Arene Exchange in the Ruthenium–Naphthalene Complex [CpRu(C₁₀H₈)]⁺

Abstract

Substitution of the naphthalene ligand in [CpRu(C10H8)]+ (1; Cp = cyclopentadienyl ligand) by other arenes occurs upon heating or visible‐light irradiation and gives complexes [CpRu(arene)]+ [arene = C6HnMe6–n, C6H5OH, C6H5OMe, C6H4(OMe)2, indene, 2,2‐paracyclophane] in 70–90 % yield. The reaction rate increases with coordinating ability of the solvent, CH2Cl2 < THF/CH2Cl2 < Me2CO, and counterion, [B(3,5‐(CF3)2C6H3)4]– < PF6– < BF4– < CF3SO3–. Acceptor or bulky substituents in the incoming arene slow down the exchange. Complexes with acceptor arenes C6H5COMe, C6H5COOH, and C6H4(COOH)2 were obtained by the exchange reaction in water. Complexes [CpRu(η6‐cycloheptatriene)]+ and [CpRu(η6‐cyclooctatetraene)]+ were obtained by irradiation of 1 with the corresponding cyclic polyenes. A similar reaction with α‐phellandrene is accompanied by dehydrogenation to give [CpRu(cymene)]+. Cation 1 reacts with 2‐naphthoic acid anion to give the zwitterionic complexes [CpRu]+[C10H7COO]– in which the [CpRu]+ fragment coordinates either at the substituted or unsubstituted ring. Upon protonation and subsequent irradiation, both isomers convert into [CpRu(C10H7COOH)]+ in which the metal atom coordinates only to the unsubstituted ring. The structures of [CpRu(p‐xylene)][PF6], [CpRu(2,2‐paracyclophane)][PF6], [CpRu(C6H5COOH)][BF4], and [CpRu(cymene)][BPh4] were determined by X‐ray diffraction.

DFT study of inter-ring haptotropic rearrangement in CpRu+ complexes of polycyclic aromatic ligands

“…Finally, it should be noted that IRHR processes can be also accelerated with the use of UV/vis irradiation, as demonstrated by Perekalin et al [16] in the case of substituted naphthalene complexes (Scheme 5) for which the rearrangement is much faster than when thermally induced even at low temperature after deprotonating of the corresponding acid in water.…”

Preparation and Structural Characterization of [CpRu(1,10‐phenanthroline)(CH3CN)][X] and Precursor Complexes (X=PF6, BArF, TRISPHAT‐N)

“…The Ru⋅⋅⋅ Cp distance of 1.811 Å in complex [1][BAr F ] is similar that observed for [1][PF 6 ] [59] and [1][TRISPHAT] [60] complexes (TRISPHAT=Tris(tetrachlorobenzenediolato)phosphate) but significantly shorter than the corresponding distance in [CpRu(benzene)][PF 6 ] derivative (1.845 Å) [61,62] . However, the Ru⋅⋅⋅ Naph distances 1.719, 1.717 and 1.725 Å for [1][PF 6 ] , [1][BAr F ] and [1][TRISPHAT] respectively, are longer than that reported for the benzene complex highlighting the known higher lability of naphthalene [62] . As observed for other [1][X] complexes, the bond lengths of the two quaternary carbons of the bicyclic ring were longer (0.05 Å) than other Ru−C Naphthalene bonds [59,60] .…”

“…[61,62] respectively, are longer than that reported for the benzene complex highlighting the known higher lability of naphthalene. [62] As observed for other [1][X] complexes, the bond lengths of the two quaternary carbons of the bicyclic ring were longer (0.05 Å) than other RuÀ C Naphthalene bonds. [59,60] The RuÀ C Cp (average 2.166 Å) in [1][BAr F ] is shorter than others reported for [CpRu(η 6 -naphthalene)] complexes.…”

Synthesis of Ruthenium Half‐Sandwich Complexes by Naphthalene Replacement in [CpRu(C10H8)]+

“…Chemical shifts are given in ppm relative to internal SiMe 4 ( 1 H) or external 85 % H 3 PO 4 ( 31 P). The preparation of [ 1 ][BF 4 ] was performed similar to a literature procedure 15,19c…”