Electronic Structures of Organometallic Complexes of f Elements. 62 Parametric Analysis of the Crystal Field Splitting Pattern of Pseudo Trigonal Planar Nd(η5-C5Me4H)3

The absorption spectrum of pseudo (Ψ) trigonal planar Nd(η5‐C5Me4H)3 (1) has been measured at room and low temperatures. From the spectra obtained, a truncated crystal field (CF) splitting pattern could be derived, and simulated by fitting the parameters of a phenomenological Hamiltonian. For 38 assignments, a reduced r.m.s. deviation of 30.7 cm−1 was achieved. On the basis of the CF parameters used, the global CF strength experienced by the Nd3+ central ion is estimated. The obtained Slater parameter F2 and the spin‐orbit coupling parameter ξ4f allow the insertion of compound 1 into truncated nephelauxetic and relativistic nephelauxetic series. Besides, the experimentally based non‐relativistic molecular orbital scheme (in the f range) of complex 1 is set up and compared with the results of an SW‐Xα calculation on the fictive trigonal planar model complex NdCp3.