2 research outputs found
Coinage Metal Complexes Supported by the Tri- and Tetraphosphine Ligands
A series of tri-
and tetranuclear phosphine complexes of d<sup>10</sup> metal ions
supported by the polydentate ligands, bisÂ(diphenylphosphinomethyl)Âphenylphosphine
(<i>PPP</i>) and trisÂ(diphenylphosphinomethyl)Âphosphine
(<i>PPPP</i>), were synthesized. All the compounds under
study, [AuM<sub>2</sub>(<i>PPP</i>)<sub>2</sub>]<sup>3+</sup> (M = Au (<b>1</b>), Cu (<b>2</b>), Ag (<b>3</b>)), [M<sub>4</sub>(<i>PPPP</i>)<sub>2</sub>]<sup>4+</sup> (M = Ag (<b>4</b>), Au (<b>5</b>)), [AuAg<sub>3</sub>(<i>PPPP</i>)<sub>2</sub>]<sup>4+</sup> (<b>6</b>), and [Au<sub>2</sub>Cu<sub>2</sub>(<i>PPPP</i>)<sub>2</sub>(NCMe)<sub>4</sub>]<sup>4+</sup> (<b>7</b>), were characterized
crystallographically. The trinuclear clusters <b>1</b>–<b>3</b> contain a linear metal core, while in the isostructural
tetranuclear complexes <b>4</b>–<b>6</b> the metal
framework has a plane star-shaped arrangement. Cluster <b>7</b> adopts a structural motif that involves a digold unit bridged by
two arms of the <i>PPPP</i> phosphines and decorated two
spatially separated Cu<sup>I</sup> ions chelated by the remaining
P donors. The NMR spectroscopic investigation in DMSO solution revealed
the heterometallic clusters <b>2</b>, <b>3</b>, and <b>6</b> are stereochemically nonrigid and undergo reversible metal
ions redistribution between several species, accompanied by their
solvation–desolvation. The complexes <b>1</b>–<b>3</b> and <b>5</b>–<b>7</b> exhibit room temperature
luminescence in the solid state (Φ<sub>em</sub> = 6–64%)
in the spectral region from 450 to 563 nm. The phosphorescence observed
originates from the triplet excited states, determined by the metal
cluster-centered d<sub>σ*</sub> → p<sub>σ</sub> transitions
Luminescent Triphosphine Cyanide d<sup>10</sup> Metal Complexes
Coinage metal cyanides efficiently
react with a triphosphine. PPh<sub>2</sub>C<sub>6</sub>H<sub>4</sub>–PPh–C<sub>6</sub>H<sub>4</sub>PPh<sub>2</sub> (P<sup>3</sup>). to give the complexes MÂ(P<sup>3</sup>)ÂCN, where M = Cu
(<b>1</b>), Ag (<b>2</b>), and Au (<b>3</b>), which
can further interact with coordinatively unsaturated metal centers
[MÂ(P<sup>3</sup>)]<sup>+</sup> to give the homobimetallic [(P<sup>3</sup>)ÂM–CN–MÂ(P<sup>3</sup>)]<sup>+</sup>X<sup>–</sup> [M = Cu (<b>4a</b> with X<sup>–</sup> = CF<sub>3</sub>SO<sub>3</sub><sup>–</sup> and <b>4b</b> with X<sup>–</sup> = BF<sub>4</sub><sup>–</sup>), Ag (<b>5</b>)] or heterometallic [(P<sup>3</sup>)ÂAu–CN–AgÂ(P<sup>3</sup>)]<sup>+</sup> (<b>6</b>) species. Extension of this
approach also provided the trinuclear complex [(P<sup>3</sup>)ÂCu–NC–Au–CN–CuÂ(P<sup>3</sup>)]<sup>+</sup> (<b>7</b>). Compounds <b>1</b>–<b>5</b> were characterized in the solid state by X-ray crystallography.
The NMR spectroscopic studies revealed that all of the complexes except <b>6</b> retain their structures in solution. The title compounds
are luminescent in the solid state, with quantum yields ranging from
8 to 87%. The observed photoemission originates mainly from the metal-to-ligand
charge-transfer states according to time-dependent density functional
theory computational studies. The crystalline bimetallic Cu complexes <b>4a</b>/<b>4b</b> demonstrate extremely high sensitivity
of the emission intensity to molecular O<sub>2</sub> (<i>K</i><sub>SV1</sub> = 639 atm<sup>–1</sup> and LOD = 0.010% for
3 times the signal-to-noise ratio)