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; G. Kociok-Köhn

doi:10.1039/c3dt53542h

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, G. Kociok-Köhn

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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, [{PhCCC(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.

Original language	English
Pages (from-to)	14249-14256
Number of pages	8
Journal	Dalton Transactions
Volume	43
Issue number	38
Early online date	9 Jan 2014
DOIs	https://doi.org/10.1039/c3dt53542h
Publication status	Published - 14 Oct 2014

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full paper hydroactylenation of carbodiimidesAccepted author manuscript, 966 KB

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title = "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, [{PhCCC(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.",

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T1 - Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

AU - Arrowsmith, M.

AU - Crimmin, M.R.

AU - Hill, M.S.

AU - Lomas, S.L.

AU - Heng, M.S.

AU - Hitchcock, P.B.

AU - Kociok-Köhn, G.

PY - 2014/10/14

Y1 - 2014/10/14

N2 - 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, [{PhCCC(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.

AB - 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, [{PhCCC(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.

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DO - 10.1039/c3dt53542h

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JF - Dalton Transactions

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Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

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Group 2: Elements of 21st Century Catalysis

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Catalytic hydroacetylenation of carbodiimides with homoleptic alkaline earth hexamethyldisilazides

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Group 2: Elements of 21st Century Catalysis

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