The transformation of C-H bonds into more reactive C-M bonds amenable to further functionalization is of fundamental importance in synthetic chemistry. We demonstrate here that the transformation of neutral bismuth compounds into their cationic analogues can be used as a strategy to facilitate CH activation reactions. In particular, the double CH activation of bismuth-bound diphenyl amide, (NPh ) , is reported along with simple one-pot procedures for the functionalization of the activated positions. The organometallic products of the first and second CH activation steps were isolated in high yields. Analysis by NMR spectroscopy, single-crystal X-ray diffraction, and DFT calculations revealed unusual ground-state properties (e.g., ring strain, moderate heteroaromaticity), and provided mechanistic insight into the formation of these compounds.
NarrowH OMO-LUMO gaps and high chargecarrier mobilities make larger acenes potentially high-efficient materials for organic electronic applications.The performance of such molecules was shown to significantly increase with increasing number of fused benzene rings.B ulk quantities, however,c an only be obtained reliably for acenes up to heptacene.T heoretically,(oligo)acenes and (poly)acenes are predicted to have open-shell singlet biradical and polyradical ground states,respectively,for which experimental evidence is still scarce.W eh ave nowb een able to dramatically lower the HOMO-LUMO gap of acenes without the necessity of unfavorable elongation of their conjugated p system, by incorporating two boron atoms into the anthracene skeleton. Stabilizing the boron centers with cyclic (alkyl)-(amino)carbenes gives neutral 9,10-diboraanthracenes,w hich are shown to feature disjointed, open-shell singlet biradical ground states.
We report the H-type supramolecular polymerization of two new hydrophobic BODIPY derivatives equipped with ester and amide linkages. Whereas the ester-containing BODIPY derivative undergoes an isodesmic supramolecular polymerization in which the monomers are parallel-oriented, the replacement of the ester by amide groups leads to a highly cooperative self-assembly process into H-type aggregates with a rotational displacement of the dye molecules within the stack. The dye organization imposed by simultaneous π-π and hydrogen bonding interactions is the driving force for the cooperative supramolecular polymerization, whereas the absence of additional hydrogen bonds for the ester-containing moiety does not suffice to induce cooperative phenomena.
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