15 research outputs found
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,
[PtĀ(NO<sub>2</sub>)<sub>4</sub>]<sup>2ā</sup>, 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 hostāguest interactions involved.
A density functional theory computational study is included to rationalize
this type of hostāguest interaction. These studies pave the
way to a better comprehension of chemical interaction and transformation
within confined nanospaces
ĻāBonded 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>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)] (<b>2</b>) are described. The presence of the metal stabilizes
this elusive intermediate by Ļ coordination and increases the
nucleophilic character of the sulfur atoms. Indeed, the Ļ-bonded
dithiolene complex <b>2</b> was found to react with the organometallic
solvated species [Cp*MĀ(acetone)<sub>3</sub>]Ā[OTf]<sub>2</sub> (M =
Rh, Ir) to give a unique class of binuclear dithiolene compounds [Cp*IrĀ(C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)ĀMCp*]Ā[OTf]<sub>2</sub> [M = Rh
(<b>3</b>), Ir (<b>4</b>)] in which the elusive dithiolene
Ī·-C<sub>6</sub>H<sub>4</sub>S<sub>2</sub> 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 Ļ-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>-(C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>-Īŗ<sup>2</sup>-<i>S</i>,<i>S</i>)] and enables these complexes Cp*IrĀ(C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)ĀMCp*]Ā[OTf]<sub>2</sub> (<b>3</b> and <b>4</b>) to act as electron reservoirs. Time-dependent DFT calculations
also predict the qualitative trends in the experimental UVāvis
spectra and indicate that the strongest transitions arise from ligandāmetal
charge transfer involving primarily the HOMOā1 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)Āethanol
with
[Cp*RuĀ(CH<sub>3</sub>CN)<sub>3</sub>]Ā[OTf] provides the single diastereomer
(<i>Sp</i>)-[Cp*RuĀ(Ī·<sup>6</sup>-(<i>S</i>)-1-(2-chlorophenyl)Āethanol)]Ā[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)Āethanol 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*RuĀ(Ī·<sup>6</sup>-(<i>S</i>)-1-(2-diphenylphosphinophenyl)Āethanol)]Ā[OTf]
((<i>Sp,S</i>)-<b>2</b>) and (<i>Rp</i>)-[Cp*RuĀ(Ī·<sup>6</sup>-(<i>R</i>)-1-(2-diphenylphosphinophenyl)Āethanol)]Ā[OTf]
((<i>Rp</i>,<i>R</i>)-<b>2</b>), in which
the āPPh<sub>2</sub> unit is attached to a chiral metalated
Ļ-arene platform. The chiral planar phosphine ligands react
with [AuClĀ(tht)] to give heterobinuclear gold complexes with planar
chirality, [AuClĀ((<i>Sp</i>,<i>S</i>)-<b>2</b>)] ((<i>Sp</i>,<i>S</i>)-<b>3</b>) and
[AuClĀ((<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)Āethanol
with
[Cp*RuĀ(CH<sub>3</sub>CN)<sub>3</sub>]Ā[OTf] provides the single diastereomer
(<i>Sp</i>)-[Cp*RuĀ(Ī·<sup>6</sup>-(<i>S</i>)-1-(2-chlorophenyl)Āethanol)]Ā[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)Āethanol 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*RuĀ(Ī·<sup>6</sup>-(<i>S</i>)-1-(2-diphenylphosphinophenyl)Āethanol)]Ā[OTf]
((<i>Sp,S</i>)-<b>2</b>) and (<i>Rp</i>)-[Cp*RuĀ(Ī·<sup>6</sup>-(<i>R</i>)-1-(2-diphenylphosphinophenyl)Āethanol)]Ā[OTf]
((<i>Rp</i>,<i>R</i>)-<b>2</b>), in which
the āPPh<sub>2</sub> unit is attached to a chiral metalated
Ļ-arene platform. The chiral planar phosphine ligands react
with [AuClĀ(tht)] to give heterobinuclear gold complexes with planar
chirality, [AuClĀ((<i>Sp</i>,<i>S</i>)-<b>2</b>)] ((<i>Sp</i>,<i>S</i>)-<b>3</b>) and
[AuClĀ((<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 ĻāBonded Catecholate Organometallic Ligands: Synthesis, Structures, TD-DFT Calculations, and Photophysical Properties
A series of bipyridyl (bpy) PtĀ(II)
complexes with Ļ-bonded catecholate (cat) [(bpy)ĀPtĀ(L<sub>M</sub>)]Ā[BF<sub>4</sub>]<sub><i>n</i></sub> (<b>2</b>ā<b>5</b>) (L<sub>M</sub> = Cp*RhĀ(cat), <i>n</i> = 2; Cp*IrĀ(cat), <i>n</i> = 2; Cp*RuĀ(cat), <i>n</i> = 1; and (C<sub>6</sub>H<sub>6</sub>)ĀRuĀ(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 Ļ-bonded catecholate
unit. For instance, while the (bpy)ĀPtĀ(II) complexes <b>2</b> and <b>3</b> with rhodium and iridium catecholates did not
show any PtĀ·Ā·Ā·Pt interactions those with the ruthenium
catecholates <b>4</b> and <b>5</b> showed the presence
of PtĀ·Ā·Ā·Pt and ĻāĻ interactions
among individual units and generated one- and two-dimensional supramolecular
chains. The photophysical properties of these compounds <b>2</b>ā<b>5</b> were investigated and showed that all compounds
are luminescent at low temperature, in contrast to the well-known
parent compound [(C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>)ĀPtĀ(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 Ļ-bonded catecholate
system
Tuning Excited States of Bipyridyl Platinum(II) Chromophores with ĻāBonded Catecholate Organometallic Ligands: Synthesis, Structures, TD-DFT Calculations, and Photophysical Properties
A series of bipyridyl (bpy) PtĀ(II)
complexes with Ļ-bonded catecholate (cat) [(bpy)ĀPtĀ(L<sub>M</sub>)]Ā[BF<sub>4</sub>]<sub><i>n</i></sub> (<b>2</b>ā<b>5</b>) (L<sub>M</sub> = Cp*RhĀ(cat), <i>n</i> = 2; Cp*IrĀ(cat), <i>n</i> = 2; Cp*RuĀ(cat), <i>n</i> = 1; and (C<sub>6</sub>H<sub>6</sub>)ĀRuĀ(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 Ļ-bonded catecholate
unit. For instance, while the (bpy)ĀPtĀ(II) complexes <b>2</b> and <b>3</b> with rhodium and iridium catecholates did not
show any PtĀ·Ā·Ā·Pt interactions those with the ruthenium
catecholates <b>4</b> and <b>5</b> showed the presence
of PtĀ·Ā·Ā·Pt and ĻāĻ interactions
among individual units and generated one- and two-dimensional supramolecular
chains. The photophysical properties of these compounds <b>2</b>ā<b>5</b> were investigated and showed that all compounds
are luminescent at low temperature, in contrast to the well-known
parent compound [(C<sub>6</sub>H<sub>4</sub>O<sub>2</sub>)ĀPtĀ(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 Ļ-bonded catecholate
system
<i>Meso</i>-Helicates with Rigid Angular Tetradentate Ligand: Design, Molecular Structures, and Progress Towards Self-Assembly of MetalāOrganic Nanotubes
The
self-assembly of two novel metallosupramolecular complexes of the
general formulas [L<sub>2</sub>M<sub>2</sub>(CH<sub>3</sub>CN)<sub>4</sub>]Ā[BF<sub>4</sub>]<sub>4</sub> (M = Co, <b>1a</b>; M
= Ni, <b>1b</b>), where L stands for the tetradentate ligand
3,5-bisĀ[4-(2,2ā²-dipyridylamino)Āphenylacetylenyl]Ātoluene, 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
Ī and Ī configurations. These <i>meso</i>-helicates
display large nanocavities with metal---metal separation distance
of >2 nm; furthermore, ĻāĻ-stacking occurs among
individual units to form one-dimensional (1D) polymers which further
autoassemble in another direction through ĻāĻ contacts
among neighboring chains to generate a two-dimensional (2D) network
with regular nanocavities. Our approach might be of interest to prepare
metalāorganic 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 iridiumĀ(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 CāC 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 iridiumĀ(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 CāC coupling reactions,
allowing its grafting to a Keggin-type polyoxometalate and thus providing
a unique iridio-POM conjugate
Dinuclear (N<sup>ā§</sup>C<sup>ā§</sup>N) Pincer Pt(II) Complexes with Bridged Organometallic Linkers: Synthesis, Structures, Self-Aggregation, and Photophysical Properties
A new family of cationic
dinuclear cyclometalated PtĀ(II) complexes
containing an organometallic assembling ligand has been reported.
The general formulas for these compounds is as follow: [R-(N<sup>ā§</sup>C<sup>ā§</sup>N)ĀPtīøL-LīøPtĀ(N<sup>ā§</sup>C<sup>ā§</sup>N)-R]Ā[X]<sub>2</sub>, where L-L = [Cp*Ir-<i>p</i>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)], R = H, X = OTf (<b>5</b>); R= CF<sub>3</sub>ā, X
= OTf (<b>6a</b>), SbF<sub>6</sub> (<b>6b</b>); L-L =
[Cp*Ir-<i>p</i>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>Se<sub>2</sub>)] R= CF<sub>3</sub>ā, X = OTf (<b>7a</b>), SbF<sub>6</sub> (<b>7b</b>). In these coordination
assemblies two cyclometalated R-(N<sup>ā§</sup>C<sup>ā§</sup>N)Pt moieties are held by either Ī·<sup>4</sup>-dithio-<i>p</i>-benzoquinone complex [Cp*Ir-<i>p</i>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)] (<b>3</b>) or Ī·<sup>4</sup>-diseleno-<i>p</i>-benzoquinone
complex [Cp*Ir-<i>p</i>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>Se<sub>2</sub>)] (<b>4</b>). The molecular structures
of the known complex [4-CF<sub>3</sub>-(N<sup>ā§</sup>C<sup>ā§</sup>N)ĀPtCl] as well as two compounds of the above family
[(N<sup>ā§</sup>C<sup>ā§</sup>N)ĀPtāCp*Ir-<i>p</i>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)īøPtĀ(N<sup>ā§</sup>C<sup>ā§</sup>N)]Ā[CF<sub>3</sub>SO<sub>3</sub>]<sub>2</sub> (<b>5</b>) and [CF<sub>3</sub>-(N<sup>ā§</sup>C<sup>ā§</sup>N)ĀPtīøCp*Ir-<i>p</i>-(Ī·<sup>4</sup>-C<sub>6</sub>H<sub>4</sub>S<sub>2</sub>)īøPtĀ(N<sup>ā§</sup>C<sup>ā§</sup>N)-CF<sub>3</sub>]Ā[CF<sub>3</sub>SO<sub>3</sub>]<sub>2</sub> (<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 ĻāĻ
and short PtĀ·Ā·Ā·Pt interactions among individual units
providing 1D supramolecular chains. To our knowledge, these are the
only known examples where two cyclometalated PtĀ(N<sup>ā§</sup>C<sup>ā§</sup>N) units are assembled by a bridging ligand (vide
infra). All compounds show phosphorescence in the bluish-green region
(486ā521 nm) in the solution at room temperature and exhibit
higher luminescence quantum yields relative to the analogous compounds
containing a PtĀ(terpy) chromophore in thin film