engleski

THE CRYSTAL STRUCTURE PREDICTION AND MODELLING OF BIS(N, N-DIETHYLGLYCINATO)COPPER(II)

The sterical interactions in copper(II) complexes with N, N-dialkylated amino acids have a pronounced role in determining both the most stable conformations and the crystal packing. Thus, this class of transition metal complexes represents very well suited model systems for the study of sterical interactions in metal-biomolecule compounds. The molecular mechanics force field FFW developed for modelling copper(II) amino acid complexes in simulated crystalline surroundings and for isolated molecules [1] reproduced well the experimental unit cell dimensions and molecular structure of bis(N, N-diethylglycinato)copper(II) [2]. Theoretical conformational analysis of the complex performed using FFW showed that the conformer found in the experimental crystal structure (named 1-3) was not the most stable conformer in vacuo. To verify the supposition that 1-3 is better suited for crystal packing than the most stable conformer in vacuo (named 12-12), the crystal structure of 12-12 was predicted by starting the energy minimisation from the 12-12 vacuum Cartesian coordinates and the same unit cell dimensions and molecule’ s orientation as in the experimental crystal structure. The difference between the intermolecular energy contributions of 12-12 and 1-3 equals 9.1 kcal mol-1 and gives a quantitative proof that the crystal packing forces favour the 1-3 conformation. [1] J. Sabolović, C. S. Tautermann, T. Loerting, K. R. Liedl, Inorg. Chem. 2003, 42, 2268-2279. [2] J. Sabolović, B. Kaitner, CrystEngComm Discusssion 2: New Trends in Crystal Engineering: Nottingham, Great Britain 2004, Poster Abstracts, page P.8

copper; amino acids; crystal; prediction; simulation; MM

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