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The oxidative formation of N−N bonds from primary amides has been recently reported and then retracted in the journal Nature Communications by Kathiravan, Nicholls, and co‐authors, utilizing a hypervalent iodane reagent. Unfortunately, the authors failed to recognize the Curtius reaction taking place under the described reaction conditions. Thus, the claimed N−N coupling products were not formed. Instead, the Curtius rearrangement urea coupling products were obtained. We demonstrate this herein by means of NMR and x‐ray analysis, as well as with the support of an alternative synthetic route. [ABSTRACT FROM AUTHOR]

A three-part experiment that leads to the synthesis of palladium(II) complex starting from a C[subscript 3]-symmetric triaminoguanidinium-based ligand is presented. In the first part, the preparation of tris-benzylidenetriaminoguanidinium chloride ([H[subscript 6]Br[subscript 3]L]Cl) by an acidic catalyzed 3-fold imine formation reaction of 5-bromo-2-hydroxybenzaldehyde and triaminoguanidinium chloride is described. Starting from the second part, the reaction procedures are performed under inert gas atmosphere. The conversion of PdCl[subscript 2] with acetonitrile to give [Pd(MeCN)[subscript 4]]Cl[subscript 2] as a precursor is performed at 80 °C. The third part of the experiment is a three-step procedure that begins with deprotonation of [H[subscript 6]Br[subscript 3]L]Cl, followed by transfer of [Pd(MeCN)[subscript 4]]Cl[subscript 2] to the reaction flask, where the chelation of Pd(II)-precursor leads to the in situ species [Pd(MeCN)H[subscript 3]Br[subscript 3]L]. Addition of PPh[subscript 3] as the final reaction step yields [Pd(PPh[subscript 3])H[subscript 3]Br[subscript 3]L]. This sequence of experiments provides an excellent example of ligand and transition metal preparation and its subsequent complexation to form an oxidant-sensitive organometallic species. Undergraduate students get the opportunity to learn Schlenk techniques and to investigate [superscript 1]H NMR spectra of organic and organometallic compounds starting from relatively simple to more advanced spectra. The distinct result of the chemical shift of the [superscript 4]J[subscript P-H]-affected doublet mirrors the preparative success of the student and demonstrates the utility of [superscript 1]H NMR experiments.

Phosphinate and phosphane substituted hierarchical helicates have been prepared, and the phosphinate derivatives could be characterized in the crystal. The helicate with phosphane substituents was submitted to an orientating study on catalysis, showing its potential to act as chelating ligand for the generation of active rhodium‐based hydrogenation catalysts. [ABSTRACT FROM AUTHOR]

Novel cobalt(II) containing compounds of tris‐(2‐pyridinylene‐N‐oxide)triaminoguanidine ligands L2− are presented: the supramolecular metallocycle [Co6(OOCMe)3(NCS)3L3]4 and the one‐dimensional coordination polymer {[Co3(μ‐OOCMe)3L]NO3}n. Analog zinc(II) complexes show similar to identical structures that are slightly influenced by different preferences regarding the coordination number. In the polymers, the coordination number is five, which is less common for zinc(II) and rare for cobalt(II). The compounds are characterized by single‐crystal as well as powder X‐ray diffraction, IR spectroscopy, and ESI mass spectrometry. Magnetic measurements revealed predominantly antiferromagnetic exchange interaction between the cobalt(II) centers linked by the triaminoguanidine backbone. [ABSTRACT FROM AUTHOR]

C10H8Cl2N2S2Zn, monoclinic, C2/c (no. 15), a = 12.317(2) Å, b = 9.868(2) Å, c = 10.947(2) Å, β = 92.37(2)°, V = 1329.3 Å3, Z = 4, Rgt(F) = 0.036, wRref(F2) = 0.132, T = 110 K.

Reactions of 2,2'-dithiobis(pyridine N-oxide) with various ZnII metal precursors and HgII halides are investigated and the products structurally characterized by X-ray crystallography. The crystal structures of the heteroleptic dinuclear complexes [HgX2(pyrithionate)2] (X = Br, I) are reported for the first time and that of the widely used antifungal and antifouling agent, the homoleptic dinuclear complex [Zn2(pyrithionate)4] (zinc pyrithione), is redetermined at low temperature, thereby improving the previous room temperature study in terms of precision. The encountered anionic chelate ligand pyrithionate results from reductive cleavage of the disulfide bond of 2,2'-dithiobis(pyridine N-oxide). [ABSTRACT FROM AUTHOR]

Reactions of 2,2'-dithiobis(pyridine N-oxide) with various ZnII metal precursors and HgII halides are investigated and the products structurally characterized by X-ray crystallography. The crystal structures of the heteroleptic dinuclear complexes [HgX2(pyrithionate)2] (X = Br, I) are reported for the first time and that of the widely used antifungal and antifouling agent, the homoleptic dinuclear complex [Zn2(pyrithionate)4] (zinc pyrithione), is redetermined at low temperature, thereby improving the previous room temperature study in terms of precision. The encountered anionic chelate ligand pyrithionate results from reductive cleavage of the disulfide bond of 2,2'-dithiobis(pyridine N-oxide). [ABSTRACT FROM AUTHOR]

The syntheses of the novel silicon‐bridged tris(tetraorganotin) compounds MeSi(CH2SnPh2R)3 (2, R=Ph; 5, R=Me3SiCH2) and their halogen‐substituted derivatives MeSi(CH2SnPh(3−n)In)3 (3, n=1; 4, n=2) and MeSi(CH2SnI2R)3 (6, R=Me3SiCH2) are reported. The reaction of compound 4 with di‐t‐butyltin oxide (t‐Bu2SnO)3 gives the oktokaideka‐nuclear (18‐nuclear) molecular diorganotin oxide [MeSi(CH2SnPhO)3]6 (7) while the reaction of 6 with sodium hydroxide, NaOH, provides the trikonta‐nuclear (30‐nuclear) molecular diorganotin oxide [MeSi(CH2SnRO)3]10 (8, R=Me3SiCH2). Both 7 and 8 show belt‐like ladder‐type macrocyclic structures and are by far the biggest molecular diorganotin oxides reported to date. The compounds have been characterized by elemental analyses, electrospray mass spectrometry (ESI‐MS), NMR spectroscopy, 1H DOSY NMR spectroscopy (7), IR spectroscopy (7, 8), and single‐crystal X‐ray diffraction analysis (2, 7, 8). [ABSTRACT FROM AUTHOR]

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Mono‐ or biscatechol esters with ether‐type substituents or spacers form either triple lithium bridged dimeric helicates or triple stranded helicates with the ability to bind three lithium cations in their interior. Hierarchical helicates with ether or thioether substituents show in solution a monomer‐dimer equilibrium which is independent of the heteroatom in the ester substituent. However, dimerization constants are significantly lower than for corresponding alkyl derivatives. Dinuclear helicates with oligoether spacers are well obtained in the presence of lithium cations. Upon removal of the cations the helicates expand and successive addition of LiCl results in compression again. [ABSTRACT FROM AUTHOR]

Hierarchical helicates based on ketone‐substituted titanium(IV)triscatecholates show different monomer‐dimer behavior depending on different solvents. The dimerization constants of a whole series of differently alkyl‐substituted complexes is analyzed to show that the solvent has a very strong influence on the dimerization. Hereby, effects like solvophobicity/philicity, sterics, electronics of the substituents and weak side‐chain—side‐chain interactions seem to act in concert. [ABSTRACT FROM AUTHOR]

The thioester moiety is introduced as a lithium binding unit for the hierarchical formation of titanium(IV) catecholate‐based lithium‐bridged helicates. In solution, the coordination compounds show a monomer–dimer equilibrium which —in comparison to the oxo esters— is significantly shifted towards the monomers. In addition, the influence of the thioester side chain on the dimerization behavior is investigated and an expansible/compressible molecular switch is synthesized. In the latter case expansion and compression are performed reversibly in methanol, whereas in DMSO spontaneous expansion occurs. [ABSTRACT FROM AUTHOR]

The synthesis of a new triaminoguanidinium‐based ligand with three tris‐chelating [NNO]‐binding pockets and C3 symmetry is described. The reaction of tris‐(2‐pyridinylene‐N‐oxide)triaminoguanidinium salts with zinc(II) formate leads to the formation of cyclic supramolecular coordination compounds which in solution bind fullerenes in their spherical cavities. The rapid encapsulation of C60 can be observed by NMR spectroscopy and single‐crystal X‐ray diffraction and is verified using computation. [ABSTRACT FROM AUTHOR]

The reexamination of the preparation of the cage compound has disclosed an incorrect structure of photodimer, as well as the putatively isolated intermediate. These products are reassigned as monomeric pyramidalized alkene and spirocyclic dichloride.

The development of a domino redox process under Willgerodt-Kindler conditions, which transforms a simple butanone side chain of suitable functionalized arenes and hetarenes into tricyclic annulated thieno[3,2-b]-thiophenes is reported. The key step in the synthesis included a nucleophilic aromatic substitution with an intermediary thioenolate.

The dissociation of hierarchically formed dimeric triple lithium bridged triscatecholate titanium(IV) helicates with hydrocarbyl esters as side groups is systematically investigated in DMSO. Primary alkyl, alkenyl, alkynyl as well as benzyl esters are studied in order to minimize steric effects close to the helicate core. The 1H NMR dimerization constants for the monomer–dimer equilibrium show some solvent dependent influence of the side chains on the dimer stability. In the dimer, the ability of the hydrocarbyl ester groups to aggregate minimizes their contacts with the solvent molecules. Due to this, most solvophobic alkyl groups show the highest dimerization tendency followed by alkenyls, alkynyls and finally benzyls. Furthermore, trends within the different groups of compounds can be observed. For example, the dimer is destabilized by internal double or triple bonds due to π–π repulsion. A strong indication for solvent supported London dispersion interaction between the ester side groups is found by observation of an even/odd alternation of dimerization constants within the series of n‐alkyls, n‐Ω‐alkenyls or n‐Ω‐alkynyls. This corresponds to the interaction of the parent hydrocarbons, as documented by an even/odd melting point alternation. [ABSTRACT FROM AUTHOR]

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Two biscatecholester ligands with oligoether spacers were used to prepare dinuclear titanium(IV) triscatecholate based helicates. In the case of Li4[(1/2)3Ti2], "classical" helicates with three internally bound Li+ ions and syn‐oriented ligands in the complex units (fac/fac isomer) were obtained. In the case of the sodium salt Na4[(2)3Ti2], a different homochiral dinuclear triple‐stranded helicate with two internally bound Na+ ions was formed. The complex units are anti‐configured, and two of the ligand spacers are connecting internal with external positions of the helicate (mer/mer isomer). Removal of the sodium ions and addition of lithium ions leads to the switching from one topology to the other with an expanded helicate [(2)3Ti2]4− as an intermediate. Switching back to the "non‐classical" helicate cannot be observed because severe structural rearrangements would be required. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The control of structural transformations triggered by external signals is important for the development of novel functional devices. In the present study, it is demonstrated that helicates can be designed to structurally respond to the presence of different counterions and to adopt either a compressed or an expanded structure. Reversible switching is not only possible between those two states, furthermore, the twist of the aggregate also can be controlled. Thus, three out of four possible states of a helicate (expanded/left‐handed, expanded/right‐handed, compressed/left‐handed) based on an enantiomerically pure ester bridged dicatecholate ligand are specifically addressed by introduction, exchange, or removal of countercations. This approach is used to reversibly switch between the different states or to successively address them. [ABSTRACT FROM AUTHOR]

The title compound, [HgI2(C10H8N2O2S2)]n, a one-dimensional coordination polymer with HgI2 units and 2,2′-di­thio­bis­(pyridine N-oxide) spacer ligands in an alternating fashion, forms helical chains running along the b axis in the crystal. Within a single coordination polymer strand, the axially chiral 2,2′-di­thio­bis­(pyridine N-oxide) ligands are homochiral, but the enanti­omeric conformation is present in adjacent strands. Within a coordination polymer strand, the iodido ligands point towards the centroids of the aromatic rings of the pyridine N-oxide moieties in the coordination sphere of HgII. Moreover, intra-strand C—HO and C—HI inter­actions, and inter-strand short SI and SO contacts are observed. [ABSTRACT FROM AUTHOR]

Group 12 halides and 2,2′-dithiobis(pyridine N-oxide) (dtpo) form the crystalline the 1D coordination polymers [Zn X2(μ-dtpo-κ2 O: O′)] n [ X = Cl ( 1), Br ( 2), I ( 3)], [Cd3(μ-Cl)4Cl2(μ-dtpo-κ2 O: O′)2(CH3OH)2] n ( 4), [(CdBr2)2(μ3-dtpo-κ3 O, O: O′)2(H2O)2] n ( 5), and [(CdI2)2(μ-dtpo-κ2 O: O′)3] n ( 6) in methanol. The compounds were structurally characterized by single-crystal X-ray analysis. Compounds 1- 3 represent an isomorphous series of single-stranded coordination polymers, whereas the CdII derivatives are structurally diverse. The metal nodes in 4 and 5 are trinuclear and dinuclear cadmium clusters, respectively. In 4 and 5, the metal nodes are linked into double-stranded 1D coordination polymers by two dtpo bridging ligands. Compound 6 contains mononuclear CdI2 units as nodes and can be viewed as an alternating copolymer of CdI2(μ-dtpo-κ2 O: O′)2 and CdI2(μ-dtpo-κ2 O: O′) entities. Owing to the disulfide moiety, the dtpo bridging ligand inevitably exhibits an axially chiral angular structure. The dtpo ligand adopts various coordination modes through the pyridine N-oxide oxygen atoms. [ABSTRACT FROM AUTHOR]

Porphyrin assemblies display interesting photophysical properties and a relatively high thermal stability. Moreover, meso-functionalized porphyrins with virtually fourfold symmetry can be relatively readily synthesized from pyrrole and the appropriate aldehyde. A number of metallo derivatives of 5,10,15,20-tetrakis(4-cyanophenyl)porphyrin, where the N atom of the linear cyano group can act both as a donor for coordination bonds or as an acceptor for hydrogen bonds, have been structurally characterized by single-crystal X-ray analysis. The supramolecular and structural chemistry of the corresponding 2- and 3-cyanophenyl isomers of the parent porphyrin, however, has remained largely unexplored. The crystal structure of [5,10,15,20-tetrakis(3-cyanophenyl)porphyrinato]copper(II) (CuTCNPP) nitrobenzene trisolvate, [Cu(C48H24N8)]·3C6H5NO2, has been determined at 80 K by synchrotron single-crystal X-ray diffraction. CuTCNPP exhibits a C2 h-symmetric ααββ conformation, despite an unsymmetrical crystal environment, and is situated on a crystallographic centre of symmetry. The CuII ion adopts a genuine square-planar coordination by the four pyrrole N atoms. The 24-membered porphyrin ring system shows no marked deviation from planarity. In the crystal, the CuTCNPP molecules and two nitrobenzene molecules are face-to-face stacked in an alternating fashion, resulting in corrugated layers. The remaining nitrobenzene guest molecule per CuTCNPP resides in the region between four neighbouring columnar stacks of CuTCNPP and sandwiched nitrobenzene molecules, and is disordered over four positions about a centre of symmetry. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The triangular clusters [Zn3Cp*3]+ and [Zn2CuCp*3] were obtained by addition of the in situ generated, electrophilic, and isolobal species [ZnCp*]+ and [CuCp*] to Carmona's compound, [Cp*ZnZnCp*], without splitting the ZnZn bond. The choice of non-coordinating fluoroaromatic solvents was crucial. The bonding situations of the all-hydrocarbon-ligand-protected clusters were investigated by quantum chemical calculations revealing a high degree of σ-aromaticity similar to the triatomic hydrogen ion [H3]+. The new species serve as molecular building units of Cu nZn m nanobrass clusters as indicated by LIFDI mass spectrometry. [ABSTRACT FROM AUTHOR]