Preparation and characterization of dinuclear Pd(ii) complexes of binucleating tetraaza-thiophenolate ligands

Abstract

The thioethers 4-tert-butyl-2,6-bis((2-(dimethylamino)ethylimino)methyl)phenyl(tert-butyl)sulfane (tBu–L³) and 4-tert-butyl-2,6-bis((2-(dimethylamino)ethylimino)methyl)phenyl(tert-butyl)sulfane (tBu–L⁴) react with PdCl₂(NCMe)₂ to give the dinuclear palladium thiophenolate complexes [(L³)Pd₂Cl₂]⁺ (2) and [(L⁴)Pd₂(µ-Cl)]²⁺ (3) (HL³ = 2,6-bis((2-(dimethylamino)ethylimino)methyl)-4-tert-butylbenzenethiol, HL⁴ = 2,6-bis((2-(dimethylamino)ethylamino)methyl)-4-tert-butylbenzenethiol). The chloride ligands in 2 could be replaced by neutral (NCMe) and anionic ligands (NCS⁻, N₃⁻, CN⁻, OAc⁻) to give the diamagnetic Pd^II complexes [(L³)Pd₂(NCMe)₂]³⁺ (4), [(L³)Pd₂(NCS)₂]⁺ (5), [(L³)Pd₂(N₃)₂]⁺ (6), [{(L³)Pd₂(µ-CN)}₂]⁴⁺ (7) and [(L³)Pd₂(OAc)]²⁺ (9). The nitrile ligands in 4 and in [(L³)Pd₂(NCCH₂Cl)₂]³⁺ are readily hydrated to give the corresponding amidato complexes [(L³)Pd₂(CH₃CONH)]²⁺ (8) and [(L³)Pd₂(CH₂ClCONH)]²⁺ (10). The reaction of [(L³)Pd₂(NCMe)₂]³⁺ with NaBPh₄ gave the diphenyl complex [(L³)Pd₂(Ph)₂]⁺ (11). All complexes were either isolated as perchlorate or tetraphenylborate salts and studied by IR, ¹H and ¹³C NMR spectroscopy. In addition, complexes 2[ClO₄], 3[ClO₄]₂, 5[BPh₄], 6[BPh₄], 7[ClO₄]₄, 9[ClO₄]₂, 10[ClO₄]₂ and 11[BPh₄] have been characterized by X-ray crystallography.