Reaction of 9-hydroxy(chloro,bromo)-4-azafluorene to bis[9-chloro(bromo-4-aza-fluoren-9-yl]

4-Aza-fluoren-9-ol and 9-chloro(bromo)-4-azafluorenes are converted in high yields upon refluxing with thionyl chloride to form bis[9-chloro(bromo)-4-azafluoren-9-yl]. At about 20C, azafluorenol and thionyl chloride form 9-chloro-4-azafluorene. Mechanisms are proposed for these reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 72–74, January, 1990.     

Synthesis of 4-Methyl-2,6-di(9H-thioxanthen-9-yl)aniline

Russian Journal of Organic Chemistry - 4-Methyl-2,6-di(9H-thioxanthen-9-yl)aniline was synthesized by the reaction of 4-methylaniline with N-thioxanthenylpyridinium perchlorate in a 1: 3 ratio at...     

Stoffwechsel-Endprodukte von PhyllochinonMenachinon-4, Ubichinon-9 und Hexahydroplastochinon-4 (Phytylplastochinon)

Phylloquinone, menaquinone-4, ubiquinone-9 and hexahydroplastoquinone-4, i.e. compounds with isoprenoid side-chains which differ by their length and degrees of unsaturation, are degraded in the rat in the same way as tocopherols. After oxidative shortening of the side-chain to seven C-atoms, the metabolites are excreted in the urine as conjugates, presumably glucuronides, which, after hydrolysis, can be isolated as γ-lactones.     

(Cyclen)(4)Ru(4)(pz)(4)](9+): a Creutz-Taube square

The use of cyclen (1,4,7,10-tetraazacyclododecane) as a blocking ligand enables assembly of the mixed-valence square complex [(cyclen)4Ru4(pz)4]9+ (pz = pyrazine). A crystal structure determination shows the molecule to possess a regular square geometry wherein each Ru atom has an equivalent coordination environment. Consistent with the presence of one RuIII and three RuII centers, cyclic voltammetry reveals a single reversible reduction wave and three successive oxidation waves. The separation between the first oxidation and reduction waves indicates a comproportionation constant of Kc = 108.9 for the [(cyclen)4Ru6(pz)4]9+ square, suggesting a greater extent of electron delocalization than that observed for the Creutz-Taube ion. The closer spacing between oxidation waves suggests a lesser degree of delocalization in the [(cyclen)4Ru6(pz)4]10+ (Kc = 102.0) and [(cyclen)4Ru6(pz)4]11+ (Kc = 103.0) species, bearing the higher average oxidation states of Ru2.5+ and Ru2.75+, respectively.     

VIBRATIONAL SPECTRA OF (t-C4H9 6Li)4 AND (t-C4H9 7Li)4: Raman Intensities and the Question of Li-Li Bonding

Abstract

Raman frequencies and intensities in methylcyclohexane solution and infrared frequencies in Nujol mull, have been obtained and assigned for the skeletal modes of (t-C₄H₉ ⁶Li)₄ and (t-C₄H₉ ⁷Li)₄. A normal coordinate analysis, neglecting hydrogen atoms, gave an overall frequency fit of 2% with a reasonable set of valence force constants. The calculated eigenvectors were used to transform the Raman intensities into bond polarizability derivatives. Because of coordinate mixing and the inherent sign ambiguity of molecular polarizability derivatives, there are eight sets of bond polarizability derivatives which are consistent with the measured intensities. Only one set, however, gives reasonable polarizability derivatives for CC stretching and CCC bending, and also shows the requisite invariance to isotope substitution. This set gives a low value for the Li-Li polarizability derivative, and application of the delta function potential equation suggests that the extent of Li-Li bonding is small, amounting to perhaps 5% of the total bonding electron density in the Li₄C₄ cage. This conclusion is consistent with the failure to observe Li[sbnd]Li spin-spin coupling in (t-C₄H₉Li)₄.     

Hybrid cluster-cages formed via cyanometalate condensation: Cs subset Co(4)Ru(6)S(2)(CN)(12), Co(4)Ru(9)S(6)(CN)(9), and Rh(4)Ru(9)S(6)(CN)(9) frameworks

Condensation of cyanometalates and cluster building blocks leads to the formation of hybrid molecular cyanometalate cages. Specifically, the reaction of [Cs subset [CpCo(CN)(3)](4)[CpRu](3)] and [(cymene)(2)Ru(3)S(2)(NCMe)(3)]PF(6) produced [Cs subset [CpCo(CN)(3)](4)[(cymene)(2)Ru(3)S(2)][CpRu](3)](PF(6))(2), Cs subset Co(4)Ru(6)S(2)(2+). Single-crystal X-ray diffraction, NMR spectroscopy, and ESI-MS measurements show that Cs subset Co(4)Ru(6)S(2)(2+ ) consists of a Ru(4)Co(4)(CN)(12) box fused with a Ru(3)S(2) cluster via a common Ru atom. The reaction of PPN[CpCo(CN)(3)] and 0.75 equiv of [(cymene)(2)(MeCN)(3)Ru(3)S(2)](PF(6))(2) in MeCN solution produced [[CpCo(CN)(3)](4)[(cymene)(2)Ru(3)S(2)](3)](PF(6))(2), Co(4)Ru(9)S(6)(2+). Crystallographic analysis, together with NMR and ESI-MS measurements, shows that Co(4)Ru(9)S(6)(2+ ) consists of a Ru(3)Co(4)(CN)(9) "defect box" core, wherein each Ru is fused to a Ru(3)S(2) clusters. The analogous condensation using [CpRh(CN)(3)](-) in place of [CpCo(CN)(3)](-) produced the related cluster-cage Rh(4)Ru(9)S(6)(2+). Electrochemical analyses of both Co(4)Ru(9)S(6)(2+) and Rh(4)Ru(9)S(6)(2+) can be rationalized in the context of reduction at the cluster and the Co(III) subunits, the latter being affected by the presence of alkali metal cations.     

9-(4-Bromophenyl)-9-fluorenyl as a safety-catch nitrogen protecting group

[reaction: see text] The 9-(4-bromophenyl)-9-fluorenyl (BrPhF) group has been developed as a novel safety-catch amine protection. This relatively acid-stable protecting group can be successfully activated by palladium-catalyzed cross-coupling reaction of the aryl bromide with morpholine and then cleaved effectively under mild conditions using dichloroacetic acid and triethylsilane. Complementary conditions are reported for selective removal of the BrPhF group in the presence of tert-butyl esters and carbamates as well as deprotection of tert-butyl esters and carbamates in the presence of BrPhF amines.     

Photochemical properties of 9-(4-azidophenyl)acridine

Syntheses are reported for 9-(azidophenyl)acridine and the corresponding N-methylacridine derivative, which have absorption bands in the near-UV and visible spectral regions. The photodissociation quantum yields upon irradiation of these azides at the long-wavelength band (365 nm) are 0.88 and <10⁻², respectively. An MNDO-PM3 semiempirical analysis was carried out on the change in the bond orders, NNN bond angle, and charge redistribution upon excitation of these molecules to the lowest excited singlet state, which accounted for the experimentally observed photochemical activity of 9-(4-azidophenyl)acridine and inertness of its quaternerized derivative. Chernogolovka Institute of Chemical Physics, Russian Academy of Sciences, Moscow Oblast, 142432 Chernogolovka. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1504–1509, November, 1997.