The Ullmann Coupling Reaction:  A New Approach to Tetraarylstannanes

• Published in: Organometallics Vol. 25; no. 17; pp. 4207 - 4214
• Main Authors: Shaikh, Nadim S, Parkin, Sean, Lehmler, Hans-Joachim
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 14.08.2006; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Physical Sciences; Science & Technology; ARYLTIN CHEMISTRY; SPECTRA; DERIVATIVES; PCB-84 ENANTIOMERS
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om060456a

Several iodobenzenes form tetraarylstannanes, in addition to other products, under reaction conditions typically employed for the Ullmann reaction, i.e., activated copper bronze (a copper−tin alloy) and 7 days at 230 °C. The isolated yields of the tetraarylstannanes were low to good (8−58%). Significantly higher yields (54−64%) of tetraphenylstannane were obtained by the direct reaction of iodobenzene with an excess of tin powder (iodobenzene:tin = 1:1 w/w) under the same conditions. Crystal structure analysis reveals that tetrakis(4-carbomethoxyphenyl)stannane crystallizes in a tetragonal space group and has 4̄ symmetry, which is the case for many symmetrical tetraarylstannanes. However, tetrakis(2,4-dichlorophenyl)stannane, tetrakis(3,4-dichlorophenyl)stannane, and tetrakis(2,4-dimethylphenyl)stannane do not crystallize in a tetragonal space group and do not have real 4̄ symmetry.