Catalytic transformation of silicon tetraisocyanate Si(NCO) 4 to a polymeric silylcarbodiimide

A new way for the preparation of inorganic polymeric carbodiimide‐based networks is presented which resembles the transformation of molecular isocyanates using 1‐phenyl‐3‐methyl‐2‐phospholene‐1‐oxide as a catalyst. The respective reaction sequence, well established in preparative organic chemistry, has been applied for the synthesis of carbodiimide‐based SiNC(O) materials. Starting from Si(NCO) 4 (silicon tetraisocyanate), a transformation to an insoluble extended inorganic array was achieved in boiling dodecan ( T  = 216 °C). Analysis of the polymer using X‐ray diffraction, FT‐IR, density measurement, matrix‐assisted laser desorption/ionization time of flight and TGA revealed that this highly moisture‐sensitive amorphous network consists of oligomers of high molar mass and exhibits a high density of around 1.5 g cm −3 , which corresponds quite well to the calculated density of crystalline Si(NCN) 2 reported in the literature. Degradation of this 'SiNC(O) phase' with the release of N 2 and (CN) 2 finally provided SiC as the only crystalline product. No indication of the formation of crystalline Si 3 N 4 or intermediate crystalline 'SiC 2 N 4 ', silicon carbodiimide (= Si(NCN) 2 ), was noticed. Copyright © 2013 John Wiley & Sons, Ltd.