Boere, Rene

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Browsing Boere, Rene by Author "Amrei, Leila M."

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    Are monophospha(III)amidines and -guanidines with ionizable hydrogens tautomeric? Towards a deeper understanding of two related hetero-element functional groups
    (Wiley, 2023) Masuda, Jason D.; Amrei, Leila M.; Boeré, René T.
    This paper presents definitive structural evidence for N,P(III)-monophosphaamidines in P=C and N=C isomeric forms from a combination of new syntheses, single-crystal X-ray diffraction (SC-XRD), solid-state NMR and FTIR. Evidence is also provided for C-amino-(σ2,λ3)-phosphaalkene and C-(σ3,λ3)-phosphinoimine tautomerism in solution using multi-nuclear NMR methods. Synthesis and SC-XRD structure determination of a trisubstituted N,N’,P(III)-monophosphaguanidine is presented, the first structure of a phospha(III)guanidine with two ionizable H atoms. The structural evidence is convincing for an N=C geometry, resulting in both N−H and P−H in the molecule. A detailed computational investigation using DFT methods is presented, with the goal of understanding the tautomeric structure preferences both at the fundamental level (parent molecules with all substituents on the heteroatoms being hydrogen) and using the full structures containing the very bulky 2,6-diisopropylphenyl (Dipp) substituents employed in this study. Arguments are espoused for treating phospha(III)amidines and -guanidines as new types of functional groups, similar to but distinct from the familiar organic analogues. Limited reactivity studies and a voltammetry study of one phospha(III)amidine are included with the supporting information.
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    Hydrogen-bonded networks in oxygen-coordinated monoamide complexes of zinc(II)
    (NRC Research Press, 2018) Amrei, Leila M.; Boeré, René T.
    The preparation of the bulky secondary amideN-(2,6-diisopropylphenyl)-2,2-dimethylpropanamide and the determi-nation of its crystal structure at 173(2) K are reported. The structure displays disorder of thetBu methyl groups due to thermalmotion and an infinite N–H····O=C hydrogen-bonded chain described by aC11 4 graph set. Reaction of this amide withZnCl2orZnBr2in tetrahydrofuran (THF) results in dihalo-(tetrahydrofurano)-(N-(2,6-diisopropylphenyl)–2,2-dimethylpropanamido)-zinc(II)complexes (Cl, Br) for which the crystal structures have also been determined. These complexes, as well as a chloroform solvate of thedichloro-complex, contain N–H····X–Zn hydrogen-bonded chains described byC11 6 graph sets. Evaporative crystallization results inthe loss of both chloroform and THF to afford crystals determined to bebis( 2-chloro)-dichloro-bis(N-(2,6-diisopropylphenyl)-2,2-dimethylpropanamido)-dizinc(II) by single crystal X-ray diffraction. This dimeric complex shows a complex network ofN–H····Cl–Zn hydrogen bonds describable byC11 6 ,C11 8 , andC22 16 chains, smallR44 28 molecular “squares”, and largerR66 44 rings