One pot grafting of tetrairon(III) single molecule magnets on silicon

Herein we report on the Si grafting of two Fe₄ derivatives, [Fe₄(Lⁱ)₂(tmhd)₆], in which tmhd is 2,2,6,6-tetramethylheptane-3,5-dionate and H₃Lⁱ = R–C(CH₂OH)₃ is a tripodal ligand with R = CH₂CH–CH₂–O–CH₂ (H₃L¹) and CH₂CH–(CH₂)₉–O–CH₂ (H₃L²). These complexes were specifically designed to be directly anchored on the H-terminated silicon surface via the hydrosilylation reaction. The complexes were grafted by a one pot route based on the photoinduced hydrosilylation followed by a ligand exchange step in the same reaction solution. The resulting decorated surfaces were characterized using X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared spectroscopy (ATR-IR) and atomic force microscopy (AFM).     

DFT study of group 8 catalysts for the hydrophenylation of ethylene: Influence of ancillary ligands and metal identity

Computational methods are used to investigate catalytic hydrophenylation of ethylene using complexes of the type [(Y)M(L)(CH₃)(NCMe)]ⁿ⁺ [Y = Mp, n = 1; Y = Tp, n = 0; M = Ru or Os; L = PMe₃, PF₃, or CO; Mp = tris(pyrazolyl)methane; Tp = hydrido-tris(pyrazolyl)borate]. The conversion of ethylene and benzene to ethylbenzene with [(Y)M(L)(Ph)]ⁿ⁺ as catalyst involves four steps: (1) ethylene coordination, (2) ethylene insertion into the M–Ph bond, (3) benzene coordination, and (4) benzene C–H activation. DFT calculations form the basis to compare stoichiometric benzene C–H activation by [(Y)M(L)(CH₃)(NCMe)]ⁿ⁺ complexes to yield methane and [(Y)M(L)(Ph)(NCMe)]ⁿ⁺. In addition, starting from the 16-electron species [(Y)M(L)(Ph)]ⁿ⁺, potential energy surfaces for the formation of ethylbenzene are calculated to reveal the impact of modifications to the scorpionate ligand (Mp or Tp), co-ligand (L) and metal center (M).     

Enol ethers and acetals: acylation with dichloroacetyl,acetyl and benzoyl chloride in ionic liquid medium

Synthesis of 4-alkoxy-1,1-dichloro-3-alken-2-ones [CHCl₂C(O)C(R²)C(R¹)-OR, where R, R¹, R² = Et, H, H; Me, Me, H; Et, H, Me; Me, –(CH₂)₂–; Me, –(CH₂)₃–; Et, Et, H; Et, Bu, H; Et, i-Pr, H; Et, i-Bu, H; Me, Ph, H; Me, thien-2-yl, H] from acylation of enol ethers and acetals with dichloroacetyl chloride, in ionic liquid ([BMIM][BF₄] or [BMIM][PF₆]) is reported. The synthesis of alkenones [R³–C(O)C(R²)C(R¹)-OR], where R/R¹/R²/R³ = Et/H/H/Ph, t-Bu/H/H/Ph, Me/-(CH₂)₄/Ph, Me/-(CH₂)₄/Me] from the reaction of enol ethers with benzoyl chloride or acetyl chloride, in ionic liquid [BMIM][BF₄], is also reported. Last products are described for the first time.     

Synthesis,characterization and reactions of the transition metal halogenoalkyl carbocation complexes [Cp(CO)2M{η2-CH2CH(CH2)nX}]PF6 (n = 1–8, 10, M = Fe; n = 3, 4 M = Ru; X = Br,I)

The halogenoalkyl complexes [Cp(CO)₂M{(CH₂)_nX}] (n = 3–10, 12, M = Fe; n = 5, 6, M = Ru, X = Br, I) react with Ph₃CPF₆ in dry CH₂Cl₂ to give the corresponding carbocation complexes [Cp(CO)₂M{η²-(CH₂CH(CH₂)_n?2X}]PF₆ in high yields. NMR evidence indicates that the metals form metallacyclopropane type structures with the carbocation ligand. The reactions of some of the cationic complexes with NaI, PPh₃, Na[Cp(CO)₂Fe] and Et₃N are discussed. NaI and Na[Cp(CO)₂Fe] displace the halogeno-olefin, while PPh₃ adds at the β-CH^δ+ giving the unstable phosphonium adducts [Cp(CO)₂Fe{CH₂CH(PPh₃)(CH₂)_n?2X}]PF₆ which decompose to the halogeno-olefins and the cationic PPh₃ complex [Cp(CO)₂Fe(PPh₃)]⁺. Et₃N causes allylic deprotonation forming internal olefin complexes of the type [Cp(CO)₂Fe{CH₂CHCH(CH₂)_n?3X}]PF₆.     

Dialkyl- and diaryl-platinum(II) complexes with secondary phosphines: Preparation,structure and thermal reaction giving the metallopolymer

Alkyl and arylplatinum complexes with 1,5-cyclooctadiene ligand, [PtR₂(cod)] (R = Me, Ph, C₆H₄-p-CF₃, C₆F₅), react with secondary phosphines, PHR′₂ (R′ = i-Bu, t-Bu, Ph), to afford the mononuclear platinum complexes, cis-[PtR₂(PHR′₂)₂] (1a: R = Me, R′ = i-Bu; 1b: R = Me, R′ = t-Bu; 1c: R = Me, R′ = Ph; 2a: R = Ph, R′ = i-Bu; 2b: R = Ph, R′ = t-Bu; 2c: R = R′ = Ph; 3a: R = C₆H₄-p-CF₃, R′ = i-Bu; 3b: R = C₆H₄-p-CF₃, R′ = t-Bu; 3c: R = C₆H₄-p-CF₃, R′ = Ph; 4a: R = C₆F₅, R′ = i-Bu; 4c: R = C₆F₅, R′ = Ph) in 81–98% yields. Molecular structures of the complexes except for 1a, 1c and 2a were determined by X-ray crystallography. Complex 1b has a square-planar structure with Pt–C(methyl) bonds of 2.083(8) and 2.109(8) Å, while the Pt–C(aryl) bonds of 2b–c, 3a–c, 4a and 4c (2.055(1)–2.073(8) Å) are shorter than them. Thermal decomposition of 1b, 2a–c, and 3a–c releases methane, biphenyl or 4,4′-bis(trifluoromethyl)biphenyl as the organic products, which are characterized by NMR spectroscopy. The solid product of the thermal reactions of 2b and 2c were characterized as the metallopolymers formulated as [Pt(PR′₂)₂]_n (5b: R′ = ^tBu; 5c: R′ = Ph), based on the solid-state NMR and elemental analyses.     

Palladium and platinum complexes with planar chiral 1,2-disubstituted ferrocenes containing phosphine and thioether donor groups

Three palladium(II) complexes and four platinum(II) complexes having general formula CpFe{1,2-C₅H₃(PPh₂)(CH₂SR)}MCl₂ (M = Pd, R = Ph, Et and tBu; M = Pt, R = Ph, Et, tBu and Cy) have been synthesized by reaction of the corresponding CpFe{1,2-C₅H₃(PPh₂)(CH₂SR)} ligands with PdCl₂(CH₃CN)₂ or PtCl₂(CH₃CN)₂. These complexes have been fully characterized in solution and in solid state. In all cases, monomeric square planar complexes were obtained as pure diastereoisomers.     

Isonitrile ligand properties as studied by He I/He II photoelectron spectroscopy

A new series of isonitrile-substituted cobalt tricarbonyl nitrosyl (Co(CO)₂(NO)CNR, R = Me, Et, ⁿPr, ⁱPr, ⁿBu, ⁿPe, CH₂Si(CH₃)₃) has been synthesized, and their He I ultraviolet photoelectron spectra are reported. The assignment of the bands in the low energy part of the spectra was performed with the aid of DFT calculations. The first vertical ionization energies of the complexes were found to be 7.73 (CNMe), 7.58 (CNEt), 7.59 (CNⁿPr), 7.70 (CNⁿBu), 7.67 (CNⁿPe), 7.77 (CNⁱPr), and 7.54 ± 0.03 eV (CNCH₂Si(CH₃)₃). In the case of ⁿPr- and CH₂Si(CH₃)₃- substitutions, He II photoelectron spectra were also recorded. The relative importance of electronic and steric effects of the isonitrile ligands, as a function of the size of group –R, is discussed.     

Insertion of ketenes into lanthanocene n-butylamide and imidazolate complexes

Reaction of Cp₂LnNHⁿBu with 1 equiv. of Ph₂CCO in toluene affords dimeric complexes [Cp₂Ln(OC(CHPh₂)NⁿBu)]₂ [Ln = Yb (1), Dy (2)], derived from a formal insertion of the CC bond of the ketene into the N–H bond. Treatment of CpErCl₂ with 2 equiv. of LiNHⁿBu followed by reacting with Ph₂CCO affords a rearrangement product [Cp₂Er(OC(CHPh₂)NⁿBu)]₂ (3). Treatment of [Cp₂Ln(μ-Im)]₃ (Im = imidazolate) with PhRCCO gives [Cp₂Ln(μ-OC(Im)CPhR)]₂ [R = Et, Ln = Yb (4); R = Ph, Ln = Yb (5), Er (6)]. In contrast to the previous observations that [Cp₂ErNⁱPr₂]₂ and [Cp₂ErNHEt]₂ react with ketenes to give di-insertion products, in the present cases the presence of excess of ketenes has no influence on the final product even with prolonged heating and only monoinsertion products are isolated. All these complexes were characterized by elemental analysis, IR and mass spectroscopies. The structures of complexes 1 and 3–6 were also determined through X-ray single crystal diffraction analysis.     

Mono- and di-nuclear complexes of thiosemicarbazones with copper(I): Synthesis,spectroscopy and structures

Reactions of copper(I) halides with a series of thiosemicarbazones, namely, benzaldehyde thiosemicarbazone (R¹R²CN–NH–C(S)–NH₂, R¹ = Ph, R² = H; Hbtsc), 2-benzoylpyridine thiosemicarbazone (R¹ = Ph, R² = py; Hbpytsc), and acetone thiosemicarbazone (R¹ = R² = Me; Hactsc), in the presence of PPh₃ has formed dimeric complexes, viz. sulfur bridged [Cu₂(μ-S-Hbtsc)₂Br₂(PPh₃)₂]·2H₂O (1), iodo-bridged [Cu₂(μ-I)₂(η¹-S-Hbtsc)₂(PPh₃)₂] (2), and heterobridged [Cu₂(μ₃-S,N³-Hactsc)(η¹-Br)(μ-Br)(PPh₃)₂] (3), as well as mononuclear complexes [CuX(η¹-S-Hbpytsc)(PPh₃)₂]·CH₃CN (X = Br, 4; Cl, 5). Complexes 1, 2, 4 and 5 involve thiosemicarbazone ligands in η¹-S bonding mode while in compound 3, ligand acts in N³, S-chelation-cum-S-bridging mode (μ₃-S,N³ mode). The intermolecular interactions such as, N²H?X, HN¹H?X (X = S, Br, Cl), CH?π interactions lead to 2D networks. All the complexes have been characterized with the help of elemental analyses, IR, ¹H, and ³¹P NMR spectroscopy, and single crystal X-ray crystallography. The role of a solvent in alteration of nuclearity and bonding modes of complexes has been highlighted.     

Oxidative addition of MeI to cationic Rh(I) carbonyl complexes with pyridyl bis(carbene) ligands

A series of cationic Rh(I) carbonyl complexes of the form [Rh(CO)(L)]PF₆ (where L = 2,6-bis (alkylimidazol-2-ylidene)-pyridine; alkyl = Me (1a), Et (1b), CH₂Ph (1c)) have been prepared by the reactions of [Rh(CO)₂(OAc)]₂ with diimidazolium pyridine salts in the presence of NEt₃. The ν(CO) values for 1 are ca. 1982 cm⁻¹, indicating that the N-heterocyclic carbene ligands impart high electron density on the Rh(I) centres, despite the overall cationic charge. Each of the Rh(I) complexes reacts with MeI to form two isomeric Rh(III) methyl species, and a third unidentified species. Kinetic measurements on the MeI oxidative addition reactions give second-order rate constants (MeCN, 25 °C) of 0.0927, 0.0633 and 0.0277 M⁻¹ s⁻¹ for 1a, 1b and 1c, respectively. Comparison of these data with those for related Rh(I) carbonyl complexes shows that 1 have remarkably high nucleophilicity for cationic species.     

An FT-IR study of the isomerization of 1-butoxy radicals under atmospheric conditions

Relative rate-studies of the reactions of 1-butoxy radicals have been carried out using a 47 L static reactor with detection of end products by FT-IR spectroscopy. Experiments were performed at 700 torr total pressure and over the temperature range 253–295 K. The chemistry of 1-butoxy is characterized by a competition between reaction with oxygen CH₃CH₂CH₂CH₂O + O₂ → n-C₃H₇CHO + HO₂ (R2), which yields butanal and isomerization CH₃CH₂CH₂CH₂O → CH₂CH₂CH₂CH₂OH (R3), to form a hydroxylated carbonyl-product. A reference spectrum attributed to the product of 1-butoxy isomerization was obtained and used to determine the competition between 1-butoxy isomerization versus reaction with oxygen. The results indicate that isomerization is the dominant fate of 1-butoxy radicals at ambient temperature and pressure and that its importance decreases with decreasing temperature. The rate-coefficient ratio k₃/k₂ (molecule cm⁻³) = 5.5 × 10²³ exp[(−25.1 ± 0.9 kJmol⁻¹)/RT] was obtained. This agrees with other estimates based on methods without monitoring of the isomerization product.     

Nickel-catalysed asymmetric SN2′ substitution chemistry of Baylis–Hillman derived allylic electrophiles

Unsymmetrical PhCHCH(CH₂X)(CO₂Me) (X = Cl, OAc) undergoes regioselective α-substitution with AlMe₃ to afford (E)-PhCHCH(Et)(CO₂Me) under Ni(acac)₂ catalysis. On the addition of planar chiral Ferrophite ligands [(R)-CpFe(1,2-C₅H₃Ar{P(OR)₂}) (Ar = Ph, 4-CF₃Ph, 3,5-Me₂Ph, 1-naphthyl; (OR)₂ = 1,1′-binaphthylene, 1,1′-biphenylene)] regioselective methylation γ to the leaving group is possible. It is proposed that the bulky Ferrophite ligand leads to an intermediate nickel allyl species Ni^II(Me)(Ferrophite){η³-PhCHCHCH(CO₂Me)} that adopts a configuration whereby the PhCH terminus of the π-allyl and the Ni–Me are syn leading to good regio (up to 6.4:1) and stereo (up to 94% ee) selectivities.     

Organoselenium(II) complexes containing organophosphorus ligands. Crystal and molecular structure of PhSeSP(S)Ph2, [2-{MeN(CH2CH2)2NCH2}C6H4]SeSP(S)R′2 (R′ = Ph,OPri) and [2-{O(CH2CH2)2NCH2}C6H4]SeSP(S)(OPri)2

Arylselenium(II) derivatives of dithiophosphorus ligands of type ArSeSP(S)R₂ [Ar = Ph, R = Ph (1), OPrⁱ (2); 2-[MeN(CH₂CH₂)₂NCH₂]C₆H₄, R = Ph (3), OPrⁱ (4); 2-[O(CH₂CH₂)₂NCH₂]C₆H₄, R = OPrⁱ (6)] were prepared by redistribution reactions between Ar₂Se₂ and [R₂P(S)S]₂. The derivative [2-{O(CH₂CH₂)₂NCH₂}C₆H₄]SeSP(S)Ph₂ (5) was obtained by the salt metathesis reaction between [2-{O(CH₂CH₂)₂NCH₂}C₆H₄]SeCl and NH₄S₂PPh₂. The compounds were investigated by multinuclear (¹H, ¹³C, ³¹P, ⁷⁷Se) NMR and infrared spectroscopy. The crystal and molecular structures of 1, 3, 4 and 6 were determined by single-crystal X-ray diffraction. In compounds 3, 4 and 6 the N(1) atom is intramolecularly coordinated to the selenium center, resulting in a T-shaped geometry (hypervalent 10-Se-3 species). The dithiophosphorus ligands act as anisobidentate in 1 and monodentate in 3, 4 and 6. Supramolecular architectures based on intermolecular S?H and N?H contacts between molecular units are formed in the hypervalent derivatives 3 and 4, while in the compounds 1 and 6 the molecules are associated into polymeric chains through either Se?S or O?H contacts, with no further inter-chain interactions.     

Synthesis,molecular structure and reactivity of new π-conjugated diyne with ferrocenyl and phenyl units

New π-conjugated butadiynyl ligand FcC(CH₃)₂Fc′–CC–CC–Ph (L₁) has been synthesized and its reaction with Co₂(CO)₈ has been studied. New clusters [FcC(CH₃)₂Fc′–CC–CC–Ph][Co₂(CO)₆]_n [(1): n = 1; (2): n = 2] and [Fc–CC–CC–Ph][Co₂(CO)₆]_n [(3): n =  1; (4): n = 2] were obtained by the reaction of ligands FcC(CH₃)₂Fc′–CC–CC–Ph (L₁) and Fc–CC–CC–Ph (L₂) with Co₂(CO)₈ respectively and the composition and structure of the clusters and ligands have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR and MS. The crystal structures of compounds L₁, L₂, 2 and 4 have been determined by X-ray single crystal analysis.     

Reaction of the RuTp(PR3)Cl fragment with alkynols: Formation of carbene,vinylidene, allenylidene,and carbyne complexes

The reaction of RuTp(COD)Cl (1) with PR₃ (PR₃ = PPh₂ⁱPr, PⁱPr₃, PPh₃) and propargylic alcohols HCCCPh₂OH, HCCCFc₂OH (Fc = ferrocenyl), and HCCC(Ph)MeOH has been studied.In the case of PR₃ = PPh₂ⁱPr, PⁱPr₃ and HCCCPh₂OH, the 3-hydroxyvinylidene complexes RuTp(PPh₂ⁱPr)(CCHC(Ph)₂OH)Cl (2a) and RuTp(PⁱPr₃)(CCHC(Ph₂)OH)Cl (2b) were isolated.With PR₃ = PPh₂ⁱPr and HCCCFc₂OH as well as with PR₃ = PPh₃ and HCCCPh₂OH dehydration takes place affording the allenylidene complexes RuTp(PPh₂ⁱPr)(CCCFc₂)Cl (3b) and RuTp(PPh₃)(CCCPh₂)Cl (3c).Similarly, with PPh₂ⁱPr and HCCC(Ph)MeOH rapid elimination of water results in the formation of the vinylvinylidene complex RuTp(PPh₂ⁱPr)(CCHC(Ph)CH₂)Cl (4).In contrast to the reactions of the RuTp(PR₃)Cl fragment with propargylic alcohols, with HCC(CH₂)_nOH (n = 2, 3, 4, 5) six-, and seven-membered cyclic oxycarbene complexes RuTp(PR₃)(C₄H₆O)Cl (5), RuTp(PR₃)(C₅H₈O)Cl (6), and RuTp(PR₃)(C₆H₁₀O)Cl (7) are obtained. On the other hand, with 1-ethynylcyclohexanol the vinylvinylidene complex RuTp(PPh₂ⁱPr)(CCHC₆H₉)Cl (8) is formed. The reaction of the allenylidene complexes 3a–c with acid has been investigated. Addition of CF₃COOH to a solution of 3a–c resulted in the reversible formation of the novel RuTp vinylcarbyne complexes [RuTp(PPh₂ⁱPr)(C–CHCPh₂)Cl]⁺ (9a), [RuTp(PPh₂ⁱPr)(C–CHCFc₂)Cl]⁺ (9b), and [RuTp(PPh₃)(C–CHCPh₂)Cl]⁺ (9c). The structures of 3a, 3b, and 5b have been determined by X-ray crystallography.     

Reaction of isocyanides with iminophosphorane-based carbene ligands: Synthesis of unprecedented ketenimine–ruthenium complexes

The RuC bond of the bis(iminophosphorano)methandiide-based ruthenium(II) carbene complexes [Ru(η⁶-p-cymene)(κ²-C,N-C[P{NP(O)(OR)₂}Ph₂]₂)] (R = Et (1), Ph (2)) undergoes a C–C coupling process with isocyanides to afford ketenimine derivatives [Ru(η⁶-p-cymene)(κ³-C,C,N-C(CNR′)[P{NP(O)(OR)₂}Ph₂]₂)] (R = Et, R′ = Bz (3a), 2,6-C₆H₃Me₂ (3b), Cy (3c); R = Ph, R′ = Bz (4a), 2,6-C₆H₃Me₂ (4b), Cy (4c)). Compounds 3–4a–c represent the first examples of ketenimine–ruthenium complexes reported to date. Protonation of 3–4a with HBF₄ · Et₂O takes place selectively at the ketenimine nitrogen atom yielding the cationic derivatives [Ru(η⁶-p-cymene)(κ³-C,C,N-C(CNHBz)[P{NP(O)(OR)₂}Ph₂]₂)][BF₄] (R = Et (5a), Ph (6a)).     

Synthesis and characterization of thiosemicarbazone derivatives of 2-chloro-4-hydroxy-benzaldehyde and their rhenium(I) complexes

N-Thioamide thiosemicarbazone derived of 2-chloro-4-hydroxy-benzaldehyde (R = H, HL¹; R = Me, HL² and R = Ph, HL³) have been prepared and their reaction with fac-[ReX(CO)₃(CH₃CN)₂] (X = Br, Cl) in chloroform gave the adducts [ReX(CO)₃(HL)] (1a X = Cl, R = H; 1a′ X = Br, R = H; 1b X = Cl, R = CH₃; 1b′ X = Br, R = CH₃; 1c X = Cl, R = Ph; 1c′ X = Br, R = Ph) in good yield. Complexes 1a′ and 1b’ were also obtained by the reaction of HL¹ and HL³ with [ReBr(CO)₅] in toluene.All the compounds have been characterized by elemental analysis, mass spectrometry (FAB), IR and ¹H NMR spectroscopic methods. Moreover, the structures of HL², HL³ and 1a·H₂O were also established by X-ray diffraction. In 1a, the rhenium atom is coordinated by the sulphur and the azomethine nitrogen atoms, forming a five-membered chelate ring, as well as three carbonyl carbon and chloride atoms. The resulting coordination polyhedron can be described as a distorted octahedron.The study of the crystals obtained by slow evaporation of methanol and DMSO solutions of the adducts 1a′ and 1b, respectively, showed the formation of dimer structures based on rhenium(I) thiosemicarbazonates [Re₂(L¹)₂(CO)₆]·3H₂O (2a)·3H₂O and [Re₂(L²)₂(CO)₆]·(CH₃)₂SO (2b)·2(CH₃)₂SO. Amounts of these thiosemicarbazonate complexes [Re₂(L)₂(CO)₆] (2) were obtained by reaction of the corresponding free ligands with [ReCl(CO)₅] in dry toluene.In 2a·3H₂O and 2b·2(CH₃)₂SO the dimer structures are established by Re–S–Re bridges, where S is the thiolate sulphur from a N,S-bidentate thiosemicarbazonate ligand. In both structures the rhenium coordination sphere is similar; the dimers are in the same diamond Re₂S₂ face.     

Synthesis and reactions of heterodinuclear organopalladium–cobalt complexes acting as copolymerization catalyst for aziridine and carbon monoxide

A series of heterodinuclear acylpalladium–cobalt complexes having a bidentate nitrogen ligand, L₂(RCO)Pd–Co(CO)₄ (L₂ = bpy, R = Me (5), Ph (6); L₂ = tmeda, R = Me (7), Ph (8); L₂ = phen, R = Me (9), Ph (10)) are prepared by metathetical reactions of PdRIL₂ with Na⁺[Co(CO)₄]⁻ followed by treatment with CO. These complexes are characterized by NMR and IR spectroscopies and elemental analyses, and the molecular structures of 6, 8, and 9 are determined by X-ray structure analysis. Geometry at Pd is essentially square planar and the Co atom is considered to have d¹⁰ tetrahedral structure, where cobalt(-I) anion coordinates to palladium(II) cation. Heterodinuclear organopalladium–cobalt complexes are shown to catalyze copolymerization of aziridines and CO under mild conditions. Reaction of (dppe)MePd–Co(CO)₄ (1) with aziridine gives a cationic (aziridine)palladium(II) complex with [Co(CO)₄]⁻ anion, [PdMe(aziridine)(dppe)]⁺[Co(CO)₄]⁻ (13).     

Long-distance electronic interaction in a molecular wire consisting of a ferrocenyl–ethynyl unit bridging two [(η5-C5H5)(dppe)M] metal centers

Several multinuclear ferrocenyl–ethynyl complexes of formula [(η⁵-C₅H₅)(dppe)M^II?CC–(fc)_n–CC–M^II(dppe)(η⁵-C₅H₅)] (fc = ferrocenyl; dppe = Ph₂PCH₂CH₂PPh₂; 1: M^II = Ru²⁺, n = 1; 2: M^II = Ru²⁺, n = 2; 3: M^II = Ru²⁺, n = 3; 4: M^II = Fe²⁺, n = 2; 5: M^II = Fe²⁺, n = 3) were studied. Structural determinations of 2 and 4 confirm the ferrocenyl group directly linked to the ethynyl linkage which is linked to the pseudo-octahedral [(η⁵-C₅H₅)(dppe)M] metal center. Complexes of 1–5 undergo sequential reversible oxidation events from 0.0 V to 1.0 V referred to the Ag/AgCl electrode in anhydrous CH₂Cl₂ solution and the low-potential waves have been assigned to the end-capped metallic centers. The solid-state and solution-state electronic configurations in the resulting oxidation products of [1]⁺ and [2]²⁺ were characterized by IR, X-band EPR spectroscopy, and UV–Vis at room temperature and 77 K. In [1]⁺ and [2]²⁺, broad intervalence transition band near 1600 nm is assigned to the intervalence transition involving photo-induced electron transfer between the Ru³⁺ and Fe²⁺ metal centers, indicating the existence of strong metal-to-metal interaction. Application of Hush’s theoretical analysis of intervalence transition band to determine the nature and magnitude of the electronic coupling between the metal sites in complexes [1]⁺ and [2]²⁺ is also reported. Computational calculations reveal that the ferrocenyl–ethynyl-based orbitals do mix significantly with the (η⁵-C₅H₅)(dppe)Ru metallic orbitals. It clearly appears from this work that the ferrocenyl–ethynyl spacers strongly contribute in propagating electron delocalization.