Novel [60]Fullerene‐Assisted ortho‐Phosphanation on a Tetrairidium Butterfly Framework

Abstract

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

Spectroscopic Characterization of μ-η1:η1-Peroxo Ligands Formed by Reaction of Dioxygen with Electron-Rich Iridium Clusters

“…This lack of phosphine oxidation is consistent with the general oxidative stability of phosphines bound to noble metals, as observed by the group of Strukul when working with Pt­(II) complexes incorporating phosphine ligands, in the presence of excess hydrogen peroxide. Furthermore, the fragmentation of an Ir–Ir bond in the tetrahedral frame to synthesize a butterfly structure would have led to spectral complexity much greater than what was observed, with new bands appearing and bands disappearing (frequencies and the symmetry of the IR bands in the CO region would have necessarily changed). , …”

“…63 Furthermore, the fragmentation of an Ir-Ir bond in the tetrahedral frame to synthesize a butterfly structure would have led to much greater spectral complexity than was observed, with new bands appearing and bands disappearing (frequencies and the symmetry of the IR bands in the CO region would have necessarily changed). 64,65 Because these changes were reversed in a stoichiometrically simple reaction when the clusters were exposed to O2, we infer that the formation of the bridging peroxo ligands took place concomitantly with the removal of hydride ligands. The mass spectra show that the latter were removed as H2 but not water.…”

Stabilization of coordinatively unsaturated Ir4clusters with bulky ligands: a comparative study of chemical and mechanical effects

“…32,33 Related surface reconstruction phenomena have been extensively characterized in functional systems dealing with catalysis on surfaces and selective adsorption.…”

21 Fullerenes

“…164 Reaction of [60]fullerene with [Ir 4 (CO) 9 (PPh 3 ) 3 ] results in the formation of a novel P-(C) n -P-(C) n -P moiety in the product, [Ir 4 (CO) 6 {m 3 -PPh 2 (o-C 6 H 4 )P(o-C 6 H 4 )PPh(g 1 -o-C 6 H 4 )}(m 3 -g 2 :g 2 :g 2 -C 60 )] via a series of ortho-phosphanation and ortho-metalation reactions of phosphanes on the tetrairidium butterfly network. 165 Reaction of Rh 6 (CO) 12 (dppm) 2 (where dppm = 1,2-bis(diphenylphosphino)methane) with [60]fullerene affords a face capped [60]fullerene derivative, Rh 6 (CO) 9 (dppm) 2 )(m 3 -g 2 :g 2 :g 2 -C 60 ) which was used to generate a bisfullerene sandwich complex, Rh 6 (CO) 5 (dppm) 2 )(CNCH 2 C 6 H 5 )(m 3g 2 :g 2 :g 2 -C 60 ) after further reaction. 166 A [60]fulleropyrrolidine decatungstatosilicate hybrid has been prepared and found to be a useful photocatalyst in water.…”