Guilty on Two Counts: Stepwise Coordination of Two Fluoride Anions to the Antimony Atom of a Noninnocent Stibine Ligand

In our efforts to investigate the coordination noninnocent behavior of transition-metal stibine complexes, we have prepared a series of platinum complexes bearing the tetradentate ligand (<i>o</i>-(Ph₂P)­C₆H₄)₃Sb (<b>L</b>). Treatment of (Et₂S)₂PtCl₂ with <b>L</b> affords the lantern complex (<i>o</i>-(Ph₂P)­C₆H₄)₃SbCl)­Pt­(Cl) (<b>1</b>-Cl), which undergoes facile exchange with fluoride to form the fluorostiboranyl complex ((<i>o</i>-(Ph₂P)­C₆H₄)₃SbF)­Pt­(Cl) (<b>1</b>-F). Starting from <b>1</b>-Cl, anion exchange and abstraction reactions afford [((<i>o</i>-(Ph₂P)­C₆H₄)₃Sb)­Pt­(CyNC)]­[SbF₆]₂, ([<b>2</b>]­[SbF₆]₂), [((<i>o</i>-(Ph₂P)­C₆H₄)₃SbF)­Pt­(CyNC)]­[SbF₆] ([<b>3</b>]­[SbF₆]), and ((<i>o</i>-(Ph₂P)­C₆H₄)₃SbF₂)­Pt­(CyNC) (<b>4</b>), which are related by the formal stepwise coordination of two fluoride ligands to the antimony center. Structural studies of this series show that the Sb–Pt bond lengthens upon sequential fluoride coordination at the antimony center, consistent with the weakening of the Sb–Pt interaction. Natural bond orbital (NBO) calculations performed at the density functional theory (DFT) optimized geometries suggest that the Sb–Pt interactions become more polarized across the series, as part of a larger “spillover” of electron density from the antimony center to platinum. QTAIM analyses of the DFT-derived wave functions for this series corroborate the weakening of the Sb–Pt interaction and suggest that the Sb–Pt bonding pair becomes increasingly polarized toward platinum upon successive fluoride coordination at the antimony center

Lewis Acid Catalysis with Cationic Dinuclear Gold(II,II) and Gold(III,III) Phosphorus Ylide Complexes

The dinuclear gold­(II,II) and gold­(III,III) complexes [Au₂(μ-PY)₂(MeCN)₂]­OTf₂ (<b>2-OTf</b>_<b>2</b>) and [Au₂(μ-PY)₂(μ-CH₂)­(MeCN)₂]­OTf₂ (<b>3-OTf</b>_<b>2</b>) (PY = [(CH₂)₂PPh₂]⁻) have been synthesized and evaluated as Lewis acid catalysts for Mukaiyama addition and alkyne hydroamination reactions. <b>2-OTf</b>_<b>2</b> and <b>3-OTf</b>_<b>2</b> provide similar or improved catalytic activity for these reactions compared to the commonly used gold­(I) Lewis acids Ph₃PAuOTf and IPrAuOTf. The versatile Lewis acidity of <b>2-OTf</b>_<b>2</b> was further demonstrated by its superior performance in a cascade reaction involving intramolecular hydroamination followed by intermolecular conjugate addition to generate a 2,3-substituted indole

High Electrical Conductivity in Ni₃(2,3,6,7,10,11-hexaiminotriphenylene)₂, a Semiconducting Metal–Organic Graphene Analogue

Reaction of 2,3,6,7,10,11-hexa­amino­tri­phenyl­ene with Ni²⁺ in aqueous NH₃ solution under aerobic conditions produces Ni₃­(HITP)₂ (HITP = 2,3,6,7,10,11-hexa­imino­tri­phenyl­ene), a new two-dimensional metal–organic framework (MOF). The new material can be isolated as a highly conductive black powder or dark blue-violet films. Two-probe and van der Pauw electrical measurements reveal bulk (pellet) and surface (film) conductivity values of 2 and 40 S·cm^–1, respectively, both records for MOFs and among the best for any coordination polymer

Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal–Organic Framework

A porous metal–organic framework Zr₆O₄(OH)₄(L-PdX)₃ (<b>1-X</b>) has been constructed from Pd diphosphinite pincer complexes ([L-PdX]^4– = [(2,6-(OPAr₂)₂C₆H₃)­PdX]^4–, Ar = <i>p</i>-C₆H₄CO₂^–, X = Cl, I). Reaction of <b>1-X</b> with PhI­(O₂CCF₃)₂ facilitates I^–/CF₃CO₂^– ligand exchange to generate <b>1-TFA</b> and I₂ as a soluble byproduct. <b>1-TFA</b> is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue ^{<b><i>t</i></b>}<b>Bu­(L-PdTFA)</b> is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization

Zirconium Metal–Organic Frameworks Assembled from Pd and Pt P^NN^NP Pincer Complexes: Synthesis, Postsynthetic Modification, and Lewis Acid Catalysis

Carboxylic acid-functionalized Pd and Pt P^NN^NP pincer complexes were used for the assembly of two porous Zr metal–organic frameworks (MOFs), 2-PdX and 2-PtX. Powder X-ray diffraction analysis shows that the new MOFs adopt cubic framework structures similar to the previously reported Zr₆O₄(OH)₄[(P^OC^OP)­PdX]₃, [P^OC^OP = 2,6-(OPAr₂)₂C₆H₃); Ar = <i>p</i>-C₆H₄CO₂^–, X = Cl^–, I^–] (1-PdX). Elemental analysis and spectroscopic characterization indicate the presence of missing linker defects, and 2-PdX and 2-PtX were formulated as Zr₆O₄(OH)₄(OAc)_2.4[M­(P^NN^NP)­X]_2.4 [M = Pd, Pt; P^NN^NP = 2,6-(HNPAr₂)₂C₅H₃N; Ar = <i>p</i>-C₆H₄CO₂^–; X = Cl^–, I^–]. Postsynthetic halide ligand exchange reactions were carried out by treating 2-PdX with Ag­(O₃SCF₃) or NaI followed by PhI­(O₂CCF₃)₂. The latter strategy proved to be more effective at activating the MOF for the catalytic intramolecular hydroamination of an <i>o</i>-substituted alkynyl aniline, underscoring the advantage of using halide exchange reagents that produce soluble byproducts

High Electrical Conductivity in Ni₃(2,3,6,7,10,11-hexaiminotriphenylene)₂, a Semiconducting Metal–Organic Graphene Analogue

Reaction of 2,3,6,7,10,11-hexa­amino­tri­phenyl­ene with Ni²⁺ in aqueous NH₃ solution under aerobic conditions produces Ni₃­(HITP)₂ (HITP = 2,3,6,7,10,11-hexa­imino­tri­phenyl­ene), a new two-dimensional metal–organic framework (MOF). The new material can be isolated as a highly conductive black powder or dark blue-violet films. Two-probe and van der Pauw electrical measurements reveal bulk (pellet) and surface (film) conductivity values of 2 and 40 S·cm^–1, respectively, both records for MOFs and among the best for any coordination polymer