Syntheses, Structures and Reactivity of Electron‐Rich Fe and Ru Complexes with the New Pentadentate Ligand Et₂NpyS₄−H₂ {4‐(Diethylamino)2,6‐bis[(2‐mercaptophenyl)thiomethyl]pyridine}

Abstract

Abstract The new pentadentate thioether thiolate ligand Et 2 NpyS 4 2− {= 4‐(diethylamino)‐2,6‐bis[(2‐mercaptophenyl)thiomethyl]pyridine(2−)} has been synthesised from dimethyl 4‐bromopyridine‐2,6‐dicarboxylate by treatment with Et 2 NH followed by reduction and tosylation. The tosylated product was subsequently used for the template alkylation of [Ni(S 2 C 6 H 4 ) 2 ] 2− to give [{Ni(Et 2 NpyS 4 )} 2 ] ( 4 ). Acidic hydrolysis of 4 resulted in the formation of the ligand Et 2 NpyS 4 −H 2 ·HCl ( 5 ). The dianion Et 2 NpyS 4 2− reacted with FeCl 2 ·H 2 O to afford the dinuclear high‐spin species [{Fe(Et 2 NpyS 4 )} 2 ] ( 6 ) [μ eff (297 K) = 5.15 μ B ]. Aerial oxidation of dinuclear 6 afforded the sulfinato complex [{Fe(Et 2 NpyS 4 −O 2 )} 2 ] ( 7 ). Complex 6 proved to be a good precursor for the syntheses of [Fe(L)(Et 2 NpyS 4 )] [L = CO ( 8 ), CNCy ( 9) , NO ( 11 ) and N 2 H 4 ( 12 )] and [Fe(NO)(Et 2 NpyS 4 )]BF 4 ( 10 ). Protonation or alkylation of the thiolate donor atoms resulted in a series of complexes [Fe(CO)(Et 2 NpyS 4 −R)]BF 4 [R = H ( 8a ), Et ( 8b )] and [Fe(CO)(Et 2 NpyS 4 −Et 2 )](BF 4 ) 2 ( 8c ) but no labilisation of the Fe−CO bond was observed. Only in complex 8 could the CO coligand be exchanged by NO + to give [Fe(NO)(Et 2 NpyS 4 )]BF 4 ( 10 ). Reduction of 10 using N 2 H 4 , NH 3 or N 3 − afforded the 19 valence electron species [Fe(NO)(Et 2 NpyS 4 )] ( 11 ). [Ru(NO)(Et 2 NpyS 4 )]Br ( 13 ) was synthesised by template alkylation of Bu 4 N[Ru(NO)(S 2 C 6 H 4 ) 2 ] using Et 2 Npy(CH 2 Br) 2 ( 3 ). Under reducing conditions, 13 releases the NO coligand to give [{Ru(Et 2 NpyS 4 )} 2 ] ( 14 ), while in the presence of N 2 H 4 , [Ru(N 2 H 4 )(Et 2 NpyS 4 )] ( 15 ) was formed. The complexes were well characterised including the solid‐state structures in most cases. X‐ray structural analyses of 7 , 8 , 9 , 10 , 12 and 15 revealed that all complexes exhibit trans ‐thiolate donors irrespective of the σ−π‐ or σ‐ligand character of L. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)