11 research outputs found
Solvent-Driven PāS vs PāC Bond Formation from a Diplatinum(III) Complex and Sulfur-Based Anions
The
outcome of the reaction of the PtĀ(III),PtĀ(III) complex [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>III</sup>(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>]Ā(<i>PtāPt</i>) (<b>1</b>) with the S-based
anions thiophenoxide (PhS<sup>ā</sup>), ethyl xanthogenate
(EtOCS<sub>2</sub><sup>ā</sup>), 2-mercaptopyrimidinate (pymS<sup>ā</sup>), and 2-mercaptopyridinate (pyS<sup>ā</sup>) was found to be dependent on the reaction solvent. The reactions
carried out in acetone led to the formation of [N<sup>n</sup>Bu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PhS-PPh<sub>2</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>2</b>), [N<sup>n</sup>Bu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-EtOCS<sub>2</sub>-PPh<sub>2</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>3</b>), [N<sup>n</sup>Bu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-pymS-PPh<sub>2</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>4</b>), and [N<sup>n</sup>Bu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-pySāPPh<sub>2</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>5</b>), respectively
(R<sub>F</sub> = C<sub>6</sub>F<sub>5</sub>). Complexes <b>2</b>ā<b>5</b> display new Ph<sub>2</sub>PĀ(SL) ligands exhibiting
a Īŗ<sup>2</sup>-<i>P</i>,<i>S</i> bridging
coordination mode, which is derived from a reductive elimination of
a PPh<sub>2</sub> group and the S-based anion. Carrying out the reaction
in dichloromethane afforded, in the cases of EtOCS<sub>2</sub><sup>ā</sup> and pymS<sup>ā</sup>, the monobridged complexes
[N<sup>n</sup>Bu<sub>4</sub>]Ā[(PPh<sub>2</sub>R<sub>F</sub>)Ā(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(EtOCS<sub>2</sub>)Ā(R<sub>F</sub>)] (<b>6</b>) and
[N<sup>n</sup>Bu<sub>4</sub>]Ā[(PPh<sub>2</sub>R<sub>F</sub>)Ā(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(pymS)Ā(R<sub>F</sub>)] (<b>7</b>), respectively, which
are derived from reductive elimination of a PPh<sub>2</sub> group
with a pentafluorophenyl ring. The reaction of <b>1</b> with
EtOCS<sub>2</sub>K in acetonitrile yielded a mixture of <b>3</b> and <b>6</b> as a consequence of the concurrence of two processes:
(a) the formation of <b>3</b> by a reaction that parallels the
formation of <b>3</b> by <b>1</b> plus EtOCS<sub>2</sub>K in acetone and (b) the transformation of <b>1</b> into the
neutral complex [(PPh<sub>2</sub>R<sub>F</sub>)Ā(CH<sub>3</sub>CN)Ā(R<sub>F</sub>)ĀPt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>(CH<sub>3</sub>CN)] (<b>8</b>), which,
in turn, reacts with EtOCS<sub>2</sub>K to give <b>6</b>. The <b>1</b> to <b>8</b> transformation was found to be fully reversible.
In fact, dissolving <b>8</b> in acetone or dichloromethane afforded
pure <b>1</b> after solvent evaporation or crystallization with <i>n</i>-hexane. The XRD structures of <b>2</b>ā<b>4</b> and <b>6</b>ā<b>8</b> were determined,
and the behavior in solution of the new complexes is discussed
A Borane Platinum Complex Undergoing Reversible Hydride Migration in Solution
Reaction of [PtĀ(Īŗ<sup>2</sup>-<i>C</i>,<i>N</i>-ppy)Ā(dmso)ĀCl], <b>1</b> (Hppy = 2-phenylpyridine), with NaĀ[H<sub>2</sub>BĀ(mb)<sub>2</sub>] (Hmb = 2-mercapto-benzimidazole) smoothly afforded the complex
{[(Īŗ<sup>3</sup>-<i>S</i>,<i>B</i>,<i>S</i>-HBĀ(mb)<sub>2</sub>]ĀPtĀ(Īŗ<sup>2</sup>-<i>C</i>,<i>N</i>-ppy)ĀH}, <b>2</b>, featuring a strong reverse-dative
Pt ā B Ļ interaction in the solid state. When dissolved
in thf (or acetone) solution, <b>2</b> undergoes a reversible
PtāH bond activation, establishing an equilibrium between the
hexacoordinated <b>2</b> and the tetracoordinate complex {[(Īŗ<sup>2</sup>-<i>S</i>,<i>S</i>-H<sub>2</sub>BĀ(mb)<sub>2</sub>]ĀPtĀ(Īŗ<sup>2</sup>-<i>C</i>,<i>N</i>-ppy)}, <b>3</b>, as ascertained by multinuclear NMR. Hydrolysis
of the BāN bond in <b>2</b>/<b>3</b> resulted ultimately
in the formation of a dimeric half-lantern platinumĀ(II,II) complex
[{PtĀ(Īŗ<sup>2</sup>-<i>C</i>,<i>N</i>-ppy)Ā(Ī¼<sub>2</sub>-Īŗ<sup>2</sup>-<i>N</i>,<i>S</i>-mb)}<sub>2</sub>], <b>4</b>. The SC-XRD structures of <b>2</b> and <b>4</b> are reported
Synthesis and Reactivity of the Unsaturated Trinuclear Phosphanido Complex [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt(PPh<sub>3</sub>)]
The reaction of [NBu<sub>4</sub>]Ā[(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>PtĀ(<i>O</i>,<i>O</i>-acac)]
(48 VEC) with [HPPh<sub>3</sub>]Ā[ClO<sub>4</sub>] gives the 46 VEC
unsaturated [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>1</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>2</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>3</sup>(PPh<sub>3</sub>)]Ā(Pt<sup>2</sup>āPt<sup>3</sup>) (<b>1</b>), a trinuclear compound endowed
with a PtāPt bond. This compound displays amphiphilic behavior
and reacts easily with nucleophiles L, yielding the saturated complexes
[(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(PPh<sub>3</sub>)ĀL] [L = PPh<sub>3</sub> (<b>2</b>), py (<b>3</b>)]. The reaction with the electrophile
[AgĀ(OClO<sub>3</sub>)ĀPPh<sub>3</sub>] affords the adduct <b>1</b>Ā·AgPPh<sub>3</sub>, which evolves, even at low temperature,
to a mixture in which [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(PPh<sub>3</sub>)<sub>2</sub>]<sup>2+</sup>(Pt<sup>III</sup>āPt<sup>III</sup>) and <b>2</b> (plus silver metal) are present. The nucleophilic nature of <b>1</b> is also demonstrated through its reaction with <i>cis</i>-[PtĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>(THF)<sub>2</sub>], which
results in the formation of [Pt<sub>4</sub>(Ī¼-PPh<sub>2</sub>)<sub>4</sub>(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>(PPh<sub>3</sub>)] (<b>4</b>). The structure and NMR features indicate that <b>1</b> can be better considered as a Pt<sup>II</sup>āPt<sup>III</sup>āPt<sup>I</sup> complex instead of a Pt<sup>II</sup>āPt<sup>II</sup>āPt<sup>II</sup> derivative. Theoretical
calculations (density functional theory) on similar model compounds
are in agreement with the assigned oxidation states of the metal centers.
The strong intermetallic interactions resulting in a Pt<sup>2</sup>āPt<sup>3</sup> metalāmetal bond and the respective
bonding mechanism were verified by employing a multitude of computational
techniques (natural bond order analysis, the Laplacian of the electron
density, and localized orbital locator profiles)
Multinuclear Solid-State NMR and DFT Studies on Phosphanido-Bridged Diplatinum Complexes
Multinuclear (<sup>31</sup>P, <sup>195</sup>Pt, <sup>19</sup>F)
solid-state NMR experiments on (<i>n</i>Bu<sub>4</sub>N)<sub>2</sub>[(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>PtĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>] (<b>1</b>), [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>PtĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>]Ā(<i>PtāPt</i>) (<b>2</b>), and <i>cis</i>-PtĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>(PHPh<sub>2</sub>)<sub>2</sub> (<b>3</b>) were carried out under cross-polarization/magic-angle-spinning
conditions or with the cross-polarization/CarrāPurcell MeiboomāGill
pulse sequence. Analysis of the principal components of the <sup>31</sup>P and <sup>195</sup>Pt chemical shift (CS) tensors of <b>1</b> and <b>2</b> reveals that the variations observed comparing
the isotropic chemical shifts of <b>1</b> and <b>2</b>, commonly referred to as āring effectā, are mainly
due to changes in the principal components oriented along the direction
perpendicular to the Pt<sub>2</sub>P<sub>2</sub> plane. DFT calculations
of <sup>31</sup>P and <sup>195</sup>Pt CS tensors confirmed the tensor
orientation proposed from experimental data and symmetry arguments
and revealed that the different values of the isotropic shieldings
stem from differences in the paramagnetic and spināorbit contributions
Synthesis and Reactivity of the Unsaturated Trinuclear Phosphanido Complex [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt(PPh<sub>3</sub>)]
The reaction of [NBu<sub>4</sub>]Ā[(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>PtĀ(<i>O</i>,<i>O</i>-acac)]
(48 VEC) with [HPPh<sub>3</sub>]Ā[ClO<sub>4</sub>] gives the 46 VEC
unsaturated [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>1</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>2</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>3</sup>(PPh<sub>3</sub>)]Ā(Pt<sup>2</sup>āPt<sup>3</sup>) (<b>1</b>), a trinuclear compound endowed
with a PtāPt bond. This compound displays amphiphilic behavior
and reacts easily with nucleophiles L, yielding the saturated complexes
[(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(PPh<sub>3</sub>)ĀL] [L = PPh<sub>3</sub> (<b>2</b>), py (<b>3</b>)]. The reaction with the electrophile
[AgĀ(OClO<sub>3</sub>)ĀPPh<sub>3</sub>] affords the adduct <b>1</b>Ā·AgPPh<sub>3</sub>, which evolves, even at low temperature,
to a mixture in which [(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(PPh<sub>3</sub>)<sub>2</sub>]<sup>2+</sup>(Pt<sup>III</sup>āPt<sup>III</sup>) and <b>2</b> (plus silver metal) are present. The nucleophilic nature of <b>1</b> is also demonstrated through its reaction with <i>cis</i>-[PtĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>(THF)<sub>2</sub>], which
results in the formation of [Pt<sub>4</sub>(Ī¼-PPh<sub>2</sub>)<sub>4</sub>(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>(PPh<sub>3</sub>)] (<b>4</b>). The structure and NMR features indicate that <b>1</b> can be better considered as a Pt<sup>II</sup>āPt<sup>III</sup>āPt<sup>I</sup> complex instead of a Pt<sup>II</sup>āPt<sup>II</sup>āPt<sup>II</sup> derivative. Theoretical
calculations (density functional theory) on similar model compounds
are in agreement with the assigned oxidation states of the metal centers.
The strong intermetallic interactions resulting in a Pt<sup>2</sup>āPt<sup>3</sup> metalāmetal bond and the respective
bonding mechanism were verified by employing a multitude of computational
techniques (natural bond order analysis, the Laplacian of the electron
density, and localized orbital locator profiles)
Oxidatively Induced PāO Bond Formation through Reductive Coupling between Phosphido and Acetylacetonate, 8āHydroxyquinolinate, and Picolinate Groups
The
dinuclear anionic complexes [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>M<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Mā²<sup>II</sup>(N<sup>ā§</sup>O)] (R<sub>F</sub> = C<sub>6</sub>F<sub>5</sub>. N<sup>ā§</sup>O = 8-hydroxyquinolinate, hq; M = Mā²
= Pt <b>1</b>; Pd <b>2</b>; M = Pt, Mā² = Pd, <b>3</b>. N<sup>ā§</sup>O = <i>o</i>-picolinate,
pic; M = Pt, Mā² = Pt, <b>4</b>; Pd, <b>5</b>) are
synthesized from the tetranuclear [NBu<sub>4</sub>]<sub>2</sub>[{(R<sub>F</sub>)<sub>2</sub>PtĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>MĀ(Ī¼-Cl)}<sub>2</sub>] by the elimination of the bridging Cl as AgCl in acetone,
and coordination of the corresponding <i>N</i>,<i>O</i>-donor ligand (<b>1</b>, <b>4</b>, and <b>5</b>) or connecting the fragments ā<i>cis</i>-[(R<sub>F</sub>)<sub>2</sub>MĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>]<sup>2ā</sup>ā and āMā²(N<sup>ā§</sup>O)ā (<b>2</b> and <b>3</b>). The electrochemical oxidation of the
anionic complexes <b>1</b>ā<b>5</b> occurring under
HRMSĀ(+) conditions gave the cations [(R<sub>F</sub>)<sub>2</sub>MĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Mā²(N<sup>ā§</sup>O)]<sup>+</sup>, presumably endowed with a MĀ(III),Mā²(III) core. The oxidative
addition of I<sub>2</sub> to the 8-hydroxyquinolinate complexes <b>1</b>ā<b>3</b> triggers a reductive coupling between
a PPh<sub>2</sub> bridging ligand and the <i>N</i>,<i>O</i>-donor chelate ligand with formation of a PāO bond
and ends up in complexes of platinumĀ(II) or palladiumĀ(II) of formula
[(R<sub>F</sub>)<sub>2</sub>M<sup>II</sup>(Ī¼-I)Ā(Ī¼-PPh<sub>2</sub>)ĀMā²<sup>II</sup>(<i>P</i>,<i>N</i>-PPh<sub>2</sub>hq)], M = Mā² = Pt <b>7</b>, Pd <b>8</b>; M = Pt, Mā² = Pd, <b>9</b>. Complexes <b>7</b>ā<b>9</b> show a new Ph<sub>2</sub>P-OC<sub>9</sub>H<sub>6</sub>N (Ph<sub>2</sub>P-hq) ligand bonded to the metal
center in a <i>P</i>,<i>N</i>-chelate mode. Analogously,
the addition of I<sub>2</sub> to solutions of the <i>o</i>-picolinate complexes <b>4</b> and <b>5</b> causes the
reductive coupling between a PPh<sub>2</sub> bridging ligand and the
starting <i>N</i>,<i>O</i>-donor chelate ligand
with formation of a PāO bond, forming Ph<sub>2</sub>P-OC<sub>6</sub>H<sub>4</sub>NO (Ph<sub>2</sub>P-pic). In these cases, the
isolated derivatives [NBu<sub>4</sub>]Ā[(Ph<sub>2</sub>P-pic)Ā(R<sub>F</sub>)ĀPt<sup>II</sup>(Ī¼-I)Ā(Ī¼-PPh<sub>2</sub>)ĀM<sup>II</sup>(R<sub>F</sub>)ĀI] (M = Pt <b>10</b>, Pd <b>11</b>) are anionic, as a consequence of the coordination of the resulting
new phosphane ligand (Ph<sub>2</sub>P-pic) as monodentate <i>P</i>-donor, and a terminal iodo group to the M atom. The oxidative
addition of I<sub>2</sub> to [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(acac)] (<b>6</b>) (acac = acetylacetonate) also results
in a reductive coupling between the diphenylphosphanido and the acetylacetonate
ligand with formation of a PāO bond and synthesis of the complex
[NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-I)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(Ph<sub>2</sub>P-acac)ĀI] (<b>12</b>).
The transformations of the starting complexes into the products containing
the PāO ligands passes through mixed valence MĀ(II),Mā²(IV)
intermediates which were detected, for M = Mā² = Pt, by spectroscopic
and spectrometric measurements
Sulfur-Assisted Phenyl Migration from Phosphorus to Platinum in PtW<sub>2</sub> and PtMo<sub>2</sub> Clusters Containing Thioether-Functionalized Short-Bite Ligands of the Bis(diphenylphosphanyl)amine-Type
The
reactivity of dichloroplatinumĀ(II) complexes containing thioether-functionalized
bisĀ(diphenylĀphosphanyl)Āamines of formula (Ph<sub>2</sub>P)<sub>2</sub>NĀ(CH<sub>2</sub>)<sub>2</sub>SR (R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>, CH<sub>2</sub>Ph) toward group
6 carbonylmetalates NaĀ[MĀ(CO)<sub>3</sub>Cp] (M = Mo or W, Cp = cyclopentadienyl)
was explored. Reactions with two or more equivalents of NaĀ[MĀ(CO)<sub>3</sub>Cp] (M = Mo or W) afforded the trinuclear complexes of general
formula [PtPhĀ{MĀ(CO)<sub>3</sub>Cp}Ā{Ī¼-<i>P</i>(Ph)ĀNĀ(CH<sub>2</sub>CH<sub>2</sub><i>S</i>R)Ā(<i>P</i>Ph<sub>2</sub>)-Īŗ<sup>3</sup><i>P</i>,<i>P</i>,<i>S</i>}ĀMĀ(CO)<sub>2</sub>Cp] (<b>3</b> M = Mo, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>4</b> M = Mo, R = CH<sub>2</sub>Ph; <b>9</b> M = W, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>10</b> M = W, R = CH<sub>2</sub>Ph), the structure of which consists of a six-membered platinacycle
condensed with a four-membered MāPāNāP cycle, together with small amounts of isomeric PtM<sub>2</sub> clusters
[PtM<sub>2</sub>(CO)<sub>5</sub>Cp<sub>2</sub>Ā{(Ph<sub>2</sub>P)<sub>2</sub>NĀ(CH<sub>2</sub>CH<sub>2</sub>SR)-Īŗ<sup>2</sup><i>P</i>,<i>P</i>}] (<b>5</b> M
= Mo, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>6</b> M = Mo, R = CH<sub>2</sub>Ph; <b>11</b> M = W, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>12</b> M = W, R = CH<sub>2</sub>Ph) in which the ligand (Ph<sub>2</sub>P)<sub>2</sub>NR solely
chelates the Pt atom or bridges an MāPt bond as in [PtM<sub>2</sub>(CO)<sub>5</sub>Cp<sub>2</sub>Ā{Ī¼-(Ph<sub>2</sub>P)<sub>2</sub>NĀ(CH<sub>2</sub>CH<sub>2</sub>SR)-Īŗ<sup>2</sup><i>P</i>,<i>P</i>}] (<b>7</b> M
= Mo, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>8</b> M = Mo, R = CH<sub>2</sub>Ph; <b>13</b> M = W, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>14</b> M = W, R = CH<sub>2</sub>Ph). The synthesis of the trinuclear complexes <b>3</b>, <b>4</b>, <b>9</b>, and <b>10</b> entails an
unexpected P-phenyl bond cleavage reaction and phenyl migration onto
Pt. When only 1 equiv of NaĀ[MĀ(CO)<sub>3</sub>Cp] (M = Mo or W) was
used, the heterodinuclear products of monosubstitution [PtClĀ{MĀ(CO)<sub>3</sub>Cp}Ā{Ph<sub>2</sub>PNĀ(R)ĀPPh<sub>2</sub>-<i>P</i>,<i>P</i>}] (<b>15</b> M = Mo, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>16</b> M = Mo, R = CH<sub>2</sub>Ph; <b>17</b> M = W, R = (CH<sub>2</sub>)<sub>5</sub>CH<sub>3</sub>; <b>18</b> M = W, R = CH<sub>2</sub>Ph) were obtained,
which are the precursors to the bicyclic products <b>3</b>, <b>4</b>, <b>9</b>, and <b>10</b>, respectively. Density
functional calculations were performed to study the thermodynamics
of the formation of all the new complexes, to evaluate the relative
stabilities of the isomeric chelated and bridged forms, and to trace
the mechanism of formation of the phosphanido-bridged products <b>3</b>, <b>4</b>, <b>9</b>, and <b>10</b>. It was concluded that PtĀ(II)
complexes containing a <i>thioether</i>-functionalized short-bite
ligand, [PtCl<sub>2</sub>{Ph<sub>2</sub>PĀNĀ(R)ĀPPh<sub>2</sub>}], react with NaĀ[MĀ(CO)<sub>3</sub>Cp] to yield first heterodinuclear
PtāM and then heterotrinuclear PtM<sub>2</sub> complexes resulting
from the activation of a PāC bond in one of the PPh<sub>2</sub> groups and phenyl migration to Pt. The critical role of an intramolecular
thioether group was demonstrated
Addition of Nucleophiles to Phosphanido Derivatives of Pt(III): Formation of PāC, PāN, and PāO Bonds
The
reactivity of the dinuclear platinumĀ(III) derivative [(R<sub>F</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>ĀPt<sup>III</sup>(R<sub>F</sub>)<sub>2</sub>]<i>(PtāPt)</i> (R<sub>F</sub> = C<sub>6</sub>F<sub>5</sub>) (<b>1</b>) toward
OH<sup>ā</sup>, N<sub>3</sub><sup>ā</sup>, and NCO<sup>ā</sup> was studied. The coordination
of these nucleophiles to a metal center evolves with reductive coupling
or reductive elimination between a bridging diphenylphosphanido group
and OH<sup>ā</sup>, N<sub>3</sub><sup>ā</sup>, and NCO<sup>ā</sup> or C<sub>6</sub>F<sub>5</sub> groups and formation
of PāO, PāN, or PāC bonds. The addition of OH<sup>ā</sup> to <b>1</b> evolves with a reductive coupling
with the incoming ligand, formation of a PāO bond, and the
synthesis of [NBu<sub>4</sub>]<sub>2</sub>[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-OPPh<sub>2</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>3</b>). The addition of N<sub>3</sub><sup>ā</sup> takes place through
two ways: (a) formation of the PāN bond and reductive elimination
of PPh<sub>2</sub>N<sub>3</sub> yielding [NBu<sub>4</sub>]<sub>2</sub>[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-N<sub>3</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>4a</b>) and (b) formation of the PāC bond
and reductive coupling with one of the C<sub>6</sub>F<sub>5</sub> groups
yielding [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-N<sub>3</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)Ā(PPh<sub>2</sub>R<sub>F</sub>)] (<b>4b</b>).
Analogous behavior was shown in the addition of NCO<sup>ā</sup> to <b>1</b> which afforded [NBu<sub>4</sub>]<sub>2</sub>[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-NCO)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>5a</b>) and [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-NCO)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(R<sub>F</sub>)Ā(PPh<sub>2</sub>R<sub>F</sub>)] (<b>5b</b>).
In the reaction of the trinuclear complex [(R<sub>F</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>III</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>ĀPt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>]<i>(Pt</i><sup><i>III</i></sup><i>āPt</i><sup><i>III</i></sup><i>)</i> (<b>2</b>) with OH<sup>ā</sup> or N<sub>3</sub><sup>ā</sup>, the coordination of the nucleophile takes place
selectively at the central platinumĀ(III) center, and the PPh<sub>2</sub>/OH<sup>ā</sup> or PPh<sub>2</sub>/N<sub>3</sub><sup>ā</sup> reductive coupling yields the trinuclear [NBu<sub>4</sub>]<sub>2</sub>[(R<sub>F</sub>)<sub>2</sub>Pt<sup>II</sup>(Ī¼-Ph<sub>2</sub>PO)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Pt<sup>II</sup>(R<sub>F</sub>)<sub>2</sub>] (<b>6</b>) and [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>Pt<sup>1</sup>(Ī¼<sub>3</sub>-Ph<sub>2</sub>PNPPh<sub>2</sub>)Ā(Ī¼-PPh<sub>2</sub>)ĀPt<sup>2</sup>(Ī¼-PPh<sub>2</sub>)ĀPt<sup>3</sup>(R<sub>F</sub>)<sub>2</sub>]<i>(Pt</i><sup><i>2</i></sup><i>āPt</i><sup><i>3</i></sup><i>)</i> (<b>7</b>). Complex <b>7</b> is fluxional
in solution, and an equilibrium consisting of PtāPt bond migration
was ascertained by <sup>31</sup>P EXSY experiments
Formation of PāC Bond through Reductive Coupling between Bridging Phosphido and Benzoquinolinate Groups. Isolation of Complexes of the Pt(II)/Pt(IV)/Pt(II) Sequence
The rational synthesis of dinuclear asymmetric phosphanido
derivatives
of palladium and platinumĀ(II), [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>MĀ(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Mā²(Īŗ<sup>2</sup>,<i>N</i>,<i>C</i>-C<sub>13</sub>H<sub>8</sub>N)] (R<sub>F</sub> = C<sub>6</sub>F<sub>5</sub>; M = Mā²
= Pt, <b>1</b>; M = Pt, Mā² = Pd, <b>2</b>; M =
Pd, Mā² = Pt, <b>3</b>; M = Mā² = Pd, <b>4</b>), is described. Addition of I<sub>2</sub> to <b>1</b>ā<b>4</b> gives complexes [(R<sub>F</sub>)<sub>2</sub>M<sup>II</sup>(Ī¼-PPh<sub>2</sub>)Ā(Ī¼-I)ĀPd<sup>II</sup>{PPh<sub>2</sub>(C<sub>13</sub>H<sub>8</sub>N)}] (M = Mā² = Pt, <b>6</b>; M = Pt, Mā² = Pd, <b>7</b>; M = Mā² = Pd, <b>8</b>; M = Pd, Mā² = Pt <b>10</b>) which contain the
aminophosphane PPh<sub>2</sub>(C<sub>13</sub>H<sub>8</sub>N) ligand
formed through a Ph<sub>2</sub>P/C<sup>ā§</sup>N reductive coupling
on the mixed valence MĀ(II)āMā²(IV) [NBu<sub>4</sub>]Ā[(R<sub>F</sub>)<sub>2</sub>M<sup>II</sup>(Ī¼-PPh<sub>2</sub>)<sub>2</sub>Mā²<sup>IV</sup>(Īŗ<sup>2</sup>,<i>N</i>,<i>C</i>- C<sub>13</sub>H<sub>8</sub>N)ĀI<sub>2</sub>] complexes,
which were identified for M<sup>II</sup> = Pd, Mā²<sup>IV</sup> = Pt (<b>9</b>), and isolated for M<sup>II</sup> = Pt, Mā²<sup>IV</sup> = Pt (<b>5</b>). Complex <b>5</b> showed an
unusual dynamic behavior consisting in the exchange of two phenyl
groups bonded to different P atoms, as well as a āthrough spaceā
spināspin coupling between <i>ortho</i>-F atoms of
the pentafluorophenyl rings
Dynamic Motions of Ligands around the Metal Centers Afford a Fidget Spinner-Type AIE Luminogen
A new type of aggregation-induced emission (AIE) luminogen
containing
a dimeric metal fragment and two or three phthalazine ligands is described,
which shows dynamic motions of ligands around the metal centers in
solution. Based on the variable-temperature and EXSY NMR spectroscopy
data, X-ray crystallography structures, and computational results,
three different pathways (i.e., reversible exchange with haptotropic
shifts, circulation of ligands around the dimeric metal fragment,
and walking on the spot of ligands on the metal centers) were considered
for this dynamic behavior. Restriction of these dynamic processes
in the aggregate forms of the compounds (in H2O/CH3CN solvent mixtures) contributes to their AIE. DFT calculations
and NMR analysis showed that bright excited states for these molecules
are not localized on isolated molecules, and the emission of them
stemmed from Ļ-dimers or Ļ-oligomers. The morphologies
and the mode of associations in the solvent mixtures were determined
by using transmission electron microscopy (TEM) and concentration-dependent
NMR spectroscopy. The computational results showed the presence of
a conical intersection (CI) between the S0 and S1 excited state, which provides an accessible pathway for nonradiative
decay in these systems