Deprotonation, deuteriation and substitution of the backbone of some azine diphosphine complexes of palladium and platinum: crystal structures of [Ptl(PPh2CHCButN–NCButCH2PPh2)] and [PtCl(PPh2CH2CButN–NCButCH2PPh2)][OC6H2(NO2)3-2,4,6]

Abstract

Treatment of the azine diphosphine Z,Z-PPh₂CH₂CBu^tN–NCBu^tCH₂PPh₂I with [PtCl₂(cod)](cod = cycloocta-1,5-diene) in CHCl₃ in the presence of NEt₃ gave the neutral deprotonated chloroplatinum(II) complex [[graphic omitted]Ph₂)], containing an ene–hydrazone backbone. The corresponding bromo- and iodo-analogues were prepared from it by metathesis. The analogous chloropalladium(II) complex was prepared by treating I with [PdCl₂(NCPh)₂] in the presence of NEt₃. Treatment of it with LiBr or MgMel gave the corresponding bromo- and methyl-palladium(II) complexes, respectively. Treatment of the neutral complexes [[graphic omitted]Ph₂)](M = Pt or Pd) with acids (HX) reprotonated the ene–hydrazone backbone to give the salts [[graphic omitted]Ph₂)]X 4[X = picrate, formate or (1S)-7,7-dimethyl-2-oxobicyclo[2.2.1]heptane-1-methanesulfonate, M = Pt or Pd]. Treatment of [[graphic omitted]Ph₂)] with 0.5 equivalent of NH₂NH₂·2HCl gave a mixture of the nine-membered ring complex [[graphic omitted]Ph₂)] and its isomerie chloride salt [[graphic omitted]Ph₂)]Cl. When [[graphic omitted]Ph₂)], containing a nine-membered chelate ring, was heated to 75 °C in C₆H₆ the methylplatnum(II) complex, [[graphic omitted]Ph₂)], containing the terdentate dehydroazine ligand, was formed by oxidative addition of NH followed by reductive elimination of CH₄. Treatment of the same PtMe₂ complex with 1 equivalent of picric acid gave the picrate salt [[graphic omitted]Ph₂)][OC₆H₂(NO₂)₃], which with 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu) gave [[graphic omitted]Ph₂)], and with Mel followed by NH₄PF₆ gave fec-[[graphic omitted]Ph₂)]PF₆ which with dbu gave fac-[[graphic omitted]Ph₂)]. Treatment of [[graphic omitted]Ph₂)] with 1 equivalent of picric acid gave [[graphic omitted]Ph₂)][OC₆H₂(NO₂)₃] which with dbu gave [[graphic omitted]Ph₂)]. Treatment of I with [Pt(nb)₃](nb = norbornene) gave the bridged binuclear platinum(0) complex [Pt₂(nb)₂(µ-PPh₂CH₂CBu^tN–NCBu^tCH₂PPh₂)₂], containing an 18-atom ring. Treatment of this with MeO₂CCCCO₂Me displaced the norbornene to form the corresponding bis(dimethyl acetylenedicarboxylate) complex. When the former was heated to 75 °C in benzene [[graphic omitted]Ph₂)] was formed. The bis(norbornene)platinum(0) complex also underwent oxidative addition with Mel to give [[graphic omitted]Ph₂)]I, which with dbu gave [[graphic omitted]Ph₂)]. Methods of forming the di- and tetra-deuteriated complexes containing the azine backbone, and also mono- and tri-deuteriated complexes containing the dehydroazine backbone are discussed (M = Pt or Pd). A novel method of functionalising (e.g. alkylation and halogenation) the ligand backbone by electrophilic attack on the enamine carbon in complexes of type 4 is described. The crystal structures of [[graphic omitted]Ph₂)] and [[graphic omitted]Ph₂)][OC₆H₂(NO₂)₃] were determined. Proton. ³¹P and some ¹³C NMR data are given.