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[RuCl(arene)(μ-Cl)]2 dimers were treated in a 1:2 molar ratio with sodium or thallium salts of bis- and tris(pyrazolyl)borate ligands [Na(Bp(Br3))], [Tl(Tp(Br3))], and [Tl(Tp(iPr, 4Br))]. Mononuclear neutral complexes [RuCl(arene)(κ(2)-Bp(Br3))] (1: arene=p-cymene (cym); 2: arene=hexamethylbenzene (hmb); 3: arene=benzene (bz)), [RuCl(arene)(κ(2)-Tp(Br3))] (4: arene=cym; 6: arene=bz), and [RuCl(arene)(κ(2)-Tp(iPr, 4Br))] (7: arene=cym, 8: arene=hmb, 9: arene=bz) have been always obtained with the exception of the ionic [Ru2 (hmb)2-(μ-Cl)3][Tp(Br3)] (5'), which formed independently of the ratio of reactants and reaction conditions employed. The ionic [Ru-(CH3OH)(cym)(κ(2)-Bp(Br3))][X] (10: X=PF6, 12: X=O3SCF3) and the neutral [Ru(O2CCF3)(cym)(κ(2)-Bp(Br3))] (11) have been obtained by a metathesis reaction with corresponding silver salts. All complexes 1-12 have been characterized by analytical and spectroscopic data (IR, ESI-MS, (1)H and (13)C NMR spectroscopy). The structures of the thallium and calcium derivatives of ligand Tp(Br3), [Tl(Tp(Br3))] and [Ca(dmso)6][Tp(Br3)]2 ⋅2 DMSO, of the complexes 1, 4, 5', 6, 11, and of the decomposition product [RuCl(cym)(Hpz(iPr, 4Br))2][Cl] (7') have been confirmed by using single-crystal X-ray diffraction. Electrochemical studies showed that 1-9 and 11 undergo a single-electron Ru(II) →Ru(III) oxidation at a potential, measured by cyclic voltammetry, which allows comparison of the electron-donor characters of the bis- and tris(pyrazol-1-yl)borate and arene ligands, and to estimate, for the first time, the values of the Lever EL ligand parameter for Bp(Br3), Tp(Br3), and Tp(iPr, 4Br). Theoretical calculations at the DFT level indicated that both oxidation and reduction of the Ru complexes under study are mostly metal-centered with some involvement of the chloride ligand in the former case, and also demonstrated that the experimental isolation of the μ(3)-binuclear complex 5' (instead of the mononuclear 5) is accounted for by the low thermodynamic stability of the latter species due to steric reasons., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The modification of conjugated organic compounds with organometallic moieties allows the modulation of the electronic and optoelectronic properties of such compounds and lends them to a variety of material applications. The organometallic complexes [M(Cp′)(L) n ] (M = Ru or Fe; Cp′ = cyclopentadiene (Cp) or pentamethylcyclopentadiene (Cp*); (L) n = (PPh3)2 or 1,2-bi(diphenylphosphino)ethane (dppe)) and [M(L) n ] (M = Ru; (L) n = (dppe)2 or (P(OEt)3)4; or M = Pt; (L) n = (PEt3)2, (PPh3)2 or tricyclohexylphosphine, (PCy3)2) modified with a 5-ethynyl-1,3,3-trimethyl-3 H -indole ligand were prepared and characterised by NMR spectroscopy, IR and single-crystal X-ray diffraction. Cyclic voltammetry and IR spectroelectrochemistry of the ruthenium systems showed a single-electron oxidation localised over the M–C≡C–aryl moiety. The N-heteroatom of the indole ligand showed Lewis base properties and was able to extract a proton from a vinylidene intermediate as well as coordinate to CuI. Examples from the wire-like compounds were also studied by single-molecule break junction experiments but molecular junction formation was not observed. This is most likely attributable to the binding characteristics of the substituted terminal indole groups used here to the gold contacts. A series of organometallic σ-alkynyl complexes incorporating the 3 H -indole moiety were designed and synthesised. The complexes were studied using electrochemical and spectroelectrochemical techniques. The N-heteroatom of the indole ligand showed Lewis base properties and could extract a proton from a vinylidene intermediate and coordinate to CuI. [ABSTRACT FROM AUTHOR]

A convenient modification to the established synthetic routes for the preparation of complexes [M(CRCR)(dppe)Cp'] (M = Fe, Ru; Cp' = η5-C5H5 (Cp), η5-C5Me5 (Cp*); R = C6H5, C6H4-p-OMe, C6H4-p-NO2, tBu) and [Ru(CRCR)(PPh3)2Cp] from the corresponding [MCl(PP)Cp0] complex and the alkyne HCRCR via an intermediate vinylidene is described. The complexes are generally obtained as high quality crystalline samples directly from the reaction mixture. In agreement with previous studies, the iron complexes undergo a predominantly metal-centred oxidation, whilst there is greater involvement of the acetylide ligand in the oxidation processes associated with the ruthenium analogues. Analysis of the redox properties and spectroelectrochemical investigations reveal limited differences in the gross electronic structures of the Cp vs. Cp* derivatives in each of the Fe and Ru series. [ABSTRACT FROM AUTHOR]

Reactions of [Ru{C=C(H)‐1,4‐C6H4C≡CH}(PPh3)2Cp]BF4 ([1 a]BF4) with hydrohalic acids, HX, results in the formation of [Ru{C≡C‐1,4‐C6H4‐C(X)=CH2}(PPh3)2Cp] [X=Cl (2 a‐Cl), Br (2 a‐Br)], arising from facile Markovnikov addition of halide anions to the putative quinoidal cumulene cation [Ru(=C=C=C6H4=C=CH2)(PPh3)2Cp]+. Similarly, [M{C=C(H)‐1,4‐C6H4‐C≡CH}(LL)Cp ]BF4 [M(LL)Cp'=Ru(PPh3)2Cp ([1 a]BF4); Ru(dppe)Cp* ([1 b]BF4); Fe(dppe)Cp ([1 c]BF4); Fe(dppe)Cp* ([1 d]BF4)] react with H+/H2O to give the acyl‐functionalised phenylacetylide complexes [M{C≡C‐1,4‐C6H4‐C(=O)CH3}(LL)Cp'] (3 a–d) after workup. The Markovnikov addition of the nucleophile to the remote alkyne in the cations [1 a–d]+ is difficult to rationalise from the vinylidene form of the precursor and is much more satisfactorily explained from initial isomerisation to the quinoidal cumulene complexes [M(=C=C=C6H4=C=CH2)(LL)Cp']+ prior to attack at the more exposed, remote quaternary carbon. Thus, whilst representative acetylide complexes [Ru(C≡C‐1,4‐C6H4‐C≡CH)(PPh3)2Cp] (4 a) and [Ru(C≡C‐1,4‐C6H4‐C≡CH)(dppe)Cp*] (4 b) reacted with the relatively small electrophiles [CN]+ and [C7H7]+ at the β‐carbon to give the expected vinylidene complexes, the bulky trityl ([CPh3]+) electrophile reacted with [M(C≡C‐1,4‐C6H4‐C≡CH)(LL)Cp'] [M(LL)Cp'=Ru(PPh3)2Cp (4 a); Ru(dppe)Cp* (4 b); Fe(dppe)Cp (4 c); Fe(dppe)Cp* (4 d)] at the more exposed remote end of the carbon‐rich ligand to give the putative quinoidal cumulene complexes [M{C=C=C6H4=C=C(H)CPh3}(LL)Cp']+, which were isolated as the water adducts [M{C≡C‐1,4‐C6H4‐C(=O)CH2CPh3}(LL)Cp'] (6 a–d). Evincing the scope of the formation of such extended cumulenes from ethynyl‐substituted arylvinylene precursors, the rather reactive half‐sandwich (5‐ethynyl‐2‐thienyl)vinylidene complexes [M{C=C(H)‐2,5‐cC4H2S‐C≡CH}(LL)Cp']BF4 ([7 a–d]BF4 add water readily to give [M{C≡C‐2,5‐cC4H2S‐C(=O)CH3}(LL)Cp'] (8 a–d)]. [ABSTRACT FROM AUTHOR]

[RuCl(arene)(μ-Cl)]2 dimers were treated in a 1:2 molar ratio with sodium or thallium salts of bis- and tris(pyrazolyl)borate ligands [Na(Bp [ABSTRACT FROM AUTHOR]

Keywords: alkynes; cumulenes; electrophiles; metal acetylides; ruthenium EN alkynes cumulenes electrophiles metal acetylides ruthenium 7143 7143 1 06/08/20 20200605 NES 200605 B The formation of "quinoidal cumulenes" b is inferred from a series of trapping reactions using ruthenium and iron vinylidene and alkynyl precursors with a variety of nucleophilic and electrophilic species. This is illustrated in the cover artwork (designed by Brady Johnston) by the transformation of a ruthenium vinylidene complex, wherein the terminal alkyne moiety reacts with water to give a corresponding acetyl group. Alkynes, cumulenes, electrophiles, metal acetylides, ruthenium. [Extracted from the article]

The electronic structures of the prototypical bimetallic buta-1,3-diyn-1,4-diyl-bridged radical cation complexes [{M(dppe)Cp'}2(μ-C=CC=C)]+ (M= Fe, Cp' = Cp* (1a), Cp (1b); M = Ru, Cp' = Cp* (2a), Cp (2b)) have been (re)investigated using a combination of UV-vis-NIR and IR spectroelectrochemistry, and quantum chemical calculations based on both dispersion-corrected global (BLYP35-D3) and local (Lh-SsirPW92-D3) hybrid functionals. Following analysis of new and existing data, including the IR-active ν(C=C) bands, the iron compounds [1]+ are reclassified as valence-trapped (Robin and Day Class II) mixed-valence complexes, in contrast to the ruthenium complexes [2]+, which are delocalized (Robin and Day Class III) systems. All members of the series exist as a thermally populated distribution of conformers in solution, and the overlapping spectroscopic profiles make the accurate extraction of the parameters necessary for the analysis of [1]+ and [2]+ within the framework of the Marcus-Hush model extremely challenging. Analysis of the spin-density distributions from a range of conformational minima provides an alternative representation of the degree of charge localization, and a comparison between members of the series is presented. [ABSTRACT FROM AUTHOR]

Reactions between [Ru(C CC CH)(dppe)Cp ∗ ] and [M 2 (NCMe) x (dppm) 2 ] 2+ (M = Cu, x = 4; Ag, x = 2) have given complexes containing M 3 (μ-dppm) 3 clusters attached to one or two C CC C[Ru(dppe)Cp ∗ ] groups. Single crystal X-ray studies are recorded for [{M 3 (μ-dppm) 3 }{μ 3 -C CC C[Ru(dppe)Cp ∗ ]}](BF 4 ) 2 ·nS (M = Cu, Ag) [isomorphous (orthorhombic) for S = (ill-defined) acetone]. A different (triclinic) polymorph has also been defined for M = Ag, nS = 5THF. Together with [{Cu 3 (μ-dppm) 3 }{μ 3 -C CC C[Ru(dppe)Cp ∗ ]} 2 ]PF 6 ·4Me 2 CO, the structures definitively confirm the complexes as clear examples of mono- or bis-diyndiyl-M 3 systems, devoid of close approaches to the vacant M 3 faces of the former by counterions in the case of their acetone solvates, except in the case of the BF 4 counterion in the AgBF 4 /thf solvate. Cyclic voltammetric studies suggest that there are only weak electronic interactions between the ruthenium centres in the bis(diynyl) complexes, consequent upon weak overlaps between the carbon chain and the M 3 (μ-dppm) 3 clusters, as confirmed by DFT calculations on model complexes [{M 3 (μ-dHpm) 3 }{C CC C[Ru(dHpe)Cp]} n ] 3-n [n = 1, 2; dHpm = CH 2 (PH 2 ) 2 , dHpe = H 2 P(CH 2 ) 2 PH 2 ]. The complexes [Ag 3 Cl 2 (dppm) 3 ]PF 6 , [M 3 (μ-dppm) 3 (X){μ 3 -C CC C[Re(CO) 3 (Bu t 2 -bpy)]}]PF 6 (M = Cu, X = C CC C[Re(CO) 3 (Bu t 2 -bpy)]; M = Ag; X = Cl), [Ag 6 (μ-dppm) 4 {C CC C[Re(CO) 3 (Bu t 2 -bpy)]} 4 ](PF 6 ) 2 have also been prepared and structurally characterised. In the M 3 clusters, some asymmetry in the attachment of at least one of the μ 3 ligands is apparent, which results from interactions with solvate molecules. [ABSTRACT FROM AUTHOR]