The synthesis of sterically demanding aminophosphine and phosphinite ligands Ar*NHPPh (1) and Ar*OPPh (2), based on 2,6-dibenzhydryl-4-methylphenyl core having bulky benzhydryl groups, and their Ru, Pd and Pt complexes is described. The reactions of 1 and 2 with [Ru(η- p-cymene)Cl] in 2:1 molar ratios produced mononuclear complexes [RuCl{(η- p-cymene)PPh-EAr*}-κ-P] (E = NH (3) and O (4)). Interestingly, complexes 3 and 4, upon refluxing in chlorobenzene, displace the p-cymene ring by one of the phenyl rings of side arms, forming rare η-arene coordinated tethered complexes [RuCl{(PPh-EAr*)-κ-P-η-arene}] (E = NH (5) and O (6)). Treatment of 1 and 2 with [M(COD)Cl] [M = Pd, Pt] in 2:1 ratios afforded mononuclear complexes [MCl{(PPhEAr*)-κ-P}] (E = NH, M= Pd (7), Pt (8); E = O, M= Pd (9), Pt (10)). Similarly, 1:1 reactions of 1 and 2 with [Pd(COD)Cl] produced chloro-bridged dinuclear complexes [PdCl{(PPhEAr*)-κ-P}] (E = NH (11) and O (12)), whereas [Pt(COD)Cl] yielded only the mononuclear complexes 8 and 10. The reactions of 1 and 2 with [Pd(η-CH)Cl] in 2:1 molar ratios produced the mononuclear complexes [PdCl{(η-CH)(PPhEAr*)-κ-P}] (E = NH (13) and O (14)). Many of these complexes have been structurally characterized, which show C-H···π interactions between the methine hydrogen of the benzhydryl and with one of the carbon atoms of the phenyl ring attached to the phosphorus center. The complex [RuCl{(η- p-cymene)PPh-NHAr*}-κ-P] (3) shows very short C-H···π interactions of 2.36 Å; in addition, C-H···M interactions were observed between the methine hydrogen of one of the benzhydryl groups and palladium centers in 11 and 13. The tethered ruthenium complex 5 is found to be an excellent catalyst for the catalytic oxidation of various styrene derivatives.

Gold(I) complexes of sterically demanding phosphines derived from 2,6-dibenzhydryl-4-methylphenyl core viz: 2,6-dibenzhydryl-N,N-bis((diphenylphosphane)-methyl)-4-methylaniline (1), (2,6-dibenzhydryl-4-methylphenyl)-diphenylphosphane (2), N-(2,6-dibenzhydryl-4-methylphenyl)-1,1-diphenylphosphanamine (3), and (2,6-dibenzhydryl-4-methylphenoxy)diphenylphosphane (4) are described. The reaction of 1 with 2 equiv of [AuCl(SMe 2 )] in dichloromethane yielded [{AuCl} 2 {Ar*N(CH 2 PPh 2 ) 2 }] (5), which on further treatment with 2 equiv of AgSbF 6 and 1 equiv ofEquimolar reactions of bulky phosphines 2, 3, and 4 with [AuCl(SMe 2 )] resulted in [AuCl(PPh 2 Ar*)] (8), [AuCl(PPh 2 NHAr*)] (9), and [AuCl(PPh 2 OAr*)] (10). Complexes 9 and 10 on treatment with AgSbF 6 in CH 3 CN produced the cationic complexes [Au(NCCH 3 )(PPh 2 NHAr*)][(SbF 6 )] (11) and [Au(NCCH 3 )(PPh 2 OAr*)][(SbF 6 )] ( 12), respectively. The molecular structure of complex 6 revealed the presence of a strong intramolecular aurophilic interaction with a Au•••Au distance of 2.9720(4) Å. Careful analysis of molecular structure of 5 revealed the presence of rare Au•••H−C (sp 3 ) interactions between the gold(I) atom and one of the methylene protons of −NCH 2 PPh 2 groups. The solution 1 H NMR signals of the methylene protons of 5 showed a considerable downfield shift (∼1 ppm) compared to that of the free ligand indicating their interactions (Au•••H) with the Au atom. Complexes 8 and 10 also showed Au•••H interactions in their molecular structures. The existence of the Au•••H interaction was studied by variable temperature 1 H NMR data in the case of complex 5 and further evinced by the QTAIM analysis in complexes 5, 8, and 10.

This paper describes the syntheses of two novel cyclodiphosphazane derivatives and their coordination chemistry with CuI, RuII, RhI, PdII and AuI is also described.

This paper describes the synthesis of a triazole based bisphosphine and its transition metal chemistry and catalytic utility in Cu-free Sonogashira alkynylation/cyclization reaction.