Coordination and rearrangement of some organic chalcogenides on a rhodium-rhodium bond; reactions with some strained ring cyclic thioethers and with selenium and tellurium ligands

When the cyclic thioethers L = SCH2CH2CH2, SCH(Me)CH2, and SCH2CH2CH2CH2 were added to [(eta(5)-C5H5)(2)Rh-2(mu-CO)(mu-eta(2):eta(2)-CF3C2CF3)] (1), the coordinative addition products [(eta(5)-C5H5)(2)Rh-2(CO)(mu-eta(1):eta(1)-CF3C2CF3)L] (2a-c) were formed reversibly. When it is left in solution in the presence of excess Ligand, the propylene sulfide complex 2b (L = SCH(Me)CH2) transforms to the bridging sulfide complex [(eta(5)-C5H5)(2)Rh-2{mu-eta(1):eta(1):eta(2)-C(O)C(CF3)}(mu-S)] (3a). A similar reaction occurred, but to a lesser extent, with the trimethylene sulfide complex 2a (L = SCH2CH2CH2). Comparable decompositions do not occur with the I I tetrahydrothiophene complex 2a (L = SCH2CH2CH2CH2). The dimethylselenane complex [(eta(5)-C5H5)(2)Rh-2(CO)(mu-eta(1):eta(1)-CF3C2CF3)(SeMe2)] (4a) was formed reversibly when SeMe2 was added to solutions of 1. The reactions of 1 with the organotelluranes L' = TeMe2 and TeEt2 gave solid addition products [(eta(5)-C5H5)(2)Rh-2(CO)(mu-eta(1):eta(1)-CF3C2CF3)L'] (4b,c), which remained intact when dissolved in polar solvents. No rearrangement products were formed when solutions of the tellurane addition products were kept for several days. The bridging sulfide complex 3a and the analogous complexes [(eta(5)-C5H5)(2)Rh-2{mu-eta(1):eta(1):eta(2)-C(O)C(CF3)C(CF3)}(mu-E)] (3b, E = Se; 3c, E = Te) were obtained from the direct reaction between E and the complex 1. Addition of the cyclic tellurane TeCH2CH2CH2CH2 to 1 gave [(eta(5)-C5H5)(2)Rh-2(CO)(mu-eta(1):eta(1)-CF3C2CF3)(TeCH2CH2CH2CH2)] (6), which underwent rapid intramolecular ligand scrambling in solution. The crystal and molecular structure of 6 was determined by X-ray crystallography.