7] a) X-ray structure analysis of 3b (C,,H,,GeN,): Irregular fragment of a crystdl obtained by sublimation. Systematic extinctions hOO (h = 2n + 1) and OkO (k = 2n +I). space group P-Z2,m (no. 113), a = 998.09(4), c = 643.12(5) pm, V = 640. 106 pm3, Z = 2, p.,,. = 1.259 gcm-', Enraf-Nonius CAD4, I =71.07 pm (Mo,., graphite monochromator), T = -70 (f3)"C, range of measurement 1.0" < 0 < 25.0', w-scan. scan width (1.2 + 0.25 tan0)" (f 25 %) before and after each reflection to determine the background, I,,, = 60s. empirical absorption correction based on Pscan data, p = 23.2 cm-', no decomposition, direct structure determination, difference Fourier technique, 620 independent reflections, of which 620 had I > 0.01a(I), 67 parameters refined by full-matrix least-squares. reflection/parameter relationship 9.25, all six heavy atoms except C1 with anisotropic thermal motion parameters, all hydrogen atoms found and independently refined, anomalous dispersions accounted for, shift/