Neutral Penta‐ and Hexacoordinate Silicon(IV) Complexes Containing Two Bidentate Ligands Derived from the α‐Amino Acids ( S )‐Alanine, ( S )‐Phenylalanine, and ( S )‐ tert ‐Leucine

The neutral hexacoordinate silicon(IV) complex 6 (SiO 2 N 4 skeleton) and the neutral pentacoordinate silicon(IV) complexes 7 – 11 (SiO 2 N 2 C skeletons) were synthesized from Si(NCO) 4 and RSi(NCO) 3 (R=Me, Ph), respectively. The compounds were structurally characterized by solid‐state NMR spectroscopy ( 6 – 11 ), solution NMR spectroscopy ( 6 and 10 ), and single‐crystal X‐ray diffraction ( 8 and 11 were studied as the solvates 8⋅ CH 3 CN and 11⋅ C 5 H 12 ⋅ 0.5 CH 3 CN, respectively). The silicon(IV) complexes 6 (octahedral Si‐coordination polyhedron) and 7 – 11 (trigonal‐bipyramidal Si‐coordination polyhedra) each contain two bidentate ligands derived from an α‐amino acid: ( S )‐alanine, ( S )‐phenylalanine, or ( S )‐ tert ‐leucine. The deprotonated amino acids act as monoanionic ( 6 ) or as mono‐ and dianionic ligands ( 7 – 11 ). The experimental investigations were complemented by computational studies of the stereoisomers of 6 and 7 .