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The July 2014 issue of the PSA Journal included an excellent article by Donna Judd titled Tennis: Photographing Its Grace and Power. Reading this article with great interest and envy [...]

This article concerns a special event in my experience with photography of sports. This event, which fulfilled one of my dreams, is something I first thought about when I was [...]

Five series of a novel class of 4-acyl-1-[2-aryl-1-diazenyl]piperazines have been synthesized and characterized: the 4-acetyl-1-[2-aryl-1-diazenyl]piperazines [series 1]; the 4-cyclohexylcarbonyl-1-[2-aryl-1-diazenyl]piperazines [series 2]; the 4-benzoyl-1[2-aryl-1-diazenyl]piperazines [series 3]; the benzyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates [series 4]; and the t-butyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates [series 5]. The compounds were synthesized by diazotization of a primary aromatic amine and subsequent coupling to an appropriate secondary amine: 1-acetylpiperazine [series 1]; 1-(cyclohexylcarbonyl)piperaizine [series 2]; 1-benzoylpiperazine [series 3]; benzyl 1-piperazinecarboxylate [series 4]; and t-butyl piperazine-1-carboxylate (1-BOC-piperazine) [series 5]. The compounds of series 1-5 were characterized by [sup.1]H NMR, [sup.13]C NMR, high-resolution MS and IR spectroscopy. The model compounds 1,4-di[2-aryl-1-diazenyl]piperazines, and ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates were used to facilitate the assignment of the chemical shifts specific to the piperazine ring carbons. HSQC spectra of select compounds established the correlation between proton and carbon resonance signals. Key words: triazene, piperazine, acyl-1-[2-aryl-1-diazenyl]piperazines, diazotization, piperazine-1-carboxylate, nuclear magnetic resonance spectroscopy, IR spectroscopy, mass spectrometry, dynamic equilibrium. Cinq series d'une nouvelle classe de 4-acyl-1-[2-aryl-1-diazenyl]piperazines ont ete synthetisees et caracterisees : les 4-acetyl-1-[2-aryl-1-diazenyl]piperazines [serie 1], les 4-cyclohexylcarbonyl-1-[2-aryl-1-diazenyl]piperazines [serie 2], les 4-benzoyl-1[2-aryl-1-diazenyl]piperazines [serie 3], les benzyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates [serie 4] et les t-butyl 4-[2-aryl1-diazenyl]-1-piperazinecarboxylates [serie 5]. Ces composes ont ete synthetises par diazotation d'une amine aromatique primaire suivie d'un couplage avec une amine secondaire appropriee : 1-acetylpiperazine [serie 1], 1-(cyclohexylcarbonyl)-piperazine [serie 2], 1-benzoylpiperazine [serie 3], benzyl 1-piperazinecarboxylate [serie 4] et t-butyl piperazine-1-carboxylate (1-BOCpiperazine) [serie 5]. Les composes des series 1 a 5 ont ete caracterises par RMN (resonance magnetique nucleaire) [sup.1]H, RMN [sup.13]C, spectrometrie de masse a haute resolution et spectroscopie IR. Les composes modeles 1,4-di[2-aryl-1-diazenyl]piperazines et ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates ont ete utilises pour faciliter l'attribution des deplacements chimiques specifiques auxcarbones du cycle de la piperazine. Les spectres HSQC d'une selection de composes ontpermis d'etablir une correlation entre les signaux de resonance du proton et du carbone. [Traduit par la Redaction] Mots-cles: triazene, piperazine, acyl-1-[2-aryl-1-diazenyl]piperazines, diazotation, piperazine-1-carboxylate, spectroscopie de resonance magnetique nucleaire, spectroscopie IR (infrarouge), spectrometrie de masse, equilibre dynamique., Introduction The objective of the work described in this paper was to synthesize and characterize several series of 4-acyl-1-[2-aryl-1-diazenyl] piperazines that adhere to the general structure shown below. [FORMULA EXPRESSION [...]

A series of 1,4-di[2-aryl-1-diazenyl]-trans-2,5-dimethylpiperazines(5a-5m), have been synthesized by the reaction of trans-2,5-dimethylpiperazine with two equivalents of the appropriate diazonium salt. The products have been characterized by IR and NMR spectroscopy, and the molecular composition has been verified by high-resolution EI mass spectrometry with accurate mass measurement of the molecular ion. The presence of stereocenters at C2 and C5 of the piperazine ring in the bis-triazene (5) creates two unique pairs of diastereotopic protons in the methylene groups at positions 3 and 6 of the piperazine ring, as evidenced by the complexity of the NMR spectra, which nevertheless can be fully assigned in some cases, such as the anisyl- (5i) and phenyl- (5j) derivatives. The assignment of the proton and carbon signals in the tolyl- derivative (5h) has been aided by the use of 2D NMR HSQC spectroscopy. These results compare favorably with assignments of proton and carbon signals reported previously for triazenes of type 1 and bis-triazenes of types 3 and 4b. Key words: triazene, piperazine, dimethylpiperazine, bis-triazenes, diazonium salts, NMR spectroscopy, IR spectroscopy, mass spectrometry, diastereotopic relationships, 2D NMR HSQC spectroscopy. Une serie de 1,4-di[2-aryl-1-diazenyl]-trans-2,5-dimethylpiperazines (5a-5m) ont ete synthetisees par reaction de la trans-2,5-dimethylpiperazine avec deux equivalents du sel de diazonium approprie. Les produits ont ete caracterises par spectroscopies IR et RMN et la composition moleculaire verifiee au moyen de la spectrometrie de masse par ionisation electronique a haute resolution en mesurant avec precision la masse de l'ion moleculaire. La presence de stereocentres au niveau des carbones C2 et C5 du cycle de la piperazine dans le bis-triazene (5) entraine la formation de deux paires uniques de protons diastereotopiques dans les groupements methylene aux positions 3 et 6 du meme cycle, comme le montrent la complexite des spectres de RMN. Ceux-ci peuvent etre cependant attribues dans certains cas comme les derives anisyl (5i) and phenyl (5j). L'attribution des signaux du proton et du carbone dans le derive tolyl (5h) a ete facilitee par l'emploi de la spectroscopie HSQC RMN bidimensionnelle. Ces resultats coincident plutot bien avec les attributions des signaux du proton et du carbone observee precedemment dans les cas des triazenes de type 1 et des bis-triazenes de types 3 et 4b. [Traduit par la Redaction] Mots-cles: triazene, piperazine, dimethylpiperazine, bis-triazenes, sels de diazonium, spectroscopie RMN, spectroscopie IR, spectrometrie de masse, relations diastereotopiques, spectroscopie HSQC RMN bidimensionnelle., Introduction In Part I of this series, (1) the diazonium coupling reaction of 1-methylpiperazine was explored to synthesize the 4-methyl-1-(2aryldiazen-1-yl-)piperazines (1). The structure of one compound, namely methyl 4-{(E)-2-(4methylpiperazino)-1-diazenyl}benzoate, in [...]

The term capturing motion has more than one interpretation in photography. In photojournalism, capturing motion implies a moving subject that is captured in the photograph in such a way that [...]

A series of 1,4-di-[2-aryl-]-diazenyl]-2,6-dimethylpiperazines (5a-51), have been synthesized by the reaction of 2,6-dimethylpiperazine with 2 equiv. of the appropriate diazonium salt. The products have been characterized by IR and NMR spectroscopy, and the molecular composition has been verified by high-resolution EI mass spectrometry with accurate mass measurement of the molecular ion. The presence of stereocenters at C2 and C6 of the piperazine ring in the bistriazene 5 creates two unique pairs of diastereotopic protons in the methylene groups at positions 3 and 5 of the piperazine ring, as evidenced by the complexity of the NMR spectra, which nevertheless can be fully assigned in most cases. The assignment of the proton and carbon signals in the 1,4-di-[2-aryl-1-diazenyl]-2.6-dimethylpiperazines has been aided by the use of 2D NMR HSQC spectroscopy, These results compare favorably with assignments of proton and carbon signals reported previously for triazenes of type 1 and bis-triazenes of type 3. Key words: triazene, bis-triazene, piperazine, 2,6-dimethylpiperazine, diastereotopic protons, diazonium coupling, 2D NMR, HSQC. On a realise la synthese d'une serie de 1,4-di-[2-aryl-1-diazenyl]-2,6-dimethylpiperazines (5a-51) par reaction de la 2,6-dimethylpiperazine avec deux equivalents du sel de diazonium approprie. Les produits ont ete caracterises par spectroscopies infrarouge et RMN et on a verifie la composition moleculaire par spectrometrie de masse a haute resolution et ionisation electronique en effectuant la mesure exacte de la masse de l'ion moleculaire. La presence de stereocentres dans les positions 2 et 6 du noyau piperazine du bis-triazene 5 conduit a la creation de deux paires distinctes de protons diastereotopes dans les groupes methylenes des positions 3 et 5 du noyau piperazine qui sont mis en evidence par la complexite du spectre RMN qu'on peut toutefois assigner completement dans la plupart des cas. L'attribution des signaux des atomes d'hydrogene et de carbone dans les 1,4-di-[2-aryl-l-diazenyl]-2, 6-dimethylpiperazines a ete rendue possible par l'utilisation de la spectroscopie RMN 2D avec correlation a quantum unique heterouucleaire (<< HSQC >>). Ces resultats se compareni favorablement avec les aitribulions des signaux des atomes d'hydrogene et de carbone rapportees anterieurement pour les triazenes du type 1 el les bis-triazenes de type 3. Mots-cles: triazene, bis-triazene, piperazine, 2,6-dimethylpiperazine, protons diastereotopes, couplage diazonium, RMN 2D, correlation a quantum unique heteronucleaire (<< HSQC >>). [Traduit par la Redaction], Introduction This paper is the latest chapter in an extensive study of the synthesis of N-aryldiazenylpiperazines and the structural characterization of these triazenes. In Part I of this series, (1) [...]

One of the joys of belonging to the Photographic Society of America (PSA) is the opportunity to view images of the world without actually being there. This opportunity presents itself [...]

Membership in the Photojournalism Division (PJD) of the Photographic Society of America (PSA) has provided many challenges, not least of which is the motivation to take better pictures to compete [...]

Abstract: A series of 1,4-di-[2-aryl-1-diazenyl]-2-methylpiperazines (4a-n) have been synthesized by the reaction of 2-methylpiperazine with 2 equiv. of the appropriate diazonium salt. The products have been characterized by IR and [...]

Abstract: A new series of bistriazenes, the 1-aryl-2-[3-(3-[2-aryl- 1-diazenyl]-1,3-diazepan-1-ylmethyl)-1,3-diazepan-1-yl] -1-diazenes (8), has been synthesized from the reaction of diazonium salts with a mixture of 1,4-diaminobutane and formaldehyde. All new compounds [...]

Abstract: The reactions of a series of arene diazonium salts with 1,4,8, 11-tetraazacyclotetradecane (cyclam) afford the novel compounds, the 1,4,8,11-tetra[2-aryl-1-diazenyl]-1,4,8, 11-tetraazacyclotetradecanes (1a-1f), which are the first examples of tetrakistriazenes to [...]

Abstract: Reaction of a series of diazonium salts with a mixture of formaldehyde and 1,2-diamino-2-methylpropane affords the 3-({5,5-dimethyl-3-[2-aryl-1-diazenyl]-1-imidazolidinyl}methyl)- 4,4-dimethyl-1-[2-aryl-1-diazenyl]imidazolidines (1a-1f) in excellent yield. The products have been characterized by IR [...]

Abstract: A series of diazonium salts has been coupled to both secondary nitrogen atoms of the bis-secondary amine, N,N'-dimethyl-1,3-propanediamine (MeNHC[H.sub.2]C[H.sub.2]C[H.sub.2]NHMe), to afford the new bistriazene series, the 3-methyl-3-{3-[1-methyl-3-aryl-2-triazenyl]propyl}-1-aryl-1-triazenes (9). These [...]

First, what are the Cyclades you may ask? The Cyclades is a group of islands of varying sizes scattered over the deep blue waters of the Aegean Sea. A fusion [...]

It is not the intention to describe and illustrate all of the windmills of Holland. Even to describe the different types of windmills in the Netherlands would need a book--indeed [...]

Just a mention of the name Don Quixote brings to mind a vision of an aging knight in shining armour on horseback charging into a windmill with a blunt lance. [...]

A new series of bistriazenes has been synthesized from a general reaction of diazonium salts with a mixture of 1,3-diaminopentane (DYTEK® EP diamine) and formaldehyde, which affords the 4-ethyl-3-({6-ethyl-3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinyl} methyl)-1-[2-aryl-1-diazenyl]hexahydropyrimidines (1). Each of the molecules of type 1 is built up of two equivalent 3-(aryldiazenyl)-6-ethylhexahydro-1-pyrimidinyl groups attached to a central methylene group. The importance of this study is in part due to the fact that the formaldehyde-1,3-diaminopentane system has not previously been investigated. All new compounds have been characterized by IR and NMR spectroscopy, with elemental analysis for selected compounds; one example from the series has been unequivocally characterized by X-ray crystallography. Although analysis of the NMR spectra is made somewhat difficult because of broadness and coalescence of signals due to the rotational dynamics of the N--N single bonds, it is possible to fully assign the proton spectra of all compounds and to detect 94% of all carbon signals. The fine structure within the proton spectra illustrate the diastereotopic nature of the methylene group protons because of the presence of a stereocenter in each hexahydropyrimidine ring. The general conclusion of this study is that alkanediamines with three carbon atoms in the spacer link between the nitrogen atoms give rise to the linear bicyclic molecules of type 1, 2, and 3, in contrast to the case of ethylenediamine (spacer link has two carbon atoms), which affords molecules of type 7 that exemplify the bridged bicyclic bistriazene structure. The new compounds of series 1 represent an extension of a broad ranging study of the synthesis of new bistriazene derivatives of (1,x)-diazacycloalkanes. Key words: triazene, diazonium coupling, hexahydropyrimidine, diaminopentane, diazacycloalkanes, stereocenter, diastereotopic protons. On a effectue la synthese d'une nouvelle serie de bistriazenes par le biais d'une reaction generale des sels de diazonium avec un melange de 1,3-diaminopentane (DYTEK ® EP diamine) et de formaldehyde qui conduit a la formation de 4-ethyl-3-({6-ethyl-3-[2-aryldiazen-1-yl]hexahydropyrimidin-1-yl} methyl)-1-[2-aryldiazen-1-yl]hexahydropyrimidines (1). Chacune des molecules du type 1 correspond a l'addition de deux equivalents de groupes 3-(aryldiazenyl)6-ethylhexahydropyrimidin-1-yle a un groupe methylene central. L'importance de cette etude reside en partie dans le fait que le systeme formaldehyde-1,3-diaminopentane n'avait pas ete etudie anterieurement. Tous les nouveaux composes ont ete caracterises par spectroscopies IR et RMN et par analyse elementaire de composes choisis; un exemple de la serie a ete caracterise sans equivoque par diffraction des rayons X. Meme si l'analyse des spectres RMN est rendue assez difficile en raison de la largeur et de la coalescence des bandes provoquee par la dynamique rotationnelle des liaisons simples N--N, il a ete possible de faire une attribution complete des spectres du proton de tous les composes et de detecter 94 % des signaux dus au carbone. La structure fine observee dans les spectres du proton illustre la nature diastereotopique des protons du groupe methylene qui decoule de la presence d'un centre stereogene dans chacun des cycles hexahydropyrimidines. La conclusion generale de cette etude est que les alcanediamines comportant trois atomes de carbone comme lien qui separe les atomes d'azote conduisent a des molecules bicycliques lineaires des types 1, 2 ou 3, en opposition avec ce qui a ete observe dans le cas de l'ethylenediamine (lien comportant deux atomes de carbone) qui conduit a des molecules du type 7, un exemple de structure bistriazene bicyclique pontee. Les nouveaux composes de la serie 1 representent une extension d'une etude de grande envergure sur la synthese de nouveaux derives bistriazene des (1,x)-diazacycloalcanes. Mots cles : triazene, couplage de diazonium, hexahydropyrimidine, diaminopentane, diazacycloalcanes, centre stereogene, protons diastereotopiques., Introduction A triazene is any molecule containing three contiguous nitrogen atoms with one N=N double bond, i.e., N=N-N. Triazenes have been studied extensively as versatile tools for organic synthesis (1), [...]

Two new series of bistriazenes have been synthesized from a general reaction of diazonium salts with a mixture of a propanediamine and formaldehyde. Such reaction with 1,3-diaminopropane itself affords the 1-[2-aryl-1-diazenyl]-3-(3-[2-aryl-1-diazenyl] hexahydro-1-pyrimidinylmethyl) hexahydropyrimidines (6). 2,2-Dimethyl-1,3-diaminopropane reacts in an analogous manner to give the 1-(5,5-dimethyl-3-[2-aryl-1-diazenyl] hexahydro-1-pyrimidinylmethyl)5,5-dimethyl-3-[2-aryl-1-diazenyl] hexahydropyrimidines (7). All new compounds have been characterized by IR and NMR spectroscopy, with elemental analysis or high resolution mass spectrometry of most of the new compounds. NMR assignments have been analyzed by a series of DEPT, COSY, and HSQC experiments. One example of each series has been unequivocally characterized by X-ray crystallography. The general conclusion of this study is that alkanediamines with three carbon atoms in the spacer link between the nitrogen atoms give rise to the linear bicyclic molecules of type 18, in contrast to the case of ethylenediamine (spacer link has two carbon atoms), which affords cage-like molecules of type 17. Key words. bistriazene, hexahydropyrimidine, diazonium coupling, formaldehyde, diaminopropane, nuclear magnetic resonance. Resume : Deux nouvelles series de bistriazenes ont ete synthetisees par une reaction generale de sels de diazonium avec un melange de propanediamine et de formaldehyde. Une telle reaction avec le 1,3-diaminopropane conduit a la formation de 1-[2-aryldiazen-1-yl]-3-(3-[2-aryldiazen-1-yl] hexahydropyrimidin-1-ylmethyl)hexahydropyrimidines (6). Le 2,2-dimethyl-1,3-diaminopropane reagit d'une facon semblable pour conduire a la formation de 1-(5,5-dimethyl-3-[2aryldiazen-1-yl] hexahydropyrimidin-1-ylmethyl)-5,5-dimethyl-3-[2-aryldiazen-1-yl] hexahydropyrimidines (7). Tous les nouveaux composes ont ete caracterises par spectroscopies IR et RMN, avec analyses elementaires ou spectrometrie de masse a haute resolution pour la plupart des nouveaux composes. Les attributions RMN ont ete analysees par une series d'experiences DEPT, COSY et HSQC. Un exemple de chacune des series a ete caracterise sans equivoque par diffraction des rayons X. La conclusion generale de cette etude est que les alcanediamines a trois atomes de carbones peuvent etre utilisees comme lien pour creer un espace entre deux atomes d'azote avec la formation des molecules bicycliques lineaires de type 18, par opposition aux produits resultant d'une insertion d'ethylbnediamine (lien pour creer un espace de deux atomes de carbone) qui conduit a la formation de molecules en forme de cage du type 17. Mots cles : bistriazene, hexahydropyrimidine, couplage de diazonium, formaldehyde, diaminopropane, resonance magnetique nucleaire.

Reaction of a series of diazonium salts with piperazine in a 2:1 molar ratio affores excellent yields of the 1,4-di-[2-aryl-l-diazenyl] piperazines (3), which have been characterized by IR and NMR spectroscopy. Structural characterization is supported by elemental analysis or by mass spectrometry with accurate mass measurement of the molecular ion. The protons of the piperazine ring hydrogens give rise to a sharp singlet at ca. 4 ppm in the NMR spectra, indicating that the conformational equilibrium in the piperazine ring is rapid on the NMR timescale. The four equivalent carbon atoms of the piperazine ring resonate in the range 46-48 ppm. A variable temperature NMR experiment suggests that there is restricted rotation around the N2--N3 bond of the triazene moiety in 3. The NMR data compares favorably with previous reported data for 1-aryldiazenyl-4-methylpiperazines (1) and 1,4-di-(2-aryldiazen-l-yl)homopiperazines (2b). Key words: triazene, piperazine, diazonium coupling, NMR. Resume : La redaction d'une serie de sels de diazonium avec de la piperazine dans un rapport molaire de 2 : 1 conduit, avec d'excellents rendements, a des 1,4-di-[2-aryldiazen-l-yl]pipeprazines (3) qui ont ete caracterisees par les spectres IR et RMN. Les caracterisations des structures sont supportees par des analyses elementaires ou par spectromedrie de masse avec des mesures precises de la masse de l'ion moleculaire. Dans le spectre RMN, les protons du noyau piperazine se presentent sous la forme d'un singulet effile a environ 4 ppm, ce qui suggere que l'equilibre conformationnel du cycle piperazine est rapide par rapport a l'echelle de temps de la RMN. La resonance des quatre atomes de carbone equivalents du noyau de la piperazine se situe entre 4e et 48 ppm. Une experience de RMN a temperature variable suggere l'existence d'une rotation empechee autour de la liaison N2--N3 de la portion triazene du compose 3. Les donnees de la RMN se comparent avantageusement avec celles rapportees anterieurement pour les 1-aryldiazenyl-4-methylpiperazines (1) et 1,4-di-(2-aryldiazen-l-yl) homopiperazines (2b). Mots cles : triazene, piperazine, couplage de diazonium, RMN. [Traduit par la Redaction]

1-Methylhomopiperazine was coupled with a series of diazonium salts to afford the 4-methyl-1-[2-aryl-1-diazenyl]-1,4-diazepanes (6), a new series of triazenes. These compounds are, in the main, stable crystalline solids (some of the series are stable oils), and they have been characterized by [sup.1]H and [sup.13]C NMR spectroscopy, IR spectroscopy, and mass spectrometry. NMR assignments were determined by 2D NMR and variable-temperature NMR experiments and by comparison with model compounds. A second series of new compounds, namely, 1,4-di-[2-aryl-1-diazenyl]-1,4-diazepanes (5), were prepared by coupling unsubstituted homopiperazine (1,4-diazepane) with 2 molar equivalents of the diazonium salt and were similarly characterized. The crystal and molecular structure of the parent member of this bis-triazene series (5, X = H) has been determined by single-crystal X-ray diffraction analysis. Key words: triazene, bis-triazene, diazenyl, bis-diazenyl, diazonium salt, NMR, diazepane.

Part I of this series (PSA Journal, August, 2004) was concerned with the sport of Biathlon--with a twist! The biathlon event that I attended was a one-off special event held [...]

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by [sup.1]H and [sup.13]C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). ADEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

3-Aminopyridine is diazotized in the conventional manner and the diazonium salt coupled with N,N'-dimethylethylenediamine to afford the title compound (1), which is a potential antitumour agent. The compound has been characterized by spectroscopic methods. The [sup.1]H NMR spectrum shows evidence of rotational conformerism, from the observation of broadening of the N-methyl signals in the room-temperature spectrum. Low-temperature NMR spectra (down to 223 K) show the presence of three distinct rotamers. The crystal structure of 1,2-bis-(1-{3-pyridyl-}3methyltriazen-3-yl)ethane (1) has been determined by single crystal X-ray diffraction analysis. The bis-triazene (1) exists as the "staggered" conformation in the solid state, with an "anti-anti" configuration around the N--N bond of the triazene units. The crystal structure of 1 is compared with the closely related bis-triazene 2 and also compared with the simple mono-triazene 3. Crystal data for 1, [C.sub.14][H.sub.18][N.sub.8]: orthorhombic, space group Pbca, a = 11.2550(8) [Angstrom], b = 8.8507(6) [Angstrom], c = 15.0069(10) [Angstrom], [beta] = 90[degrees], and V = 1494.91(18) [[Angstrom].sup.3] for Z = 4. Key words: triazene, bis-triazene, pyridine, X-ray, VT NMR, diazonium coupling.

A computational study of triazene, methyltriazene, dimethyltriazene, and trimethyltriazene is presented. A number of different conformers are analyzed and rationalized using hyperconjugation and steric interaction arguments. The transition states for rotation, inversion, and proton and methyl shifts (including water-mediated) are found and the barriers determined. Key words: triazene, ab initio, methyltriazene, 1,3-proton shift.

A novel type of bis-triazene, the 3,8-di(2-aryl-1-azenyl)-1,3,6,8-tetraazabicyclo(4.4.1)undecanes was synthesized by the reaction of a diazonium salt with a mixture of formaldehyde and ethylenediamine. An analysis of data generated via nuclear magnetic resonance, infrared and elemental techniques showed that the reaction of diazonium salts with ethylenediamine and formaldehyde solutions results in the formation of the 3,8-di(2-acryl-1-azenyl)-1,3,6,8-tetraazabicyclo(4.4.1)undecanes.

This article was written to provide information about the photographic opportunities for PSA members planning to undertake a vacation in the Maritime Provinces of Canada. The emphasis will be to […]