Structural and Photophysical Study on Alkynyl Cyclometalated Pt₂Pb₂ and Pt₂Pb Clusters

Neutralization reactions of (NBu₄)­[Pt­(bzq)­(CCR)₂] (bzq = 7,8-benzoquinolinyl) with [Pb­(HBpz₃)]­Cl (pz = pyrazolyl) afford tetranuclear neutral Pt₂Pb₂ derivatives [{Pt­(bzq)­(CCR)₂}­{Pb­(HBpz₃)}]₂ (R = Ph, <b>1</b>; C₆H₄OMe-3, <b>2</b>) or the anionic trinuclear Pt₂Pb cluster (NBu₄)­[{Pt­(bzq)­(CCC₆H₄CF₃-4)₂}₂­{Pb­(HBpz₃)}], <b>3</b>, stabilized by Pt–Pb and Pb^II···η²-(CCR) bonding interactions in the solid state, as confirmed by X-ray crystallography. The variable-temperature ¹H NMR spectra of <b>3</b> confirm the existence of a dynamic equilibrium that averages the “Pt­(bzq)­(CCC₆H₄CF₃-4)₂” groups in solution. 1D ¹H PGSE-NMR, 2D DOSY, and ¹H variable-temperature NMR experiments for the tetranuclear clusters <b>1</b> and <b>2</b> indicate that in solution these dimers generate mainly binuclear [{Pt­(bzq)­(CCR)₂}­{Pb­(HBpz₃)}] units by cleavage of the Pb^II···η²-(CCR) interactions. All clusters exhibit phosphorescent emission in rigid media (solid, glasses) and <b>3</b> also in CH₂Cl₂ solution. The emission maxima of <b>1</b> and <b>2</b> are slightly blue-shifted in relation to the precursors, being assigned to a mixed ³MLCT/³LC (L = bzq) excited state, perturbed by the Pt–Pb bond. However, the emission maximum of <b>3</b> coincides with that of its precursor, indicating little or no involvement of the Pt–Pb bonds in the emissive state

Synthesis, Structural, and Photophysical Studies of Phenylquinoline and Phenylquinolinyl Alkynyl Based Pt(II) Complexes

We present the synthesis, characterization, and photophysical properties of two series of alkynyl–platinum­(II) complexes containing the phenylquinoline (Hpq) or the cyclometalated phenylquinolinyl (pq) ligand. Unusual monoanionic complexes (NBu₄)­[Pt­(CCR)₃­(Hpq)] (R = Tol <b>1</b>, C₆H₄OMe-3 <b>2</b>, C₆H₄CF₃-4 <b>3</b>) were generated in moderate yield by treatment of [Pt­(pq)­(μ-Cl)]₂ with an excess of LiCCR (1:8), followed by subsequent treatment with NBu₄ in <i>i</i>PrOH. However, a similar reaction with LiCC<i>^t</i>Bu evolves with formation of [Pt­(pq)­(μ–<i>κC</i>^α:​η²-CC^<i>t</i>Bu)]₂ <b>4</b>. Related dimers [Pt­(pq)­(μ–<i>κC</i>^α:​η²-CCR)]₂ (R = Tol <b>5</b>, C₆H₄OMe-3 <b>6</b>, C₆H₄CF₃-4 <b>7</b>) were successfully prepared by modification of the reaction conditions. Single-crystal studies were performed on <b>2</b>, <b>4</b>, and <b>5</b>, revealing the presence of <i>intramolecular</i> (H···Pt and H···CC) and <i>intermolecular</i> O_methoxy···H_Hpq contacts in <b>2</b> and the formation of butterfly structures in <b>4</b> and <b>5</b>. In the <i>^t</i>Bu derivative <b>4</b>, a shorter intramolecular Pt···Pt separation was found [3.0936(3) Å in <b>4</b> vs 3.2109(3) Å in <b>5</b>], which is related to the nature of η²-alkynyl linkages (η²-<i>asymmetrical</i> in <b>4</b> vs η²-<i>symmetrical</i> in <b>5</b>). Anionic <b>1</b>–<b>3</b> display bright emissions in rigid media (solid, glass) with resolved side vibronic bands at 77 K. The energy of the emissions (supported by computational studies on <b>2</b>) allows us to ascribe these emissions primarily to a mixed alkynyl–metal to the phenylquinoline ³[(L′ + M)­LCT] excited state, being perturbed in <b>2</b> (solid) by the <i>intermolecular</i> O_methoxy···H_Hpq contacts. Whereas diplatinum complexes <b>5</b>–<b>7</b> have no visible emission at 298 K in the solid state, <b>4</b> shows a structureless band (578 nm), which is significantly red-shifted at 77 K (595 nm). Theoretical studies suggest a notable distortion in the excited state in relation to S₀ and identify the emission within the dimetallacycle Pt₂(CC)₂ with alkynyl to pq charge-transfer ³[(MM + L′)­LCT] [with minor ³IL (pq) contribution], whereas, in <b>5</b>, the emission is tentatively ascribed to a mixture of ³L′LCT with minor ³MMLCT character. The emission profiles observed in glassy solution for all <b>4</b>–<b>7</b> complexes (556–562 nm, CH₂Cl₂) and in the solid state for <b>6</b>–<b>7</b> are consistent with those exhibited by mononuclear related chromophores ³[(L′ + M)­LCT] (L′ = CCR, L = pq), suggesting negligible contribution of the Pt···Pt interaction

Synthesis, Structural, and Photophysical Studies of Phenylquinoline and Phenylquinolinyl Alkynyl Based Pt(II) Complexes

We present the synthesis, characterization, and photophysical properties of two series of alkynyl–platinum­(II) complexes containing the phenylquinoline (Hpq) or the cyclometalated phenylquinolinyl (pq) ligand. Unusual monoanionic complexes (NBu₄)­[Pt­(CCR)₃­(Hpq)] (R = Tol <b>1</b>, C₆H₄OMe-3 <b>2</b>, C₆H₄CF₃-4 <b>3</b>) were generated in moderate yield by treatment of [Pt­(pq)­(μ-Cl)]₂ with an excess of LiCCR (1:8), followed by subsequent treatment with NBu₄ in <i>i</i>PrOH. However, a similar reaction with LiCC<i>^t</i>Bu evolves with formation of [Pt­(pq)­(μ–<i>κC</i>^α:​η²-CC^<i>t</i>Bu)]₂ <b>4</b>. Related dimers [Pt­(pq)­(μ–<i>κC</i>^α:​η²-CCR)]₂ (R = Tol <b>5</b>, C₆H₄OMe-3 <b>6</b>, C₆H₄CF₃-4 <b>7</b>) were successfully prepared by modification of the reaction conditions. Single-crystal studies were performed on <b>2</b>, <b>4</b>, and <b>5</b>, revealing the presence of <i>intramolecular</i> (H···Pt and H···CC) and <i>intermolecular</i> O_methoxy···H_Hpq contacts in <b>2</b> and the formation of butterfly structures in <b>4</b> and <b>5</b>. In the <i>^t</i>Bu derivative <b>4</b>, a shorter intramolecular Pt···Pt separation was found [3.0936(3) Å in <b>4</b> vs 3.2109(3) Å in <b>5</b>], which is related to the nature of η²-alkynyl linkages (η²-<i>asymmetrical</i> in <b>4</b> vs η²-<i>symmetrical</i> in <b>5</b>). Anionic <b>1</b>–<b>3</b> display bright emissions in rigid media (solid, glass) with resolved side vibronic bands at 77 K. The energy of the emissions (supported by computational studies on <b>2</b>) allows us to ascribe these emissions primarily to a mixed alkynyl–metal to the phenylquinoline ³[(L′ + M)­LCT] excited state, being perturbed in <b>2</b> (solid) by the <i>intermolecular</i> O_methoxy···H_Hpq contacts. Whereas diplatinum complexes <b>5</b>–<b>7</b> have no visible emission at 298 K in the solid state, <b>4</b> shows a structureless band (578 nm), which is significantly red-shifted at 77 K (595 nm). Theoretical studies suggest a notable distortion in the excited state in relation to S₀ and identify the emission within the dimetallacycle Pt₂(CC)₂ with alkynyl to pq charge-transfer ³[(MM + L′)­LCT] [with minor ³IL (pq) contribution], whereas, in <b>5</b>, the emission is tentatively ascribed to a mixture of ³L′LCT with minor ³MMLCT character. The emission profiles observed in glassy solution for all <b>4</b>–<b>7</b> complexes (556–562 nm, CH₂Cl₂) and in the solid state for <b>6</b>–<b>7</b> are consistent with those exhibited by mononuclear related chromophores ³[(L′ + M)­LCT] (L′ = CCR, L = pq), suggesting negligible contribution of the Pt···Pt interaction

Facile Metalation of Hbzq by [<i>cis</i>-Pt(C₆F₅)₂(thf)₂]: A Route to a Pentafluorophenyl Benzoquinolate Solvate Complex That Easily Coordinates Terminal Alkynes. Spectroscopic and Optical Properties

A new neutral cyclometalated platinum­(II) solvate complex [<i>cis</i>-Pt­(bzq)­(C₆F₅)­(acetone)] (<b>1</b>) has been prepared by easy C–H activation of 7,8-benzo­[<i>h</i>]­quinoline on the coordination sphere of [<i>cis</i>-Pt­(C₆F₅)₂(thf)₂] (thf = tetrahydrofuran). The study of the reaction pathway has led us to the preparation of the bis­(Hbzq) product [<i>cis</i>-Pt­(C₆F₅)₂(Hbzq)₂] (<b>2</b>) and the benzoquinoline–benzoquinolate derivative [Pt­(bzq)­(C₆F₅)­(Hbzq)] (<b>3</b>). This latter complex has been characterized by X-ray diffraction, showing the occurrence of π···π intermolecular stacking interactions associated to the deprotonated bzq units. The acetone molecule in [<i>cis</i>-Pt­(bzq)­(C₆F₅)­(acetone)] can be easily displaced by alkynes, allowing the synthesis of the first reported η²-alkyne-cycloplatinate complexes [Pt­(bzq)­(C₆F₅)­(η²-RCCR′)] (R = H, R′ = Ph <b>4</b>, ^tBu <b>5</b>, Fc <b>6</b>; R = R′ = Ph <b>7</b>), which have been fully characterized spectroscopically and by DFT studies. These alkyne complexes are only moderately stable in solution, and all attempts to obtain crystals suitable for X-ray diffraction were fruitless. Nevertheless, in the case of the ferrocenyl derivative, crystals of complex [Pt­(κ<i>N</i>:η²-bzq-C≡CFc)­(C₆F₅)­(μ-κ<i>C</i>^α:η²-C≡CFc)­Pt­(bzq)­(C₆F₅)] (<b>8</b>), containing an unusual alkynyl-functionalized benzoquinoline chelate ligand, were systematically obtained. All complexes (except those containing the ferrocenyl fragment) present emissive properties in solution and solid state (77 K), related, in general, with intraligand (bzq) excited states with some mixing ³MLCT character, as supported by theoretical calculations. In solid state at room temperature, aggregation induced emission (AIE) is observed likely generated by intermolecular π···π stacking, as supporting by DFT calculations on <b>3</b>_<b>2</b>. Interestingly, both types of excited states (³IL/³MLCT and AIE) seem to be close in energy in complexes <b>1</b> and <b>3</b>, which show a significant luminescent thermochromism (green 77 K to orange 298 K)

Facile Metalation of Hbzq by [<i>cis</i>-Pt(C₆F₅)₂(thf)₂]: A Route to a Pentafluorophenyl Benzoquinolate Solvate Complex That Easily Coordinates Terminal Alkynes. Spectroscopic and Optical Properties

A new neutral cyclometalated platinum­(II) solvate complex [<i>cis</i>-Pt­(bzq)­(C₆F₅)­(acetone)] (<b>1</b>) has been prepared by easy C–H activation of 7,8-benzo­[<i>h</i>]­quinoline on the coordination sphere of [<i>cis</i>-Pt­(C₆F₅)₂(thf)₂] (thf = tetrahydrofuran). The study of the reaction pathway has led us to the preparation of the bis­(Hbzq) product [<i>cis</i>-Pt­(C₆F₅)₂(Hbzq)₂] (<b>2</b>) and the benzoquinoline–benzoquinolate derivative [Pt­(bzq)­(C₆F₅)­(Hbzq)] (<b>3</b>). This latter complex has been characterized by X-ray diffraction, showing the occurrence of π···π intermolecular stacking interactions associated to the deprotonated bzq units. The acetone molecule in [<i>cis</i>-Pt­(bzq)­(C₆F₅)­(acetone)] can be easily displaced by alkynes, allowing the synthesis of the first reported η²-alkyne-cycloplatinate complexes [Pt­(bzq)­(C₆F₅)­(η²-RCCR′)] (R = H, R′ = Ph <b>4</b>, ^tBu <b>5</b>, Fc <b>6</b>; R = R′ = Ph <b>7</b>), which have been fully characterized spectroscopically and by DFT studies. These alkyne complexes are only moderately stable in solution, and all attempts to obtain crystals suitable for X-ray diffraction were fruitless. Nevertheless, in the case of the ferrocenyl derivative, crystals of complex [Pt­(κ<i>N</i>:η²-bzq-C≡CFc)­(C₆F₅)­(μ-κ<i>C</i>^α:η²-C≡CFc)­Pt­(bzq)­(C₆F₅)] (<b>8</b>), containing an unusual alkynyl-functionalized benzoquinoline chelate ligand, were systematically obtained. All complexes (except those containing the ferrocenyl fragment) present emissive properties in solution and solid state (77 K), related, in general, with intraligand (bzq) excited states with some mixing ³MLCT character, as supported by theoretical calculations. In solid state at room temperature, aggregation induced emission (AIE) is observed likely generated by intermolecular π···π stacking, as supporting by DFT calculations on <b>3</b>_<b>2</b>. Interestingly, both types of excited states (³IL/³MLCT and AIE) seem to be close in energy in complexes <b>1</b> and <b>3</b>, which show a significant luminescent thermochromism (green 77 K to orange 298 K)

Phenylbenzothiazole-Based Platinum(II) and Diplatinum(II) and (III) Complexes with Pyrazolate Groups: Optical Properties and Photocatalysis

Based on 2-phenylbenzothiazole (pbt) and 2-(4-dimethylaminophenyl)benzothiazole (Me2N-pbt), mononuclear [Pt(pbt)(R′2-pzH)2]PF6 (R′2-pzH = pzH 1a, 3,5-Me2pzH 1b, 3,5-iPr2pzH 1c) and diplatinum (PtII–PtII) [Pt(pbt)(μ-R′2pz)]2 (R′2-pz = pz 2a, 3,5-Me2pz 2b, 3,5-iPr2pz 2c) and [Pt(Me2N-pbt)(μ-pz)]2 (3a) complexes have been prepared. In the presence of sunlight, 2a and 3a evolve, in CHCl3 solution, to form the PtIII–PtIII complexes [Pt(R-pbt)(μ-pz)Cl]2 (R = H 4a, NMe2 5a). Experimental and computational studies reveal the negligible influence of the pyrazole or pyrazolate ligands on the optical properties of 1a–c and 2a,b, which exhibit a typical 3IL/3MLCT emission, whereas in 2c the emission has some 3MMLCT contribution. 3a displays unusual dual, fluorescence (1ILCT or 1MLCT/1LC), and phosphorescence (3ILCT) emissions depending on the excitation wavelength. The phosphorescence is lost in aerated solutions due to sensitization of 3O2 and formation of 1O2, whose determined quantum yield is also wavelength dependent. The phosphorescence can be reversibly photoinduced (365 nm, ∼ 15 min) in oxygenated THF and DMSO solutions. In 4a and 5a, the lowest electronic transitions (S1–S3) have mixed characters (LMMCT/LXCT/L’XCT 4a and LMMCT/LXCT/ILCT 5a) and they are weakly emissive in rigid media. The 1O2 generation property of complex 3a is successfully used for the photooxidation of p-bromothioanisol showing its potential application toward photocatalysis

An Extended Chain and Trinuclear Complexes Based on Pt(II)–M (M = Tl(I), Pb(II)) Bonds: Contrasting Photophysical Behavior

The syntheses and structural characterizations of a Pt–Tl chain [{Pt­(bzq)­(C₆F₅)₂}­Tl­(Me₂CO)]_<i>n</i> <b>1</b> and two trinuclear Pt₂M clusters (NBu₄)­[{Pt­(bzq)­(C₆F₅)₂}₂Tl] <b>2</b> and [{Pt­(bzq)­(C₆F₅)₂}₂Pb] <b>3</b> (bzq = 7,8-benzoquinolinyl), stabilized by donor–acceptor Pt → M bonds, are reported. The one-dimensional heterometallic chain <b>1</b> is formed by alternate “Pt­(bzq)­(C₆F₅)₂” and “Tl­(Me₂CO)” fragments, with Pt–Tl bond separations in the range of 2.961(1)–3.067(1) Å. The isoelectronic trinuclear complexes <b>2</b> (which crystallizes in three forms, namely, <b>2a</b>, <b>2b</b>, and <b>2c</b>) and <b>3</b> present a sandwich structure in which the Tl­(I) or Pb­(II) is located between two “Pt­(bzq)­(C₆F₅)₂” subunits. NMR studies suggest equilibria in solution implying cleavage and reformation of Pt–M bonds. The lowest-lying absorption band in the UV–vis spectra in CH₂Cl₂ and tetrahydrofuran (THF) of <b>1</b>, associated with ¹MLCT/¹L′LCT ¹[5d_π(Pt) → π*­(bzq)]/¹[(C₆F₅) → bzq], displays a blue shift in relation to the precursor, suggesting the cleavage of the chain maintaining bimetallic Pt–Tl fragments in solution, also supported by NMR spectroscopy. In <b>2</b> and <b>3</b>, it shows a blue shift in THF and a red shift in CH₂Cl₂, supporting a more extensive cleavage of the Pt–M bonds in THF solutions than in CH₂Cl₂, where the trinuclear entities are predominant. The Pt–Tl chain <b>1</b> displays in solid state a bright orange-red emission ascribed to ³MM′CT (M′ = Tl). It exhibits remarkable and fast reversible vapochromic and vapoluminescent response to donor vapors (THF and Et₂O), related to the coordination/decoordination of the guest molecule to the Tl­(I) ion, and mechanochromic behavior, associated with the shortening of the intermetallic Pt–Tl separations in the chain induced by grinding. In frozen solutions (THF, acetone, and CH₂Cl₂) <b>1</b> shows interesting luminescence thermochromism with emissions strongly dependent on the solvent, concentration, and excitation wavelengths. The Pt₂Tl complex <b>2</b> shows an emission close to <b>1</b>, ascribed to charge transfer from the platinum fragment to the thallium [³(L+L′)­MM′CT]. <b>2</b> also shows vapoluminescent behavior in the presence of vapors of Me₂CO, THF, and Et₂O, although smaller and slower than those of <b>1</b>. The trinuclear neutral complex Pt₂Pb <b>3</b> displays a blue-shift emission band, tentatively assigned to admixture of ³MM′CT ³[Pt­(d) → Pb­(sp)] with some metal-mediated intraligand (³ππ/³ILCT) contribution. In contrast to <b>1</b> and <b>2</b>, <b>3</b> does not show vapoluminescent behavior

Synthesis, Characterization, and Properties of Doubly Alkynyl Bridging Dinuclear Cyclometalated Iridium(III) Complexes

Bis­(cyclometalated) diiridium complexes [Ir­(ppy)₂(μ–κ<i>C</i>^α:η²-CCR)]₂ (R = Tol <b>1</b>, C₆H₄OMe-4 <b>2</b>, 1-Np <b>3</b>, SiMe₃ <b>4</b>, ^<i>t</i>Bu <b>5</b>), stabilized by a double alkynyl bridging system, have been synthesized by alkynylation of [Ir­(ppy)₂(μ-Cl)]₂ with excess of the appropriate LiCCR (1:6 or 1:10 molar ratio). Complexes <b>1</b>–<b>3</b> were alternatively generated by treatment of [Ir­(ppy)₂(MeCN)₂]­(OTf) with 2.5 equiv of LiCCR. However, the related reaction with LiCC^<i>t</i>Bu evolves with the formation of mixtures from which the unexpected dinuclear complex [Ir­(ppy)₂(μ-CH₂CN)]₂ <b>6</b> was crystallized, as confirmed by X-ray diffraction studies. Complexes <b>1</b>–<b>5</b> have been characterized by NMR, IR, absorption and emission spectroscopies, cyclic voltammetry, and mass spectrometric methods. Characterization indicates that <b>1</b>–<b>3</b> and <b>5</b> are obtained as a unique diastereoisomer (ΛΛ/ΔΔ), whereas <b>4</b> gives the two diastereoisomers (ΔΛ and ΛΛ/ΔΔ). Single crystals of [Ir­(ppy)₂(μ-CCTol)]₂ <b>1</b> contains the inversion related ΛΛ/ΔΔ isomers, and crystals of <b>4</b> (chosen from a mixture of two different types of crystals) consist of the <i>meso</i>-ΔΛ isomer. Electrochemical studies showed the presence in <b>1</b>–<b>3</b> and <b>5</b> of two consecutive one-electron-oxidation Ir^III/Ir^IV processes, whereas <b>4</b> displayed only one irreversible oxidation peak. In degassed fluid solutions, complexes <b>1</b>–<b>5</b> are emissive in the 505–515 nm region with quantum yields higher (ϕ = 0.007–0.024) than that of the dichloro bridged precursor (0.0037). The influence of the alkynyl substituent in the emissive state at room and at low temperatures has been investigated. For the naphthylacetylide derivative <b>3</b>, a clear switch from a mixed charge transfer ³MLCT/³L′LCT excited state at 298 K (515 nm) to a characteristic long-lived low lying naphthalene emission at low temperature (77 K) is observed. DFT and TD-DFT calculations were performed on complexes <b>1</b> and <b>3</b> in the ground and triplet states to gain insight into the structural, electronic, and photophysical properties

Unexpected Formation of Ferrocenyl(vinyl)benzoquinoline Ligands by Oxidation of an Alkyne Benzoquinolate Platinum(II) Complex

Oxidation of [Pt­(bzq-κ<i>N</i>,κ<i>C</i>¹⁰)­(C₆F₅)­(η²-HCCFc)] (<b>1</b>) with PhICl₂ and I₂ affords the unusual halideferrocenyl­(vinyl)­benzoquinoline Pt^II derivatives [Pt­{bzq-κ<i>N</i>-η²-CHC­(X)­Fc}­(C₆F₅)­X] (X = Cl (<b>4a</b>), I (<b>4b</b>)), arising from C–X and C–C coupling processes, together with small amounts of the corresponding Pt^IV products [{Pt­(bzq-κ<i>N</i>,κ<i>C</i>¹⁰)­(C₆F₅)­X­(μ-X)}₂] (X = Cl (<b>5a</b>), I (<b>5b</b>)), respectively. Complexes <b>4</b> are very stable but they undergo easy displacement reactions with PPh₃, yielding <i>trans</i>-[Pt­(C₆F₅)­X­(PPh₃)₂] and the corresponding new functionalized (vinyl)­benzoquinoline ligands [(<i>Z</i>)-bzq-CHC­(X)­Fc] (X = Cl (<b>6a</b>), I (<b>6b</b>)). The dinuclear Pt^IV derivatives <b>5</b> are alternatively obtained in high yield by oxidation of the solvate [Pt­(bzq-κ<i>N</i>,κ<i>C</i>¹⁰)­(C₆F₅)­(CH₃COCH₃)] (<b>2</b>). Treatment of <b>5</b> with dmso or direct oxidation of [Pt­(bzq-κ<i>N</i>,κ<i>C</i>¹⁰)­(C₆F₅)­(tht)] (<b>3</b>) provides mononuclear [Pt­(bzq-κ<i>N</i>,κ<i>C</i>¹⁰)­(C₆F₅)­X₂(L)] (L = dmso (<b>7a</b>–<b>c</b>), tht (<b>8a</b>–<b>c</b>)) as a mixture of <i>cis</i> and <i>trans</i> isomers

Synthesis, Characterization, and Properties of Doubly Alkynyl Bridging Dinuclear Cyclometalated Iridium(III) Complexes

Bis­(cyclometalated) diiridium complexes [Ir­(ppy)₂(μ–κ<i>C</i>^α:η²-CCR)]₂ (R = Tol <b>1</b>, C₆H₄OMe-4 <b>2</b>, 1-Np <b>3</b>, SiMe₃ <b>4</b>, ^<i>t</i>Bu <b>5</b>), stabilized by a double alkynyl bridging system, have been synthesized by alkynylation of [Ir­(ppy)₂(μ-Cl)]₂ with excess of the appropriate LiCCR (1:6 or 1:10 molar ratio). Complexes <b>1</b>–<b>3</b> were alternatively generated by treatment of [Ir­(ppy)₂(MeCN)₂]­(OTf) with 2.5 equiv of LiCCR. However, the related reaction with LiCC^<i>t</i>Bu evolves with the formation of mixtures from which the unexpected dinuclear complex [Ir­(ppy)₂(μ-CH₂CN)]₂ <b>6</b> was crystallized, as confirmed by X-ray diffraction studies. Complexes <b>1</b>–<b>5</b> have been characterized by NMR, IR, absorption and emission spectroscopies, cyclic voltammetry, and mass spectrometric methods. Characterization indicates that <b>1</b>–<b>3</b> and <b>5</b> are obtained as a unique diastereoisomer (ΛΛ/ΔΔ), whereas <b>4</b> gives the two diastereoisomers (ΔΛ and ΛΛ/ΔΔ). Single crystals of [Ir­(ppy)₂(μ-CCTol)]₂ <b>1</b> contains the inversion related ΛΛ/ΔΔ isomers, and crystals of <b>4</b> (chosen from a mixture of two different types of crystals) consist of the <i>meso</i>-ΔΛ isomer. Electrochemical studies showed the presence in <b>1</b>–<b>3</b> and <b>5</b> of two consecutive one-electron-oxidation Ir^III/Ir^IV processes, whereas <b>4</b> displayed only one irreversible oxidation peak. In degassed fluid solutions, complexes <b>1</b>–<b>5</b> are emissive in the 505–515 nm region with quantum yields higher (ϕ = 0.007–0.024) than that of the dichloro bridged precursor (0.0037). The influence of the alkynyl substituent in the emissive state at room and at low temperatures has been investigated. For the naphthylacetylide derivative <b>3</b>, a clear switch from a mixed charge transfer ³MLCT/³L′LCT excited state at 298 K (515 nm) to a characteristic long-lived low lying naphthalene emission at low temperature (77 K) is observed. DFT and TD-DFT calculations were performed on complexes <b>1</b> and <b>3</b> in the ground and triplet states to gain insight into the structural, electronic, and photophysical properties