RESUMEN
The reaction between [IrCl(CO)(PMe(3))(2)] and the Cs[arachno-6-SB(9)H(12)] salt in CH(2)Cl(2) yields pale-yellow 11-vertex [8,8,8-(CO)(PMe(3))(2)-nido-8,7-IrSB(9)H(10)] (4). Reaction of this CO-ligated iridathiaborane with Me(3)N=O affords pale-yellow 11-vertex [1,1,1-(H)(PMe(3))(2)-isonido-1,2-IrSB(9)H(9)] (6), which is also formed from the thermal decarbonylation of 4. Compound 4 has a conventional cluster structure based on classical 11-vertex nido geometry, with the iridium center and the sulfur atom in the adjacent 8- and 7-positions on the pentagonal open face. Compound 6 exhibits an 11-vertex isonido structure based on an octadodecahedron with the {Ir(H)(PMe(3))(2)} occupying the apical position of connectivity six, but with one long non-bonding Ir-B distance generating the quadrilateral isonido open-face. Compound 6 reverts to 4 upon reaction with CO, and the Lewis acid character of 6 is further demonstrated in the reaction with EtNC to give [8,8,8-(EtNC)(PMe(3))(2)-nido-8,7-IrSB(9)H(10)] (7). The three new compounds 4, 6, and 7 have been characterized by single-crystal X-ray diffraction analyses and by NMR spectroscopy. Each of the nido iridathiaboranes 4 and 7 exhibits two different {Ir(L)(PMe(3))(2)}-to-{SB(9)H(10)} conformers in solution and in the solid state. Density functional theory (DFT) calculations reveal that the iridium atom inverts the nido-isonido-closo energy profile previously found for the rhodathiaborane congener [8,8-(PPh(3))(2)-nido-8,7-RhSB(9)H(10)] (3), demonstrating how the structure of these 11-vertex clusters can be controlled and fine-tuned by the tailoring of the metal center.
RESUMEN
A sensitive cluster: The labile rhodathiaborane [(PPh(3))(2)(H)-nido-RhSB(9)H(9)(NC(5)H(5))] combines the redox and coordinative flexibility of the {(PPh(3))(2)(H)Rh} fragment with the capability of the 11-vertex rhodathiaborane cluster to undergo oxidative nido-to-closo transformations induced by coordination of alkynes to the metal centre, which leads to hydrogenation of the triple bond, dehydrogenation of the cluster and oxidative addition of sp C-H bonds.
RESUMEN
The reaction of [Rh(µ-SH)(CO)(PPh(3))](2) or [Rh(µ-SH){P(OPh)(3)}(2)](2) with [Cp*MCl(2)](2) (M = Rh, Ir) in the presence of NEt(3) afforded the Rh(3) and IrRh(2) sulfido-bridged compounds [Cp*M(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (M = Rh, 1; Ir, 2) and [Cp*Rh(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (3). The reaction with [MCl(2)(cod)] (M = Pd, Pt), cis-[PtCl(2)(PPh(3))(2)] or [(η(6)-C(6)H(6))RuCl(2)](2) under the same experimental conditions gave [(cod)M(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (M = Pd, 6; Pt, 7), [(cod)M(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (M = Pd, 8; Pt, 9), [(PPh(3))(2)Pt(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (10) and [(η(6)-C(6)H(6))Ru(µ(3)-S)(2)Rh(2)(CO)(2)(PPh(3))(2)] (12), with PdRh(2), PtRh(2) and RuRh(2) trimetallic cores. The aggregates derived from [Rh(µ-SH)(CO)(PPh(3))](2) were isolated as a mixture of trans and cis isomers in which the trans isomer predominates. The reaction of [Rh(µ-SH){P(OPh)(3)}(2)](2) with 2 equiv. of n-BuLi at 253 K followed by addition of [Cp*IrCl(2)](2) gave [Cp*Ir(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (4) and [Cp*(2)ClIr(2)(µ(3)-S)(2)Rh{P(OPh)(3)}(2)] (5) in a 3 : 2 ratio. The RuRh(2) compound [(η(6)-C(6)H(6))Ru(µ(3)-S)(2)Rh(2){P(OPh)(3)}(4)] (11) was prepared similarly from [Rh(µ-SH){P(OPh)(3)}(2)](2) and [(η(6)-C(6)H(6))RuCl(2)](2) using n-BuLi as a deprotonating agent. The molecular structures of compounds 3, 6, 7, 9 and 11 have been determined by X-ray analysis. The trinuclear complexes exhibit an asymmetric triangular metal core with two triply bridging sulfido ligands resulting in a distorted trigonal-bipyramidal M(3)(µ(3)-S)(2) heterometallic metal-sulfur core.
RESUMEN
The reaction of [8,8-(PPh(3))(2)-nido-8,7-RhSB(9)H(10)] (1) with PR(3) in a 1:2 ratio affords mixtures that contain the mono-substituted bis-PR(3)-ligated rhodathiaboranes [8,8-(PPh(3))(L)-nido-8,7-RhSB(9)H(10)] [L = PMe(2)Ph (5), PMe(3) (6)] and the corresponding tris-PR(3)-ligated compounds [8,8,8-(L)(3)-nido-8,7-RhSB(9)H(10)] [L = PMe(2)Ph (7), PMe(3) (8)]. These latter species are more conveniently prepared from the reaction of 1 with three equivalents of the monodentate phosphines, PMe(2)Ph and PMe(3). Reaction between 1 and PMePh(2) in a 1:2 ratio yields the disubstituted rhodathiaborane [8,8-(PMePh(2))(2)-nido-8,7-RhSB(9)H(10)] (4), whereas the use of three equivalents of phosphine leads to the formation of B-ligated eleven-vertex [8,8,8-(PMePh(2))(2)(H)-nido-8,7-RhSB(9)H(9)-9-(PMePh(2))] (9). Compounds 4-9 have been characterized by NMR spectroscopy, and the structures of 8 and 9 confirmed by X-ray diffraction analyses. The characterization of the cluster compounds has been aided by the use of DFT calculations on some of the species. Variable-temperature NMR studies have demonstrated a lability of the PMePh(2) ligands in compounds 4 and 9, providing mechanistic insights about the ligand substitutional chemistry in these eleven-vertex rhodathiaboranes.