“…24 The average Ir-Re distances are 2.879 Å in the iridium-capped, carbido cluster, [Re 7 C(CO) 21 Ir(η 2 -C 2 H 4 )(CO)] 2-, 25 and 2.914(1) Å in the linear compound, {Re(CO) 5 } 2 IrH(CO) 3 . 26 The cluster [IrRe 3 (µ-H)(CO) 16 ] -has an average Ir-Re distance of 2.93 Å within the IrRe 2 triangle and a distance of 2.935 Å for the spike Ir-Re bond. 11 The dinuclear compound, IrRe(µ-CO) 2 -(CO) 2 (η 5 -C 5 H 5 )(η 5 -C 5 Me 5 ), containing semi-bridging CO ligands, has an Ir-Re distance of 2.8081(6) Å.…”
The slow addition of Re(2)(&mgr;-H)(2)(CO)(8) to a solution of Ir(CO)(eta(2)-C(8)H(14))(eta(5)-C(9)H(7)) in hexane at reflux provides IrRe(2)(&mgr;-H)(2)(CO)(9)(eta(5)-C(9)H(7)) (1) in 80% yield. The molecular structure of 1 shows an IrRe(2) triangle incorporating one Ir(CO)(eta(5)-C(9)H(7)) and two Re(CO)(4) fragments. The strongly different Ir-Re distances suggest that one hydride ligand bridges one Ir-Re edge and the other hydride bridges the Re-Re edge. Low-temperature (1)H and (13)C NMR spectra are consistent with this structure; at higher temperatures a dynamic process involving migration of one hydride ligand between the two Ir-Re edges is observed. Cluster 1 is readily deprotonated with KOH/EtOH, and the resulting anion has been isolated as the PPN salt, [PPN][IrRe(2)(&mgr;-H)(CO)(9)(eta(5)-C(9)H(7))] (2). Both the (1)H and low temperature (13)C NMR spectra of 2 are consistent with a structure in which the remaining hydride ligand bridges the Re-Re edge. Variable-temperature (13)C NMR spectra indicate that 2 undergoes CO scrambling localized on the Ir-Re edges. The reaction of 1 with PPh(3) leads to IrRe(2)(&mgr;-H)(2)(CO)(8)(PPh(3))(eta(5)-C(9)H(7)) (3), which contains the phosphine on a rhenium atom, as well as to cluster fragmentation.
“…24 The average Ir-Re distances are 2.879 Å in the iridium-capped, carbido cluster, [Re 7 C(CO) 21 Ir(η 2 -C 2 H 4 )(CO)] 2-, 25 and 2.914(1) Å in the linear compound, {Re(CO) 5 } 2 IrH(CO) 3 . 26 The cluster [IrRe 3 (µ-H)(CO) 16 ] -has an average Ir-Re distance of 2.93 Å within the IrRe 2 triangle and a distance of 2.935 Å for the spike Ir-Re bond. 11 The dinuclear compound, IrRe(µ-CO) 2 -(CO) 2 (η 5 -C 5 H 5 )(η 5 -C 5 Me 5 ), containing semi-bridging CO ligands, has an Ir-Re distance of 2.8081(6) Å.…”
The slow addition of Re(2)(&mgr;-H)(2)(CO)(8) to a solution of Ir(CO)(eta(2)-C(8)H(14))(eta(5)-C(9)H(7)) in hexane at reflux provides IrRe(2)(&mgr;-H)(2)(CO)(9)(eta(5)-C(9)H(7)) (1) in 80% yield. The molecular structure of 1 shows an IrRe(2) triangle incorporating one Ir(CO)(eta(5)-C(9)H(7)) and two Re(CO)(4) fragments. The strongly different Ir-Re distances suggest that one hydride ligand bridges one Ir-Re edge and the other hydride bridges the Re-Re edge. Low-temperature (1)H and (13)C NMR spectra are consistent with this structure; at higher temperatures a dynamic process involving migration of one hydride ligand between the two Ir-Re edges is observed. Cluster 1 is readily deprotonated with KOH/EtOH, and the resulting anion has been isolated as the PPN salt, [PPN][IrRe(2)(&mgr;-H)(CO)(9)(eta(5)-C(9)H(7))] (2). Both the (1)H and low temperature (13)C NMR spectra of 2 are consistent with a structure in which the remaining hydride ligand bridges the Re-Re edge. Variable-temperature (13)C NMR spectra indicate that 2 undergoes CO scrambling localized on the Ir-Re edges. The reaction of 1 with PPh(3) leads to IrRe(2)(&mgr;-H)(2)(CO)(8)(PPh(3))(eta(5)-C(9)H(7)) (3), which contains the phosphine on a rhenium atom, as well as to cluster fragmentation.
“…The presence of a bridging hydride apparently is the key factor in determining the L-shape of these 50 valence electron trinuclear clusters. In fact [Mn 3 (CO) 14 ] - , [MnFeMn(CO) 14 ], [ReIrReH(CO) 13 ], and many others, which lack a bridging hydride, have a linear metal skeleton. However, when a pseudotetrahedral metal atom is forced in the middle position, like in [(CO) 2 CpRuZr(Cp) 2 RuCp(CO) 2 ], an L-shaped skeleton is also observed.…”
The addition of [M(CO) 5 ] -anions (M ) Re, Mn) to the electronically unsaturated [Re 2 (µ-H) 2 (CO) 8 ] complex rapidly and selectively gives the trinuclear anions [ReM(CO) 9 {(µ-H)ReH-(CO) 4 }] -(M ) Re, 2; M ) Mn, 3). The single-crystal X-ray analysis of [NEt 4 ]2 has revealed a fully staggered L-shaped structure. The anion 2 has been obtained with good selectivity also by reacting (i) [Re 2 (CO) 9 (THF)] with [H 2 Re(CO) 4 ] -and (ii) [HRe 2 (CO) 9 ] -with [HRe-(CO) 5 ]. The last reaction can be reversed upon treatment with CO. The reaction of the trinuclear open cluster [Re 2 (CO) 9 {(µ-H)Re(CO) 5 }] with [H 2 Re(CO) 4 ] -affords 2 as well, evenif not quantitatively. 1 H and 13 C NMR spectra of 2 show conformational freedom around both the Re-Re interactions and a dynamic process exchanging the two hydrides and the carbonyls trans to them (E a ) 67(2) kJ/mol). This last is attributable to a windshield-wiper motion of the H 2 Re(CO) 4 fragment around the two trans diaxial carbonyls. The exchange of the hydrides with comparable ∆G q has been observed also for 3, suggesting that the same type of motion is occurring. 13 C-NMR studies of the related [Re 2 (CO) 9 {(µ-H)Re(CO) 5 }] complex have shown the facile mobility of the bridging hydride between the two metal-metal interactions (at variance with the anion 2), resulting in a "dynamic" C 2v symmetry of the molecule in solution. Upon heating, the anion 2 looses CO and gives irreversibly the previously known triangular cluster anion [Re 3 (µ-H) 2 (CO) 12 ] -. The addition of a strong acid (CF 3 SO 3 H) results in fragmentation of the trinuclear skeleton of 2, affording [HRe(CO) 5 ] and [Re 2 (µ-H) 2 (CO) 8 ].
“…A comparison of selected bond lengths and angles for the compounds Re 4 , Re 3 Pt , RePt 3 , and Pt 4 is given in Table . This comparison shows that the mixing of Re(CO) 3 and PtMe 3 fragments to form heterometallic hydroxy cubanes causes only slight perturbation to the general structure adopted by these compounds. , The M−O bond distances are essentially invariant, but the M−O-M and O−M-O angles show smooth variations. 2 Structural diagram of RePt 3 showing the atomic labeling scheme (35% thermal ellipsoids).…”
Section: Resultsmentioning
confidence: 86%
“…This comparison shows that the mixing of Re(CO) 3 and PtMe 3 fragments to form heterometallic hydroxy cubanes causes only slight perturbation to the general structure adopted by these compounds. 21 shifts of the platinum methyl groups also progress downfield with increasing rhenium incorporation, and the 1 H-195 Pt coupling constant depends systematically on the environment of the trans hydroxyl group. The stepwise increase in coupling as the hydroxyl is shared with more rhenium centers reflects its decreasing donor ability.…”
The heterobimetallic hydroxy cubanes {Re(CO)3}4
-
n
{PtMe3}
n
(OH)4 (n = 1−3) have been synthesized and characterized by analytical and spectroscopic data. The structures of Re
3
Pt and RePt
3
have been determined by X-ray crystallography.
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