The reactivity of antimony and bismuth N , C , N -pincer compounds toward K[BEt 3 H] - the formation of heterocyclic compounds vs . element-element bonds vs. stable terminal Sb-H bonds.

The oxidative addition of CF 3 SO 3 CH 2 Si(CH 3 ) 3 (Np Si OTf) toward organopnictogen(I) N , C , N -pincer compounds, i.e. [2,6-(DippNCH) 2 C 6 H 3 ]E (1-E, where E = Sb, Bi; Dipp = 2,6-iPr 2 C 6 H 3 ) produced compounds [2,6-(DippNCH) 2 C 6 H 3 ]E(Np Si )(OTf) (2-E, where E = Sb, Bi). By analogy, the in situ reduction of [2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]ECl 2 (3-E, where E = Sb, Bi) followed by treatment with Np Si OTf or MeI gave compounds [2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]E(R)(X) (R/X = Np Si /OTf 4-E, where E = Sb, Bi; R/X = Me/I 5-Sb). The reactivity of these compounds toward 1 eq. of K[BEt 3 H] was examined showing remarkable differences depending both on the ligand backbone and the pnictogen used. Thus in the case of 2-E, the addition of the hydride across the imino-function was achieved thereby yielding azapnicta-heterocyclic compounds [2-(DippNCH 2 )-6-(DippNCH)C 6 H 3 ]E(Np Si ) (6-E, where E = Sb, Bi). The same reaction of 4-Bi produced dibismuthine {[2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]Bi(Np Si )} 2 (7-Bi), but in the case of 4/5-Sb the analogous distibines {[2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]Sb(R)} 2 (R = Np Si 7-Sb, Me 8-Sb) were not formed directly and hydrides [2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]Sb(R)H (R = Np Si 9-Sb, Me 10-Sb) could be isolated instead. Nevertheless, heating of both 9-Sb and 10-Sb led to an activation of a labile Sb-H bond and the formation of distibines 7/8-Sb.