Synthese und Struktur von benzylsubstituierten Derivaten des Dinickel-Tripeldeckerkomplexes µ - η
5, η
5-(2,3-Dihydro-1,3-diborolyl)- ( η
3-allyl)( η
4-1,5-hexadien)dinickel
Synthesis and Structure of Benzyl Substituted Derivatives of the Dinickel Triple-Decker Complex
µ-η5,η
5-(2,3-Dihydro-1,3-diborolyl)- (
η3-allyl)(
η4-1,5-hexadiene)dinickel
Walter Siebert, Stefan Huck und Hans Pritzkow
Anorganisch-Chemisches Institut der Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg
Sonderdruckanforderungen an Prof. W. Siebert. Fax: + 49 (0)6221Ð545609.
E-mail: ci5@ix.urz.uni-heidelberg.de
Herrn Prof. Dr. M. Schmidt zum 75. Geburtstag gewidmet
Z. Naturforsch.56 b, 73Ð78 (2001); eingegangen am 4. September 2000 Nickel,µ-η5,η5-(2,3-Dihydro-1,3-diborolyl)(η3-allyl)(η4-1,5-hexadiene)dinickel, Polydecker Complexes
Hydroboration of phenyl- and mesitylethyne within situformed HBCl2leads to an isome- ric mixture of 1,1-bis(dichloroboryl)-2-phenylethane (4a) and 1,1-bis(dichloroboryl)-1-pheny- lethane (4b) (ratio 3 : 1) and regioselectively to 1,1-bis(dichloroboryl)-2-mesitylethane (4c).
Treatment of4a/b and4cwith BI3 gives the corresponding tetraiodo compounds5, which undergo redox reactions with butyne-2to form the 1,3-diiodo-4,5-dimethyl-2,3-dihydro-1,3- diborole derivatives6a/band6c. Reactions of the diiodo-1,3-diboroles with AlMe3or LiMe result in the formation of the very air-sensitive pentaorganyl-1,3-diboroles 1a, 1cand the hexaorganyl-1,3-diborole1b.
The mixture of1a/bas well as1creact with bis(η3-allyl)nickel to give black products, which are chromatographed on silica with hexane as eluent. The brown solids were recrystallized from pentane to give the light-brown crystals ofµ-η5,η5-[2-benzyl-1,3,4,5-tetramethyl-2,3-dihydro- 1,3-diborolyl](η3-allyl)(η4-1,5-hexadiene)dinickel (2a, 34%) and µ-η5,η5-[2-(2,4,6-trimethyl- benzyl)-1,3,4,5-tetramethyl-2,3-dihydro-1,3-diborolyl](η3-allyl)(η4-1,5-hexadiene)dinickel (2c, 43%).1bdoes not react with Ni(C3H5)2to form any triple-decker. The compositions of the new compounds follow from spectroscopic and analytical data, and from X-ray structure analyses of6aand of2a. The structure of theη4-1,5-hexadiene-η3-allyl-dinickel triple-decker2afinally disproved the alternative tris(allyl)dinickel arrangement.
