Trinuclear mixed-valence complexes with the linear [Rh3]4+ core

Chemical Redox Agents for Organometallic Chemistry

“…In this way, [Fe(CO) 3 (η 4 -cot)] was oxidatively dimerized to [Fe 2 (CO) 6 (η 5 ,η 5′ -C 16 H 16 )][PF 6 ] 2 , 241 and [Rh 3 (µ 3 -L) 2 (CO) 4 (PPh 3 ) 2 ] + (L ) 1,8-naphthyridin-2onate) was oxidized to the mixed-valence complex [Rh 3 (µ 3 -L) 2 (CO) 4 (PPh 3 ) 2 ] 2+ . 242 The applications in organic chemistry of arylaminium cations as catalysts [243][244][245][246][247][248] or as intermediates in indirect electrosynthesis (the amine is added as the mediator) 228,229 have been extensively reviewed. The solid arylaminium salt is usually used in catalytic applications; efficient catalysis is made possible by the stability of both the amine and its radical cation.…”

“…High product yields can be obtained without the need to use the isolated arylaminium cation salts; solutions of [N(C 6 H 4 Br-4) 3 ] + may be generated in situ by treatment of [N(C 6 H 4 Br-4) 3 ] with either [NO] + or Ag + in CH 2 Cl 2 and removal of the byproducts, NO and Ag, by purging the reaction mixture with a stream of nitrogen (or argon) or by filtration, respectively. In this way, [Fe(CO) 3 (η 4 -cot)] was oxidatively dimerized to [Fe 2 (CO) 6 (η 5 ,η 5‘ -C 16 H 16 )][PF 6 ] 2 , and [Rh 3 (μ 3 -L) 2 (CO) 4 (PPh 3 ) 2 ] + (L = 1,8-naphthyridin-2-onate) was oxidized to the mixed-valence complex [Rh 3 (μ 3 -L) 2 (CO) 4 (PPh 3 ) 2 ] 2+ …”

Paramagnetic (Alkene)Rh and (Alkene)Ir Complexes: Metal or Ligand Radicals?

“…Their small g anisotropy and quite weak metal hyperfine couplings suggest that these species might not be real d 9 metal-centered radicals, but are perhaps better described as highly delocalized systems in which the unpaired spin density is substantially spread out over the metal and the trop ligand fragments. This is, however, not very clear and theoretical investigations are probably required to understand the electronic structure of these species.…”

“…Examples are the wire-like tri-and tetranuclear Rh and Ir compounds of the type [Rh 3 (µ 3 -L) 2 (CO) 2 (η 4 -cod) 2 ] 2+ , [9] [Rh 2 Ir(µ 3 -OMe 2 napy) 2 (CO) 2 (cod) 2 ] 2+ , [10] and [M 4 (µ-PyS 2 ) 2 (bis-alkene) 4 ] + (M = Rh, Ir). [11] These "molecular wires" have the unpaired electron delocalized over multiple metal centers, suggestive of potential conducting properties of such wires.…”

Synthesis of Paramagnetic Tetranuclear Rhodium and Iridium Complexes with the 2,6-Pyridinedithiolate Ligand. Redox-Induced Degradation to Diamagnetic Triiridium Compounds

“…The diolefin complexes [Rh 2 (μ-1,8-(NH) 2 C 10 H 6 )(diolefin) 2 ] (diolefin = cod, nbd, tfbb) also exhibit mean g -values in the range 2.149−2.141 in CH 2 Cl 2 at room temperature . Interestingly, the linear trinuclear rhodium complexes ( n = 3) [Rh 3 (μ 3 -Onapy)(CO) 4 (PPh 3 ) 2 ] 2+ and [Rh 3 (μ 3 -OMe 2 napy)(CO) 4 (PPh 3 ) 2 ] 2+ (Onapy = 1,8-naphthyridine-2-onate, OMe 2 napy = 5,7-dimethyl-1,8-naphthyridine-2-onate) show smaller mean g -factors of 2.091 and 2.085, respectively, while the mean g -values for the diolefin trinuclear complexes [Rh 3 (μ 3 -Onapy)(CO) 2 (cod) 2 ] 2+ and Rh 3 (μ 3 -OMe 2 napy)(CO) 2 (cod) 2 ] 2+ , 2.122 and 2.119, respectively, are slightly larger . Although there is less data concerning the mean g -factor in iridium complexes, the mononuclear complex [Ir(C 6 Cl 5 ) 2 (cod)] shows a mean g -value of 2.540, whereas the values found for the dinuclear complexes [Ir 2 (μ-2,5-Me 2 pz)(cod)][BF 4 ] and [Ir 2 (μ-anp)(cod)] + (anp = 2-anilinopyridinato) are 2.34 and 2.27, respectively.…”