Research

beta-Diketiminato Calcium Acetylides: Synthesis, Solution Dimerization, and Catalytic Carbon-Carbon Bond Formation


Reference:

Barrett, A. G. M., Crimmin, M. R., Hill, M. S., Hitchcock, P. B., Lomas, S. L., Mahon, M. F., Procopiou, P. A. and Suntharalingam, K., 2008. beta-Diketiminato Calcium Acetylides: Synthesis, Solution Dimerization, and Catalytic Carbon-Carbon Bond Formation. Organometallics, 27 (23), pp. 6300-6306.

Related documents:

This repository does not currently have the full-text of this item.
You may be able to access a copy if URLs are provided below. (Contact Author)

Official URL:

http://dx.doi.org/10.1021/om800738r

Abstract

The beta-diketiminate-stabilized calcium amide [{ArNC(Me)CHC(Me)NAr} Ca{N(SiMe3)(2)}(THF)] (1) reacts with terminal acetylenes in hydrocarbon solvents to yield the corresponding calcium acetylide complexes [{ArNC(Me)CHCN(Me)Ar}Ca{C CR1}](2) (R-1 = n-Bu, t-Bu, Ph, 4-MeC6H4, ferrocenyl, Ar = 2,6-di-isopropylphenyl, 2a-e). Although in all instances solid and solution state data were consistent with the reaction products existing as dimeric species with aggregation occurring via three-center-two-electron bridging acetylide units, a further reaction of 1 with HC CSi(Pr-i)(3) demonstrated that both monomeric solvated [{ArNC(Me)CHC(Me)NAr}Ca{C CSi(Pr-i)(3)}(THF)(2)] (3b) or dimeric acetylide [{ArNC(Me)CHC(Me)NAr}Ca{C CSi(Pr-i)(3)}](2) (3a) species could be isolated from the reaction depending Upon the exact conditions of the crystallization of the reaction product from solution. Further solution Studies demonstrated the presence of a monomer-dimer equilibrium in Solution. A van't Hoff analysis allowed Delta G degrees(298 K) for the dimerization reaction to be calculated as +27.0 kJ mol(-1). The reaction of these hydrocarbon-soluble kinetically stabilized calcium acetylides with 1,3-dialkylcarbodiimides gave the corresponding heteroleptic calcium C-propargyl amidinate complexes [{ArNC(Me)CHCN(Me)Ar}Ca{((RN)-N-2)(2)CC CR1}(THF)(n)] (R-1 = 4-MeC6H4, n = 0, 4a; 4-MeC6H4, n = 1, 4a center dot THF; R-2 = Pr-i; R-1 = Si(Pr-i(3)), R-2 = Cy, n = 1, 4b center dot THF) via insertion of the carbodiimide into the calcium-carbon sigma-bond. The latter complexes have been characterized in both solution and the solid state including single-crystal X-ray analysis of 4a center dot THF. Extension of this reactivity to catalytic systems has allowed the application of amide 1 (5 mol %) to the catalytic hydroacetylenation of 1.3-di-isopropylcarbodiimide with phenylacetylene, yielding the corresponding propargyl amidine in 59% yield following crystallization from hexane solution.

Details

Item Type Articles
CreatorsBarrett, A. G. M., Crimmin, M. R., Hill, M. S., Hitchcock, P. B., Lomas, S. L., Mahon, M. F., Procopiou, P. A. and Suntharalingam, K.
DOI10.1021/om800738r
DepartmentsFaculty of Science > Chemistry
RefereedYes
StatusPublished
ID Code12398

Export

Actions (login required)

View Item