A SYSTEMATIC METHOD OF PROMOTING AN ARYL FLUORIDE TO COORDINATE TO RUTHENIUM(II)

The phosphino hydrazone Z-PPh(2)CH(2)C(Bu(t))=NNH2 (I) condenses with 2,6-difluorobenzaldehyde to give Z,E-PPh(2)CH(2)C(Bu(t))=N-N=CH(C6H3F2-2,6) (2a), which reacts rapidly with the labile ruthenium(If) complex [RuCl2(PPh(3))(3)] to give mer, trans-[RuCl2(PPh(3)){PPh(2)CH(2)C(Bu(t)) =N-N=CH(C6H3F2-2,6)] (3a). In the F-19{H-1} NMR spectrum of 3a the fluorines are coupled equally to P-A but are not coupled to PB. In the P-31{H-1} NMR spectrum, P-A is coupled equally to both fluorines, i.e. there is a dynamic system with both fluorines coordinated to ruthenium in turn and coupled to P-A, (2)J(PAF)=68 Hz. Similar condensations of 1 with other fluorine-substituted benzaldehydes, viz. pentafluorobenzaldehyde, 2-chloro-6-fluorobenzaldehyde, 2-fluorobenzaldehyde, 2,3-difluorobenzaldehyde, gave mixed azine phosphines. In each case these mixed azine phosphines when treated with [RuCl2(PPh(3))(3)], displaced two tripbenylphosphines to give terdentate chelates showing fluorine coordination to ruthenium. Proton, P-31{H-1} and F-19{1H} NMR data are given and discussed.