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The short-time cothermolysis of [{Cp‘‘‘(OC)2Fe}2](Fe−Fe) (1) and white phosphorus, P4, in toluene gives the butterfly complex [{Cp‘‘‘(OC)2Fe}2(μ-η1:η1-P4)] (2), Cp‘‘‘ = C5H2But 3-1,2,4, as the only product in 75% isolated yield. The open-edged exo/exo-P4 derivative 2 where one of the six P−P bonds of P4 has been selectively cleaved gives, on thermolysis, the sandwich complexes [Cp‘‘‘Fe(η5-P5)] (3) and [{Cp‘‘‘Fe}2 (μ-η4:η4-P4)] (4) with a cisoid P4 chain.

[Structure: see text]. The synthesis and characterization of a series of organochalcogen (Se, Te) compounds derived from benzyl alcohol 13 are described. The synthesis of the key precursor dichalcogenides 15, 22, and 29 was achieved by the ortho-lithiation route. Selenide 18 was obtained by the reaction of the dilithiated derivative 14 with Se(dtc)2. Oxidation of 15 and 22 with H2O2 afforded the corresponding cyclic ester derivatives 17 and 24, respectively. Oxidation of selenide 18 with H2O2 affords the spirocyclic compound 19. The presence of intramolecular interactions in dichalcogenides 15 and 22 has been proven by single-crystal X-ray studies. The cyclic compounds 17 and 19 have also been characterized by single-crystal X-ray studies. GP(X)-like antioxidant activity of selenium compounds has been evaluated by the coupled bioassay method. Density functional theory calculations at the mPW1PW91 level on ditelluride 22 have identified a fairly strong nonbonding interaction between the hydroxy oxygen and tellurium atom. The second-order perturbation energy obtained through NBO analysis conveys the involvement of n(O) --> sigma(Te-Te) orbital overlap in nonbonding interaction. Post wave function analysis with the Atoms in Molecules (AIM) method identified distinct bond critical point in 15 and 22 and also indicated that the nonbonding interaction is predominantly covalent. Comparison between diselenide 15 and ditelluride 22 using the extent of orbital interaction as well as the value of electron density at the bond critical points unequivocally established that a ditelluride could be a better acceptor in nonbonding interaction, when the hydroxy group acts as the donor.

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The synthesis and characterization of benzisochalcogenazolones (ebselen derivatives 16−21) is described. The synthesis of 16−21 was achieved by treating the bromo precursors 11−13 with an appropriate dilithium dichalcogenide. The synthesis of benzisoselenazolones 16 and 18 was also accomplished by an alternative route, that is, by treating the corresponding methoxymethyl selenides 22 and 23 with 1 equiv. of bromine. The synthesis of methoxymethyl selenides 22 and 23 was accomplished by lithiation of the bromo precursors followed by treatment with bis(methoxymethyl) dis-

Octaisopropylmetallocenes of the lanthanoids Sm(1-Sm), Eu (1-Eu), and Yb (1-Yb) can be obtained easily from the diiodides of the rare earth elements. Like the hexa-(tert.-butyl)metallocenes 2-Sm, 2-Eu, and 2-Yb, they show no tendency towards coordination of donor solvent molecules or alkali salts. The decaisopropylmetallocenes 3-Sm, 3-Eu und 3-Yb have been synthesized from the metal and the free pentaisopropylcyclopentadienyl radical. The three europocenes 1-Eu, 2-Eu, and 3-Eu show fluorescence in day-light or under UV irradiation (336 nm). Crystalline 1-Eu and 2-Eu are bent sandwich complexes, whereas for the decaisopropyl derivative 3-Eu axial symmetry with parallel fivemembered rings has been observed.

Hexaphosphabenzene, P6, long a goal of chemical synthesis, has been obtained for the first time as a complex‐stabilized ligand. The triple‐decker sandwich complex 1 forms air‐stable, amber‐colored crystals. According to an X‐ray structure analysis, the aromatic P6 ring is planar and lies parallel to the two five‐membered rings.