Charge density study of N-acetyl-L-tyrosine ethyl ester monohydrate derived from CCD area detector data

The crystal structure, thermal vibrations and electron density of the pepti de N-acetyl-L-tyrosine ethyl ester monohydrate, C13H17NO4. H2O, have been a nalysed using single-crystal X-ray diffraction data collected at 110K with Mo K alpha radiation to a resolution of (sin theta/lambda)(max) = 1.1 Angst rom(-1). A CCD area detector was used to collect 98 393 data during one wee k. A multipolar atom density model was fitted against the 10 189 unique dat a with I > 2 sigma(I) [R(F) = 0.027, wR(F) = 0.020, g.o.f. = 0.65] in order to map the valence electron distribution. These deformation densities comp are very well with those obtained from conventional diffractometers equippe d with scintillation detectors. This work shows that area detectors permit charge density studies in a more routine way than is possible with conventi onal diffractometers.