Manganese Nitride Complexes in Oxidation States III, IV, and V: Synthesis and Electronic Structure

The synthesis and characterization of a series of manganese nitrides in a tripodal chelating tris­(carbene) ligand framework is described. Photolysis of [(TIMENxyl)­Mn­(N3)]+ (where TIMENxyl = tris­[2-(3-xylylimidazol-2-ylidene)­ethyl]­amine) yields the isolable molecular MnIV nitride, [(TIMENxyl)­Mn­(N)]+. Spectroscopic and DFT studies indicate that this MnIV d3 complex has a doublet electronic ground state. The metal-centered one-electron oxidation of this MnIV species results in formation of the pentavalent MnV nitride, [(TIMENxyl)­Mn­(N)]2+. Unlike previously reported, tetragonal MnV nitrides with a d2, nonmagnetic S = 0 ground state, this trigonal bipyramidal complex has a triplet ground state S = 1. One-electron reduction of [(TIMENxyl)­Mn­(N)]+ produces the neutral, nonmagnetic trivalent [(TIMENxyl)­Mn­(N)] species with a d4 low-spin, S = 0, ground state.

本文报道了一类以三足螯合三卡宾配体为骨架的氮化锰配合物的合成与表征工作。对配合物[(TIMENxyl)Mn(N3)]+（其中TIMENxyl为三[2-(3-二甲苯基咪唑-2-亚基)乙基]胺）进行光解，可得到可分离的分子态锰(IV)（MnIV）氮化物配合物[(TIMENxyl)Mn(N)]+。光谱学表征与密度泛函理论（DFT）研究表明，该具有d3电子构型的锰(IV)配合物具有二重态电子基态。对该锰(IV)物种进行金属中心单电子氧化，可得到锰(V)（MnV）氮化物配合物[(TIMENxyl)Mn(N)]2+。与此前报道的具有d2电子构型、非磁性S=0基态的四方结构锰(V)氮化物不同，该三角双锥结构配合物的电子基态为三重态S=1。对[(TIMENxyl)Mn(N)]+进行单电子还原，可得到中性、非磁性的三价锰配合物[(TIMENxyl)Mn(N)]，其具有d4低自旋、S=0的电子基态。