Reactivity of 2-(2-hydroxyphenyl)benzoxazole and 2-(2-hydroxyphenyl)benzothiazole towards group 10 transition metals. Evaluation in palladium catalyzed Suzuki–Miyaura C–C couplings

•A series of group 10 metal complexes with HPBO and HPBT were synthesized in a facile manner in moderate to high yields.•The palladium derivative of HPBO exhibited good catalytic activity in Suzuki–Miyaura couplings.•Depending on the metal the ligand HPBT exhibited up to four different coordination modes.•Depending on the metal the ligand HPBT may produce either coordination or organometallic species.•Studies in the solid state reveal important non-covalent interactions.

A series of group 10 transition metal complexes based on 2-(2-hydroxyphenyl)benzoxazole (HPBO) and 2-(2-hydroxyphenyl)benzothiazole (HPBT) have been prepared. Reactions of nickel or palladium acetates with HPBT and HPBO produce chelate N–O coordinated compounds respectively. Whilst reaction of [K2PtCl4] with HPBT affords organometallic species product of a C–H bond activation of the phenolic moiety at room temperature. The molecular structures of the three complexes were unambiguously determined by means of single crystal X-ray diffraction analyses. The nickel compound [{Ni(κ2-N,O-HPBT)}2(μ2-O-HPBT)2(μ2-OOCCH3)] (1) showing to be binuclear with the nickel ions found in six-coordinated distorted octahedral environments. Conversely, compound [Pd(κ2-N,O-HPBO)2] (2) is a tetracoordinated monomer with the Pd center having a slightly distorted square planar geometry. Similarly, platinacycle [Pt(κ1-N-HPBT)(κ2-N,C-HPBT)Cl] (3) shows the Pt center into a slightly distorted square planar geometry, exhibiting ligand HPBT in two different coordination modes, as single κ1-N coordinated and as κ2-N-C metalated chelate bidentate ligand, completing the coordination sphere with a chloride ligand. The catalytic activity of the palladium complex (2) was evaluated in Suzuki–Miyaura cross couplings, showing good activity.

Graphical abstractGroup 10 metal complexes of 2-(2-hydroxyphenyl)benzoxazole (HPBO) and 2-(2-hydroxyphenyl)benzothiazole (HPBT) were prepared. Reactions with nickel or palladium acetates produce chelate N–O coordinated complexes and reaction of [K2PtCl4] with HPBT affords organometallic species via C–H bond activation. Crystal structures of the complexes were determined. The palladium complex was employed in Suzuki–Miyaura couplings.Figure optionsDownload full-size imageDownload as PowerPoint slide