Encapsulation of a Metal Complex within a Self-Assembled Nanocage: Synergy Effects, Molecular Structures, and Density Functional Theory Calculations

A novel palladium-based metallacage was self-assembled. This nanocage displayed two complementary effects that operate in synergy for guest encapsulation. Indeed, a metal complex, [Pt­(NO₂)₄]^2–, was hosted inside the cavity, as demonstrated by solution NMR studies. Single-crystal X-ray diffraction shows that the guest adopts two different orientations, depending on the nature of the host–guest interactions involved. A density functional theory computational study is included to rationalize this type of host–guest interaction. These studies pave the way to a better comprehension of chemical interaction and transformation within confined nanospaces

π‑Bonded Dithiolene Complexes: Synthesis, Molecular Structures, Electrochemical Behavior, and Density Functional Theory Calculations

The synthesis and X-ray molecular structure of the first metal-stabilized <i>o</i>-dithiobenzoquinone [Cp*Ir-<i>o</i>-(η⁴-C₆H₄S₂)] (<b>2</b>) are described. The presence of the metal stabilizes this elusive intermediate by π coordination and increases the nucleophilic character of the sulfur atoms. Indeed, the π-bonded dithiolene complex <b>2</b> was found to react with the organometallic solvated species [Cp*M­(acetone)₃]­[OTf]₂ (M = Rh, Ir) to give a unique class of binuclear dithiolene compounds [Cp*Ir­(C₆H₄S₂)­MCp*]­[OTf]₂ [M = Rh (<b>3</b>), Ir (<b>4</b>)] in which the elusive dithiolene η-C₆H₄S₂ acts as a bridging ligand toward the two Cp*M moieties. The electrochemical behavior of all complexes was investigated and provided us with valuable information about their redox properties. Density functional theory (DFT) calculations on the π-bonded dithiobenzoquinone ligand and related bimetallic systems show that the presence of Cp*M at the arene system of the dithiolene ligand increases the stability compared to the known monomeric species [Cp*Ir-<i>o</i>-(C₆H₄S₂-κ²-<i>S</i>,<i>S</i>)] and enables these complexes Cp*Ir­(C₆H₄S₂)­MCp*]­[OTf]₂ (<b>3</b> and <b>4</b>) to act as electron reservoirs. Time-dependent DFT calculations also predict the qualitative trends in the experimental UV–vis spectra and indicate that the strongest transitions arise from ligand–metal charge transfer involving primarily the HOMO–1 and LUMO. All of these compounds were fully characterized and identified by single-crystal X-ray crystallography. These results illustrate the first examples describing the coordination chemistry of the elusive <i>o</i>-dithiobenzoquinone to yield bimetallic complexes with an <i>o</i>-benzodithiolene ligand. These compounds might have important applications in the area of molecular materials

Enantiomerically Pure, Planar Chiral Cp*Ru Complexes: Synthesis, Molecular Structures, DFT and Coordination Properties

Reaction of (<i>S</i>)-1-(2-chlorophenyl)­ethanol with [Cp*Ru­(CH₃CN)₃]­[OTf] provides the single diastereomer (<i>Sp</i>)-[Cp*Ru­(η⁶-(<i>S</i>)-1-(2-chlorophenyl)­ethanol)]­[OTf] ((<i>Sp</i>,<i>S</i>)-<b>1</b>), in which the metal center is preferentially placed on one side of the arene ring. The other enantiomer (<i>R</i>)-1-(2-chlorophenyl)­ethanol provides the planar chiral ruthenium compound (<i>Rp</i>,<i>R</i>)-<b>1</b>. The structures of both enantiomers were ascertained by single-crystal X-ray diffraction. These compounds can be used as precursors to prepare the enantiopure metalated phosphino ligands (<i>Sp</i>)-[Cp*Ru­(η⁶-(<i>S</i>)-1-(2-diphenylphosphinophenyl)­ethanol)]­[OTf] ((<i>Sp,S</i>)-<b>2</b>) and (<i>Rp</i>)-[Cp*Ru­(η⁶-(<i>R</i>)-1-(2-diphenylphosphinophenyl)­ethanol)]­[OTf] ((<i>Rp</i>,<i>R</i>)-<b>2</b>), in which the −PPh₂ unit is attached to a chiral metalated π-arene platform. The chiral planar phosphine ligands react with [AuCl­(tht)] to give heterobinuclear gold complexes with planar chirality, [AuCl­((<i>Sp</i>,<i>S</i>)-<b>2</b>)] ((<i>Sp</i>,<i>S</i>)-<b>3</b>) and [AuCl­((<i>Rp</i>,<i>R</i>)-<b>2</b>)] ((<i>Rp</i>,<i>R</i>)-<b>3</b>), as confirmed by their CD traces. Our method provides an entry to the preparation of a wide range of optically pure coordination compounds with potentially important properties

Enantiomerically Pure, Planar Chiral Cp*Ru Complexes: Synthesis, Molecular Structures, DFT and Coordination Properties

Reaction of (<i>S</i>)-1-(2-chlorophenyl)­ethanol with [Cp*Ru­(CH₃CN)₃]­[OTf] provides the single diastereomer (<i>Sp</i>)-[Cp*Ru­(η⁶-(<i>S</i>)-1-(2-chlorophenyl)­ethanol)]­[OTf] ((<i>Sp</i>,<i>S</i>)-<b>1</b>), in which the metal center is preferentially placed on one side of the arene ring. The other enantiomer (<i>R</i>)-1-(2-chlorophenyl)­ethanol provides the planar chiral ruthenium compound (<i>Rp</i>,<i>R</i>)-<b>1</b>. The structures of both enantiomers were ascertained by single-crystal X-ray diffraction. These compounds can be used as precursors to prepare the enantiopure metalated phosphino ligands (<i>Sp</i>)-[Cp*Ru­(η⁶-(<i>S</i>)-1-(2-diphenylphosphinophenyl)­ethanol)]­[OTf] ((<i>Sp,S</i>)-<b>2</b>) and (<i>Rp</i>)-[Cp*Ru­(η⁶-(<i>R</i>)-1-(2-diphenylphosphinophenyl)­ethanol)]­[OTf] ((<i>Rp</i>,<i>R</i>)-<b>2</b>), in which the −PPh₂ unit is attached to a chiral metalated π-arene platform. The chiral planar phosphine ligands react with [AuCl­(tht)] to give heterobinuclear gold complexes with planar chirality, [AuCl­((<i>Sp</i>,<i>S</i>)-<b>2</b>)] ((<i>Sp</i>,<i>S</i>)-<b>3</b>) and [AuCl­((<i>Rp</i>,<i>R</i>)-<b>2</b>)] ((<i>Rp</i>,<i>R</i>)-<b>3</b>), as confirmed by their CD traces. Our method provides an entry to the preparation of a wide range of optically pure coordination compounds with potentially important properties

Tuning Excited States of Bipyridyl Platinum(II) Chromophores with π‑Bonded Catecholate Organometallic Ligands: Synthesis, Structures, TD-DFT Calculations, and Photophysical Properties

A series of bipyridyl (bpy) Pt­(II) complexes with π-bonded catecholate (cat) [(bpy)­Pt­(L_M)]­[BF₄]_<i>n</i> (<b>2</b>–<b>5</b>) (L_M = Cp*Rh­(cat), <i>n</i> = 2; Cp*Ir­(cat), <i>n</i> = 2; Cp*Ru­(cat), <i>n</i> = 1; and (C₆H₆)­Ru­(cat), <i>n</i> = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)­Pt­(II) complexes <b>2</b> and <b>3</b> with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates <b>4</b> and <b>5</b> showed the presence of Pt···Pt and π–π interactions among individual units and generated one- and two-dimensional supramolecular chains. The photophysical properties of these compounds <b>2</b>–<b>5</b> were investigated and showed that all compounds are luminescent at low temperature, in contrast to the well-known parent compound [(C₆H₄O₂)­Pt­(bpy)] (<b>1</b>), which is weakly luminescent at 77 K. Time-dependent density functional theory studies are advanced to explain this difference in behavior and to highlight the role of the π-bonded catecholate system

Tuning Excited States of Bipyridyl Platinum(II) Chromophores with π‑Bonded Catecholate Organometallic Ligands: Synthesis, Structures, TD-DFT Calculations, and Photophysical Properties

A series of bipyridyl (bpy) Pt­(II) complexes with π-bonded catecholate (cat) [(bpy)­Pt­(L_M)]­[BF₄]_<i>n</i> (<b>2</b>–<b>5</b>) (L_M = Cp*Rh­(cat), <i>n</i> = 2; Cp*Ir­(cat), <i>n</i> = 2; Cp*Ru­(cat), <i>n</i> = 1; and (C₆H₆)­Ru­(cat), <i>n</i> = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)­Pt­(II) complexes <b>2</b> and <b>3</b> with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates <b>4</b> and <b>5</b> showed the presence of Pt···Pt and π–π interactions among individual units and generated one- and two-dimensional supramolecular chains. The photophysical properties of these compounds <b>2</b>–<b>5</b> were investigated and showed that all compounds are luminescent at low temperature, in contrast to the well-known parent compound [(C₆H₄O₂)­Pt­(bpy)] (<b>1</b>), which is weakly luminescent at 77 K. Time-dependent density functional theory studies are advanced to explain this difference in behavior and to highlight the role of the π-bonded catecholate system

<i>Meso</i>-Helicates with Rigid Angular Tetradentate Ligand: Design, Molecular Structures, and Progress Towards Self-Assembly of Metal–Organic Nanotubes

The self-assembly of two novel metallosupramolecular complexes of the general formulas [L₂M₂(CH₃CN)₄]­[BF₄]₄ (M = Co, <b>1a</b>; M = Ni, <b>1b</b>), where L stands for the tetradentate ligand 3,5-bis­[4-(2,2′-dipyridylamino)­phenylacetylenyl]­toluene, is reported together with their molecular structures ascertained by single-crystal X-ray diffraction studies. Complexes <b>1a</b> and <b>1b</b> are isostructural and show the formation of dinuclear <i>meso</i>-helicates with the two octahedral metal centers displaying respectively Δ and Λ configurations. These <i>meso</i>-helicates display large nanocavities with metal---metal separation distance of >2 nm; furthermore, π–π-stacking occurs among individual units to form one-dimensional (1D) polymers which further autoassemble in another direction through π–π contacts among neighboring chains to generate a two-dimensional (2D) network with regular nanocavities. Our approach might be of interest to prepare metal–organic nanotubes via a bottom-up strategy depending on the assembling functional ligand and the geometry of molecular building block

Elegant Approach to the Synthesis of a Unique Heteroleptic Cyclometalated Iridium(III)-Polyoxometalate Conjugate

A novel heteroleptic cyclometalated iridium­(III) complex with one picolinic acid derivative bearing a pendant terminal alkynyl tether has been prepared following a new synthetic route. This pendant alkynyl tether can be further engaged in palladium C–C coupling reactions, allowing its grafting to a Keggin-type polyoxometalate and thus providing a unique iridio-POM conjugate

Elegant Approach to the Synthesis of a Unique Heteroleptic Cyclometalated Iridium(III)-Polyoxometalate Conjugate

A novel heteroleptic cyclometalated iridium­(III) complex with one picolinic acid derivative bearing a pendant terminal alkynyl tether has been prepared following a new synthetic route. This pendant alkynyl tether can be further engaged in palladium C–C coupling reactions, allowing its grafting to a Keggin-type polyoxometalate and thus providing a unique iridio-POM conjugate

Dinuclear (N^∧C^∧N) Pincer Pt(II) Complexes with Bridged Organometallic Linkers: Synthesis, Structures, Self-Aggregation, and Photophysical Properties

A new family of cationic dinuclear cyclometalated Pt­(II) complexes containing an organometallic assembling ligand has been reported. The general formulas for these compounds is as follow: [R-(N^∧C^∧N)­PtL-LPt­(N^∧C^∧N)-R]­[X]₂, where L-L = [Cp*Ir-<i>p</i>-(η⁴-C₆H₄S₂)], R = H, X = OTf (<b>5</b>); R= CF₃–, X = OTf (<b>6a</b>), SbF₆ (<b>6b</b>); L-L = [Cp*Ir-<i>p</i>-(η⁴-C₆H₄Se₂)] R= CF₃–, X = OTf (<b>7a</b>), SbF₆ (<b>7b</b>). In these coordination assemblies two cyclometalated R-(N^∧C^∧N)Pt moieties are held by either η⁴-dithio-<i>p</i>-benzoquinone complex [Cp*Ir-<i>p</i>-(η⁴-C₆H₄S₂)] (<b>3</b>) or η⁴-diseleno-<i>p</i>-benzoquinone complex [Cp*Ir-<i>p</i>-(η⁴-C₆H₄Se₂)] (<b>4</b>). The molecular structures of the known complex [4-CF₃-(N^∧C^∧N)­PtCl] as well as two compounds of the above family [(N^∧C^∧N)­Pt–Cp*Ir-<i>p</i>-(η⁴-C₆H₄S₂)Pt­(N^∧C^∧N)]­[CF₃SO₃]₂ (<b>5</b>) and [CF₃-(N^∧C^∧N)­PtCp*Ir-<i>p</i>-(η⁴-C₆H₄S₂)Pt­(N^∧C^∧N)-CF₃]­[CF₃SO₃]₂ (<b>6a</b>) were ascertained by single crystal X-ray diffraction study and confirmed the formation of the target molecules. The solid-state packing of <b>5</b> and <b>6a</b> confirms the presence π–π and short Pt···Pt interactions among individual units providing 1D supramolecular chains. To our knowledge, these are the only known examples where two cyclometalated Pt­(N^∧C^∧N) units are assembled by a bridging ligand (vide infra). All compounds show phosphorescence in the bluish-green region (486–521 nm) in the solution at room temperature and exhibit higher luminescence quantum yields relative to the analogous compounds containing a Pt­(terpy) chromophore in thin film