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The first derivative of the methylium cation with the triple-decker substituent, [CpCo(C3B2Me5)RuC5Me4CH2]PF6 ( 2PF6), was synthesized from the reaction of the triple-decker complex CpCo(C3B2Me5)RuCp* ( 1) with the salt of the trityl cation [CPh3]+. The X-ray crystal structure of 2PF6 reveals that the methylium carbon is bound to the ruthenium with Ru−C bond length of 2.259 Å and corresponds to the description of its structure as η6-fulvene-ruthenium. Reactions of 2PF6 with nucleophiles OH−, Ph3P, Et3N led to the corresponding derivatives of 1 in high yields. Aromatic amines PhNEt2 and 4-MeC6H4NH2 react with 2PF6 to give the electrophilic aromatic substitution products quantitatively. Chemical reduction of 2PF6 with Zn powder in tetrahydrofuran leads to the formation of the bis(triple-decker) derivative (CpCo(C3B2Me5)RuC5Me4CH2)2 ( 10) with a CH2CH2-bridge. The structures of complexes 4, 7 - 10 were determined by X-ray diffraction. Density functional calculations support the crystallographically determined geometry of 2 and allow rationalization of some characteristics of its structure, spectroscopy, and reactivity. [ABSTRACT FROM AUTHOR]

The reaction of the bromide complexes [CpCo(μ-1,3-C3B2Me5)MBr2]2 [M = Rh ( 1), Ir ( 2); Cp = cyclopentadienyl] with AgBF4 in acetonitrile affords the tris(acetonitrile) μ-diborolyl triple-decker complexes [CpCo(μ-1,3-C3B2Me5)M(MeCN)3]2+ [Rh ( 3), Ir ( 4)]. The labile nitromethane solvates [CpCo(μ-1,3-C3B2Me5)M(MeNO2)3]2+, generated in a similar way, react with benzene and its methylated derivatives to give the arene triple-decker complexes [CpCo(μ-1,3-C3B2Me5)M(arene)]2+ [M = Rh ( 5), Ir ( 6); arene = C6H6 ( a), 1,2,4,5-Me4C6H2 ( b), C6Me6 ( c)]. The structures of 5b(BF4)2, 5c(BF4)2, 6b(BF4)2 and 6c(BF4)2 were determined by X-ray diffraction. The electron-transfer ability of the arene complexes was ascertained by electrochemical techniques. In general, they are able to undergo two separate one-electron reductions reversibly. DFT calculations revealed structural changes caused by redox processes and satisfactorily predicted the redox potentials. The second reduction is accompanied by a η6 → η4 hapticity change of the arene ligand. Energy decomposition analysis revealed that the Rh-benzene bond in cation 5a is weaker than in cyclopentadienyl analogues [(C5R5)Rh(C6H6)]2+; however, 5a proved to be the least reactive in benzene replacement with acetonitrile and mesitylene. [ABSTRACT FROM AUTHOR]

Triple-decker complexes with a bridging diborolyl ligand CpCo(µ-1,3-C3B2Me5)M(CO)3 (M = Mn, 2; Re, 3), CpCo(µ-1,3-C3B2Me5)Ru(CO)2Cl (4) and CpCo(µ-1,3-C3B2Me5)Ru(CO)(µ- CO)2Ru(CO)Cp (5) were synthesized by reaction of the sandwich anion [CpCo(1,3-C3B2Me5)]-- (1) with [(naphthalene)Mn(CO)3]+, [Re(CO)3(THF)2Br]2, or [Ru(CO)3Cl2]2. Structures of 4 and 5 were determined by X-ray diffraction. The spectroelectrochemical behaviour of compounds 2 and 3 was studied. IR-spectroscopical and computational data suggest that anion 1 is significantly stronger donor than Cp- but slightly weaker than Cp*--. [ABSTRACT FROM AUTHOR]

Highlights: [•] The title compound 4 was synthesized with high yield. [•] Triple-decker complex 4 was structurally characterized. [•] The calculated Rh–C2H4 bonding in 4 is 10kcalmol−1 weaker compared to CpRh(C2H4)2. [Copyright &y& Elsevier]

The reaction of CpCo(1,3-C3B2Me5H) ( 1) with CpTl affords the thallium derivative CpCo(1,3-C3B2Me5)Tl ( 2). The structures of 1 and 2 were determined by X-ray diffraction at 100 K. An 'extra' hydrogen atom in 1 occupies a C-H ···B bridging position. According to DFT calculations, 1 exists as a mixture of two enantiomers with an enantiomerization barrier of only 0.5 kcal mol-1. The transition state has Cs symmetry with an endo-CH hydrogen atom. The isomeric iso- 1with the Co-H ···B bridge is less stable than 1 by 10 kcal mol-1.The formation of 1 and iso- 1 from C3B2Me5H and CpCo(C2H4)2 have almost equal activation energies. The isomerization of iso- 1 to 1 was shown to proceed as a two-step hydrogen transfer. The bonding of the 'extra' hydrogen atom in the related CHB-bridged carborane nido-2,3,5-C3B3R5H2 and metallacarboranes M(C5R5)(C3B2R′5H) (R, R′ = H, Me; M = Co, Rh, Ir) as well as their hydridic isomers MH(C5R5)(C3B2R′5) was compared. According to energy decomposition analysis, the bonding of the parent anion [CpCo(1,3-C3B2H5)]- with metal cations becomes stronger in the following order: K+ < Na+ < Tl+ < Li+ < [RuCp]+. The attractive interactions between the [CpCo(1,3-C3B2H5)]- and Tl+ fragments are 68 % electrostatic and 32 % covalent. [ABSTRACT FROM AUTHOR]

Abstract: The dimeric triple-decker type halides [CpCo(μ-1,3-C3B2Me5)MX2]2 (M = Rh, X = Cl, 1; M = Ir, X = Cl, 2; M = Rh, X = Br, 3; M = Ir, X = Br, 4) react with Me2SO and PPh3 giving adducts CpCo(μ-1,3-C3B2Me5)M(L)X2 (5–12). The Me2SO ligand is S-bonded to the metal atom in the solid state, while in acetone it is O-bonded. Structures of 5–12 were confirmed by X-ray diffraction. [Copyright &y& Elsevier]

Abstract: The B-phenylborole complex CpRh(η5-C4H4BPh) (1) reacts with [ML]+ fragments to give the arene-type cationic complexes [CpRh(μ-η5:η6-C4H4BPh)ML]+ (ML=RuCp∗ (3), Co(C4Me4) (4), Rh(cod) (5), and Ir(cod) (6)). Cation 4 undergoes a reversible rearrangement into the triple-decker complex [CpRh(μ-η5:η5-C4H4BPh)Co(C4Me4)]+ (7) under visible light irradiation in CH2Cl2 solution. DFT calculations revealed greater stability of arene-type complexes over triple-decker isomers. The structure of [3]BF4 was determined by X-ray diffraction. [Copyright &y& Elsevier]

• A review of indenyl complexes of Group 9 metals is given. • Synthesis and reactivity of indenyl cobalt, rhodium and iridium complexes are described. • Catalytic applications of indenyl complexes are considered. • Recent advances in C H activation and reductive amination catalyzed by indenyl complexes are reviewed. Since their discovery in 1953, indenyl complexes of Group 9 metals have attracted much attention, due to their high performances in many catalytic processes. The indenyl effect, which is expressed in the facilitation of auxiliary ligand substitution as a result of η5–η3 isomerization of indenyl ligand, allows to formation of an addition vacant coordination site. At the same time, this structural flexibility imposes restrictions on the synthesis of indenyl complexes. In the recent years, significant progress has been achieved in the development of their synthetic methods, especially Rh(III) and Ir(III) derivatives, which has triggered new interest in catalytic application of such compounds. The present review starts with a description of the synthesis and reactivity of cobalt, rhodium and iridium complexes bearing indenyl ligand. At the end, their catalytic applications are given. The influence of the ligand environment and the indenyl effect on the catalytic activity is discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Cyclopentadienyl cobalt complexes have been known since 1953. In the recent years, they have attracted attention of chemists due to their application in C–H activation reactions. The review covers the synthesis of cyclopentadienyl cobalt(III) complexes with diverse auxiliary ligands (such as carbonyl, halides, solvents, arenes, amines, phosphines etc.) as well as their catalytic activity. The influence of auxiliary ligands on the catalytic activity is discussed. [ABSTRACT FROM AUTHOR]