Self-assembly of Mn(I)-based oxamidato-bridged dinuclear molecular tweezers and tetranuclear molecular rectangles

Abstract

Oxamidato-bridged Mn(I)-based dinuclear hetero-ligand self-assemblies [(L)(CO)3Mn(μ-η4-dbo)Mn(CO)3(L)] (1−3) were obtained by the reaction of Mn2(CO)10, N,N′-dibutyloxamide (H2-dbo) and monodentate pyridyl ligand (L = 4-picoline (pic), 4-phenylpyridine (ppy) and N-anthracenyl-2-isonicotinamide (anin)). On the other hand, similar reaction involving Mn2(CO)10, N,N′-dibutyloxamide and linear bidentate dipyridyl linker (L′ = 4,4′-bipyridine (bpy), trans-1,2-bis(4-pyridyl)ethylene (bpe) and phenyl-1,4-bis(isonicotinate) (pbin)) has afforded the corresponding tetranuclear molecular rectangles [{(CO)3Mn(μ-η4-dbo)Mn(CO)3}2(µ-L′)2] (4−6). Compounds 1−6 were synthesized under one-pot reaction condition in a single-step and they were characterized using elemental analyses, IR, UV−Vis, and NMR spectroscopic techniques. The formation of dinuclear molecular tweezers 1−3 and tetranuclear molecular rectangles 4−6 was confirmed by high resolution electrospray ionization mass spectrometry (HR-ESI-MS). Furthermore, the molecular structures of 1, 2, and 4 were structurally elucidated using single-crystal X-ray crystallographic methods that revealed an open tweezers-like dinuclear framework for 1 and 2, whereas 4 displayed a tetranuclear rectangular architecture. © 2022