N,N'-Diaryl-Sulfurdiimides are Strongly Redox Tuned.

The synthesis and extensive characterization of nine aryl sulfur diimides (SDIs, Ar-NSN-Ar) are presented with a robust computational and experimental investigation of the fundamental properties of these important members of the thiazyl family of compounds, with particular attention paid to their highly tunable electrochemical behaviour. This is the first work to undertake a systematic comparison of the electrochemical profiles of a coherent series of SDIs to demonstrate and quantify the response of their reduction potentials to substituent electron-donating and -withdrawing properties. This effect is found to be not only exceptionally strong, but also correlates very closely with computed orbital energies. Electron paramagnetic resonance spectroscopy is used to determine the nature, localization, and qualitative lifetimes of the radical anions of SDIs. This work also addresses significant misconceptions about physical properties of SDIs. Experimental data and modern computational methods are employed to provide a resolute answer to the long-standing contention of the solution-state conformations of SDIs, and to correct historical mistakes in the assignment of infrared spectroscopic data. High-quality crystal structures of all SDIs in this work showcase the utility of the recently introduced structural refinement software NoSpherA2, enabling full anisotropic refinement of H-atoms with accurate C-H bond lengths.

Accurate Crystal Structures of C12H9CN, C12H8(CN)2, and C16H11CN Valence Isomers Using Nonspherical Atomic Scattering Factors.

Fourteen crystal structures, mostly from good-quality datasets but including some marginal and twinned exemplars, from a series of novel polycyclic benzo- and naphtho-fused organic nitriles are presented and accurately described, including some related structures of a bromo-substituted and partially hydrogenated analogues. These structures represent a considerable increase in the number of published structures within their archetypes. This work highlights the significant advancement in structural refinement software proffered by NoSpherA2, which enables Hirshfeld Atom Refinement (HAR) of the structures within Olex2 v1.5. This results in the determination of C-H bond lengths with near to neutron diffraction accuracies at far lower experimental cost, and with an average improvement in C-C bond precision of 42% compared to Independent Atom Model refinements. H-atoms (apart from disordered components) refined well with anisotropic displacement parameters. Nonclassical H-bonding (C-H···N≡C) in this series is analyzed, and dipolar nitrile-nitrile interactions (C≡N···C≡N) in three major motifs described by (Wood, P. A. Acta Cryst. B, 2008, 64, 393-396) are found in 9 out of 13 nitrile-containing compounds of this series, a much higher proportion than the global average of 21% of nitrile-containing compounds. The HAR/NoSpherA2 approach shows increasing benefits with better data quality without apparent discontinuities.

Two tris-(3,5-disubstituted phen-yl)phosphines and their isostructural PV oxides.

The crystal structures of tris-(3,5-di-methyl-phen-yl)phosphine (C24H27P), (I), tris-(3,5-di-methyl-phen-yl)phosphine oxide (C24H27OP), (II), tris-(4-meth-oxy-3,5-di-methyl-phen-yl)phosphine (C27H33O3P), (III), and tris-(4-meth-oxy-3,5-di-methyl-phen-yl)phosphine oxide (C27H33O4P), (IV), are reported. The strucure of (III) has been described before [Romain et al. (2000 ▸). Organometallics, 19, 2047-2050], but it is rereported here on the basis of modern area-detector data and to facilitate comparison with the other structures reported here. Compounds (I) and (II) crystallize isostructurally in P21/c. Similarly, (III) and (IV) crystallize isostructurally in Pbca. The conformations of (I) and (II) in the solid state deviate strongly from helical, whereas those of (III) and (IV) are found to be closer to an ideal threefold rotational symmetry. The pyramidality indices, ∑(C-P-C), are 305.35 (16), 317.23 (15), 307.2 (4) and 318.67 (18)° for (I), (II), (III) and (IV), respectively. Each is found to be more pyramidal than Ph3P or Ph3PO. Hybrid DFT calculations incorporating terms for dispersion provide evidence that the causes of the increased pyramidality, despite the 3,5-dimethyl group substitution, include dispersion inter-actions. The calculated ∑(C-P-C) values are 304.8° for both (I) and (III) and 317.4° for both (II) and (IV), with no difference arising from the substitution at ring position 4.

The First Lanthanide Complexes with a Redox-Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*2 (RN=)2 S], Ln=Sm, Eu, Yb; R=SiMe3.

The first lanthanide complexes with a redox-active sulfur diimide ligand, [LnCp*2 (Me3 SiN=)2 S] (Ln=Sm, Eu, Yb; Cp*=η5 -C5 Me5 ), are reported. The complexes were synthesized by using [LnCp*2 (THF)2 ] and (Me3 SiN=)2 S and have been thoroughly characterized by single-crystal X-ray diffraction, EPR spectroscopy, UV/Vis/NIR electronic absorption spectroscopy and SQUID magnetometry. The results, as interpreted by CASSCF/SOC-RASSI calculations providing a non-perturbative treatment of spin-orbit coupling, indicate that these paramagnetic complexes are best described as Ln3+ and [(Me3 SiN=)2 S]-. adducts. As such, these complexes contain the first isolated and structurally characterized acyclic [(RN=)2 S]-. radical anions.