Studies with the ruthenacarborane complex [Ru(CO) (PPh3)(THF)(eta(5)-7,8-C2B9H11)]: Reactions with terminal alkynes

摘要

The syntheses of the complexes [Y] [RuX(L)(PPh3)(eta(5)-7,8-C2B9H11)] (X = Cl, Y = K(18-crown-6), L = CO (1), PPh3 (2); X = I, Y = NEt4, L = CO (3)) are reported, and the structure of 3 has been established by an X-ray diffraction study. The anion adopts the "piano stool" structure with the ruthenium atom eta(5)-coordinated on one side by a nido-7,8-C2B9H11 group and on the other by the CO, PPh3, and I ligands. Treatment of 1 with TlPF6 in THF (tetrahydrofuran) affords solutions of the labile species [Ru(THF)(CO)(PPh3)(eta(5)-7,8-C2B9H11)] (5), which readily react with a 3-fold excess of the monosubstituted alkynes RC=CH(R = Ph, Bu-t, SiMe3). The product from PhC=CH is [Ru(CO)(PPh3)(eta(2): eta(5)-9-(E)-C(H)=C(H)Ph-7,8-C2B9H10)] (8), the structure of which was determined by X-ray crystallography: The metal atom is eta(5)-coordinated by the open face of the nido-7,8-C2B9 cage and also eta(2)-coordinated by the C=C bond of the E-C(H)=C(H)Ph group, the latter being attached to a boron atom in an alpha-site with respect to the carbons of the CCBBB ring ligating the ruthenium. Reaction between 5 and (BuC)-C-t=CH gives [Ru(CO)(PPh3)(eta(2):eta(5)-9-(E)-C(H)=C(H)Bu-t-10-(E)-C(H)=C(H)Bu-t-7,8-C 2B9H9)] (9), The eta(2) bonding mode of the 9-(E)-C(H)=C(H)Bu-t group to the metal is displaced in reactions with PMe3, CNBut, and CO, yielding the species [Ru(CO)(PPh3)(L)(eta(5)-9, 10-{(E)-C(H)=C(H)Bu-t}(2)-7,8-C2B9H9)] L= PMe3 (10), CNBut(11), CO (12)). The alkyne Me3SiC=CH reacts with 5 in the presence of traces of moisture to give [Ru(CO)(PPh3)(eta(2): eta(5)-9-C(H)=CH2-7,8-C2B9H10)] (13), having a molecular structure closely related to that of 8, as confirmed by an X-ray diffraction study. Compound 13 reacts with CNBut to afford [Ru(CO)(PPh3)(CNBut)(eta(5)-9-C(H)=CH2-7,8-C2B9H10)] (14), studied by X-ray diffraction, and with PMe3 to give the ylide complex [Ru(CO)(PPh3)(sigma:eta(5)-9-C(H)(PMe3)CH2-7,8-C2B9H10)] (15). The NMR data (H-1, C-13(H-1), B-11(H-1}) are reported and discussed. [References: 17]