STRUCTURES OF CHARGE-PERTURBED OR STERICALLY OVERCROWDED MOLECULES .29. STERIC OVERCROWDING IN N-TRIMETHYLSILYL-SUBSTITUTED-P-PHENYLENEDIAMINES - THE ORIGIN OF A WURSTERS BLUE RADICAL-ANION

The crystal structure of N,N'-bis(trimethylsilyl)-p-phenylene diamine proves an almost planar, though heavily distorted SiHN-C6H4-NHSi skeleton, whereas in the sterically overcrowded N,N,N',N'-tetrakis(trimethylsilyl) derivative the p-type electron pairs of the flattened (R3Si)2N groups are twisted into the plane of the benzene ring and, therefore, provide a rationale for its unexpectedly possible one-electron reduction to a Wurster's Blue radical anion.