Portal de Periódicos da CAPES

Kinetische und mechanistische untersuchungen von übergangsmetallkomplex-reaktionen

1981; Elsevier BV; Volume: 220; Issue: 3 Linguagem: Inglês

10.1016/s0022-328x(00)82283-4

1872-8561

Helmut Fischer, Andreas Motsch,

Organoboron and organosilicon chemistry

Pentacarbonyl(diethylaminocarbyne)chromium tetrafluoroborate, [(CO)5− CrCNEt2]BF4 (I), reacts with PPh3 with substitution of CO and formation of trans-tetracarbonyl(diethylaminocarbyne)triphenylphosphanechromium tetra-fluoroborate, trans-[PPh3(CO)4CrCNEt2]BF4 (III). Substitution of CO by PPh3 in neutral trans-tetracarbonyl(halo)(diethylaminocarbyne)chromium complexes, trans-X(CO)4CrCNEt2 (IVa: X = Br, IVb: X = I), leads in a reversible reaction to the corresponding tricarbonyl complexes, mer-X(PPh3)(CO)3− CrNEt2 (V), PPh3 occupying the cis-position to the carbyne ligand. With PPh3 in large excess both reactions follow a first-order rate law. This as well as the activation parameters (ΔH≠ = 104–113 kJ mol−1, ΔS≠ = 64–71 J mol−1 K−1) indicate a dissociative mechanism. Pentacarbonyl(diethylaminocarbin)chrom-tetrafluoroborat, [(CO)5CrCNEt2]-BF4 (I), reagiert mit PPh3 unter CO-Substitution und Bildung von trans-Tetracarbonyl(diethylaminocarbin)triphenylphosphanchrom-tetrafluoroborat, trans-[PPh3(CO)4CrCNEt2]BF4 (III). Substitution von CO durch PPh3 in neutralen trans-Tetracarbonyl(halogeno)(diethylaminocarbin)chrom-Komplexen, trans-X(CO)4CrCNEt2 (IVa: X = Br, IVb: X = I), führt in reversibler Reaktion zu den entsprechenden Tricarbonyl-Komplexen, mer-X(PPh3)(CO)3CrCNEt2 (V), mit PPh3 in cis-Position zum Carbinliganden. Beide Reaktionen erfolgen mit