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We present the syntheses of two new star-shaped penta-ligands containing five pyridyls, which may be considered as starting materials for the preparation of fullerene-like molecules by coordination chemistry. One synthetic strategy is similar to that used for pentaphenylferrocenyl di-tert-butylphosphine. The penta-4-pyridyl derivative was prepared in two steps from ferrocene. A second strategy involving a Suzuki cross-coupling reaction with a penta-bromoaryl scorpionate is presented.

The flexible bidentate ligand 1,3-bis(benzimidazol-2-yl)propane, L3, and its N-methylated derivative L4, form complexes with CUI and CUII. The X-ray crystal structure of [Cu(L4)(MeCN)] (PF6) (1) shows a trigonal coordination of the CuI with the eight-membered chelate ring adopting a half-chair conformation. With CuII in EtOH, L3 forms dimeric [(L3)Cu(??EtO)2Cu(L3)](ClO4)2 · 2EtOH (2) whose X-ray crystal structure shows CuII in a distorted square-planar environment with one bidentate ligand and two bridging ethoxides. The chelate ring now has a boat-chair conformation which forms a hydrophobic pocket around the metal.

Single crystals of hydrated and anhydrous carnidazole have been subjected to X-irradiation at 77 K and studied by EPR. The determination of the EPR tensors shows that NO2, sulfur-centered radicals as well as a radical pair can be generated from this molecule; it appears that the species trapped at 77 K are not the same in the hydrated and in the anhydrous crystal. The results are discussed in the context of the radiosensitizing action of molecules containing a 5-nitroimidazole moiety.

The methylene blue (MB)-sensitized photo-oxygenation of indene (1) in CH3OH gave trans-2-hydroperoxy-1-methoxyindane (9), homophthalaldehyde (4), and its cyclic acetal 8. The same reaction conducted in acetaldehyde gave only 4. Repetition of the photo-oxygenation of 1 in slightly acidic aq. acetone (1:9) gave essentially trans-2-hydroperoxy-1-hydroxyindane (14) together with some cis-5,6-dihydro-3,3-dimethyl-1,2,4-trioxinol[1,2-e]indene. The MB-sensitized photo-oxygenation of 1,2-dihydronaphthalene (16) in CH3OH gave l,4-dihydro-1-hydroperoxynaphthalene (17) and trans-l,2,3,4-tetrahydro-2-hydroperoxy-1-methoxynaphthalene (19). In acetaldehyde, 16 furnished only 17. In aq. acetone (1:9) 16 gave 17 and trans-2-hydroperoxy-1-hydroxy-1,2,3,4-tetrahydronaphthalene (23). Product compositions were rationalized in terms of the 2-peroxides of the 1-cation of 1 and 16, namely 11 and 20. Treatment of 23 with aldehydes and ketones on catalysis with Amberlyst-15 or trimethylsilyl trifluoromethanesulfonate afforded the trans-fused 1,2,4-trioxanes 25. The 1,2-dioxetanes of 1 and 16 condensed with acetaldehyde on catalysis with CF3COOH to give the cis-fused 1,2,4-trioxanes 12 and 22.

A series of [Cr(benzene)(CO)2L] complexes with L = PPh3, P(OMe)3, PPh2 ((?)-menthyl), P(OPh)2(O-(?)-menthyl), P(O-(?)-menthyl)3 were subjected to a nueleophile addition/acylation sequence to give trans-5,6-disubstituted cyelohexadienes. Low-to-moderate asymmetric induction was observed with the chira] ligands. Experimental and theoretical evidence for an alkylation at the metal center trans to the P ligand is presented, and a crystal structure determination of a [Cr(?5–cyclohexadienyl)(P(OMe)3)(CO)2SnPh3] complex is included.

The highly strained ?-sultine 4, resulting from the addition of SO2 to benzobenzvalene, is shown to undergo a thermal cycloreversion which gives 1H-indene-1-thiocarbaldehyde dioxide (6) as an intermediate and subsequently 1H-indene-1-carbaldehyde (5). The sulfene can be intercepted with electron poor C=C bonds in a cycloaddition process leading to a five-membered ring. The structure of the fused heterocyclic product 8b resulting from addition of the sulfene 6 to N-phenyl-maleimide was ascertained by X-ray analysis. Pent-4-enethial dioxide (12) produced by a sulfo-Cope rearrangement from allyl vinyl sulfone (11) is found to add to N-phenylmaleimide in the same 1,3-dipolar fashion as the sulfene 6. The cycloadditions need not be via concerted pathways.