Alkinstabilisierte monomere Organo-Kupfer(I)-Verbindungen als Organyl-Transfer Reagenzien

The reaction chemistry of the monomeric organo-copper(I) species {[Ti](CCR 1 ) 2 }CuR {[Ti]=(η 5 -C 5 H 4 SiMe 3 ) 2 Ti; R 1 =SiMe 3 : 1a , R=CH 3 ; 1b , R=C 6 H 5 ; 1c , R=C 6 H 4 OMe-4; 1d , R=CC t Bu; 1e , R=CCSiMe 3 ; R 1 = t Bu: 8a , R=CCSiMe 3 ; 8b , R=CH 3 } towards different inorganic and organic reagents is described. On treatment of 1a – 1e with one equivalent of X 2 ( 2a : X=Br, 2b : X=I) selective cleavage of the copper–carbon σ-bond is observed, producing {[Ti](CCSiMe 3 ) 2 }CuX ( 4a : X=Br, 4b : X=I) along with RX (X=Br: 3a , R=CH 3 ; 3b , R=C 6 H 5 ; 3c , R=C 6 H 4 OMe-4; 3d , R=CC t Bu; 3e , R=CCSiMe 3 ; X=I: 3f , R=CCSiMe 3 ; 3g , R=CC t Bu). Treatment of {[Ti](CCSiMe 3 ) 2 }CuCCR 3 ( 1d : R 3 = t Bu, 1e : R 3 =SiMe 3 ) with ICN ( 7 ) produces {[Ti](CC t Bu) 2 }CuCN ( 9 ) and 3f or 3g . Copper–carbon σ-bond cleavage is also obtained, when 1a or 8b is treated with stoichiometric amounts of HX ( 10a : X=Br, 10b : X=Cl), NH 4 Cl or NEt 3 HCl. In contrast, a carbon–carbon coupling is observed when {[Ti](CCR 1 ) 2 }CuR ( 1 , 8 ) is reacted with R 2 X (R 2 =CH 3 , CH 2 CH 3 , CH 2 C 6 H 5 , CCSiMe 3 ; X=Cl, Br, I) in a 1:1 molar ratio. This yields R 2 R and {[Ti](CCR 1 ) 2 }CuX (R 1 =SiMe 3 : 4a , X=Br; 4b : X=I; 4c : X=Cl; R 1 = t Bu: 11a : X=Cl; 11b : X=Br; 11c : X=I). The latter molecules can be transformed into the corresponding starting materials 1 or 8 by their reaction with, e.g., LiR ( 5 ). However, when aromatic halides, such as IC 6 H 4 Me-4, are added to {[Ti](CCSiMe 3 ) 2 }CuCCR 3 ( 1d : R 3 = t Bu, 1e : R 3 =SiMe 3 ), elimination of Me 3 SiCCR 3 takes place and the titanium(IV)–copper(I) acetylide {[Ti](CCSiMe 3 )(CCCu)} 2 ( 15 ) is formed. In addition, organo copper(I) compounds can be considered as key molecules in the decarboxylative bromination of copper(I) carboxylates: heating the copper(I)-carboxylate {[Ti](CCSiMe 3 ) 2 }CuO 2 CR 2 ( 6a : R 2 =CH 3 , 6b : R 2 =C 6 H 5 ) to 100°C produces the organo copper(I) species 1a and 1b by loss of CO 2 . On treatment of 1a and 1b with equimolar amounts of Br 2 , oxidative cleavage of the CuC σ-bond is induced and {[Ti](CCSiMe 3 ) 2 }CuBr ( 4a ) as well as R 2 Br are formed. Complex 4a can be transformed to the starting material 6a or 6b by subsequent reaction with AgO 2 CR 2 (R 2 =CH 3 , C 6 H 5 ) on precipitation of AgBr. All compounds synthesized were characterized by elemental analysis and spectroscopy (IR, 1 H-NMR, 13 C{ 1 H}-NMR). The organic products were characterized additionally by GC–mass spectrometry.