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Understanding Pd–Pd Bond Length Variation in (PNP)Pd–Pd(PNP) Dimers
No full textAnalysis of the structures of three
(PNP)Pd–Pd(PNP) dimers [where PNP stands for anionic diarylamido/bis(phosphine)
pincer ligands] has been carried out with the help of single-crystal
X-ray diffractometry and density functional theory (DFT) calculations
on isolated molecules. The three dimers under study possess analogous
ancillary ligands; two of them differ only by an F versus Me substituent
in a remote (five bonds away from Pd) position of the pincer ligand.
Despite these close similarities, X-ray structural determinations
revealed two distinct structural motifs: a highly symmetric molecule
with a long Pd–Pd bond or a highly distorted molecule with
Pd–Pd bonds ca. 0.14 Å shorter. DFT calculations on a
series of (PNP)Pd–Pd(PNP) dimers (as molecules in the gas phase)
confirmed the existence of these distinct minima for dimers carrying
large isopropyl substituents on the P-donor atoms (as in the experimental
structure). These minima are nearly isoergic conformers. Evidently,
the electronically preferred symmetric structure for the dimer (with
a square-planar environment about Pd and a linear N–Pd–Pd–N
vector) is not sterically possible with the preferred Pd–Pd
distance. Thus, the minima correspond to either a symmetric structure
with a long Pd–Pd bond distance or a structure with a short
Pd–Pd distance but with substantial distortions in the Pd coordination
environment to alleviate steric conflict. This notion is supported
by finding only a single minimum (symmetric and with short Pd–Pd
bonds) for each of the dimers carrying smaller substituents (H or
Me) on the P atoms, regardless of the remote substitution
Understanding Pd–Pd Bond Length Variation in (PNP)Pd–Pd(PNP) Dimers
No full textAnalysis of the structures of three
(PNP)Pd–Pd(PNP) dimers [where PNP stands for anionic diarylamido/bis(phosphine)
pincer ligands] has been carried out with the help of single-crystal
X-ray diffractometry and density functional theory (DFT) calculations
on isolated molecules. The three dimers under study possess analogous
ancillary ligands; two of them differ only by an F versus Me substituent
in a remote (five bonds away from Pd) position of the pincer ligand.
Despite these close similarities, X-ray structural determinations
revealed two distinct structural motifs: a highly symmetric molecule
with a long Pd–Pd bond or a highly distorted molecule with
Pd–Pd bonds ca. 0.14 Å shorter. DFT calculations on a
series of (PNP)Pd–Pd(PNP) dimers (as molecules in the gas phase)
confirmed the existence of these distinct minima for dimers carrying
large isopropyl substituents on the P-donor atoms (as in the experimental
structure). These minima are nearly isoergic conformers. Evidently,
the electronically preferred symmetric structure for the dimer (with
a square-planar environment about Pd and a linear N–Pd–Pd–N
vector) is not sterically possible with the preferred Pd–Pd
distance. Thus, the minima correspond to either a symmetric structure
with a long Pd–Pd bond distance or a structure with a short
Pd–Pd distance but with substantial distortions in the Pd coordination
environment to alleviate steric conflict. This notion is supported
by finding only a single minimum (symmetric and with short Pd–Pd
bonds) for each of the dimers carrying smaller substituents (H or
Me) on the P atoms, regardless of the remote substitution
Understanding Pd–Pd Bond Length Variation in (PNP)Pd–Pd(PNP) Dimers
No full textAnalysis of the structures of three
(PNP)Pd–Pd(PNP) dimers [where PNP stands for anionic diarylamido/bis(phosphine)
pincer ligands] has been carried out with the help of single-crystal
X-ray diffractometry and density functional theory (DFT) calculations
on isolated molecules. The three dimers under study possess analogous
ancillary ligands; two of them differ only by an F versus Me substituent
in a remote (five bonds away from Pd) position of the pincer ligand.
Despite these close similarities, X-ray structural determinations
revealed two distinct structural motifs: a highly symmetric molecule
with a long Pd–Pd bond or a highly distorted molecule with
Pd–Pd bonds ca. 0.14 Å shorter. DFT calculations on a
series of (PNP)Pd–Pd(PNP) dimers (as molecules in the gas phase)
confirmed the existence of these distinct minima for dimers carrying
large isopropyl substituents on the P-donor atoms (as in the experimental
structure). These minima are nearly isoergic conformers. Evidently,
the electronically preferred symmetric structure for the dimer (with
a square-planar environment about Pd and a linear N–Pd–Pd–N
vector) is not sterically possible with the preferred Pd–Pd
distance. Thus, the minima correspond to either a symmetric structure
with a long Pd–Pd bond distance or a structure with a short
Pd–Pd distance but with substantial distortions in the Pd coordination
environment to alleviate steric conflict. This notion is supported
by finding only a single minimum (symmetric and with short Pd–Pd
bonds) for each of the dimers carrying smaller substituents (H or
Me) on the P atoms, regardless of the remote substitution
Understanding Pd–Pd Bond Length Variation in (PNP)Pd–Pd(PNP) Dimers
No full textAnalysis of the structures of three
(PNP)Pd–Pd(PNP) dimers [where PNP stands for anionic diarylamido/bis(phosphine)
pincer ligands] has been carried out with the help of single-crystal
X-ray diffractometry and density functional theory (DFT) calculations
on isolated molecules. The three dimers under study possess analogous
ancillary ligands; two of them differ only by an F versus Me substituent
in a remote (five bonds away from Pd) position of the pincer ligand.
Despite these close similarities, X-ray structural determinations
revealed two distinct structural motifs: a highly symmetric molecule
with a long Pd–Pd bond or a highly distorted molecule with
Pd–Pd bonds ca. 0.14 Å shorter. DFT calculations on a
series of (PNP)Pd–Pd(PNP) dimers (as molecules in the gas phase)
confirmed the existence of these distinct minima for dimers carrying
large isopropyl substituents on the P-donor atoms (as in the experimental
structure). These minima are nearly isoergic conformers. Evidently,
the electronically preferred symmetric structure for the dimer (with
a square-planar environment about Pd and a linear N–Pd–Pd–N
vector) is not sterically possible with the preferred Pd–Pd
distance. Thus, the minima correspond to either a symmetric structure
with a long Pd–Pd bond distance or a structure with a short
Pd–Pd distance but with substantial distortions in the Pd coordination
environment to alleviate steric conflict. This notion is supported
by finding only a single minimum (symmetric and with short Pd–Pd
bonds) for each of the dimers carrying smaller substituents (H or
Me) on the P atoms, regardless of the remote substitution
Addition of Ammonia, Water, and Dihydrogen Across a Single Pd−Pd Bond
No full textPincer-supported Pd alkyl complexes (PNP)PdR undergo photochemical conversion to a dimeric (PNP)Pd−Pd(PNP) complex with a single Pd−Pd bond. Dissociation of the dimer into monomeric (PNP)Pd species is kinetically accessible thermally and photochemically. (PNP)Pd−Pd(PNP) reacts with ammonia, water, and dihydrogen by adding the H−X bond of the substrate (X = NH2, OH, H) across the Pd−Pd bond. For ammonia, this represents a rare example of conversion of NH3 to terminal hydride and amide ligands by a bimetallic complex
Addition of Ammonia, Water, and Dihydrogen Across a Single Pd−Pd Bond
No full textPincer-supported Pd alkyl complexes (PNP)PdR undergo photochemical conversion to a dimeric (PNP)Pd−Pd(PNP) complex with a single Pd−Pd bond. Dissociation of the dimer into monomeric (PNP)Pd species is kinetically accessible thermally and photochemically. (PNP)Pd−Pd(PNP) reacts with ammonia, water, and dihydrogen by adding the H−X bond of the substrate (X = NH2, OH, H) across the Pd−Pd bond. For ammonia, this represents a rare example of conversion of NH3 to terminal hydride and amide ligands by a bimetallic complex
A case study of Pd⋯Pd intramolecular interaction in a benzothiazole based palladacycle; catalytic activity toward amide synthesis via an isocyanide insertion pathway
No full textAn acetate bridge benzothiazolepalladacycle containing a rare metallophilic intramolecular Pd⋯Pd interaction was synthesized and thoroughly characterized. The synthesized benzothiazolepalladacycle directly anchored on SBA-15 to form an efficient heterogeneous catalyst for amide synthesis via the migratory isocyanide insertion pathway
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Themes generated from open comments of older adults (OA) and individuals with PD (PD).
No full textThemes generated from open comments of older adults (OA) and individuals with PD (PD).</p
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