A General Method of generating Agostic Interaction between RuII and C-H Bonds of tert-Butyl, Methyl, Aryl, Heterocyclic or Alkenyl Groups using Azine Phosphines

Article abstract of DOI:10.1039/DT9950003861

Treatment of 2 with the azine phosphine Z,E-PPh2CH2C(Bu^t)=N-N=C(Me)Bu^t 3a, derived from MeC(=O)Bu^t, gave the δ-agostic tert-butyl complex mer,trans-t)=N-N=C(Me)Bu^t>> 4a, in which all nine hydrogens of the tert-butyl group are agostically interacting with ruthenium on the NMR time-scale at 20 deg C.The analogous δ-agostic tert-butyl complex mer,trans-t)=N-N=C(H)Bu^t>> 4b was also prepared.Treatment of 2 with the symmetrical azine diphosphine Z,Z-PPh2CH2C(Bu^t)=N-N=C(Bu^t)CH2PPh2 5 gave the δ-agostic tert-butyl complex mer,trans-t)=N-N=C(Bu^t)CH2PPh2>> 6, in which one of the PPh2 groups is unco-ordinated.Treatment of 2 with the azine phosphine Z,E-PPh2CH2C(Bu^t)=N-N=C10H16 7, derived from pinacolone-fenchone mixed azine, gave the δ-agostic methyl complex mer,trans-t)=N-N=C10H16>> 8, in which the methyl group (C¹⁰H3) in the 1-position of the fenchone residue interacts with ruthenium (fenchone=1,3,3-trimethylbicyclo<2.2.1>heptan-2-one).The unsymmetrical camphor azine monophosphine Z,Z-PPh2C10H15=N-N=C10H16 9 also gave a similar δ-agostic methyl complex mer,trans-> 10 (camphor=1,7,7-trimethylbicyclo<2.2.1>heptan-2-one).Treatment of 2 with the azine Z,E-PPh2CH2C(Bu^t)=N-N=CH(C6H4NMe2-4) 11a, derived from 4-dimethylaminobenzaldehyde, gave the δ-agostic complex mer,trans-t)=N-N=CH(C6H4NMe2-4)>> 12a, in which the hydrogens in the 2 and 6 positions of the aryl group are agostically interacting with ruthenium.Similarly, the azines 11b and 11c, derived from 4-methoxybenzaldehyde or 4-nitrobenzaldehyde, gave the δ-agostic complexes 12b and 12c, respectively.Treatment of 2 with the azine 13, derived from 1-methylpyrrole-2-carbaldehyde, gave the δ-agostic complex 14, in which the hydrogen in the 3-position of the heterocyclic group is agostically interacting with ruthenium.Treatment of 2 with the azine 15, derived from benzylideneacetone, gave the δ-agostic alkenyl complex 16.Proton, 31P-<1H> and some 13C-<1H> NMR data are given.

Full text of DOI:10.1039/DT9950003861

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