Synthesis of triple-decker iron and cobalt complexes with a central tetramethylphospholyl ligand

30-Electron triple-decker complexes [(η-C₅H₅)Fe(μ-η:η-C₄Me₄P)Fe(η-C₅Me₅)]PF₆ and [(η-C₄Me₄)Co(μ-η:η-C₄Me₄P)Fe(η-C₅Me₅)]PF₆ with a central tetramethylphospholyl ligand were synthesized by stacking reactions of cationic fragments [(η-C₅H₅)Fe]⁺ and [(η-C₄Me₄)Co]⁺ with nonamethylphosphaferrocene (η-C₄Me₄P)Fe(η-C₅Me₅). Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1647–1649, September, 2000.     

Photochemical replacement of benzene in the tetramethylcyclopentadienyl complex of iron, [η-C<Subscript>5</Subscript>Me<Subscript>4</Subscript>H)Fe(η-C<Subscript>6</Subscript>H<Subscript>6</Subscript>)]<Superscript>+</Superscript>

Irradiation of the cation [η-C₅Me₄H)Fe(η-C₆H₆)]⁺+ (1) and Bu^tNC with visible light in acetonitrile results in the displacement of the benzene ligand, giving [(η-C₅Me₄H)Fe(Bu^tNC)₃]+ (2). Reactions of complex 1 with P(OR)₃ and dppe in M_eCN yield the complexes [(η-C₅Me₄H)-Fe(M_eCN)P(OR)_{3 2}]+ (R = Me (3) and Et (4)) and [(η-C₅Me₄H)Fe(MeCN)(dppe)]+ (5) containing two Fe—P bonds. The same reactions in CH₂Cl₂ give the tris(phosphite) complexes [(η-C₅Me₄H)FeP(OR)_{3 3}]+ (6, 7). A photochemical reaction of complex 1 with pentaphos-phaferrocene Cp*Fe(η-cyclo-P₅) yields the triple-decker cation [(η-C₅Me₄H)Fe(μ-η:η-cyclo-P₅)FeCp*]+ (8) with a bridging pentaphospholyl ligand. Structures [2]PF₆ and [3]PF₆ were identified by X-ray diffraction.     

Mono and dinuclear rhodium, iridium and ruthenium complexes containing chelating 2,2′-bipyrimidine ligands: Synthesis, molecular structure, electrochemistry and catalytic properties

The mononuclear cations [(η⁵-C₅Me₅)RhCl(bpym)]⁺ (1), [(η⁵-C₅Me₅)IrCl(bpym)]⁺ (2), [(η⁶-p-PrⁱC₆H₄Me)RuCl(bpym)]⁺ (3) and [(η⁶-C₆Me₆)RuCl(bpym)]⁺ (4) as well as the dinuclear dications [{(η⁵-C₅Me₅)RhCl}₂(bpym)]²⁺ (5), [{(η⁵-C₅Me₅)IrCl}₂(bpym)]²⁺ (6), [{(η⁶-p-PrⁱC₆H₄Me)RuCl}₂(bpym)]²⁺ (7) and [{(η⁶-C₆Me₆)RuCl}₂(bpym)]²⁺ (8) have been synthesised from 2,2′-bipyrimidine (bpym) and the corresponding chloro complexes [(η⁵-C₅Me₅)RhCl₂]₂, [(η⁵-C₅Me₅)IrCl₂]₂, [(η⁶-PrⁱC₆H₄Me)RuCl₂]₂ and [(η⁶-C₆Me₆)RuCl₂]₂, respectively. The X-ray crystal structure analyses of [3][PF₆], [5][PF₆]₂, [6][CF₃SO₃]₂ and [7][PF₆]₂ reveal a typical piano-stool geometry around the metal centres; in the dinuclear complexes the chloro ligands attached to the two metal centres are found to be, with respect to each other, cis oriented for 5 and 6 but trans for 7. The electrochemical behaviour of 1-8 has been studied by voltammetric methods. In addition, the catalytic potential of 1-8 for transfer hydrogenation reactions in aqueous solution has been evaluated: All complexes catalyse the reaction of acetophenone with formic acid to give phenylethanol and carbon dioxide. For both the mononuclear and dinuclear series the best results were obtained (50 °C, pH 4) with rhodium complexes, giving turnover frequencies of 10.5 h⁻¹ for 1 and 19 h⁻¹ for 5.     

Synthesis and characterization of complexes imparting N-pyridyl bonded meso-pyridyl substituted dipyrromethanes

The meso-pyridyl substituted dipyrromethane ligands 5-(4-pyridyl)dipyrromethane (4-dpmane) and 5-(3-pyridyl)dipyrromethane (3-dpmane) have been employed in the synthesis of a series of complexes with the general formulations [(η⁶-arene)RuCl₂(L)] (η⁶-arene = C₆H₆, C₁₀H₁₄) and [(η⁵-C₅Me₅)MCl₂(L)] (M = Rh, Ir). The reaction products have been characterized by microanalyses and spectral studies and molecular structures of the complexes [(η⁶-C₁₀H₁₄)RuCl₂(4-dpmane)] and [(η⁵-C₅Me₅)IrCl₂(3-dpmane)] have been determined crystallographically. For comparative studies, geometrical optimization have been performed on the complex [(η⁵-C₅Me₅)IrCl₂(4-dpmane)] using exchange correlation functional B3LYP. Optimized bond length and angles are in good agreement with the structural data of the complex [(η⁵-C₅Me₅)IrCl₂(3-dpmane)]. The complexes [(η⁶-C₁₀H₁₄)RuCl₂(3-dpmane)], [(η⁵-C₅Me₅)RhCl₂(3-dpmane)] and [(η⁵-C₅Me₅)IrCl₂(3-dpmane)] have been employed as a transfer hydrogenation catalyst in the reduction of aldehydes. It was observed that the rhodium and iridium complexes mentioned above are more effective in this regard in comparison to the ruthenium complex.     

1,2,3,4,7-Pentamethylindenyl complex [(η5-C9H2Me5)RhI2]2 as a synthon for the [(η5-C9H2Me5)Rh]2+ fragment

The reaction of the iodide complex [(η⁵-C₉H₂Me₅)RhI₂]₂ (1) or the acetonitrile complex [(η⁵-C₉H₂Me₅)Rh(MeCN)₃]²⁺ with Tl[Tl(η-7,8-C₂B₉H₁₁)] afforded rhodacarborane (η⁵-C₉H₂Me₅)Rh(7,8-C₂B₉H₁₁) (2). The cationic triple-decker complex with the bridging boratabenzene ligand [Cp*Fe(μ-η:η-C₅H₃Me₂BMe)Rh(η⁵-C₉H₂Me₅)]²⁺ (3) was synthesized by the reaction of the nitromethane solvate [(η⁵-C₉H₂Me₅)Rh(MeNO₂)₃]²⁺ with the sandwich compound Cp*Fe(η-C₅H₃Me₂BMe). The structure of 2 was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1623–1625, August, 2008.     

Iron and ruthenium triple-decker complexes with a central pentaphospholyl ligand

Thirty-electron triple-decker complexes with a central pentaphospholyl ligand [(η-C₅Me₅)Fe(μ-η:η-P₅)M(η-C₅R₅)]BF₄ (M=Fe, R=Me or M=Ru, R=H, Me) were synthesized by a stacking reaction of cationic 12-electron fragments [(η-C₅R₅)M]⁺ with (η-C₅Me₅)Fe(η-P₅). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1625–1626, August, 1998.     

Synthesis of asymmetrical bis(arene) iron complexes

Visible light irradiation of the [(η-C₆H₇)Fe(η-C₆H₆)]⁺ cation (1) in CH₂Cl₂ in the presence of alkyl-substituted benzenes results in arene exchange forming the [(η⁵-C₆H₇)Fe(η-C₆R₆)]⁺ cations (2a–d: C₆R₆ is toluene, p-xylene, mesitylene, and durene). The mixed bis(arene) [(η-C₆H₆)Fe(η-C₆R₆)]²⁺ iron complexes (3a–d) were synthesized by hydride ion abstraction from 2a–d by [Ph₃C]⁺. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1864–1865, September, 2007.     

Mono and dinuclear complexes of half-sandwich platinum group metals (Ru, Rh and Ir) bearing a flexible pyridyl-thiazole multidentate donor ligand

The mononuclear cationic complexes [(η⁶-C₆H₆)RuCl(L)]⁺ (1), [(η⁶-p-ⁱPrC₆H₄Me)RuCl(L)]⁺ (2), [(η⁵-C₅H₅)Ru(PPh₃)(L)]⁺ (3), [(η⁵-C₅Me₅)Ru(PPh₃)(L)]⁺ (4), [(η⁵-C₅Me₅)RhCl(L)]⁺ (5), [(η⁵-C₅Me₅)IrCl(L)]⁺ (6) as well as the dinuclear dicationic complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (7), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (8), [{(η⁵-C₅H₅)Ru(PPh₃)}2(L)]²⁺ (9), [{(η⁵-C₅Me₅)Ru(PPh₃)}₂(L)]²⁺ (10), [{(η⁵-C₅Me₅)RhCl}₂(L)]²⁺ (11) and [{(η⁵-C₅Me₅)IrCl}₂(L)]²⁺ (12) have been synthesized from 4,4′-bis(2-pyridyl-4-thiazole) (L) and the corresponding complexes [(η⁶-C₆H₆)Ru(μ-Cl)Cl]₂, [(η⁶-p-ⁱPrC₆H₄Me)Ru(μ-Cl)Cl]₂, [(η⁵-C₅H₅)Ru(PPh₃)₂Cl)], [(η⁵-C₅Me₅)Ru(PPh₃)₂Cl], [(η⁵-C₅Me₅)Rh(μ-Cl)Cl]₂ and [(η⁵-C₅Me₅)Ir(μ-Cl)Cl]₂, respectively. All complexes were isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV-vis spectroscopy. The X-ray crystal structure analyses of [3]PF₆, [5]PF₆, [8](PF₆)₂ and [12](PF₆)₂ reveal a typical piano-stool geometry around the metal centers with a five-membered metallo-cycle in which 4,4′-bis(2-pyridyl-4-thiazole) acts as a N,N′-chelating ligand.     

Routes to Higher Nuclearity Mixed-Metal Carbonyl Clusters Using the [Rh(η<Superscript>5</Superscript>-C<Subscript>5</Subscript>Me<Subscript>5</Subscript>)(NCMe)<Subscript>3</Subscript>]<Superscript>2+</Superscript> Dication as a Building Block

Reaction of the [Rh(η⁵-C₅Me₅)(NCMe)₃]²⁺ (1) dication with the hexaosmium [Os₆(CO)₁₇]²⁻ (2) dianion leads to the initial formation of [Os₆(CO)₁₇Rh(η⁵-C₅Me₅)] (3). This cluster readily adds CO to form [Os₆(CO)₁₈Rh(η⁵-C₅Me₅)] (4) which has been characterised crystallographically. 3 also adds dihydrogen to give [Os₆H₂(CO)₁₇Rh(η⁵-C₅Me₅)] (5) and undergoes a substitution reaction with PPh₃ to form [Os₆(CO)₁₆(PPh₃)Rh(η⁵-C₅Me₅)] (6). With the [Ru₆(CO)₁₈]²⁻ (7) dianion, [Rh(η⁵-C₅Me₅)(NCMe)₃]²⁺ (1) reacts to form three mixed-metal clusters [Ru₅(CO)₁₅Rh(η⁵-C₅Me₅)] (8), [Ru₆(CO)₁₈Rh(η⁵-C₅Me₅)] (9) and [Ru₆(CO)₁₈Rh₂(η⁵-C₅Me₅)₂] (10). The clusters have been characterised spectroscopically and the structures of 8 and 10 have been confirmed crystallographically. The cluster 8 undergoes a substitution reaction with P(OMe)₃ to form the disubstituted product [Ru₅(CO)₁₃(P(OMe)₃)₂Rh((η⁵-C₅Me₅)] (11) which has also been characterised crystallographically.     

Synthesis, characterisation and theoretical studies on some piano-stool ruthenium and rhodium complexes containing substituted phenyl imidazole ligands

Reactions of the chloro-bridged arene ruthenium complexes [{(η⁶-arene)RuCl(μ-Cl}₂] (η⁶-arene = benzene, p-cymene) and structurally analogous rhodium complex [{(η⁵-C₅Me₅)RhCl(μ-Cl}₂] with imidazole based ligands viz., 1-(4-nitro-phenyl)-imidazole (NOPI), 1-(4-formylphenyl)-imidazole (FPI) and 1-(4-hydroxyphenyl)-imidazole (HPI) have been investigated. The resulting complexes have been characterised by elemental analyses, IR, ¹H and ¹³C NMR, electronic absorption and emission spectral studies. Crystal structure of the representative complex [(η⁵-C₅Me₅)RhCl₂(NOPI)] has been determined crystallographically. Geometrical optimisation on the complexes have been performed using exchange correlation functional B3LYP. Optimised bond lengths and angles of the complexes have been found to be in good agreement with our earlier reports and single crystal X-ray data of the complex [(η⁵-C₅Me₅)RhCl₂(NOPI)].