Synthesis, structural characterization, and spectroscopy of the cadmium-cadmium bonded molecular species Ar'CdCdAr' (Ar' = C6H3-2,6-(C6H3-2,6-Pri2)2)

The synthesis and first structural characterization of a cadmium-cadmium bonded molecular compound Ar'CdCdAr' (Ar' = C6H3-2,6-(C6H3-2,6-Pri2)2) are reported. The existence of the Cd-Cd bond was established by 113Cd NMR spectroscopy and X-ray diffraction (Cd-Cd = 2.6257(5) A). Like its group 12 analogue Ar'ZnZnAr', DFT calculations showed that Ar'CdCdAr' had significant p-character in the Cd-Cd sigma-bonding HOMO.     

Solid-state 119Sn NMR and Mössbauer spectroscopy of "distannynes": evidence for large structural differences in the crystalline phase

The "distannynes" Ar'SnSnAr' (Ar' = C6H3-2,6(C6H3-2,6-Pr(i)2)2) and ArSnSnAr (Ar = C6H3-2,6(C6H2-2,4,6-Pr(i)3)2) were examined by solid-state (119)Sn NMR and M?ssbauer spectroscopy. The two compounds display substantially different spectroscopic parameters, while differing only in the absence (Ar'SnSnAr') or presence (ArSnSnAr) of a para-Pr(i) group in the flanking aryl rings of their terphenyl substituents. The spectroscopic differences can be interpreted in terms of a more trans-bent geometry and a longer Sn-Sn bond for ArSnSnAr in comparison to the wider Sn-Sn-C angle (125.24(7) degrees ) and shorter Sn-Sn bond length (2.6675(4)A) determined from the crystal structure of Ar'SnSnAr'. The differences are consistent with previously published calculations by Nagase and Takagi for ArSnSnAr.     

Synthesis and structural characterisation of lower rim halogenated pyrogallol[4]arenes: bi-layers and hexameric nano-capsules

Two lower rim halogenated pyrogallol[4]arenes have been synthesised and structurally characterised as either bi-layer or hexameric nano-capsule motifs depending upon chain length and functionalisation.     

Lawvere theories enriched over a general base

We generalise the correspondence between Lawvere theories and finitary monads on in two ways. First, we allow our theories to be enriched in a category V that is locally finitely presentable as a symmetric monoidal closed category: symmetry is convenient but not necessary. And second, we allow the arities of our theories to be finitely presentable objects of a locally finitely presentable V-category A. We call the resulting notion that of a Lawvere A-theory. We extend the correspondence for ordinary Lawvere theories to one between Lawvere A-theories and finitary V-monads on A. We illustrate this with examples leading up to that of the Lawvere -theory for cartesian closed categories, i.e., the -enriched theory on the category for which the models are all small cartesian closed categories. We also briefly investigate change-of-base.