Intrinsische Stickstoff‐Aktivierung an “nackten” Metallatomen

Abstract

Das Interesse an Metallkomplexen, die molekularen Stickstoff binden und seine Reduktion oder Oxidation unter milden Bedingungen bewirken, ist weiterhin ungebrochen. In der Natur katalysiert das Enzym Nitrogenase diesen Prozess. Unter milden Zellbedingungen findet die Distickstoff‐Fixierung an einem Metall‐Schwefel‐Cluster im Zentrum des MoFe‐Proteins statt. Details des Mechanismus sind jedoch weithin unbekannt, obwohl gerade in den letzten Jahren wichtige Entdeckungen in diesem Gebiet gemacht wurden. Im vorliegenden Aufsatz werden neueste Resultate über Wechselwirkungen von N2 mit Metallatomen und Metallatom‐Dimeren aller Gruppen des Periodensystems diskutiert, die vor allem in Gasphasen‐ und Matrixisolationsexperimenten gewonnen wurden. Die Relevanz dieser intrinsischen Distickstoff‐Aktivierung an ligandenfreien Metallatomen für die entsprechenden Reaktionen an Komplexen, Clustern und Oberflächen wird hervorgehoben.

Dinitrogen Cleavage by a Diniobium Tetrahydride Complex: Formation of a Nitride and Its Conversion into Imide Species

“…[12] Reduction of dinitrogen by 2 results in cleavage of the NN bond, as evidenced by the N···N separation of 2.589 (5) . Each niobium center displays five-coordinate, distorted trigonal-bipyramidal coordination, with N(1) and O(2) in the axial positions of Nb (1) [N(2) and O(6) for Nb (2)]. The {Nb 2 N 2 } core is nearly planar with a Nb(1)-N(2)-Nb(2)-N(1) torsion angle of 6.2(1)8.…”

“…Activation and functionalization of molecular nitrogen by soluble metal complexes has attracted widespread attention from both fundamental and practical points of view. [1,2] Typically, metal complexes capable of strongly activating N 2 and cleaving the NN bond are formed from low-valent earlytransition-metal precursors [2b, 3] or using strong reducing reagents, such as alkali metals. [4,5] Another method is the use of metal hydride complexes.…”

The Electronic Structure of the Tris(ethylene) Complexes [M(C2H4)3] (M=Ni, Pd, and Pt): A Combined Experimental and Theoretical Study

“…However, Keywords: density functional calculations · Group 10 elements · olefin complexes · palladium · vibrational spectroscopy the DCD model, although advantageous in providing straightforward answers, has been shown in many cases to be an oversimplification. [7] Many derivatives, including some for Pd and Pt, have been structurally characterized in subsequent years; for example, the crystal structure of tris-A C H T U N G T R E N N U N G (bicycloA C H T U N G T R E N N U N G [2.2.1]heptene)platinum that features doublebonded C atoms and a Pd atom in one plane. [8] [PtA C H T U N G T R E N N U N G (C 2 H 4 ) 2 -A C H T U N G T R E N N U N G (C 2 F 4 )] is another example, which has been structurally characterized and for which the planar geometry has been confirmed.…”

Remarkable Dinitrogen Activation and Cleavage by the Gd Dimer: From Dinitrogen Complexes to Ring and Cage Nitrides

“…Many dinitrogen complexes exhibit subsequent reactivity at the N 2 unit that can lead to its further activation, complete N À N bond cleavage, and functionalization. [1][2][3] Reactions of metal atoms and small clusters with dinitrogen serve as ideal models for fundamental understanding of the multifaceted mechanisms of dinitrogen activation by d-and fmetal complexes and surfaces.Previous investigations have demonstrated N À N bond cleavage by some transition-metal atoms and dimers. [4, 5] Herein we report a joint matrix-isolation infrared-spectroscopic and theoretical study of the reaction of Gd 2 with N 2 , which proceeds by the initial formation of an unprecedented dinuclear lanthanide dinitrogen complex with a simultaneously side-on and end-on bonded N 2 ligand.…”