An Innovative Structural Rearrangement in Imine Palladacycle Metaloligand Chemistry: From Single-Nuclear to Double-Nuclear Pseudo-Pentacoordinated Complexes.

Treatment of the double nuclear complex , di-μ-cloro-bis[N-(4-formylbenzylidene)cyclohexylaminato-C6, N]dipalladium, with PhPCHCH)PPh (triphos) and NHPF gave the single nuclear species , 1-N-(cyclohexylamine)-4-N-(formyl)palladium(triphos)(hexafluorophasphate). Reaction of with PhPCHCHNH in refluxing chloroform via a condensation reaction of the amine and formyl groups to produce the C=N double bond, gave , 1-N-(cyclohexylamine)-4- N-(diphenylphosphinoethylamine)palladium(triphos)(hexafluorophasphate); a potentially bidentate [,] metaloligand. However, attempts to coordinate a second metal by treatment of 3a with [PdCl(PhCN)] were to no avail. Notwithstanding, complexes and left to stand in solution spontaneously self-transformed to give in either case the double nuclear complex , 1,4-N,N-terephthalylidene(cyclohexilamine)-3,6-[bispalladium(triphos)]di(hexafluorophosphate), after undergoing further metalation of the phenyl ring, then bearing two mutually [Pd(PhPCHCH)PPh)-,,] moieties: an unprecedented and serendipitous result indeed. On the other hand, reaction of the double nuclear complex 1b, di-μ-cloro-bis[N-(3-formylbenzylidene)cyclohexylaminato-C6, N]dipalladium, with PhPCHCH)PPh (triphos) and NHPF gave the single nuclear species , 1-N-(cyclohexylamine)-4-N-(formyl)palladium(triphos)(hexafluorophasphate), Treatment of with HO/glacial MeCOOH gave cleavage of the C=N double bond and of the Pd···N interaction, yielding , isophthalaldehyde-6-palladium(triphos)hexafluorophosphate, which then reacted with PhP(CH)NH to yield complex , N,N-(isophthalylidene(diphenylphosphinopropylamine)-6-(palladiumtriphos)di(hexafluorophosphate), with two pairs of non-coordinated nitrogen and phosphorus donor atoms. Treatment of with [PdCl(PhCN)], [PtCl(PhCN)], or [PtMe(COD)] gave the new double nuclear complexes , and , palladiumdichloro-, platinumdichloro- and platinumdimethyl[N,N-(isophthalylidene(diphenylphosphinopropylamine)-6-(palladiumtriphos)(hexafluorophosphate)-P,P], respectively, showing the behavior of as a palladated bidentate [,] metaloligand. The complexes were fully characterized by microanalysis, IR, H, and P NMR spectroscopies, as appropriate. The X-ray single-crystal analyses for compounds 10 and 5b have been previously described as the perchlorate salts by JM Vila et al.