Synthesis and reactions of the triruthenamonocarboncarborane cluster complex [NHMe3][Ru-3(CO)(8)(eta(5)-7-CB10H11)]

In thf (tetrahydrofuran) at reflux temperatures the compounds [Ru-3(CO)(12) ] and [NHMe3][nido-7-CB10H13] give the anionic triruthenium complex [Ru-3(C O)(8)(eta(5)-7-CB10H11)](-), characterized as its [PPh4](+) Salt (4a). Prot onation of [NHMe3][Ru-3(CO)(8)(eta(5)-7-CB10H11)] (4b) with HBF4. Et2O yiel ds the hydride cluster complex [Ru-3(mu-H)(CO)(8)(eta(5)-7-CB10H11)] (5), t he structure of which has been determined by X-ray diffraction. The molecul e has a triangle of ruthenium atoms. One ruthenium atom is Ligated by the e ta(5)-7-CB10H11 cage system and carries two CO groups, while the other two ruthenium atoms each carry three CO molecules with a hydride ligand bridgin g the metal-metal bond which joins them. In addition, these two metal atoms are linked to the cage through two exopolyhedral B-H-->Ru bonds. These are formed using boron atoms lying in beta sites with respect to the carbon in the open CBBBB face of the nido-CB10H11 fragment ligating the Ru(CO)(2) gr oup. Treatment of 4b in thf with [CuCl(PPh3)(3)] in the presence of TlPF6, or with Ag[BF4] and PPh3, affords the bimetallic complexes [Ru-3(mu-H)(CO)( 7)(PPh3){eta(5)-10-M(PPh3)-7-CB10H10}] (M = Cu (6a), Ag (6b)), respectively . The structure of 6a was established by X-ray diffraction. A triangle of r uthenium atoms is formed by Ru(CO)(2), Ru(CO)(3), and Ru(CO)(2)(PPh3) units . This triangle is bridged by a nido-10-Cu(PPh3)-7-CB10H10 fragment, the op en CBBBB face of which is eta(5)-coordinated to the Ru(CO)(2) group. The tw o boron atoms lying in the beta-sites in the CBBBB ring coordinated to the Ru(CO)(2) moiety form exopolyhedral B-H --> Ru and B-Cu-->Ru linkages, resp ectively, to the Ru(CO)(2)(PPh3) and Ru(CO)(3) groups, which have their Ru- Ru bond bridged by a hydride ligand. A novel feature of the structure is a three-center-two-electron B-H-->Cu bond involving the B(2) site in the nido -10-Cu(PPh3)-7-CB10H10 cage system. The reaction between 4b and [AuCl(PPh3) ] gives [Ru-3(mu-H)(CO)(8){eta(5)-10-Au(PPh3)-7-CB10H10}] (6c), the structu re of which was also determined by X-ray crystallography. It is similar to that of 6a, except there is no exopolyhedral B-H-->Au bond supplementing th e B(10)-Au-->Ru and Au-P bonds.