Reactions of Terphenylbismuth Dihalides with KSi(SiMe₃)₃, K₂Si₂(SiMe₃)₄ and Na₂[Fe(CO)]₄: Reduction vs. Metathesis

Abstract

Abstract The reactions of terphenylbismuth dihalides with various reducing agents were investigated. Attempted metathesis of Ar′BiCl 2 [Ar′ = 2,6‐(2,6‐ i Pr 2 ‐C 6 H 3 ) 2 ‐C 6 H 3 ] with one equivalent of KSi(SiMe 3 ) 3 gave the 1,2‐dichlorodibismuthane Ar′(Cl)Bi–Bi(Cl)Ar′ ( 1 ) in 40 % yield. The reaction of Ar′BiCl 2 ( 1 ) with the dianionic salt K 2 Si 2 (SiMe 3 ) 4 yielded the dibismuthene Ar′Bi=BiAr′ ( 2 ) in 72 %. The terphenylbismuth dihalides ArBiCl 2 [Ar = 2,6‐(2,6‐ i Pr 2 ‐C 6 H 3 ) 2 ‐C 6 H 3 (Ar′), 2,6‐(2,4,6‐Me 3 ‐C 6 H 2 ) 2 ‐C 6 H 3 (Ar # )] were treated with Na 2 [Fe(CO) 4 ] in THF to afford the iron dibismuthene complexes [Fe(CO) 4 (Bi 2 Ar′ 2 )] ( 3 ) and [Fe(CO) 4 (Bi 2 Ar # 2 )] ( 4 ) in modest yields (25 and 15 % respectively). The compounds 1 – 4 were characterized by X‐ray crystallography and by spectroscopic methods ( 1 H and 13 C NMR, IR, and UV/Vis spectroscopy). The results show that reduction of the bismuth center is strongly preferred over salt metathesis chemistry due to the reducing power of the silanide and ferrate salts and the strength of the Bi=Bi bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)