Tiara-like Octanuclear Palladium(II) and Platinum(II) Thiolates and Their Inclusion Complexes with Dihalo- or Iodoalkanes

Abstract

A tiara-like octanuclear palladium thiolate complex, [Pd(-SCH 2 CO 2 Me) 2 ] 8 that has a toroidal structure, was synthesized via reactions of either PdCl 2 with methyl thioglycolate/N,N-diisopropylethylamine (DIEA) (conventional method) or [PdCl 2 (MeCN) 2 ] with m-C 6 H 4 (CMe 2 SCH 2 CO 2 Me) 2 (alternative method). In the latter method, the tiara-like complex formed via the corresponding SCS-pincer complex and/or 1:1 PdCl 2 and ligand complexes. With respect to the platinum analogs, the alternative method efficiently produced the tiara-like octanuclear complex, [Pt(-SCH 2 CO 2 Me) 2 ] 8 , in high purity. Small molecules, such as CH 2 Cl 2 , ClCH 2 CH 2 Cl, CH 2 Br 2 , and CH 3 I, were accommodated in the inner voids of the tiara rings to form 1:1 inclusion complexes. These complexes are stabilized by weak CH···X hydrogen bonds (X = Cl or Br) between the methylene protons of four or eight axially positioned methoxycarbonylmethyl groups on the tiara rings and the halogen atoms of the guest molecules, as well as weak coordination of the halogen atoms to the transition-metal atoms.2

Synthesis and Properties Evolution of a Family of Tiara-like Phenylethanethiolated Palladium Nanoclusters

“…solubility). Third, the regular distribution of variously sized Pd clusters (for instance, the even-odd law) implies that they probably adopt similar structures as ones reported previously (see Table S1)11121314151617181920222324252627282930313233343536373839404142434445. Single crystal X-ray crystallography of [Pd(SC 2 H 4 Ph) 2 ] 6 demonstrate that six palladium atoms arranged in an approximately hexagonal ring, with six bridging sulfur atoms above and six below the plane (see Fig.…”

“…There are two existing mechanisms for the formation of tiara-like [M(SR) 2 ] n : one is termed as “template mechanical assistance”1416, and the other is “addition polymerization of monomer”45. However, the two existing mechanisms are not well applied to this case.…”

“…Although tiara-like nickel complexes based on diverse thiolate ligands ([Ni(SR) 2 ] n with n = 4 ~ 6, 8 ~ 12111213141516171819222324252627282930313233343536373839) have been prepared (Table S1), only two sizes of Pd clusters ([Pd(SR) 2 ] 6 18204041424344 and [Pd(SR) 2 ] 8 2045) and one Pt cluster ([Pt(SCH 2 COOMe) 2 ] 8 45) have been reported. Additional questions that naturally arise include: Are there any other sized Pd (Pt) clusters beside the reported [Pd(SR) 2 ] 6 18204041424344 and [Pd(SR) 2 ] 8 2045 ([Pt(SCH 2 COOMe) 2 ] 8 45)? Are there any other tiara-like [M(SR) 2 ] n with n value bigger than 1211, etc.…”

Synthesis of pincer-type extractants for selective extraction of palladium from PGMs: An improved liquid-liquid extraction approach to current refining processes

“…The results of the 1 HNMR analysis of 3 and 3 -Pd are presented in Table S3. The 1 H NMR of 3 -Pd indicates that Pd is bonded directly to C(2) and that the C(2) proton is removed upon extraction 46 . The 1 H NMR spectra of 4 and 4 -Pd are shown in Fig.…”

“…The 1 H NMR results of 4 and 4 -Pd are collected in Table S4. The 1 H NMR of 4 -Pd indicates that Pd is not bonded to C(2) upon complexation and does not form an SCS Pd-pincer complex 46 . In extractants 1 and 3 46 , the steric hindrance generated by the four methyl groups at the benzylic positions facilitates aromatic C(sp 2 )-H bond activation and promotes Pd-C(2) bond formation.…”