Selenium-bridged complexes

YbSe". With (Me3Si)2N]3M (M = La, Ce) and (Me3Si)SiSeH, 3-coordinate monomers result in toluene but the Y derivative occurs in solution as a selenium bridged dimer. The La, Sm and Yb(III) derivatives complex with 2 moles of THF100. 

Other selenium-containing complexes include the benzeneseleninato compounds [Ru(RC6H4-SeO,)3] and [Ru(RC6H4Se02)2X], (R = H p- and m-Cl, Br p-Me X = Cl, Br), whose IR spectra indicate O.O -seleninato coordination. The tris-complexes are octahedral and the bis are polymeric, octahedral with bridging halides.2279,2280 Reaction of [Ru(CO)3(PPh3)2] with (SeCN)2 affords [Ru(NCSe)2 (CO)2(PPh3 )2], 2281... 

Liu, Y. Li, L., Fan. Z. Zhang. H.-Y. Wu, X. Guan, X.-D. Liu, S.-X. Supramolecular aggregates formed by intermolecular inclusion complexation of organo-selenium bridged bis(cyclodextrin)s with calyx[4]arene derivative. Nano Lett. 2002, 2. 257-261. 

Like sulfur, selenium based electron donors are heavily studied due to their potential as antithyroid agents. Of the 28 complexes reported, the majority (20) are diiodine based, and most of these (16) are simple adducts. One diiodine complex is bridged, one contains only extended adducts, one contains only bridged adducts, and one contains both bridged and extended adducts. All of the interhalogen complexes are simple adducts except one with iodine monobromine, which forms an extended adduct. 

It is noteworthy that 108 reacts in AcOH with benzenesulfenyl chloride to give a 1 1 mixture of the sulfur analogues of 138 and 140, but when the reaction is carried out in the presence of LiClC>4 a complex mixture of at least five products was detected. From this comparison the authors suggest that areneselenenylation is much less affected by the solvent than arenesulfenylation, and if the reaction profiles for the two product-forming processes are assumed to be similar, the difference in product distributions can be interpreted in terms of a more efficient bridging ability of selenium than that of sulfur. In the addition of selenenyl derivatives, the solvent-dependent product distribution has also... 

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