Hayes, Paul

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    Rhodium-mediated dehydrogenation of hydroboranes and group 14 compounds: base-stabilized silylene and germylene complexes vs. transmetalation
    (Wiley, 2024) Hayes, Paul G.; Hsiang, Shou-Jen
    Monocarbonyl rhodium complex LRh(CO), 1, which is stabilized by a pyrrole-based bis(phosphinimine) pincer ligand (L=k3- NNN’=2,5-[iPr2P=N(4-iPrC6H4)]2-N’(C4H2)􀀀 ), serves as a versatile platform for the dehydrogenation of group 14 substrates. Reaction with primary and secondary silanes and germanes (MesSiH3, Et2SiH2, Ph2GeH2, tBuGeH3; Mes=mesityl) liberates H2 and yields base-stabilized tetrylene compounds of the form k2- L(CO)Rh(ER2) (E=Si: R=Mes, H, 2; R=Et, 5; E=Ge: R=Ph, 6; R= tBu, H, 8). The “:ER2” fragment in these species bridges between the rhodium center and a phosphinimine donor. Preliminary reactions between pinacol (Pin) and k2-L(CO)Rh(ER2), E=Si, Ge, indicate that such complexes can serve as silylene and germylene synthons, releasing :ER2 and catalytically generating PinER2. In contrast, combination of complex 1 and MesGeH3 does not yield the anticipated dehydrogenation product, but rather, transmetalation similar to that observed upon reaction between 1 and 3,5-dimethylphenylborane prevails.
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    X-ray crystal structure of [L2Ag3]+[OTf]−·5C6D6: a monoanionic bis­­phosphinimine ligand supported tris­­ilver complex
    (2021) Drescher, Sam L.; Forfar, Christopher P.; Boeré, René T.; Hayes, Paul G.
    The compound bis­{μ3-2,5-bis­[N-(4-iso­propyl­phen­yl)-P,P-di­phenyl­phospho­r­im­i­do­yl]pyrrol-1-ido-κ3N:N′:N′′}tris­ilver(I) tri­fluoro­methane­sulfonate deuterated benzene penta­solvate, [Ag3(C46H44N3P2)2](CF3O3S)·5C6D6, (I), was synthesized from two equivalents of NaL [L = 2,5-(4-iPrC6H4N=PPh2)C4H2N] and three equivalents of AgOTf (OTf = OSO2CF3). High-quality crystals of (I) formed with five deuterated benzene solvent mol­ecules in the asymmetric unit. Notably, the bond lengths and angles between the three silver atoms are markedly different, unlike in most other reported tris­ilver complexes that tend to form three equivalent metal centers. Additionally, to the best of our knowledge, this is the first report of a tris­ilver complex with six nitro­gen donors from two bis­phosphinimine ligands.
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    Triamidoamine-supported zirconium: hydrogen activation, Lewis acidity, and rac-lactide polymerization
    (Royal Society of Chemistry, 2016) Leshinski, Sarah E.; Wheaton, Craig A.; Sun, Hongsui; Roering, Andrew J.; Tanski, Joseph M.; Fox, Daniel J.; Hayes, Paul G.; Waterman, Rory
    Investigation of a triamidoamine-supported zirconium hydride intermediate, important to a range of catalytic reactions, revealed the potential Lewis acidity of [k5-N,N,N,N,C-(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH2]Zr (1). A preliminary study of 1 as a precursor for the polymerization of rac-lactide showed modest activity but indicated that five-coordinate zirconium complexes with tetra-N donor ligands may be an avenue for further development in group 4 metal lactide polymerization catalysis.
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    Crystal structure of a dimeric ß-diketiminate magnesium complex
    (International Union of Crystallography, 2016) MacNeil, Connor S.; Johnson, Kevin R. D.; Hayes, Paul G.; Boeré, René T.
    The solid-state structure of a dimeric ß-diketiminate magnesium(II) complex is discussed. The compound, di- -iodido-bis[({4-amino-1,5-bis[2,6-bis(propan-2- yl)phenyl]pent-3-en-2-ylidene}azanido- 2N,N0)magnesium(II)] toluene sesquisolvate, [Mg2(C29H41N2)2I2] 1.5C7H8, crystallizes as two independent molecules, each with 2/m crystallographic site symmetry, located atWyckoff sites 2c and 2d. These have symmetry-equivalent magnesium atoms bridged by -iodide ligands with very similar Mg—I distances. The two Mg atoms are located slightly below ( 0.5 A ° ) the least-squares plane defined by N–C—C–N atoms in the ligand scaffold, and are approximately tetrahedrally coordinated. One and one-half toluene solvent molecules are disordered with respect to mirror-site symmetry at Wyckoff sites 4i and 2a, respectively. In the former case, two toluene molecules interact in an off-center parallel stacking arrangement; the shortest C to C0 ( – ) distance of 3.72 (1) A ° was measured for this interaction.