Transition-metal–carbon bonds. Part 43. Some long-chain and large-ring complexes of nickel, palladium, or platinum with tetramethylene- and hexamethylene-dioxydiphenyl

Abstract

The dibromo-ethers 1,4-bis(o-bromophenoxy)butane and 1,6-bis(o-bromophenoxy)hexans are dilithiated by n-butyl-lithium (halogen–metal exchange). The dilithio-derivative LiC₆H₄O[CH₂]₄OC₆H₄Li (Li₂L) reacts with trans-[NiBr₂Y₂](Y = PEt₂Ph or PEt₃) to give yellow [NiLY₂] where L acts as a trans-bonded bidentate chelate giving an 11 -membered ring. In contrast, LiC₆H₄O[CH₂]₆OC₆H₄Li (Li₂L′) gives a green unidentified product. Corresponding complexes of platinum are not formed : instead binuclear species of the type [Y₂XPt(C₆H₄O[CH₂]_nOC₆H₄) PtY₂X](X = Br or I) are obtained (Y = PEt₂Ph, PMe₂Bu^t, or AsMe₂Bu^t). The dibromo-complexes [(Bu^tMe₂P)₂XPt(C₆H₄O[CH₂]_nOC₆H₄)PtX(PMe₂Bu^t)₂](X = Br) react with Na[BH₄] to give the corresponding dihydrides (X = H). Palladium complexes of the type [(Et₃P)₂XPd(C₆H₄O[CH₂]₄OC₆H₄)PdX(PEt₃)₂](X = Cl or Br) have also been synthesized. Treatment of trans-[PdBr₂(PEt₃)₂] with Li₂L(1 : 1 mol proportion) gives an impure product of the approximate composition [{PdL(PEt₃)₂}_x](x= ?). Hydrogen-1 and ³¹P n.m.r. data and i.r. data are given.