Bis(silylene)‐Mediated N═N Bond Scission of Diazo Compounds

Abstract

ABSTRACT Diazo compounds, >C═N═N, typically undergo C═N bond cleavage to form carbenes and N 2 , whereas direct N═N bond breaking remains exceedingly rare in main‐group chemistry. We report the N═N bond scission of diazodiarylmethanes, Ar 2 C═N═N (Ar = phenyl, Ar 2 C = 9,9‐fluorendiyl), mediated by a chelating bis‐NHSi (NHSi = N‐heterocyclic silylene). Three bis‐NHSi scaffolds with tunable Si···Si distances were examined: While XT(LSi:) 2 (XT = 9,9‐dimethyl‐9H‐xanthene‐4,5‐diyl, L = PhC(tBuN) 2 ) and PhN(LSi:) 2 lead to end‐on addition products with partial N═N bond activation, the carborane‐based CB(LSi:) 2 (CB = 1,2‐C 2 B 10 H 10 ) engenders complete N═N bond cleavage to afford isolable disilicon nitrido imino species containing a Si═N─Si─N═CAr 2 unit that hydrolyzes to Ar 2 C═NH, NH 3 , SiO 2 , C 2 B 10 H 12 , and LH. According to density functional theory (DFT) calculations, the N═N cleavage stems from a unique cooperative interaction of the two divalent silicon centers.