crystal of dimensions 0.37 x 0.37 x 0.27 mm, rhombohedral. R3, a = b = 15.0677(7), c = 48.7214(49) A, 1 = = 1 102 g~m -~, 2 = 6, j~ = 12.22 cm-', 2328 independent reflections, R(Rw) = 0.105(0.103) for 1309 [I > 20(1)] observed reflections. Maximum final difference Fourier peak 0.83 e k ' . Seifert XRD3000-S, four-circle diffractometer, Cu,, radiation, graphite monochromator, 4 2 0 scan, Om,, = 60". Two set of data were collected due to the instability of the crystal, and although the present set was recorded more quickly the decay factor was 7%. Semiempirical Y-scan absorption correction was applied. Refinement on Fo with full matrix. The structure was solved by direct methods [15] and the molecule was located on a threefold crystallographic axis. An anisotropic thermal model was used for the non-hydrogen atoms, while the thermal and positional parameters for H atoms, which were obtained unambiguously from difference Fourier synthesis, were kept fixed during the last cycles of refinement. The water molecules appear to be disordered and the hydrogen atoms of the water molecule situated on the threefold axis could not be located. Moreover, in spite of the high displacement parameters of the C17-C22 atoms no disorder model could be obtained. The weighting scheme was established as to give no trends in

Die Bindungsverhältnisse im präzedenzlosen Komplex [Cp*AlFe(CO)4] wurden anhand des Modells [CpAlFe(CO)4] quantentheoretisch untersucht. Für diesen Komplex ist die Donor‐Acceptor‐Bindung Al → Fe charakteristisch (rechts), deren Stärke etwa 50 kcal mol−1 beträgt.