11 research outputs found
Formation of Specific Configurations at Stereogenic Nitrogen Centers upon Their Coordination to Zinc and Mercury
The coordination of (<i>R</i>,<i>R</i>)-tetramethylcyclohexane-1,2-diamine
derivatives with stereogenic nitrogen centers to zinc and mercury
halides is investigated. It is shown that the resulting complexes
display one specific configuration at the stereogenic nitrogen centers.
This fact is unusual due to the fast inversion of nitrogen centers
but highly desirable as the stereoinformation of the ligands is brought
closer to the metal centers of the potential catalysts. A combination
of NMR studies and quantum chemical calculations gives insight into
the selective formation of one specific configuration at the stereogenic
nitrogen centers of the zinc complexes
Formation of Specific Configurations at Stereogenic Nitrogen Centers upon Their Coordination to Zinc and Mercury
The coordination of (<i>R</i>,<i>R</i>)-tetramethylcyclohexane-1,2-diamine
derivatives with stereogenic nitrogen centers to zinc and mercury
halides is investigated. It is shown that the resulting complexes
display one specific configuration at the stereogenic nitrogen centers.
This fact is unusual due to the fast inversion of nitrogen centers
but highly desirable as the stereoinformation of the ligands is brought
closer to the metal centers of the potential catalysts. A combination
of NMR studies and quantum chemical calculations gives insight into
the selective formation of one specific configuration at the stereogenic
nitrogen centers of the zinc complexes
Experimental and Theoretical Studies on the Mechanism of the C–S Bond Activation of Pd<sup>II</sup> Thiolate/Thioether Complexes
Two equivalents of <b>L</b> (<b>L</b> = 4-methylthio-2-thioxo-1,3-dithiole-5-thiolate
or Medmit) react with <i>cis</i>-Pd(PR<sub>3</sub>)<sub>2</sub>Cl<sub>2</sub> (R = Ph and Et) to afford Pd(PR<sub>3</sub>)(η<sup>1</sup>-<b>L</b>)(η<sup>2</sup>-<b>L</b>) (R = Et: <b>1</b> ; R = Ph: <b>2</b>) complexes, which
have been characterized by X-ray crystallography. These compounds
are dynamic in solution due to an exchange of the thiomethyl groups
on palladium. Variable-temperature <sup>1</sup>H NMR spectroscopy
reveals a low coalescence temperature (173 K). Treatment of Pd(<i>diphos</i>)Cl<sub>2</sub> (<i>diphos</i> = dppe or
dppm) with 2 equiv of <b>L</b> affords thiolato complexes Pd(dppe)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (<b>3</b>) and Pd(dppm)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (<b>4</b>). Whereas <b>3</b> is rigid in solution with firm η<sup>2</sup>-coordination
of dppe and η<sup>1</sup>-coordination of the thiolate, two
linkage isomers Pd(η<sup>2</sup>-dppm)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> and Pd(η<sup>1</sup>-dppm)(η<sup>1</sup>-<b>L</b>)(η<sup>2</sup>-<b>L</b>) coexist
in a solution of <b>4</b>. <b>L</b> coordinated on Pd<sup>II</sup> undergoes a S-demethylation reaction leading to dithiolene
complexes and Me<b>L</b>. This transformation requires high
temperature, and its efficiency depends on the nature of the phosphines
as well as the nature of the metal (Pd vs Pt). DFT calculations reveal
that the most likely mechanism depends on the lability of phosphines.
Starting from M(PR<sub>3</sub>)<sub>2</sub>(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (M= Pd and Pt; R = Ph and Et), the favored
sequence implies decoordination of one triethyl phosphine (M(PEt<sub>3</sub>)(η<sup>1</sup>-<b>L</b>)(η<sup>2</sup>-<b>L</b>)<sub>2</sub> as intermediate) or two triphenylphosphines
(Pd(η<sup>2</sup>-<b>L</b>)<sub>2</sub> as intermediate)
followed by oxidative addition and reductive elimination (OA/RE) reactions.
In the case of PEt<sub>3</sub>, this OA/RE sequence can also compete
with an intramolecular nucleophilic addition (<b><b>A<sub>N</sub></b></b>), which can be described as an attack of a thiolate
sulfur atom on a CH<sub>3</sub><sup>+</sup> carbocation. An intramolecular <b>S<sub>N</sub>2</b> process was found to be the most feasible,
starting from M(dppe)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (M= Pd and Pt), with the nucleophile approaching the thiomethyl
group at an angle of 180° with respect to the C<sub>CH<sub>3</sub></sub>–S bond. The influence of the coligand has also been
studied experimentally. Structurally characterized disulfide <b>L</b>–<b>L</b> dimer has been isolated upon reaction
of 2 equiv of <b>L</b> with MCl<sub>2</sub> (M = Pd and Pt)
Experimental and Theoretical Studies on the Mechanism of the C–S Bond Activation of Pd<sup>II</sup> Thiolate/Thioether Complexes
Two equivalents of <b>L</b> (<b>L</b> = 4-methylthio-2-thioxo-1,3-dithiole-5-thiolate
or Medmit) react with <i>cis</i>-Pd(PR<sub>3</sub>)<sub>2</sub>Cl<sub>2</sub> (R = Ph and Et) to afford Pd(PR<sub>3</sub>)(η<sup>1</sup>-<b>L</b>)(η<sup>2</sup>-<b>L</b>) (R = Et: <b>1</b> ; R = Ph: <b>2</b>) complexes, which
have been characterized by X-ray crystallography. These compounds
are dynamic in solution due to an exchange of the thiomethyl groups
on palladium. Variable-temperature <sup>1</sup>H NMR spectroscopy
reveals a low coalescence temperature (173 K). Treatment of Pd(<i>diphos</i>)Cl<sub>2</sub> (<i>diphos</i> = dppe or
dppm) with 2 equiv of <b>L</b> affords thiolato complexes Pd(dppe)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (<b>3</b>) and Pd(dppm)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (<b>4</b>). Whereas <b>3</b> is rigid in solution with firm η<sup>2</sup>-coordination
of dppe and η<sup>1</sup>-coordination of the thiolate, two
linkage isomers Pd(η<sup>2</sup>-dppm)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> and Pd(η<sup>1</sup>-dppm)(η<sup>1</sup>-<b>L</b>)(η<sup>2</sup>-<b>L</b>) coexist
in a solution of <b>4</b>. <b>L</b> coordinated on Pd<sup>II</sup> undergoes a S-demethylation reaction leading to dithiolene
complexes and Me<b>L</b>. This transformation requires high
temperature, and its efficiency depends on the nature of the phosphines
as well as the nature of the metal (Pd vs Pt). DFT calculations reveal
that the most likely mechanism depends on the lability of phosphines.
Starting from M(PR<sub>3</sub>)<sub>2</sub>(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (M= Pd and Pt; R = Ph and Et), the favored
sequence implies decoordination of one triethyl phosphine (M(PEt<sub>3</sub>)(η<sup>1</sup>-<b>L</b>)(η<sup>2</sup>-<b>L</b>)<sub>2</sub> as intermediate) or two triphenylphosphines
(Pd(η<sup>2</sup>-<b>L</b>)<sub>2</sub> as intermediate)
followed by oxidative addition and reductive elimination (OA/RE) reactions.
In the case of PEt<sub>3</sub>, this OA/RE sequence can also compete
with an intramolecular nucleophilic addition (<b><b>A<sub>N</sub></b></b>), which can be described as an attack of a thiolate
sulfur atom on a CH<sub>3</sub><sup>+</sup> carbocation. An intramolecular <b>S<sub>N</sub>2</b> process was found to be the most feasible,
starting from M(dppe)(η<sup>1</sup>-<b>L</b>)<sub>2</sub> (M= Pd and Pt), with the nucleophile approaching the thiomethyl
group at an angle of 180° with respect to the C<sub>CH<sub>3</sub></sub>–S bond. The influence of the coligand has also been
studied experimentally. Structurally characterized disulfide <b>L</b>–<b>L</b> dimer has been isolated upon reaction
of 2 equiv of <b>L</b> with MCl<sub>2</sub> (M = Pd and Pt)
Reactivity of Silyl-Substituted Iron–Platinum Hydride Complexes toward Unsaturated Molecules: 4. Insertion of Fluorinated Aromatic Alkynes into the Platinum–Hydride Bond. Synthesis and Reactivity of Heterobimetallic Dimetallacylopentenone, Dimetallacyclobutene, μ‑Vinylidene, and μ<sub>2</sub>‑σ-Alkenyl Complexes
Insertion
of <i>p</i>-FC<sub>6</sub>H<sub>4</sub>CCH, <i>p</i>-CF<sub>3</sub>C<sub>6</sub>H<sub>4</sub>CCH, and <i>m</i>-CF<sub>3</sub>C<sub>6</sub>H<sub>4</sub>CCH into
the Pt–H bond of [(OC)<sub>3</sub>Fe{Si(OMe)<sub>3</sub>}(μ-dppm)Pt(H)(PPh<sub>3</sub>)] (<b>1a</b>) yields first the σ-alkenyl complexes
[(OC)<sub>3</sub>Fe{μ-Si(OMe)<sub>2</sub>(OMe)}(μ-dppm)Pt(ArCCH<sub>2</sub>)] (<b>2a</b>, Ar = C<sub>6</sub>H<sub>4</sub>F-<i>p</i>; <b>2d</b>, C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>-<i>p</i>; <b>2e</b>, C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>-<i>m</i>), which react in a second step with the
liberated PPh<sub>3</sub> ligand to afford the structurally characterized
μ-vinylidene complexes [(OC)<sub>3</sub>Fe(μ-dppm){μ-CC(H)C<sub>6</sub>H<sub>4</sub>F-<i>p</i>}Pt(PPh<sub>3</sub>)] (<b>3a</b>) and [(OC)<sub>3</sub>Fe(μ-dppm){μ-CC(H)C<sub>6</sub>H<sub>4</sub>R}Pt(PPh<sub>3</sub>)] (<b>3d</b>, R = <i>p</i>-CF<sub>3</sub>; <b>3e</b>, R = <i>m</i>-CF<sub>3</sub>). In contrast, treatment of <b>1a</b> with <i>o</i>-FC<sub>6</sub>H<sub>4</sub>CCH produces first
[(OC)<sub>3</sub>Fe{μ-Si(OMe)<sub>2</sub>(OMe)}(μ-dppm)Pt(<i>o</i>-FC<sub>6</sub>H<sub>4</sub>CCH<sub>2</sub>)] (<b>2b</b>), which evolves to the dimetallacyclopentenone complex
[(OC)<sub>2</sub>Fe(μ-dppm){μ-C(O)C(H)C(C<sub>6</sub>H<sub>4</sub>F-<i>o</i>)}Pt(PPh<sub>3</sub>)] (<b>4b′</b>). The latter slowly rearranges to the structurally
characterized thermodynamic isomer [(OC)<sub>2</sub>Fe(μ-dppm){μ-C(O)C(C<sub>6</sub>H<sub>4</sub>F-<i>o</i>)C(H)}Pt(PPh<sub>3</sub>)] (<b>4b</b>). Treatment of <b>1a</b> with 2,4-F<sub>2</sub>C<sub>6</sub>H<sub>3</sub>CCH produces via transient
alkenyl complex <b>2c</b> an isomeric mixture of [(OC)<sub>3</sub>Fe(μ-dppm){μ-CC(H)C<sub>6</sub>H<sub>3</sub>F<sub>2</sub>-2,4}Pt(PPh<sub>3</sub>)] (<b>3c</b>), [(OC)<sub>2</sub>Fe(μ-dppm){μ-C(O)C(H)C(C<sub>6</sub>H<sub>3</sub>F<sub>2</sub>-2,4)}Pt(PPh<sub>3</sub>)] (<b>4c′</b>), and [(OC)<sub>2</sub>Fe(μ-dppm){μ-C(O)C(C<sub>6</sub>H<sub>3</sub>F<sub>2</sub>-2,4)C(H)}Pt(PPh<sub>3</sub>)] (<b>4c</b>). Alternatively, <b>4b</b>,<b>c</b> and [(OC)<sub>2</sub>Fe(μ-dppm){μ-C(O)C(Ar)C(H)}Pt(PPh<sub>3</sub>)] (<b>4a</b>, Ar = C<sub>6</sub>H<sub>4</sub>F-<i>p</i>, <b>4d</b>, Ar = C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>-<i>p</i>) were obtained by reaction of [(OC)<sub>3</sub>Fe(μ-dppm)(μ-CO)Pt(PPh<sub>3</sub>)] with
the respective terminal alkyne. Upon reaction of <b>1a</b>,
[(OC)<sub>3</sub>Fe{Si(OMe)<sub>3</sub>}(μ-dppa)Pt(H)(PPh<sub>3</sub>)] (<b>1b</b>; dppa = bis(diphenylphosphino)amine),
and [(OC)<sub>3</sub>Fe{Si(OMe)<sub>3</sub>}(μ-dppm)Pt(H)(PMePh<sub>2</sub>)] (<b>1c</b>) with <i>o</i>-F<sub>3</sub>CC<sub>6</sub>H<sub>4</sub>CCH, the dimetallacyclobutenes
[(OC)<sub>3</sub>Fe(μ-PPh<sub>2</sub>XPPh<sub>2</sub>){μ-C(C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>-<i>o</i>)CC(H)}Pt(PPh<sub>2</sub>R)] (<b>5a</b>, X = CH<sub>2</sub>, R = Ph; <b>5b</b>, X = NH, R = Ph; <b>5c</b>, X = CH<sub>2</sub>, R = Me) are
formed as the sole products. Complexes <b>5</b> result also
from the reaction of [(OC)<sub>3</sub>Fe(μ-Ph<sub>2</sub>PXPPh<sub>2</sub>)(μ-CO)Pt(PPh<sub>3</sub>)] (X = CH<sub>2</sub>, NH) with <i>o</i>-trifluorophenylacetylene. NMR studies
at variable temperatures reveal that dimetallacyclobutenes <b>5</b> are in equilibrium with dimetallacyclopentenones [(OC)<sub>2</sub>Fe(μ-Ph<sub>2</sub>PXPPh<sub>2</sub>){μ-C(O)C(C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>-<i>o</i>)C(H)}Pt(PPh<sub>2</sub>R)] (<b>4e</b>, X = CH<sub>2</sub>, R = Ph; <b>4f</b>, X = NH, R = Ph; <b>4g</b>, X = CH<sub>2</sub>, R = Me). Addition
of HBF<sub>4</sub> to <b>5</b> leads to formation of the Fe-σ:μ<sub>2</sub>-alkenyl salts [(OC)<sub>3</sub>Fe(μ-Ph<sub>2</sub>PXPPh<sub>2</sub>){μ-C(C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>-<i>o</i>)CH<sub>2</sub>}Pt(PPh<sub>3</sub>)][BF<sub>4</sub>] (<b>6a</b>, X = CH<sub>2</sub>;<b> 6b</b>, X = NH).
Protonation of <b>4</b> gives the isomeric Pt-σ:μ<sub>2</sub>-alkenyl salts [(OC)<sub>3</sub>Fe(μ-dppm){μ-CH<sub>2</sub>C(Ar)}Pt(PPh<sub>3</sub>)][BF<sub>4</sub>] (<b>7</b>) together with small amounts of the Fe-σ:μ<sub>2</sub>-alkenyl salts [(OC)<sub>3</sub>Fe(μ-dppm){μ-C(Ar)CH<sub>2</sub>}Pt(PPh<sub>3</sub>)][BF<sub>4</sub>] (Ar = <i>p</i>-C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>, <i>p</i>-C<sub>6</sub>H<sub>4</sub>F, 2,4-C<sub>6</sub>H<sub>3</sub>F<sub>2</sub>). Protonation of the vinylidene complexes [(OC)<sub>3</sub>Fe(μ-dppm){μ-CC(H)Ar}Pt(PPh<sub>3</sub>)] (<b>3</b>; Ar = <i>p</i>-C<sub>6</sub>H<sub>4</sub>CF<sub>3</sub>, Ph, <i>p</i>-C<sub>6</sub>H<sub>4</sub>CH<sub>3</sub>) with HBF<sub>4</sub> occurs exclusively at
the α-position of the vinylidene unit to produce a mixture of
the isomeric σ-alkenyl salts <i>cis</i>-[(OC)<sub>3</sub>Fe(μ-dppm){μ-C(H)C(H)Ar}Pt(PPh<sub>3</sub>)][BF<sub>4</sub>] (<b>8-<i>cis</i></b>) and <i>trans</i>-[(OC)<sub>3</sub>Fe(μ-dppm){μ-C(H)C(H)Ar}Pt(PPh<sub>3</sub>)][BF<sub>4</sub>] (<b>8-</b><i><b>trans</b></i>)
1,4-Bis(arylthio)but-2-enes as Assembling Ligands for (Cu<sub>2</sub>X<sub>2</sub>)<sub><i>n</i></sub> (X = I, Br; <i>n</i> = 1, 2) Coordination Polymers: Aryl Substitution, Olefin Configuration, and Halide Effects on the Dimensionality, Cluster Size, and Luminescence Properties
CuI reacts with <i>E</i>-PhS(CH<sub>2</sub>CHCHCH<sub>2</sub>)SPh, <b>L1</b>, to afford the coordination polymer
(CP) [Cu<sub>2</sub>I<sub>2</sub>{μ-<i>E</i>-PhS(CH<sub>2</sub>CHCHCH<sub>2</sub>)SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>1a</b>). The unprecedented
square-grid network of <b>1</b> is built upon alternating two-dimensional
(2D) layers with an ABAB sequence and contains rhomboid Cu<sub>2</sub>(μ<sub>2</sub>-I)<sub>2</sub> clusters as secondary building
units (SBUs). Notably, layer A, interconnected by bridging <b>L1</b> ligands, contains exclusively dinuclear units with short Cu···Cu
separations [2.6485(7) Å; 115 K]. In contrast, layer B exhibits
Cu···Cu distances of 2.8133(8) Å. The same network
is observed when CuBr reacts with <b>L1</b>. In the 2D network
of [Cu<sub>2</sub>Br<sub>2</sub>{μ-<i>E</i>-PhS(CH<sub>2</sub>CHCHCH<sub>2</sub>)SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>1b</b>), isotype to <b>1a</b>, one
square-grid-type layer contains Cu<sub>2</sub>(μ<sub>2</sub>-Br)<sub>2</sub> SBUs with short Cu···Cu contacts
[2.7422(6) Å at 115K], whereas the next layer incorporates exclusively
Cu<sub>2</sub>(μ<sub>2</sub>-Br)<sub>2</sub> SBUs with a significantly
longer Cu···Cu separation [2.9008(10) Å]. The
evolution of the crystallographic parameters of <b>1a</b> and <b>1b</b> was monitored between 115 and 275 K. Conversely, the isomeric <i>Z</i>-PhS(CH<sub>2</sub>CHCHCH<sub>2</sub>)SPh ligand <b>L2</b> reacts with CuI to form the 2D CP [Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>(μ-<i>Z</i>-PhS(CH<sub>2</sub>CHCHCH<sub>2</sub>)SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>2a</b>) with closed-cubane SBUs. A dinuclear
zero-dimensional complex [Cu<sub>2</sub>Br<sub>2</sub>{μ-<i>Z</i>-PhS(CH<sub>2</sub>CHCHCH<sub>2</sub>)SPh}<sub>2</sub>] (<b>2b</b>) is formed when CuBr is reacted with <b>L2</b>. Upon reaction of <i>E</i>-TolS(CH<sub>2</sub>CHCHCH<sub>2</sub>)STol, <b>L3</b>, with
CuI, the 2D CP [{Cu(μ<sub>3</sub>-I)}<sub>2</sub>(μ-<b>L3</b>)]<sub><i>n</i></sub> containing parallel-arranged
infinite inorganic staircase ribbons, is generated. When CuX reacts
with <i>Z</i>-TolS(CH<sub>2</sub>CHCHCH<sub>2</sub>)STol, <b>L4</b>, the isostructural 2D CPs [Cu<sub>2</sub>X<sub>2</sub>{μ-<i>Z</i>-TolS(CH<sub>2</sub>CHCHCH<sub>2</sub>)STol}<sub>2</sub>] <b>(4a</b> X = I; <b>4b</b> X = Br) are formed. In contrast
to the CPs <b>1a,b</b>, the layers based on rhombic grids of <b>4a,b</b> incorporate Cu<sub>2</sub>(μ<sub>2</sub>-X)<sub>2</sub> SBUs featuring uniformly identical Cu···Cu
distances within each layer. The TGA traces showed that all these
materials are stable up to ∼200 °C. Moreover, the photophysical
properties have been studied, including absorption, emission, excitation
spectra, and emission lifetimes at 298 and 77 K. The spectra were
interpreted using density functional theory (DFT) and time-dependent
DFT calculations
Reactivity of CuI and CuBr toward Dialkyl Sulfides RSR: From Discrete Molecular Cu<sub>4</sub>I<sub>4</sub>S<sub>4</sub> and Cu<sub>8</sub>I<sub>8</sub>S<sub>6</sub> Clusters to Luminescent Copper(I) Coordination Polymers
The 1D coordination polymer (CP)
[(Me<sub>2</sub>S)<sub>3</sub>{Cu<sub>2</sub>(μ-I)<sub>2</sub>}]<sub><i>n</i></sub> (<b>1</b>) is formed when CuI
reacts with SMe<sub>2</sub> in <i>n</i>-heptane, whereas
in acetonitrile (MeCN), the reaction forms exclusively the 2D CP [(Me<sub>2</sub>S)<sub>3</sub>{Cu<sub>4</sub>(μ-I)<sub>4</sub>}]<sub><i>n</i></sub> (<b>2</b>) containing “flower-basket”
Cu<sub>4</sub>I<sub>4</sub> units. The reaction product of CuI with
MeSEt is also solvent-dependent, where the 1D polymer [(MeSEt)<sub>2</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>2</sub>(μ<sub>2</sub>-I)<sub>2</sub>}(MeCN)<sub>2</sub>]<sub><i>n</i></sub> (<b>3</b>) containing “stepped-cubane” Cu<sub>4</sub>I<sub>4</sub> units is isolated in MeCN. In contrast, the reaction
in <i>n</i>-heptane affords the 1D CP [(MeSEt)<sub>3</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}]<sub><i>n</i></sub> (<b>4</b>) containing “closed-cubane”
Cu<sub>4</sub>I<sub>4</sub> clusters. The reaction of MeSPr with CuI
provides the structurally related 1D CP [(MeSPr)<sub>3</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}]<sub><i>n</i></sub> (<b>5</b>), for which the X-ray structure has been determined
at 115, 155, 195, 235, and 275 K, addressing the evolution of the
metric parameters. Similarly to <b>4</b> and the previously
reported CP [(Et<sub>2</sub>S)<sub>3</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}]<sub><i>n</i></sub> (<i>Inorg.
Chem.</i> <b>2010</b>, <i>49</i>, 5834), the
1D chain is built upon closed cubanes Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub> as secondary building units (SBUs) interconnected
via μ-MeSPr ligands. The 0D tetranuclear clusters [(L)<sub>4</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}] [L = EtSPr (<b>6</b>), Pr<sub>2</sub>S (<b>7</b>)] respectively result
from the reaction of CuI with EtSPr and <i>n</i>-Pr<sub>2</sub>S. With <i>i</i>-Pr<sub>2</sub>S, the octanuclear
cluster [(<i>i</i>-Pr<sub>2</sub>S)<sub>6</sub>{Cu<sub>8</sub>(μ<sub>3</sub>-I)<sub>3</sub>}(μ<sub>4</sub>-I)<sub>2</sub>}] (<b>8</b>) is formed. An X-ray study has also been performed
at five different temperatures for the 2D polymer [(Cu<sub>3</sub>Br<sub>3</sub>)(MeSEt)<sub>3</sub>]<sub><i>n</i></sub> (<b>9</b>) formed from the reaction between CuBr and MeSEt in heptane.
The unprecedented framework of <b>9</b> consists of layers with
alternating Cu(μ<sub>2</sub>-Br)<sub>2</sub>Cu rhomboids, which
are connected through two μ-MeSEt ligands to tetranuclear open-cubane
Cu<sub>4</sub>Br<sub>4</sub> SBUs. MeSPr forms with CuBr in heptane
the 1D CP [(Cu<sub>3</sub>Br<sub>3</sub>)(MeSPr)<sub>3</sub>]<sub><i>n</i></sub> (<b>10</b>), which is converted to
a 2D metal–organic framework [(Cu<sub>5</sub>Br<sub>5</sub>)(μ<sub>2</sub>-MeSPr)<sub>3</sub>]<sub><i>n</i></sub> (<b>11</b>) incorporating pentanuclear [(Cu<sub>5</sub>(μ<sub>4</sub>-Br)(μ<sub>2</sub>-Br)] SBUs when recrystallized in
MeCN. The thermal stability and photophysical properties of these
materials are also reported
Reactivity of CuI and CuBr toward Dialkyl Sulfides RSR: From Discrete Molecular Cu<sub>4</sub>I<sub>4</sub>S<sub>4</sub> and Cu<sub>8</sub>I<sub>8</sub>S<sub>6</sub> Clusters to Luminescent Copper(I) Coordination Polymers
The 1D coordination polymer (CP)
[(Me<sub>2</sub>S)<sub>3</sub>{Cu<sub>2</sub>(μ-I)<sub>2</sub>}]<sub><i>n</i></sub> (<b>1</b>) is formed when CuI
reacts with SMe<sub>2</sub> in <i>n</i>-heptane, whereas
in acetonitrile (MeCN), the reaction forms exclusively the 2D CP [(Me<sub>2</sub>S)<sub>3</sub>{Cu<sub>4</sub>(μ-I)<sub>4</sub>}]<sub><i>n</i></sub> (<b>2</b>) containing “flower-basket”
Cu<sub>4</sub>I<sub>4</sub> units. The reaction product of CuI with
MeSEt is also solvent-dependent, where the 1D polymer [(MeSEt)<sub>2</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>2</sub>(μ<sub>2</sub>-I)<sub>2</sub>}(MeCN)<sub>2</sub>]<sub><i>n</i></sub> (<b>3</b>) containing “stepped-cubane” Cu<sub>4</sub>I<sub>4</sub> units is isolated in MeCN. In contrast, the reaction
in <i>n</i>-heptane affords the 1D CP [(MeSEt)<sub>3</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}]<sub><i>n</i></sub> (<b>4</b>) containing “closed-cubane”
Cu<sub>4</sub>I<sub>4</sub> clusters. The reaction of MeSPr with CuI
provides the structurally related 1D CP [(MeSPr)<sub>3</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}]<sub><i>n</i></sub> (<b>5</b>), for which the X-ray structure has been determined
at 115, 155, 195, 235, and 275 K, addressing the evolution of the
metric parameters. Similarly to <b>4</b> and the previously
reported CP [(Et<sub>2</sub>S)<sub>3</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}]<sub><i>n</i></sub> (<i>Inorg.
Chem.</i> <b>2010</b>, <i>49</i>, 5834), the
1D chain is built upon closed cubanes Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub> as secondary building units (SBUs) interconnected
via μ-MeSPr ligands. The 0D tetranuclear clusters [(L)<sub>4</sub>{Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub>}] [L = EtSPr (<b>6</b>), Pr<sub>2</sub>S (<b>7</b>)] respectively result
from the reaction of CuI with EtSPr and <i>n</i>-Pr<sub>2</sub>S. With <i>i</i>-Pr<sub>2</sub>S, the octanuclear
cluster [(<i>i</i>-Pr<sub>2</sub>S)<sub>6</sub>{Cu<sub>8</sub>(μ<sub>3</sub>-I)<sub>3</sub>}(μ<sub>4</sub>-I)<sub>2</sub>}] (<b>8</b>) is formed. An X-ray study has also been performed
at five different temperatures for the 2D polymer [(Cu<sub>3</sub>Br<sub>3</sub>)(MeSEt)<sub>3</sub>]<sub><i>n</i></sub> (<b>9</b>) formed from the reaction between CuBr and MeSEt in heptane.
The unprecedented framework of <b>9</b> consists of layers with
alternating Cu(μ<sub>2</sub>-Br)<sub>2</sub>Cu rhomboids, which
are connected through two μ-MeSEt ligands to tetranuclear open-cubane
Cu<sub>4</sub>Br<sub>4</sub> SBUs. MeSPr forms with CuBr in heptane
the 1D CP [(Cu<sub>3</sub>Br<sub>3</sub>)(MeSPr)<sub>3</sub>]<sub><i>n</i></sub> (<b>10</b>), which is converted to
a 2D metal–organic framework [(Cu<sub>5</sub>Br<sub>5</sub>)(μ<sub>2</sub>-MeSPr)<sub>3</sub>]<sub><i>n</i></sub> (<b>11</b>) incorporating pentanuclear [(Cu<sub>5</sub>(μ<sub>4</sub>-Br)(μ<sub>2</sub>-Br)] SBUs when recrystallized in
MeCN. The thermal stability and photophysical properties of these
materials are also reported
Construction of (CuX)<sub>2<i>n</i></sub> Cluster-Containing (X = Br, I; <i>n</i> = 1, 2) Coordination Polymers Assembled by Dithioethers ArS(CH<sub>2</sub>)<sub><i>m</i></sub>SAr (Ar = Ph, <i>p</i>‑Tol; <i>m</i> = 3, 5): Effect of the Spacer Length, Aryl Group, and Metal-to-Ligand Ratio on the Dimensionality, Cluster Nuclearity, and the Luminescence Properties of the Metal–Organic Frameworks
Reaction of CuI with bis(phenylthio)propane in a 1:1
ratio yields the two-dimensional coordination polymer [{Cu(μ<sub>2</sub>-I)<sub>2</sub>Cu}{μ-PhS(CH<sub>2</sub>)<sub>3</sub>SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>1</b>).
The 2D-sheet structure of <b>1</b> is built up by dimeric Cu<sub>2</sub>I<sub>2</sub> units, which are connected via four bridging
1,3-bis(phenylthio)propane ligands. In contrast, treatment of 2 equiv
of CuI with 1,3-bis(phenylthio)propane in MeCN solution affords in
a self-assembly reaction the strongly luminescent metal–organic
2D-coordination polymer [Cu<sub>4</sub>I<sub>4</sub>{μ-PhS(CH<sub>2</sub>)<sub>3</sub>Ph}<sub>2</sub>]<sub><i>n</i></sub> (<b>2</b>), in which cubane-like Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub> cluster units are linked by the dithioether
ligands. The crystallographically characterized one-dimensional (1D)
compound [{Cu(μ<sub>2</sub>-Br)<sub>2</sub>Cu}{μ-PhS(CH<sub>2</sub>)<sub>3</sub>SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>3</b>) is obtained using CuBr. The outcome of the reaction
of PhS(CH<sub>2</sub>)<sub>5</sub>SPh with CuI also depends of the
metal-to-ligand ratio employed. Mixing CuI and the dithioether in
a 2:1 ratio results in formation of [Cu<sub>4</sub>I<sub>4</sub>{μ-PhS(CH<sub>2</sub>)<sub>5</sub>Ph}<sub>2</sub>]<sub><i>n</i></sub> (<b>4</b>) in which cubane-like Cu<sub>4</sub>(μ<sub>3</sub>-I)<sub>4</sub> clusters are linked by the bridging dithioether
ligand giving rise to a 1D necklace structure. A ribbon-like 1D-polymer
with composition [{Cu(μ<sub>2</sub>-I)<sub>2</sub>Cu}{μ-PhS(CH<sub>2</sub>)<sub>5</sub>SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>5</b>), incorporating rhomboid Cu<sub>2</sub>I<sub>2</sub> units, is produced upon treatment of CuI with 1,5-bis(phenylthio)pentane
in a 1:1 ratio. Reaction of CuBr with PhS(CH<sub>2</sub>)<sub>5</sub>SPh produces the isomorphous 1D-compound [{Cu(μ<sub>2</sub>-Br)<sub>2</sub>Cu}{μ-PhS(CH<sub>2</sub>)<sub>5</sub>SPh}<sub>2</sub>]<sub><i>n</i></sub> (<b>6</b>). Strongly
luminescent [Cu<sub>4</sub>I<sub>4</sub>{μ-<i>p</i>-TolS(CH<sub>2</sub>)<sub>5</sub>STol-<i>p</i>}<sub>2</sub>]<sub><i>n</i></sub> (<b>7</b>) is obtained after
mixing 1,5-bis(<i>p</i>-tolylthio)pentane with CuI in a
1:2 ratio, and the 2D-polymer [{Cu(μ<sub>2</sub>-I)<sub>2</sub>Cu}<sub>2</sub>{μ-<i>p</i>-TolS(CH<sub>2</sub>)<sub>5</sub>STol-<i>p</i>}<sub>2</sub>]<sub><i>n</i></sub> (<b>8</b>) results from reaction in a 1:1 metal-to-ligand
ratio. Under the same reaction conditions, 1D-polymeric [{Cu(μ<sub>2</sub>-Br)<sub>2</sub>Cu}{μ-<i>p</i>-TolS(CH<sub>2</sub>)<sub>5</sub>STol-p}<sub>2</sub>]<sub><i>n</i></sub> (<b>9</b>) is formed using CuBr. This study reveals that the
structure of the self-assembly process between CuX and ArS(CH<sub>2</sub>)<sub><i>m</i></sub>SAr ligands is hard to predict.
The solid-state luminescence spectra at 298 and 77 K of <b>2</b> and <b>4</b> exhibit very strong emissions around 535 and
560 nm, respectively, whereas those for <b>1</b> and <b>5</b> display weaker ones at about 450 nm. The emission lifetimes are
longer for the longer wavelength emissions (>1.0 μs arising
from the cubane species) and shorter for the shorter wavelength ones
(<1.4 μs arising from the rhomboid units). The Br-containing
species are found to be weakly fluorescent
Regio- and Stereoselective Synthesis of Spiropyrrolizidines and Piperazines through Azomethine Ylide Cycloaddition Reaction
A series
of original spiropyrrolizidine derivatives has been prepared
by a one-pot three-component [3 + 2] cycloaddition reaction of (<i>E</i>)-3-arylidene-1-phenyl-pyrrolidine-2,5-diones, l-proline, and the cyclic ketones 1<i>H</i>-indole-2,3-dione
(isatin), indenoquinoxaline-11-one and acenaphthenequinone. We disclose
an unprecedented isomerization of some spiroadducts leading to a new
family of spirooxindolepyrrolizidines. Furthermore, these cycloadducts
underwent retro-1,3-dipolar cycloaddition yielding unexpected regioisomers.
Upon treatment of the dipolarophiles with <i>in situ</i> generated azomethine ylides from l-proline or acenaphthenequinone,
formation of spiroadducts and unusual polycyclic fused piperazines
through a stepwise [3 + 3] cycloaddition pathway is observed. The
stereochemistry of these N-heterocycles has been confirmed by several
X-ray diffraction studies. Some of these compounds exhibit extensive
hydrogen bonding in the crystalline state. To enlighten the observed
regio- and stereoselectivity of the [3 + 2] cycloaddition, calculations
using the DFT approach at the B3LYP/6-31G(d,p) level were carried
out. It was found that this reaction is under kinetic control