A general method of generating agostic interaction between Ru<sup>II</sup>and C–H bonds of tert-butyl, methyl, aryl, heterocyclic or alkenyl groups using azine phosphines
作者:Sarath D. Perera、Bernard L. Shaw
DOI:10.1039/dt9950003861
日期:——
Treatment of [RuCl2(PPh(3))(3)] 2 with the azine phosphine Z,E-PPh(2)CH(2)C(Bu(t))=N-N=C(Me) Bu(t) 3a, derived from MeC(=O)Bu(t), gave the delta-agostic tert-butyl complex mer,trans-[RuCl2(PPh(3))PPh(2)CH(2)-C(Bu(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 degrees C. The analogous delta-agostic tert-butyl complex mer,trans-[RuCl2(PPh(3))PPh(2)CH(2)C(Bu(t))=N-N=C(H)Bu(t)}] 4b was also prepared. Treatment of 2 with the symmetrical azine diphosphine Z,Z-PPh(2)CH(2)C(Bu(t))=N-N=C(Bu(t))CH(2)PPh(2) 5 gave the delta-agostic tert-butyl complex mer,trans-[RuCl2(PPh(3))PPh(2)CH(2)C(Bu(t))=N-N=C(Bu(t))CH(2)PPh(2)}] 6, in which one of the PPh, groups is unco-ordinated. Treatment of 2 with the azine phosphine Z,E-PPh(2)CH(2)C(Bu(t))=N-N=C10H16 7, derived from pinacolone-fenchone mixed azine, gave the F-agostic methyl complex mer,trans-[RuCl2(PPh(3))PPh(2)CH(2)C(Bu(t))=N-N=C10H16}] 8, in which the methyl group ((CH3)-H-10) 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-PPh(2)-C10H15N-N=C10H16 9 also gave a similar delta-agostic methyl complex mer,trans-[RuCl2(PPh(3))PPh(2)C(10)H(15)N-N=C10H16}] 10 (camphor = 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one). Treatment of 2 with the azine Z,E-PPh(2)CH(2)C(Bu(t))=N-N=CH(C(6)H(4)NMe(2)-4) 11a, derived from 4-dimethylaminobenzaldehyde, gave the delta-agostic complex mer,trans-[RuCl2(PPh(3))PPh(2)CH(2)C(Bu(t))=N-N=CH(C(6)H(4)NMe(2)- 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 delta-agostic complexes 12b and 12c, respectively. Treatment of 2 with the azine 13, derived from 1-methylpyrrole-2-carbaldehyde. gave the delta-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 delta-agostic alkenyl complex 16. Proton, P-31-H-1} and some C-13-H-1} NMR data are given.