Issue 38, 2014

Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

Abstract

The homoleptic alkaline earth hexamethyldisilazides, [M{N(SiMe3)2}2(THF)2] (M = Mg 1a; Ca 1b; Sr 1c), have been shown to act as efficient precatalysts for the hydroacetylenation of organic carbodiimides with alkyl- and arylacetylenes. Catalytic activity was observed to increase with the size of the group 2 metal centre employed and to be strongly influenced by the steric properties of the carbodiimide substrate. The intermediate dimeric calcium and strontium bis(amidinate) complexes, [{PhC[triple bond, length as m-dash]CC(NiPr)2}2M]2 (M = Ca 2b, Sr 2c), have been isolated and crystallographically characterised. Kinetic studies using the strontium precursor, 1c, provided a reaction rate law independent of [acetylene] but proportional to [carbodiimide]2 and inversely proportional to the concentration of the amidine product in solution.

Graphical abstract: Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

Supplementary files

Article information

Article type
Paper
Submitted
17 Dec 2013
Accepted
08 Jan 2014
First published
09 Jan 2014

Dalton Trans., 2014,43, 14249-14256

Author version available

Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

M. Arrowsmith, M. R. Crimmin, M. S. Hill, S. L. Lomas, M. S. Heng, P. B. Hitchcock and G. Kociok-Köhn, Dalton Trans., 2014, 43, 14249 DOI: 10.1039/C3DT53542H

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