and one N -heterocyclic donor in the trans -site to the Cu /N(IDA-like) bond). These findings are attributed to the influence of p,p-stacking interactions involving both rings of two 2,2?bipy ligands in the molecular recognition process, forming pairs of complex molecules which probably build the crystal of compound 5 with non-coordinated water. # 2003 Elsevier Science Ltd. All rights reserved.