Various forms of linear dipyridyls in discrete rectangles, dinuclear rods, and one-dimensional networks containing (η5-pentamethylcyclopentadienyl)rhodium(iii)

Abstract

[Cp*Rh(η¹-NO₃)(η²-NO₃)] (1) reacted with pyrazine (pyz) to give a dinuclear complex [Cp*Rh(η¹-NO₃)(μ-pyz)_0.5]₂·CH₂Cl₂ (3·CH₂Cl₂). Tetranuclear rectangles of the type [Cp*Rh(η¹,μ-X)(μ-L)_0.5]₄(OTf)₄ (4a: X = N₃, L = bpy; 4b: X = N₃, L = bpe; 4c: X = NCO, L = bpy) were prepared from [Cp*Rh(H₂O)₃](OTf)₂ (2), a pseudo-halide (Me₃SiN₃ or Me₃SiNCO), and a linear dipyridyl {4,4′-bipyridine (bpy) or trans-1,2-bis(4-pyridyl)ethylene (bpe)} by self-assembly through one-pot synthesis at room temperature. Treating complex 2 with NH₄SCN and dipyridyl led to the formation of dinuclear rods, [Cp*Rh(η¹-SCN)₃]₂(LH₂) (5a: L = bpy; 5b: L = bpe), in which two Cp*Rh(η¹-SCN)₃ units are connected by the diprotonated dipyridyl (LH₂²⁺) through N⁺–H⋯N hydrogen bonds. Reactions of complex 2 with 1-(trimethylsilyl)imidazole (TMSIm) and dipyridyl (bpy or bpe) also produced another family of dinuclear rods [Cp*Rh(ImH)₃]₂·L (6a: L = bpy; 6b: L = bpe). Treating 1 and 2 with TMSIm and NH₄SCN (in the absence of dipyridyl) generated a 1-D chain [Cp*Rh(ImH)₃](NO₃)₂ (7) and a 1-D helix [Cp*Rh(η¹-SCN)₂(η¹-SHCN)]·H₂O (8·H₂O), respectively. The structures of complexes 3·CH₂Cl₂, 4a·H₂O, 4c·2H₂O, 5b, 6a, 7 and 8·H₂O were determined by X-ray diffraction.