Five‐ and Four‐Coordinate 1,3‐Diaza‐2‐yttria‐ and 1,3‐Diaza‐2‐scandia‐[3]ferrocenophanes

2‐Chloro‐1,3‐bis(trimethylsilyl)‐1,3‐diaza‐2‐metalla‐[3]ferrocenophanes with M = Y ( 3 ) and Sc ( 4 ) have been prepared as the dipyridine adducts, starting from YCl 3 and ScCl 3 , respectively, and N , N′ ‐dilithio‐ N , N′ ‐bis(trimethylsilyl)‐1,1′‐diaminoferrocene ( 2 ). The reaction of 3 with sodium pentamethylcyclopentadienide (NaCp*) gave the complex 5 , in which the yttrium atom is four‐coordinate, bearing the diamido ligand, Cp* and one pyridine ligand. An ate complex of four‐coordinate yttrium ( 6 ) was obtained, when YCl 3 was treated with 2 equiv. of 2 . In 6a , the lithium atom is threefold coordinated by two of the four amido nitrogen atoms and by pyridine, and addition of an excess of pyridine gave the separated ion pairs ( 6b ) in solution. The molecular structures of 3 , 5 and 6a were determined by X‐ray structural analysis, and the solution‐state structures were deduced from consistent NMR spectroscopic data sets ( 1 H, 13 C, 29 Si, 89 Y NMR). The 89 Y nuclear magnetic shielding of amido complexes appears to increase with the coordination number (3, 4, 5) of yttrium.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)