0000000001155043
AUTHOR
Andrea Armstrong
showing 5 related works from this author
Synthesis and Structures of Aluminum and Magnesium Complexes of Tetraimidophosphates and Trisamidothiophosphates: EPR and DFT Investigations of the P…
2005
Reactions of (RNH)3PNSiMe3 (3a, R = tBu; 3b, R = Cy) with trimethylaluminum result in the formation of {Me2Al(μ-NtBu)(μ-NSiMe3)P(NHtBu)2]} (4) and the dimeric trisimidometaphosphate {Me2Al[(μ-NCy)(μ-NSiMe3)P(μ-NCy)2P(μ-NCy)(μ-NSiMe3)]AlMe2} (5a), respectively. The reaction of SP(NHtBu)3 (2a) with 1 or 2 equiv of AlMe3 yields {Me2Al[(μ-S)(μ-NtBu)P(NHtBu)2]} (7) and {Me2Al[(μ-S)(μ-NtBu)P(μ-NHtBu)(μ-NtBu)]AlMe2} (8), respectively. Metalation of 4 with nBuLi produces the heterobimetallic species {Me2Al[(μ-NtBu)(μ-NSiMe3)P(μ-NHtBu)(μ-NtBu)]Li(THF)2} (9a) and {[Me2Al][Li]2[P(NtBu)3(NSiMe3)]} (10) sequentially; in THF solutions, solvation of 10 yields an ion pair containing a spirocyclic tetraimid…
Computational modeling of isotropic electron paramagnetic resonance spectra of doublet state main group radicals
2007
The combined use of theoretical and mathematical methods in the analysis of electron paramagnetic resonance data has greatly increased the ability to interpret even the most complex spectra reported for doublet state inorganic main group radicals. This personal account summarizes the theoretical basis of such an approach and provides an in-depth discussion of some recent illustrative examples of the utilization of this methodology in practical applications. The emphasis is on displaying the enormous potential embodied within the approach. peerReviewed
Cubic and Spirocyclic Radicals Containing a Tetraimidophosphate Dianion [P(NR)3(NR‘)]•2-
2005
The reaction of Cl3PNSiMe3 with 3 equiv of LiHNR (R = iPr, Cy, tBu, Ad) in diethyl ether produces the corresponding tris(amino)(imino)phosphoranes (RNH)3PNSiMe3 (1a, R = iPr; 1b, R = Cy; 1c, R = tBu; 1d, R = Ad); subsequent reactions of 1b−d with nBuLi yield the trilithiated tetraimidophosphates {Li3[P(NR)3(NSiMe3)]} (2a, R = Cy; 2b, R = tBu; 2c, R = Ad). The reaction of [(tBuNH)4P]Cl with 1 equiv of nBuLi results in the isolation of (tBuNH)3PNtBu (1e); treatment of 1e with additional nBuLi generates the symmetrical tetraimidophosphate {Li3[P(NtBu)4]} (2d). Compounds 1 and 2 have been characterized by multinuclear (1H, 13C, and 31P) NMR spectroscopy; X-ray structures of 1b,c were also obtai…
Theoretical investigation of paramagnetic group 13 diazabutadiene radicals: insights into the prediction and interpretation of EPR spectroscopy param…
2006
The electronic structures and the spin density distributions of the group 13 1,4-diaza(1,3)butadiene (DAB) radicals [(R-DAB)2M]˙, [(R-DAB)MX2]˙ and {[(R-DAB)MX]2}˙˙ (M = Al, Ga, In; X = F, Cl, Br, I; R = H, Me, tBu, Ph) are studied using density functional theory at both non-relativistic and relativistic levels of theory. The calculations demonstrate that all systems share a qualitatively similar electronic structure and are primarily ligand centred π-radicals. The calculated metal, nitrogen and hydrogen hyperfine couplings are found to be independent of the identity of the R-group and the halogen atom. They are, however, dependent on the geometry and oxidation state of the metal centre. Bo…
Theoretical Investigation of Paramagnetic Diazabutadiene Gallium(III)−Pnictogen Complexes: Insights into the Interpretation and Simulation of Electro…
2005
The electronic structures and the spin density distributions of the paramagnetic gallium 1,4-diaza(1,3)butadiene (DAB) model systems {(tBu-DAB)Ga(I)[Pn(SiH3)2]}• and the related dipnictogen species {(tBu-DAB)Ga[Pn(SiH3)2]2}• (Pn = N, P, As) were studied using density functional theory. The calculations demonstrate that all systems share a qualitatively similar electronic structure and are primarily ligand-centered π-radicals. The calculated electron paramagnetic resonance (EPR) hyperfine coupling constants (HFCCs) for these model systems were optimized using iterative methods and were used to create accurate spectral simulations of the parent radicals {(tBu-DAB)Ga(I)[Pn(SiMe3)2]}• (Pn = N, …