Synthesis and characterization of [Pd₂X₂(μ-X)₂{Ph₂P(CH₂CH₂O)_nCH₂CH₂PPh₂-P,P′}]_m(n = 3, 5, X = Cl, I) dimetallacrown ethers and the related dinuclear [Pd₂Cl₂(μ-Cl)₂{Ph₂P(CH₂)₁₂PPh₂-P,P′}]_mand [Pd₂X₂(μ-X₂){Ph₂P(CH₂CH₂O)₂CH₂CH₃-P)₂}] (X = Cl, I) complexes

Abstract

Reactions of the metallacrown ethers, [PdCl2{PPh2(CH2CH2O)nCH2CH2PPh2-P,P′}]m (n = 3, 5), with PdCl2 or Pd(PhCN)2Cl2 yield the new dimetallacrown ethers, [Pd2Cl2(μ-Cl)2{PPh2(CH2CH2O)nCH2CH2PPh2-P,P′}]m (n = 3 (3), n = 5 (4)). Similar reactions of [PdCl2{PPh2(CH2)12PPh2-P,P′}]m and [PdCl2{PPh2(CH2CH2O)2CH2CH3-P}2] with PdCl2 or Pd(PhCN)2Cl2 yield [Pd2Cl2(μ-Cl2){PPh2(CH2)12PPh2-P,P′}]m (5) and [Pd2Cl2(μ-Cl)2{PPh2(CH2CH2O)2CH2CH3-P}2] (6), respectively. The chloride-bridged dimetallacrown ethers, 3 and 4, are cleanly converted into the iodide-bridged dimetallacrown ethers, [Pd2I2(μ-I)2{PPh2(CH2CH2O)nCH2CH2PPh2-P,P′}]m (n = 3 (7), n = 5 (8)) by reaction with excess NaI. In solution, 3 and 4 exist as mixtures of syn monomers and cyclic oligomers while 7 and 8 exist as mixtures of both syn and anti monomers and cyclic oligomers. The solid state structures of syn-[Pd2I2(μ-I)2{PPh2(CH2CH2O)3CH2CH2PPh2-P,P′}] (syn-7) and of anti-[Pd2I2(μ-I)2{Ph2P(CH2CH2O)2CH2CH3)2-P}2} (anti-9) have been determined. These structures are consistent with the major species present in the solutions. They also suggest that syn-7 experiences ring-strain, which is consistent with the results from the 31P{1H} NMR studies.