Search

The crystallization of cadmium bis(1,3-thiazolidine-2-thionate), Cd[([C.sub.3][H.sub.4]N[S.sub.2]).sub.2] (1), is reported. Freshly prepared 1 reacts with [Ph.sub.4][P.sup.+][X.sup.-] in a 1:2 ratio to give [([Ph.sub.4]P).sub.2][[[Cd.sub.2]([C.sub.3][H.sub.4]N[S.sub.2]).sub.2] [X.sub.4]](X = I (4) or Br (5)). Crystallization of 1 from pyridine produces a solvate 7. which loses pyridine readily. X-ray analyses show that 1 has a polymeric sheet structure in which the [C.sub.3][H.sub.4]N[S.sub.2-] ligands act as bidentate bridges through N and the exocyclic S and the Cd has a Cd[N.sub.2][S.sub.2] kernel; 5 is isomorphous with 4, which contains a dimeric anion again with bridging through the N and exocyclic S of the heterocyclic ligands: and 7 is Cd([[C.sub.3][H.sub.4]N[S.sub.2]).sub.2][([C.sub.5][H.sub.5]N).sub.3] x [C.sub.5][H.sub.5]N, containing trigonal bipyramidal Cd[([C.sub.3][H.sub.4] N[S.sub.2]).sub.2] [([C.sub.5][H.sub.5]N).sub.3] molecules, in which the [C.sub.3][H.sub.4]N [S.sub.2-] ligands, both of which are monodentate and in equatorial positions, occur as a unique combination of S- and N-bound. Cadmium-113 NMR data for 1 in pyridine solution and solid-state CP-MAS [sup.113]Cd data for 1, 7, bis(pyridinium-4-thiolate)cadmium, and tetrakis(pyridinium-2-thiolate)cadmium nitrate are reported and discussed. The compound 1 has chemical and NMR spectroscopic properties that make it a useful standard for solid-state CP-MAS [sup.113]Cd NMR spectroscopy. Key words: cadmium, 1,3-thiazolidine-2-thionate, X-ray analysis, solid-state [sup.113]Cd NMR, [sup.113]Cd NMR standard compound.

Research has been conducted on the diol synthesis. Results indicate that their X-ray crystal structures have been determined and the role of the crystal engineering in the hydroxy group hydrogen bonding has been investigated.

The synthesis and structural characterization of a family of 4-substituted-1-cubanecarboxylic acids are described. The results showed that four of the seven crystal structures contain the unusual syn-anti O-H...catemer. These compounds were 4-chloro-1-cubanecarboxylic acid, 4-bromo-1-cubanecarboxylic acid, 4-iodo-1-cubanecarboxylic acid and 4-(methoxycarbonyl)-1-cubanecarboxyillic acid. This is attributed to the stabilization from C-H...O bonds formed by the acidic cubyl C-H donors and the carboxyl O-acceptor atoms.

The palladium(II)-catalyzed coupling of 3-bromopyridine with norbornene analogues led to the synthesis of rigid bichromophoric systems with dimethoxynaphthalene and dimethoxybenzene. The bichromophoric system with dimethoxynaphthalene contained a competing nonradiative electron transfer or energy transfer process. Furthermore, a syn relationship was detected between the methoxy groups of the bichromophoric compound's naphthalene unit.

The indol-2-ylglyoxylamide moiety may be used as a building block for the self-assembly of hydrogen bond motifs in crystal engineering. This was revealed by x-ray crystallographic studies of a primary and secondary indol-2-ylglyoxylamide that formed a six-membered and a five-membered hydrogen bonded rings. The compounds, which were synthesized from 3-(4'-chlorophenyl)-4,6-dimethoxyindole, dimerized in the crystalline state to become 6,5,6,5-fused four-ring systems.

The crystal structure of organic diamondoid solids is simplified into a network that is dissected into nodes and node connections. The effects of the node connections, or supramolecular synthons, on crystal packing and their interchangeability with molecular synthons show that simplifying the crystal structure can be a useful strategy for crystal structure design, particularly in complex networks.

The crystals of 2,6-dimethylbicyclo(3.3.1)nonane-exo-2,exo-6-diol (1) constitute a series of spiral hydrogen bonded spines ...OH...OH...OH...OH... surrounding parallel canals. The compounds of 1 have guests trapped in the canals along c. In some compounds the guests affect the structure of the resulting inclusion compounds. The helical tubuland structures are present in the samples of the guest-free compounds of 1.

Bis(1,5-dimethyl-3, 7-dithiabicyclo(3.3.1)non-9-ylidene) is a 'tide-back' analogue of tetra-tert-butylethylene. It is preceded by the synthesis of a selenadiazoline which is extremely inhibited. Derivatives of retrocyclization and degeneration are formed when an inhibited complex is subjected to pyrdysis. The 'tied-back' analogue is not formed probably because of the constriction of the strain. McMurry pairing to the analogue is not affected by the ketone 1,5-dimethyl-3, 7-dithiabicyclo(3.3.1)nonan-9-one.

10b,l10c-trans-4,5,9,10-tetramethoxyperhydro-3a,5a,8a, 10a-tetraazapyrene, 1,3-diazacyclohexane-2-carboxylic acid, and 10b, 10c-trans-5,10-dimethoxyperhydro-3a,5a,8a,10a-tetraazapyrene-4,9-dione are formed when perhydro-2,2'-bipyrimidine is exposed to glyoxal, glyoxylic acid, and ethyl glyoxylate respectively. A fused mixture of 10b,10c-trans-4,5,9, 10-tetramethoxy-2,2,7,7-tetramethylperhydro-3a-5a-8a-10a- tetraazapyrene is produced when glyoxal is added to 5,5,5',5'-tetramethylperhydro-2, 2'-bipyrimidine. Ethyl 4a,4b-trans-9-hydroxy-10-oxoperhydro-4,5,8a, 10a-tetraazaphenanthrene-9-carbox ylate is produced due to an isomeric substance and interaction with diethyl oxomalonate.

The reaction of (trans-4,4',6,6')-tetramethylperhydro-2, 2'-bipyrimidine with formaldehyde stereoselectively produces tetraazafluorenes. With excess HCHO in methanol, the product is a (trans-1,3,5,7)-tetracycle. In ether, the (cis-1,3,5,7)-isomer is formed. The use of less HCHO in methanol results in a 1:5 mix of (trans/cis-1,3,6,8)-tricycles while the use of ether leads exclusively to the trans-isomer. The structures, conformation and mechanism of formation of the tetraazafluorenes are also discussed.