Heating grey selenium with [v5-C5H4(t-Bu)lzZr(CsHq@-OCH3))2 in boiling octane affords the diselenophenylenezirconocene complex containing a methoxy group in the ortho position. A similar reaction, although less selective, occurs when starting from [v5-C5H4(t-Bu)12Zr-(Cd&(p-CH3))2. The structures of the diselenophenylenezirconocenes obtained were confirmed by NMR spectroscopy and definitively proved by comparison with the authentic orthosubstituted derivatives prepared from the corresponding methyl-o-anisyl-and methyl-otolylzirconocene. The mechanism proposed to explain this transformation involves the activation of a tert-butyl C-H bond by a transient benzynezirconocene species. The cyclometalation product, which is obtained by heating the diphenylzirconocene, reacts toward selenium and unsaturated organic compounds like the benzynezirconocene but the reaction takes place at room temperature. The cyclometalation pathway allows a more sterically hindered selenium-containing derivative [q5-C5H4(t-Bu)l2ZrSe2C6H3(o,o'-(CH&) to be prepared. The new diselenophenylenezirconocenes described are good precursors to generate benzodiselenagermoles and related spiro compounds by a zirconium-germanium transmetalation reaction. All the new products synthesized, zirconocene complexes and cyclometalated derivatives, benzodiselenagermoles, and spirobisbenzodiselenagermoles, were identified by the multinuclear NMR methods and mass spectrometry. The structure of the cyclometalated product [q5-C5H4(t-Bu)IZr[(2,5-(CH3)2CgH3)(1;1l: v5-CH2C(CH3)2C5H4)I was determined by X-ray diffraction analysis. This compound crystallizes in the monoclinic space group P21/c with two molecules per asymmetric unit with cell dimensions a = 8.278(3) .$, b = 20.113(9) A, c = 27.661(9) .$, and / 3 = 93.13(2)' at 295 K. Least-squares refinement led to a value for the final R index of 0.0642 for 2701 reflections with I =-2 4 1 ) .

ABSTRACT

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The first examples of compounds R1R2GeSe,C,H,RZ (R1,R2 = CH,,' C2H,, C3H7, n-C,H,,, i-CsH,l, Ph, p-CH,Ph. RZ = H. CH,, OCH,) were easily obtained (40-80% yield) from electrophilic.cleavage of diselenophenylene zirconocenes by dialkyl or diaryl dichlorogermanes. The synthesis of a spirodiselenagermole was achieved in the same way using germanium tetrachloride. Analytical data, 'H and 77Se NMR. mass spectra are perfectly consistent with the expected structures.

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ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Benzodichalcogenagermoles R'2Ge(-S-C6H4-o-X-) (R'=C2H5, Ph ; X = Se, Te) and spirobisbenzodichalcogenagermoles [(-S-C6H4-o-X-)2Ge] (X = Se, Te) were synthesized from the appropriate lithium benzene dichalcogenolate and germanedichlorides (R'2GeCl2) or germanium tetrachloride respectively. The compounds were characterized by microanalysis, lH, 13 C , 77 Se NMR and mass spectrometry. Comparative comments with homodichalcogenate congeners are reported. 565 Brought to you by | Purdue University Libraries Authenticated Download Date | 5/30/15 1:50 PM