Nitrido Complexes of Transition Metals

Abstract

In the past decade new syntheses and numerous structural determinations have enlivened studies in the still relatively young field of nitrido-transition-metal complexes. Aside from the terminal function of the nitrido ligand MEN:, this group also occurs as linear p,-bridging ligand in symmetric and asymmetric coordination; examples are known with almost rightangled bridge function; and, finally, it also functions as p3-bridging ligand. Accordingly, the fresh impulses given to synthetic chemistry by nitrido complexes are also many-sided: such complexes are used, inter aha, for the preparation of phosphaniminato and thionitrosyl complexes as well as for the synthesis of metallaheterocycles of the type MN,S, and MN,P2 with delocalized x-systems. In technetium chemistry complexes with terminal nitrido group are employed as radiopharmaceuticals, and, owing to the strong trans influence of the M=N: group, nitrido complexes of molybdenum are suitable as catalysts in olefin metathesis. Finally, nitrido complexes are also of wide interest in theoretical studies.

Formation and Reactivity of the Terminal Vanadium Nitride Functionality

“…[1,2,41] Despite all these available routes, the most common approach to preparing metal nitrides is by photolysis and/or thermolysis of azide complexes, leading to dinitrogen evolution with concomitant two-electron oxidation of the metal center [Reaction (10), Scheme 1]. [2,3,5] It is by the latter route that putative and isolable uranium nitride species [14b] as well as a host of examples of reactive group 8 [6,12,[42][43][44] and 9 [15,16,45] nitride complexes can be prepared. Given the importance of such a general synthetic method for nitride formation, as well as the broad interest in the reactivity of metal nitrides, we were surprised to find that the mechanism for conversion of metal azides to the corresponding nitrides had been rarely investigated according to the literature.…”

“…Terminal metal nitride complexes occupy an important niche in the realm of inorganic chemistry [1][2][3][4][5][6] and continue to garner longstanding attention for their intermediacy in the activation of dinitrogen and its conversion to ammonia. [7][8][9][10][11] Although the nitride functionality has long been regarded primarily as a stabilizing spectator ligand for transition metals in high oxidation states (redox inactive), in recent years, unusual nitrides anchored by redox-active an S = 1 system, while the dimeric azide system is weakly antiferromagnetically coupled with a spin singlet ground state and thermally accessible triplet and quintet states.…”

“…[30] Other exotic synthetic routes to metal nitrides include the bimetallic deoxygenation of NO [Reaction (2), Scheme 1], [31] reductive decarbonylation from isocyanate [Reaction (3), Scheme 1], N-N bond cleavage in N 2 O reduction [Reaction (4), Scheme 1)], [32] N-atom transfer via reduction and strain release by anthracene elimination [Reaction (5), Scheme 1], [21,33] intermetallic nitrogen-atom transfer [Reaction (6), Scheme 1], [34][35][36][37][38][39] metathesis of nitrile from metal alkylidyne and metal-metal-multiple-bonded complexes [Reactions (7) and (8), Scheme 1], [40] and by several desilylation methods [Reaction (9), Scheme 1]. [1,2,41] Despite all these available routes, the most common approach to preparing metal nitrides is by photolysis and/or thermolysis of azide complexes, leading to dinitrogen evolution with concomitant two-electron oxidation of the metal center [Reaction (10), Scheme 1]. [2,3,5] It is by the latter route that putative and isolable uranium nitride species [14b] as well as a host of examples of reactive group 8 [6,12,[42][43][44] and 9 [15,16,45] nitride complexes can be prepared.…”

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

“…The instability of the azide complex 1 in acetonitrile solution prevented its isolation; the nature of the decomposition products is under investigation. The formula of the intermediate was assigned in analogy to the recently reported heptaazido complex (Bu 4 N) 3 [U(N 3 ) 7 ] prepared from the reaction of the tetravalent (Bu 4 N) 2 [UCl 6 ] with AgN 3 in acetonitrile. [22] The difference in stability of the two compounds is probably due to the presence of a very different counterion.…”

Antimony as a symmetrically bridged ligand in a novel neutral complex

“…11 Numerous compounds of the form [L n MNENML n ] are known, which contain a symmetrical nitrogen bridge, but not for pnictogens heavier than phosphorus. 12 Stephan and co-workers succeeded in the synthesis of the complex [{Cp 2 Zr} 2 (m-P)]. 13 Cummins and co-workers isolated [{(RARN) 3 Mo} 2 (m-P)] (R = Ph; RA = t-Bu) at 235 °C as a labile intermediate in the transfer reaction of a terminal P 1 ligand from the phosphido complex 1 to the d 3 complex [(RARN) 3 Mo] (RA = C 6 H 5 , R = t-Bu).…”