6 research outputs found
Group 10 Metal Complexes with Chelating Macrocyclic Dicarbene Ligands Bearing a 2,6-Lutidinyl Bridge: Synthesis, Reactivity, and Catalytic Activity
Palladium(II) and platinum(II) complexes
of the title ligands have
been prepared; the two carbene moieties of the ligand coordinate to
the metal in <i>cis</i> fashion, while the bridging pyridyl
group remains outside the metal coordination sphere but close to the
metal center. In this peculiar situation, the pyridyl group can assist
the oxidation of the metal center to the +IV oxidation state upon
coordination to the metal in the product. Furthermore, the pyridyl
group is found to promote the catalytic role of the palladium(II)
complexes in copper- and amine-free Sonogashira reactions
Group 10 Metal Complexes with Chelating Macrocyclic Dicarbene Ligands Bearing a 2,6-Lutidinyl Bridge: Synthesis, Reactivity, and Catalytic Activity
Palladium(II) and platinum(II) complexes
of the title ligands have
been prepared; the two carbene moieties of the ligand coordinate to
the metal in <i>cis</i> fashion, while the bridging pyridyl
group remains outside the metal coordination sphere but close to the
metal center. In this peculiar situation, the pyridyl group can assist
the oxidation of the metal center to the +IV oxidation state upon
coordination to the metal in the product. Furthermore, the pyridyl
group is found to promote the catalytic role of the palladium(II)
complexes in copper- and amine-free Sonogashira reactions
Blue-Emitting Dinuclear N-heterocyclic Dicarbene Gold(I) Complex Featuring a Nearly Unit Quantum Yield
Dinuclear N-heterocyclic dicarbene gold(I) complexes
of general
formula [Au<sub>2</sub>(RIm-Y-ImR)<sub>2</sub>](PF<sub>6</sub>)<sub>2</sub> (R = Me, Cy; Y = (CH<sub>2</sub>)<sub>1–4</sub>, <i>o</i>-xylylene, <i>m</i>-xylylene) have been synthesized
and screened for their luminescence properties. All the complexes
are weakly emissive in solution whereas in the solid state some of
them show significant luminescence intensities. In particular, crystals
or powders of the complex with R = Me, Y = (CH<sub>2</sub>)<sub>3</sub> exhibit an intense blue emission (λ<sub>max</sub> = 450 nm)
with a high quantum yield (Φ<sub>em</sub> = 0.96). The X-ray
crystal structure of this complex is characterized by a rather short
intramolecular Au···Au distance (3.272 Ǻ).
Time dependent density functional theory (TDDFT) calculations have
been used to calculate the UV/vis properties of the ground state as
well as of the first excited state of the complex, the latter featuring
a significantly shorter Au···Au distance
Platinum(II) Complexes with Novel Diisocyanide Ligands: Catalysts in Alkyne Hydroarylation
A series of novel diisocyanide ligands
(<i>o</i>-CNC<sub>6</sub>H<sub>4</sub>O)<sub>2</sub>Y (diNC-1:
Y = P(O)Ph; diNC-2:
Y = <i>o</i>-C(O)C<sub>6</sub>H<sub>4</sub>C(O); diNC-3:
Y = <i>m</i>-C(O)C<sub>6</sub>H<sub>4</sub>C(O); diNC-4:
Y = C(O)C<sub>2</sub>H<sub>4</sub>C(O); diNC-5: Y = <i>trans</i>-C(O)C<sub>2</sub>H<sub>2</sub>C(O)) was successfully synthesized
by reaction of lithium 2-isocyanophenate (generated in situ from benzoxazole
and <i>n</i>-BuLi) and a diacylic or phosphonic dichloride.
The corresponding platinum(II) complexes of general formula [PtX<sub>2</sub>(diNC)]<sub>1,2</sub> (X = Cl, Me; diNC = diisocyanide ligand)
were isolated by simple substitution of 1,5-cyclooctadiene in the
starting [PtX<sub>2</sub>(COD)] complexes. The structure of the complexes,
mononuclear or dinuclear, was confirmed by single-crystal X-ray analysis.
A dinuclear complex of formula {(μ-diNC)[<i>cis</i>-PtCl<sub>2</sub>(PPh<sub>3</sub>)]<sub>2</sub>} could also be obtained
with the diisocyanide ligand having a rigid fumaryl bridge and consequently
the isocyanide moieties pointing in opposite directions. All the complexes
were employed as catalysts in the hydroarylation of alkynes, showing
generally good activity and selectivity toward the <i>trans</i>-hydroarylation product. With <i>N</i>-methylindole as
aromatic substrate the major product was instead a heterocycle:alkyne
2:1 adduct
N‑Phosphorylated Azolylidenes: Novel Ligands for Dinuclear Complexes of Coinage Metals
Dinuclear silver(I) complexes with bridging N-phosphorylated
azolylidene
ligands have been synthesized. Subsequent transfer of the ligands
to other group 11 metal centers (Cu, Au) has been accomplished, highlighting
the usefulness of the silver complexes as an easy to handle, air-
and moisture-stable source of these ligands. Preliminary results indicate
that dinuclear copper(I) complexes with N-phosphorylated imidazolylidene
ligands display notable catalytic efficiency in nitrene transfer reactions
Platinum(II) Complexes with Novel Diisocyanide Ligands: Catalysts in Alkyne Hydroarylation
A series of novel diisocyanide ligands
(<i>o</i>-CNC<sub>6</sub>H<sub>4</sub>O)<sub>2</sub>Y (diNC-1:
Y = P(O)Ph; diNC-2:
Y = <i>o</i>-C(O)C<sub>6</sub>H<sub>4</sub>C(O); diNC-3:
Y = <i>m</i>-C(O)C<sub>6</sub>H<sub>4</sub>C(O); diNC-4:
Y = C(O)C<sub>2</sub>H<sub>4</sub>C(O); diNC-5: Y = <i>trans</i>-C(O)C<sub>2</sub>H<sub>2</sub>C(O)) was successfully synthesized
by reaction of lithium 2-isocyanophenate (generated in situ from benzoxazole
and <i>n</i>-BuLi) and a diacylic or phosphonic dichloride.
The corresponding platinum(II) complexes of general formula [PtX<sub>2</sub>(diNC)]<sub>1,2</sub> (X = Cl, Me; diNC = diisocyanide ligand)
were isolated by simple substitution of 1,5-cyclooctadiene in the
starting [PtX<sub>2</sub>(COD)] complexes. The structure of the complexes,
mononuclear or dinuclear, was confirmed by single-crystal X-ray analysis.
A dinuclear complex of formula {(μ-diNC)[<i>cis</i>-PtCl<sub>2</sub>(PPh<sub>3</sub>)]<sub>2</sub>} could also be obtained
with the diisocyanide ligand having a rigid fumaryl bridge and consequently
the isocyanide moieties pointing in opposite directions. All the complexes
were employed as catalysts in the hydroarylation of alkynes, showing
generally good activity and selectivity toward the <i>trans</i>-hydroarylation product. With <i>N</i>-methylindole as
aromatic substrate the major product was instead a heterocycle:alkyne
2:1 adduct