Reactions of low-valent metal complexes with fluorocarbons. Part XIX. Bis(t-butyl isocyanide)palladium and tetrakis(trimethyl phosphite or dimethylphenylarsine)palladium

A Search for π/σ Equilibria in Chiral Rhenium Imine Complexes of the Formula [(η5-C5H5)Re(NO)(PPh3)(N(H)C(CF3)X)]+TfO-: Investigation of Electronic Effects upon the Binding Mode

“…A σ-binding mode was assigned to the imine ligand in 4 on the basis of 13 C NMR data. Importantly, π-aldehyde and -ketone complexes of I give CO resonances that are markedly upfield from those of the free ligands. − ,10a,e An identical trend has been established for nickel π-imine complexes 3h 5a,,,10b,c Thus, an authentic sample of hexafluoroisopropylideneamine (HNC(CF 3 ) 2 ) was prepared .…”

“…As noted above, some π-imine complexes have been reported . However, to our knowledge, these all involve metal fragments that (1) are highly electropositive, such as (η 5 -C 5 H 5 ) 2 Zr(L), 3b,e or (2) have less than 16 valence electrons, such as (η 5 -C 5 Me 5 )Ta(CH 3 ) 2 , 3a,f Ta(OAr) 2 (Cl) 2 ,3c Ta(OAr) 2 (L),3d W(NR)(NR‘R‘‘)(CH 3 ),3g (bipy)Ni,3h and (Ph 3 P) 2 Pd 3i. In the latter category, the π-binding mode may be stabilized by a donor interaction involving the nitrogen lone pair, as illustrated in H in Chart .…”

“…Iminoacyl complexes in which both carbon and nitrogen ligate to the metal are also abundant ( B ) . However, π complexes of imines ( C ) seem to be rarer …”