Synthesis of Zwitterionic Group 14 Centered Complexes: Traditional Coordination and Unusual Insertion Chemistry

Novel cationic E–Cl (E = Ge, Sn) fragments stabilized by a bis­(phosphino)­borate ligand (<b>2E</b>) were synthesized by a 1:1 stoichiometric addition of ECl₂ and [Tl]­[(Ph₂PCH₂)₂BPh₂]. The metrical parameters are consistent with dative bonds between the phosphorus atoms and the electron-deficient group 14 element, which is in contrast to the traditionally used aryl- and nitrogen-based ligands, which are always covalently bound. The reaction of a second equivalent of bis­(phosphino)­borate results in the unexpected insertion of the main group center into the aliphatic B–C bond of the ligand backbone to form <b>3E</b>, in addition to phosphine-borane dimer (Ph₂PCH₂BPh₂)₂ (<b>4</b>). The pendant phosphine on <b>3E</b> was shown to possess donor ability in the coordination of BH₃ (<b>5E</b>)

Addressing the Chemical Sorcery of “GaI”: Benefits of Solid-State Analysis Aiding in the Synthesis of P→Ga Coordination Compounds

The differing structures and reactivities of “GaI” samples prepared with different reaction times have been investigated in detail. Analysis by FT-Raman spectroscopy, powder X-ray diffraction, ⁷¹Ga solid-state NMR spectroscopy, and ¹²⁷I nuclear quadrupole resonance (NQR) provides concrete evidence for the structure of each “GaI” sample prepared. These techniques are widely accessible and can be implemented quickly and easily to identify the nature of the “GaI” in hand. The “GaI” prepared from exhaustive reaction times (100 min) is shown to possess Ga₂I₃ and an overall formula of [Ga⁰]₂[Ga⁺]₂[Ga₂I₆^2–], while the “GaI” prepared with the shortest reaction time (40 min) contains GaI₂ and has the overall formula [Ga⁰]₂[Ga⁺]­[GaI₄^–]. Intermediate “GaI” samples were consistently shown to be fractionally composed of each of these two preceding formulations and no other distinguishable phases. These “GaI” phases were then shown to give unique products upon reactions with the anionic bis­(phosphino)­borate ligand class. The reaction of the early-phase “GaI” gives rise to a unique phosphine Ga­(II) dimeric coordination compound (<b>3</b>), which was isolated reproducibly in 48% yield and convincingly characterized. A base-stabilized GaI→GaI₃ fragment (<b>4</b>) was also isolated using the late-phase “GaI” and characterized by multinuclear NMR spectroscopy and X-ray crystallography. These compounds can be considered unique examples of low-oxidation-state P→Ga coordination compounds and possess relatively long Ga–P bond lengths in the solid-state structures. The anionic borate backbone therefore results in interesting architectures about gallium that have not been observed with neutral phosphines

Synthesis of Zwitterionic Triphosphenium Transition Metal Complexes: A Boron Atom Makes The Difference

A collection of zwitterionic phosphanide metal carbonyl coordination complexes has been synthesized and fully characterized, representing the first isolated series of metal complexes for the triphosphenium family of compounds. The dicoordinate phosphorus atom of the zwitterion is formally in the +1 oxidation state and can coordinate to one metal, <b>2M</b> (M = Cr, Mo, W) and <b>2Fe</b>, or two metals, a Co₂(CO)₆ fragment <b>4</b>, depending on the starting reagents. All complexes have been isolated in greater than 80% yield, and structures were confirmed crystallographically. Metrical parameters are consistent with <b>1</b> being a weak donor and results in long metal–phosphorus bonds being observed in all cases. Unique bimetallic structures, <b>3M</b> (M = Cr, Mo, W), consisting of a M­(CO)₅ fragment on phosphorus and a piano-stool M­(CO)₃ fragment on a boron phenyl group have been identified in the ³¹P­{¹H} NMR spectra and confirmed using X-ray diffraction studies. Use of the borate backbone in <b>1</b>, which renders the molecule zwitterionic, proves to be a determining factor in whether these metal complexes will form; the halide salt of a cationic triphosphenium ion, <b>6</b>[Br], shows no evidence for formation of the analogous metal complexes by ³¹P­{¹H} NMR spectroscopy, and tetraphenylborate salts, <b>6</b>[BPh₄] and <b>7</b>[BPh₄], produce complexes that are unstable

Synthesis and Characterization of Primary Aluminum Parent Amides and Phosphides

The synthesis and characterization of the sterically crowded primary alanes (Ar^{<i>i</i>Pr₄}AlH₂)₂ (Ar^{<i>i</i>Pr₄} = C₆H₃-2,6­(C₆H₃-2,6-^<i>i</i>Pr₂)₂) and (Ar^{<i>i</i>Pr₈}AlH₂)₂ (Ar^{<i>i</i>Pr₈} = C₆H-2,6­(C₆H₂-2,4,6-^<i>i</i>Pr₆)₂-3,5-^<i>i</i>Pr₂) are described. They, along with their previously reported less-hindered analogue (Ar^Me₆AlH₂)₂ (Ar^Me₆ = C₆H₃-2,6­(C₆H₂-2,4,6-Me₃)₂), were reacted with ammonia to give the parent amido alanes {Ar^<i>x</i>Al­(H)­NH₂}₂ (Ar^<i>x</i> = Ar^Me₆, <b>1</b>; Ar^{<i>i</i>Pr₄}, <b>2</b>; Ar^{<i>i</i>Pr₈}, <b>3</b>), which are the first well-characterized hydride amido derivatives of aluminum and are relatively rare examples of parent aluminum amides. In contrast, the reaction of (Ar^Me₆AlH₂)₂ with phosphine yielded the structurally unique Al/P cage species {(Ar^Me₆Al)₃(μ-PH₂)₃(μ-PH)­PH₂} (<b>4</b>) as the major product and a smaller amount of {(Ar^Me₆Al)₄(μ-PH₂)₄(μ-PH)} (<b>5</b>) as a minor product. All compounds were characterized by NMR and IR spectroscopy, while compounds <b>2</b>–<b>5</b> were also characterized by X-ray crystallography

Synthesis and Characterization of Primary Aluminum Parent Amides and Phosphides

The synthesis and characterization of the sterically crowded primary alanes (Ar^{<i>i</i>Pr₄}AlH₂)₂ (Ar^{<i>i</i>Pr₄} = C₆H₃-2,6­(C₆H₃-2,6-^<i>i</i>Pr₂)₂) and (Ar^{<i>i</i>Pr₈}AlH₂)₂ (Ar^{<i>i</i>Pr₈} = C₆H-2,6­(C₆H₂-2,4,6-^<i>i</i>Pr₆)₂-3,5-^<i>i</i>Pr₂) are described. They, along with their previously reported less-hindered analogue (Ar^Me₆AlH₂)₂ (Ar^Me₆ = C₆H₃-2,6­(C₆H₂-2,4,6-Me₃)₂), were reacted with ammonia to give the parent amido alanes {Ar^<i>x</i>Al­(H)­NH₂}₂ (Ar^<i>x</i> = Ar^Me₆, <b>1</b>; Ar^{<i>i</i>Pr₄}, <b>2</b>; Ar^{<i>i</i>Pr₈}, <b>3</b>), which are the first well-characterized hydride amido derivatives of aluminum and are relatively rare examples of parent aluminum amides. In contrast, the reaction of (Ar^Me₆AlH₂)₂ with phosphine yielded the structurally unique Al/P cage species {(Ar^Me₆Al)₃(μ-PH₂)₃(μ-PH)­PH₂} (<b>4</b>) as the major product and a smaller amount of {(Ar^Me₆Al)₄(μ-PH₂)₄(μ-PH)} (<b>5</b>) as a minor product. All compounds were characterized by NMR and IR spectroscopy, while compounds <b>2</b>–<b>5</b> were also characterized by X-ray crystallography

Photoinduced Carbene Generation from Diazirine Modified Task Specific Phosphonium Salts To Prepare Robust Hydrophobic Coatings

3-Aryl-3-(trifluormethyl)­diazirine functionalized highly fluorinated phosphonium salts (HFPS) were synthesized, characterized, and utilized as photoinduced carbene precursors for covalent attachment of the HFPS onto cotton/paper to impart hydrophobicity to these surfaces. Irradiation of cotton and paper, as proof of concept substrates, treated with the diazirine-HFPS leads to robust hydrophobic cotton and paper surfaces with antiwetting properties, whereas the corresponding control samples absorb water readily. The contact angles of water were determined to be 139° and 137° for cotton and paper, respectively. In contrast, water placed on the untreated or the control samples (those treated with the diazirine-HFPS but not irradiated) is simply absorbed into the surface. Additionaly, the chemically grafted hydrophobic coating showed high durability toward wash cycles and sonication in organic solvents. Because of the mode of activation to covalently tether the hydrophobic coating, it is amenable to photopatterning, which was demonstrated macroscopically