Manganese and iron PCP pincer complexes – the influence of sterics on structure and reactivity
作者:Wolfgang Eder、Daniel Himmelbauer、Berthold Stöger、Luis F. Veiros、Marc Pignitter、Karl Kirchner
DOI:10.1039/d1dt02407h
日期:——
reaction of 1a with [Fe2(CO)9] afforded the Fe(II) PCP pincer complex [Fe(PCPCH2-iPr)(CO)2Br] (4). Treatment of 4 with Li[HBEt3] afforded the Fe(I) complex [Fe(PCPCH2-iPr)(CO)2] (5a). When using the sterically more demanding ligands (P(C–Br)PCH2-tBu) (1c) and (P(C–Br)PO-tBu)(1d) striking differences in reactivity were observed. While neither 1c nor 1d showed any reactivity towards [Mn2(CO)10], the reaction
A series of cobalt(I)–dinitrogen complexes bearing anionic 4-substituted benzene-based PCP-type pincer ligands are synthesized and characterized. These complexes work as highly efficient catalysts for the formation of silylamine from dinitrogen under ambient reaction conditions to produce up to 371 equiv of silylamine based on the cobalt atom of the catalyst.
formation of ammonia and hydrazine from the reaction of dinitrogen (1 atm) with a reductant and a proton source at −78 °C, producing up to 252 equiv of ammonia and 68 equiv of hydrazine (388 equiv of fixed N atom) based on the iron atom of the catalyst. Anionic iron(0)–dinitrogen complexes, considered an essential reactive species in the catalytic reaction, are newly isolated from the reduction of the corresponding
ligand is synthesized and characterized. The reactivity of these complexes toward ammoniaformation and silylamine formationfromdinitrogenunder mild conditions is evaluated to produce only stoichiometric amounts of ammonia and silylamine, probably because the manganese pincer complexes are unstable underreducingconditions.
Co(III) complexes [CoI(PCPY-R)(CO)2] and [CoIII(PCPY-R)X2]. The later are paramagnetic exhibiting a solution magnetic moment in the range of 3.0–3.3 μB which is consistent with a d6 intermediate spin system corresponding to two unpaired electrons. In the case of P(C-X)PY ligands (X = Br, Cl; R = tBu; Y = NH) the formation of the square planar Co(II) complex [Co(PCPNH-tBu)X] was favored. This complex gives