Stereomutation at Hexacoordinate Silicon by a Ligand ... William B. Farnham* and John F. Whitney ... Contribution No. 3352 from the Central Research & Development Department, E. I. du Pont de Nemours & Company, Inc., Experimental Station, Wilmington, Delaware 19898. Received September 21, 1983 ... Abstract: NMR studies and X-ray analysis show that the hexacoordinate complex formed from spiro silane 1 and 1,lO- ... While hexacoordinate silicon species ...