The synthesis and reactivity of the thiophyne and furyne clusters [Ru3(CO)7(mu-dppm)(mu3-eta2-C4H2E)(mu-P(C4H3E)2)(mu-H)] (E = S, O) is reported. Addition of P(C4H3E)3 to [Ru3(CO)10(mu-dppm)] (1) at room temperature in the presence of Me3NO gives simple substitution products [Ru3(CO)9(mu-dppm)(P(C4H3E)3)] (E = S, 2; E = O, 3). Mild thermolysis in the presence of further Me3NO affords the thiophyne and furyne complexes [Ru3(CO)7(mu-dppm)(mu3-eta2-C4H2E)(mu-P(C4H3E)2)(mu-H)] (E = S, 4; E = O, 6) resulting from both carbon-hydrogen and carbon-phosphorus bond activation. In each the C4H2E (E = S, O) ligand donates 4-electrons to the cluster and the rings are tilted with respect to the mu-dppm and the phosphido-bridged open triruthenium unit. Heating 4 at 80 degrees C leads to the formation of the ring-opened cluster [Ru3(CO)5(mu-CO)(mu-dppm)(mu3-eta3-SC4H3)(mu-P(C4H3S)2)] (5) resulting from carbon-sulfur bond scission and carbon-hydrogen bond formation and containing a ring-opened mu3-eta3-1-thia-1,3-butadiene ligand. In contrast, a similar thermolysis of 3 affords the phosphinidene cluster [Ru3(CO)7(mu-dppm)(mu3-eta2-C4H2O)(mu3-P(C4H3O))] (7) resulting from a second phosphorus-carbon bond cleavage and (presumably) elimination of furan. Treatment of 4 and 6 with PPh3 affords the simple phosphine-substituted products [Ru3(CO)6(PPh3)(mu-dppm)(mu3-eta2-C4H2E)(mu-P(C4H3E)2)(mu-H)] (E = S, 8; E = O, 9). Both thiophyne and furyne clusters 4 and 6 readily react with hydrogen bromide to give [Ru3(CO)6Br(mu-Br)(mu-dppm)(mu3-eta2-eta1-C4H2E)(mu-P(C4H3E)2)(mu-H)] (E = S, 10; E = O, 11) containing both terminal and bridging bromides. Here the alkynes bind in a highly unsymmetrical manner with one carbon acting as a bridging alkylidene and the second as a terminally bonded Fisher carbene. As far as we are aware, this binding mode has only previously been noted in ynamine complexes or those with metals in different oxidation states. The crystal structures of seven of these new triruthenium clusters have been carried out, allowing a detailed analysis of the relative orientations of coordinated ligands.
Heating a mixture of Ir(4)(CO)(9)(PPh(3))(3) (1) and 2 equiv of C(60) in refluxing chlorobenzene (CB) affords a "butterfly" tetrairidium-C(60) complex Ir(4)(CO)(6){mu(3)-kappa(3)-PPh(2)(o-C(6)H(4))P(o-C(6)H(4))PPh(eta(1)-o-C(6)H(4))}(mu(3)-eta(2):eta(2):eta(2)-C(60)) (3, 36%). Brief thermolysis of 1 in refluxing chlorobenzene (CB) gives a "butterfly" complex Ir(4)(CO)(8){mu-k(2)-PPh(2)(o-C(6)H(4))PPh}{mu(3)-PPh(2)(eta(1):eta(2)-o-C(6)H(4))} (2, 64%) that is both ortho-phosphorylated and ortho-metalated. Interestingly, reaction of 2 with 2 equiv of C(60) in refluxing CB produces 3 (41%) by C(60)-assisted ortho-phosphorylation, indicating that 2 is the reaction intermediate for the final product 3. On the other hand, reaction of Ir(4)(CO)(8)(PMe(3))(4) (4) with excess (4 equiv) C(60) in refluxing 1,2-dichlorobenzene, followed by treatment with CNCH(2)Ph at 70 degrees C, affords a square-planar complex with two C(60) ligands and a face-capping methylidyne ligand, Ir(4)(CO)(3)(mu(4)-CH)(PMe(3))(2)(mu-PMe(2))(CNCH(2)Ph)(mu-eta(2):eta(2)-C(60))(mu(4)-eta(1):eta(1):eta(2):eta(2)-C(60)) (5, 13%) as the major product. Compounds 2, 3, and 5 have been characterized by spectroscopic and microanalytical methods, as well as by single-crystal X-ray diffraction studies. Cyclic voltammetry has been used to examine the electrochemical properties of 2, 3, 5, and a related known "butterfly" complex Ir(4)(CO)(6)(mu-CO){mu(3)-k(2)-PPh(2)(o-C(6)H(4))P(eta(1)-o-C(6)H(4))}(mu(3)-eta(2):eta(2):eta(2)-C(60)) (6). These cyclic voltammetry data suggest that a C(60)-mediated electron transfer to the iridium cluster center takes place for the species 3(3)(-) and 6(2)(-) in compounds 3 and 6. The cyclic voltammogram of 5 exhibits six well-separated reversible, one-electron redox waves due to the strong electronic communication between two C(60) cages through a tetrairidium metal cluster spacer. The electrochemical properties of 3, 5, and 6 have been rationalized by molecular orbital calculations using density functional theory and by charge distribution studies employing the Mulliken and Hirshfeld population analyses.
The extensive use of [60]fullerene, the most abundant member of the fullerene family, as a ligand in organometallic chemistry has been attributed to its pivotal role in material science owing to its unique electronic, optical, and magnetic properties. [1] In particular, the interaction of a carbon cluster such as C 60 with metal clusters has been a topic of great interest in exohedral metallofullerene chemistry, [2] because C 60 -metal cluster complexes have a direct analogy to carbon nanotubes decorated with metal nanoparticles.[3] Furthermore, they exhibit very strong electronic communication between C 60 and metal-cluster centers that can be fine-tuned by ligands attached to the metal atoms.[2a] As part of our studies on the chemistry of C 60 -metal cluster complexes, we examined the reaction between the phosphane-substituted iridium carbonyl cluster [Ir 4 (CO) 9 (PPh 3 ) 3 ] (1) [4] and C 60 . We demonstrated a new behavior of C 60 as a noninnocent ligand, stemming from its multifunctionality, for the chemical transformation of ligands on the cluster surface. Here we report a novel C 60 -induced formation of a P-(C) n -P-(C) n -P moiety by a series of ortho-phosphanation and ortho-metalation reactions of phosphanes on a tetrairidium butterfly framework (Scheme 1).Heating a mixture of 1 and 2 equiv of C 60 in refluxing chlorobenzene (CB) for 2 h afforded [Ir 4 (CO) 6 {m 3 -PPh 2 (o-C 6 H 4 )P(o-C 6 H 4 )PPh(h 1 -o-C 6 H 4 )}(m 3 -h 2 :h 2 :h 2 -C 60 )] (3) in moderate yield (36 %). Thermolysis of 1 in refluxing CB gave [Ir 4 (CO) 8 {m-PPh 2 (o-C 6 H 4 )PPh}{m 3 -PPh 2 (h 1 :h 2 -o-C 6 H 4 )}] (2) in 64 % yield. Reaction of 2 with C 60 in refluxing CB produced 3 in 41 % yield, that is, 2 is indeed the reaction intermediate for the final product 3 (see Scheme 1 and Experimental Section). The formulas of 2 and 3 were established by microanalytical data and molecular-ion isotope multiplets at m/z 1624 for 2 and 2210 for 3 in the positive-ion FAB mass spectra.The molecular structures of 2 and 3 are shown in Figures 1 and 2, respectively. Both complexes exhibit a butterfly geometry of four iridium atoms, in which the two wings are nearly perpendicular to each other, as was observed in previously reported wingtip-bridged Ir 4 butterfly complexes.[5]The P1 atom bearing two phenyl groups in 2 is coordinated to the Ir4 center, and the two wingtip Ir atoms are almost symmetrically bridged by the P2 atom. An o-phenylene group bridges the P1 and P2 atoms in the bidentate diphosphane moiety Ph 2 P(o-C 6 H 4 )PPh, which in turn forms a five-membered metallacyclic P1-C301-C306-P2-Ir4 moiety on the cluster. Another interesting structural feature of 2 is the presence of a m 3 -PPh 2 (h 1 :h 2 -o-C 6 H 4 ) ligand (a five-electron donor), which is coordinated through P3 to the Ir3 atom by an IrÀC(phenylene) s bond to the Ir2 center, and by an h
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