Crystal structure and spectroscopic characterization of a cobalt(II) tetraazamacrocycle: completing a series of first‐row transition‐metal complexes

The tetraazamacrocyclic ligand 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane (TMC) has been used to bind a variety of first‐row transition metals but to date the crystal structure of the cobalt(II) complex has been missing from this series. The missing cobalt complex chlorido(1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane‐κ⁴N )cobalt(II) chloride dihydrate, [CoCl(C₁₄H₃₂N₄)]Cl·2H₂O or [Co^IICl(TMC)]Cl·2H₂O, crystallizes as a purple crystal. This species adopts a distorted square‐pyramidal geometry in which the TMC ligand assumes the trans‐I configuration and the chloride ion binds in the syn‐methyl pocket of the ligand. The Co^II ion adopts an S = spin state, as measured by the Evans NMR method, and UV–visible spectroscopic studies indicate that the title hydrated salt is stable in solution. Density functional theory (DFT) studies reveal that the geometric parameters of [Co^IICl(TMC)]Cl·2H₂O are sensitive to the cobalt spin state and correctly predict a change in spin state upon a minor perturbation to the ligand environment.     

Functional characterization of ttnI completing the tailoring steps for tautomycetin biosynthesis in Streptomyces griseochromogenes

The tautomycetin (TTN) biosynthetic gene cluster has been recently cloned and sequenced from Streptomyces griseochromogenes, unveiling four genes, ttnCDFI, as candidates to encode the tailoring steps for TTN biosynthesis. It is reported that (i) TtnC plays no essential role in TTN biosynthesis, (ii) TtnI catalyzes C-5 oxidation, and (iii) combining the previous findings with TtnFD, the tailoring steps from TTN F-1 to TTN take place in the order of TtnF-catalyzed C-1"/C-2" dehydration, TtnD-catalyzed C-3" decarboxylation, and TtnI-catalyzed C-5 oxidation.     

Studies in the cycloproparene series: 2-halocyclopropabenzenes

Labelling studies show that dehydrohalogenation of the tetrahalobicycloheptane (8b,c) yields the title compounds (5a,b) both with and without skeletal rearrangement. 2-Chlorocyclopropabenzene (5b) is the major product and the expected 2-bromo derivative (5a) the minor product of reaction from the ‘mixed’ tetrahalide (8c).     

Core-extended perylene tetracarboxdiimides: the homologous series of coronene tetracarboxdiimides

Two novel coronenediimide (CDI) derivatives, CDI 2 and dinaphtho-CDI 4, were synthesized via straightforward synthetic routes completing the homologous series of coronene tetracarboxdiimides, which show remarkable optical properties with absorption wavelengths ranging from 380 to 600 nm, high absorption coefficients, and high fluorescence quantum yields.     

Studies in the eburnane series: a new dimerization process

The behaviour of the synthetic (−)-16-(aminomethyl)eburnamenine (prepared from apovincamine) with formaldehyde was studied. Carrying out the reaction in acetic acid led to an original dimer, while in trifluoroacetic acid a 12-functionalized eburnamonine was isolated.     

Isoelectronic series: a fundamental periodic property

The usefulness of isoelectronic series (same number of total electrons and atoms and of valence electrons) across Periods is often overlooked. Here we show the ubiquitousness of isoelectronic sets by means of matrices, arrays, and sequential series. Some of these series have not previously been identified. In addition, we recommend the use of the term valence-isoelectronic for species which differ in the number of core electrons and pseudo-isoelectronic for matching (n) and (n + 10) species.     

Hofmeister series: The quantum mechanical viewpoint

It is suggested that electromagnetic quantum vacuum fluctuations are at the very deep root of the so-called “specific ions effects” in concentrated solutions or in living cells. A many-body quantum-mechanical frame of thinking is proposed based on the concept of quantum coherence taking into account explicitly density and excitation frequencies of molecules and/or ionic species. It is also proposed that Hofmeister phenomena could have a natural explanation in the harmonic relationships between sets of characteristic frequencies ruled by quantum mechanical laws. It then follows that physical chemistry of concentrated media and biology should be ruled more by a quantum “symphony” between indistinguishable constituents rather than localized two-body electrical interactions between molecular or ionic species.     

Organometallic alkenes: The first stable silene in the neopentyl series

The simple synthesis in nearly quantitative yield of dimesitylneopentylsilene 3, the first stable silene in the neopentyl series, was performed using t-butyllithium and dimesitylvinyifiuorosilane. 3 was isolated by crystallization from pentane and characterized by ₁₃C (doubly bonded carbon at +110.4 ppm) and ²⁹Si (+77.6 ppm) NMR spectroscopy and analysis.     

N-oxides of the quinoxaline series

The reaction of quinoxaline N-oxides with benzenesulfonyl chloride and benzoyl chloride is investigated, and its mechanism discussed. The reaction products are investigated.     

Triterpenoids of the cycloartane series

In this review on triterpenoids of the cycloartane series, new achievements in this field of natural compounds are considered, the literature up to 1983 and, in part, 1984 being covered.Institute of Chemistry of Plant Substance, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 431–478, July–August, 1985.     

Synthesis in the phenothiazine series

A method was developed for the preparation of 3,7-diamino-10-acetylphenothiazine 5-oxide by the reduction of 3,7-dinitro-10-acetylphenothiazine 5-oxide with hydrazine hydrate in the presence of a nickel catalyst.See [1] for communication XXXIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 325–327, March, 1972.     

N-oxides of the quinoxaline series

A further study of the chemical behavior of quinoxaline and its -methyl and hydrdxy derivatives and their N-oxides in oxidation reactions and reactions with acetic anhydride has been carried out. The features of these reactions connected with the structure of the reacting N-oxides are discussed.For part XIV, see [10].     

Investigations in the imidazole series

2,3-Dihydro derivatives of naphth[1,2-d]imidazo[3,2-b]imidazole were synthesized by the reaction of 2-chloro-3-(-haloalkyl)naphth[1,2-d]imidazole with ammonia and primary amines and by the reaction of 2-chloro-3-(-hydroxyaIkyl)naphth[1,2-d]imidazole with ammonia and amines with subsequent cyclization of the resulting 2-amino(alkylamino, arylamino)-3-(-hydroxyalkyl)naphth[1,2-d]imidazoles under the influence of thionyl chloride or phosphorus oxychloride. Dihydro derivatives of the condensed naphth[1,2-d]imidazo[3,2-b]imidazole system have not been described in the literature.See [1] for communication LX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1127, August, 1971.     

Studies in the imidazole series

A new synthesis of derivatives of thiazolo[3,2-a]benzimidazoles based on 2-halogenobenzimidazoles has been performed. The reaction of 2-chlorobenzimidazole with -halogeno ketones and the subsequent heating of the resulting 1-acylmethyl-2-chlorobenzimidazoles with thiourea has given 1-acylmethyl-2-mercaptobenzimidazoles. The cyclization of the latter under the action of mineral acids or water-abstracting agents has given a series of 2-alkyl-, 2-aryl-, and 2-heteryl-substituted thiazolo[3,2-a]benzimidazoles.For Communication XLIX, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 6, pp. 827–831, June, 1970.     

Investigations in the imidazole series

The synthesis of derivatives of 2,3-dihydropyrrolo[1,2-a]imidazole from 1,2-dialkylimidazolines or 1,2-diarylkylimidazolines and phenacyl bromides with subsequent heating of the 1,2-disubstituted 3-phenacyl-imidazolinium bromides in aqueous or ethanolic solution in the presence of bases has been effected.For part XXXVIII, see [7].     

Investigations in the imidazole series

Cyclization of 2--oxoalkylthio- and 2--oxoaralkylthiobenzimidazoles and the reaction of 2-mercaptobenzimidazoles with -halogenoketones in the absence of bases has given a number of derivatives of thiazolo[3, 2-a]benzimidazole, cyclopentenothiazolo[3, 2-a]benzimidazole, and tetrahydrobenzothiazolo[3, 2-a]benzimidazole.For part XXXVI, see [6].     

Investigations in the imidazole series

The catalytic dechlorination of 1-alkyl-5-chloro-, 1-alkyl-4-chloro-, and 1-alkyl(aralkyl)-2-alkyl(aryl)-5-chloroimidazoles in the presence of Raney nickel, which makes it possible to simplify the synthesis of a number of 1-alkyl- and 1-alkyl(aralkyl)-2-alkyl(aryl)imidazoles, was investigated.See [1] for communication LXXV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 820–822, June, 1972.     

Cobalamins and the spectrochemical series

UV-visible-NIR spectra of a variety of cobalamins were run in water and methanol. A broad absorption band (band A) with extinction coefficients of about an order of magnitude less than those of the alphabeta bands was found in the red and NIR regions for Cl-cobalamin (Cl-cbl), Br-cbl, I-cbl, SC(NH(2))(2)-cbl(+) and SeCN-cbl. OCrO(3)-cbl(-), which also has a broad absorption band in the NIR was prepared for the first time. After deconvolution, similar broad bands were seen in the visible region for many other cobalamins. The wavelengths for band A placed the cobalamins in an order similar to the spectrochemical series but different from that of the alphabeta and gamma bands (pi-pi* transitions), which follow the nephelauxetic series. Band A was ascribed to a ligand-to-metal charge transfer (LMCT) transition from a pi orbital in the corrin ring to Co(iii). This is the first systematic study of LMCT bands in cobalamins.