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.

Bismepines are 3-fold unsaturated sevenmembered rings containing one bismuth atom. A set of dibenzobismepine complexes have been synthesized and isolated, among them a dinuclear bismepine, halobismepines, and cationic bismepines. They were investigated with respect to the structural properties, olefin−bismuth interactions, heteroaromaticity, and Lewis acidity (including a comparison with a range of simple bismuth and group 13 Lewis acids). Applied analytical techniques include NMR spectroscopy, single-crystal X-ray analysis, elemental analysis, and density functional theory calculations.Forum Article pubs.acs.org/IC

A positive effect: the bis(allyl)bismuth cation in [Bi(C(3)H(5))(2)(thf)(2)][B(C(6)H(3)Cl(2))(4)] is superior to neutral tris(allyl)bismuth in the additive-free allylation of unsaturated C-heteroatom functionalities and the controlled living radical polymerization of activated olefins.

Three‐coordinate cationic bismuth compounds [Bi(diaryl)(EPMe3)][SbF6] have been isolated and fully characterized (diaryl=[(C6H4)2C2H2]2−, E=S, Se). They represent rare examples of molecular complexes with Bi⋅⋅⋅EPR3 interactions (R=monoanionic substituent). The 31P NMR chemical shift of EPMe3 has been found to be sensitive to the formation of LA⋅⋅⋅EPMe3 Lewis acid/base interactions (LA=Lewis acid). This corresponds to a modification of the Gutmann–Beckett method and reveals information about the hardness/softness of the Lewis acid under investigation. A series of organobismuth compounds, bismuth halides, and cationic bismuth species have been investigated with this approach and compared to traditional group 13 and cationic group 14 Lewis acids. Especially cationic bismuth species have been shown to be potent soft Lewis acids that may prefer Lewis pair formation with a soft (S/Se‐based) rather than a hard (O/N‐based) donor. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, single‐crystal X‐ray diffraction analysis, and DFT calculations.

Cationic bismuth(III) compounds [BiR2]+ with weakly coordinating counteranions feature two monoanionic ligands R (such as aryls, amides, alcoholates or halides), a vacant bismuth-centred p-orbital, and an occupied bismuth-centred s-orbital. The...

As eries of diorgano(bismuth)chalcogenides, [Bi(di-aryl)EPh],h as been synthesised and fully characterised (E = S, Se, Te). These molecular bismuthc omplexes have been exploited in homogeneous photochemically-induced radical catalysis,u sing the coupling of silanes with TEMPO as am odel reaction (TEMPO = (tetramethyl-piperidin-1-yl)-oxyl). Their catalytic propertiesa re complementary or superior to those of known catalysts for these coupling reactions. Catalyticallyc ompetent intermediateso f the reaction have been identified. Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy,m ass spectrometry,s ingle-crystal X-ray diffraction analysis, and (TD)-DFT calculations. Covalent bonds ZÀXw ith ah eavy p-block element Za so ne of the bondingp artnerss how low homolytic bond dissociation energies due to inefficient spatial and energetic overlap of the relevant atomic orbitals. [1] This allows access to reversible homolyticb ond dissociations (ZÀXQZC + XC)u nder mild reaction conditions, whichi sakey feature for potentialc atalytic applications via radicalp athways. [2] For instance,e quilibrium scenarios have been reported for the homolysis of the Sn Sn bond in (SnAr) 2 and the PnÀPn bonds in (Pn(CSiMe 3 CH 2) 2) 2 (Ar = C 6 H 3-2,6-(C 6 H 3-2,6-iPr 2) 2 ;P n = Sb, Bi). [3, 4] Such findingsh ave paved the way for new catalytic applicationsof well-defined, molecular complexes of heavy p-block elements in radical reactions. [2c] Among potentialc atalystso ft his kind, bismuth compounds in particulara re attractive synthetic targets due to characteristics such as low cost, (relatively) low toxicity,a nd prospects for recyclability. [5, 8a] In this context, the radicald ehydrocoupling of SiPhH 3 and TEMPO with [Bi(NON Dipp)]C and the radicalc yclo-isomerisationo fd-iodo-olefins with Ph 2 Bi-Mn(CO) 5 have recently been reported (Scheme 1; TEMPO = (tetramethylpiperidin-1-yl)-oxyl;N ON Dipp = O(SiMe 2 N Dipp) 2 ,D ipp = 2,6-iPr 2 C 6 H 3). [6, 7] While these reactions are thermally-initiated, pho-tochemically-induced transformations represent an important complementary approach to radical catalysis. Indeed, ar ange of inorganic bismuth compounds such as (nanostructured) oxides(Bi 2 O 3), [8] titanates (Bi 4 Ti 3 O 12), [9] vanadates (BiVO 4), [10] halidep erovskites(Cs 3 Bi 2 Br 9), [11] and an oxybromide (Bi 24 O 31 Br 10 (OH) d) [12] have been exploited in photocatalytic transformations. Catalysed types of reactions includet he degradationo fo rganic dyes such as methyl orange, [9] antibiotics such as tetracycline, [10] and biocides such as triclosan, [8b] as well as CH activation of aliphatic and aromatich ydrocarbons, [11] transfer (de)hydrogenation of alcohols/ketones, [12] and olefin polymerisation. [8a] These applications of bismuthc ompounds in heterogeneous catalysis suggest that photochemical strategies mighta lso be applicable for well-defined, molecular bismuth compounds under homogeneous conditions.I ndeed, the lightsensitivity of molecular bismuth complexes such as organobismuthanes, dibismut...

The first insertion reaction of CO with a molecular complex of the heavy p-block elements is reported (principal quantum number > 4).

The reinvestigation of two allyl zinc compounds, parent bis(allyl)zinc [Zn(C(3)H(5))(2)] (1) and 2-methallyl chloro zinc [Zn(C(4)H(7))Cl] (2), revealed two new coordination modes in the solid state for the allyl ligand, viz cis- and trans-μ(2)-η(1):η(1). These results call for modification of the conventional interpretation of zinc-allyl interactions. Computational results indicate that the classical η(3)-bonding mode of the allyl ligand is not favored in zinc compounds. A rare case of a zinc-olefin interaction in the dimer of [Zn(η(1)-C(3)H(5))(OC(C(3)H(5))Ph(2))] was found in the monoinsertion product of 1 with benzophenone.