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}

The new pentadentate thioether thiolate ligand Et2NpyS42− {= 4‐(diethylamino)‐2,6‐bis[(2‐mercaptophenyl)thiomethyl]pyridine(2−)} has been synthesised from dimethyl 4‐bromopyridine‐2,6‐dicarboxylate by treatment with Et2NH followed by reduction and tosylation. The tosylated product was subsequently used for the template alkylation of [Ni(S2C6H4)2]2− to give [{Ni(Et2NpyS4)}2] (4). Acidic hydrolysis of 4 resulted in the formation of the ligand Et2NpyS4−H2·HCl (5). The dianion Et2NpyS42− reacted with FeCl2·H2O to afford the dinuclear high‐spin species [{Fe(Et2NpyS4)}2] (6) [μeff (297 K) = 5.15 μB]. Aerial oxidation of dinuclear 6 afforded the sulfinato complex [{Fe(Et2NpyS4−O2)}2] (7). Complex 6 proved to be a good precursor for the syntheses of [Fe(L)(Et2NpyS4)] [L = CO (8), CNCy (9), NO (11) and N2H4 (12)] and [Fe(NO)(Et2NpyS4)]BF4 (10). Protonation or alkylation of the thiolate donor atoms resulted in a series of complexes [Fe(CO)(Et2NpyS4−R)]BF4 [R = H (8a), Et (8b)] and [Fe(CO)(Et2NpyS4−Et2)](BF4)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)(Et2NpyS4)]BF4 (10). Reduction of 10 using N2H4, NH3 or N3− afforded the 19 valence electron species [Fe(NO)(Et2NpyS4)] (11). [Ru(NO)(Et2NpyS4)]Br (13) was synthesised by template alkylation of Bu4N[Ru(NO)(S2C6H4)2] using Et2Npy(CH2Br)2 (3). Under reducing conditions, 13 releases the NO coligand to give [{Ru(Et2NpyS4)}2] (14), while in the presence of N2H4, [Ru(N2H4)(Et2NpyS4)] (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)