Nitrogen-Atom Exchange Mediated by Nitrido Complexes of Molybdenum

Abstract

Nitrido complexes NMo(OC(CF3)2Me)3 and NMo(OC(CF3)3)3(NCMe) containing fluorinated alkoxide ancillary ligands are synthesized in 57% and 50% yield, respectively. Both complexes undergo N-atom exchange within hours at 30 degrees C with acetonitrile and benzonitrile in either THF-d8 or CD2Cl2, as shown by 15N NMR studies using labeled 15NCMe. In both solvents, is the more active in this process. Additionally, both compounds are substantially more active in THF-d8 than in CD2Cl2. Complex crystallizes in the space group P2(1)/c, adopting a pseudo-square-pyramidal structure in which the nitrido moiety occupies the apical position, 1.633(3) A away from Mo.

Alkyne Metathesis: Catalysts and Synthetic Applications

“…[16] Johnson found that although in the case of trialkoxytungsten(VI) complex 35, the formation of nitride 36 from alkylidyne 35 and nitrile is favored, [48][49][50] the molybdenum(VI) analogue showed thermodynamic preference for the formation of alkylidyne complex from nitride species and alkynes (Scheme 8). Although no terminal nitrido com-plexes were formed in the reaction between propylidyne complex 38 and nitriles, heating nitride 37 [51] with 3-hexyne and 1 equiv. of DME at 95 8C for several days generated compound 38.…”

Synthesis and characterization of a trianionic pincer supported Mo-alkylidene anion and alkyne insertion into a Mo(IV)-C bond to form metallocyclopropene(η2-vinyl) complexes

“…Fürstner et al [18,19] utilize Br 3 WhCPh(dme) [20,21] as an accessible reagent to form siloxy-based alkylidyne complexes [22]. For example, (Ph 3 SiO) 3 MohCPh(OEt 2 ) reacts with many substrates bearing diverse functional groups, and the activity is impressive [23]. In the presence of 5 Å molecular sieves, (Ph 3 SiO) 3 MohCPh(OEt 2 ) completes the metathesis of 1-phenyl-1-propyne within 5 min.…”

“…Moore [17], employing the Lewis acid B(C 6 F 5 ) 3 , activate Mo-nitrides toward metathesis with alkynes. This discovery implies that Mnitrides, already known to exchange N-atoms with nitriles [23,24], may be a general entry point to alkyne metathesis catalysts [15,16]. Recently, we proposed that a trianionic pincer ligand may provide the appropriate ligand arrangement for a reactive AM or NACM catalyst [25].…”

Catalytic alkyne metathesis and stoichiometric metal–alkylidyne formation from N Mo(OR)3 complexes promoted by Lewis acids

“…Bis(4-methoxyphenyl)acetylene [24,25], VCl 3 (thf) 3 [26], N^Mo(OCMe 3 ) 3 (6) [27], N^Mo(OCMe(CF 3 ) 2 ) 3 (1) [28], and N^Mo(OC(CF 3 ) 3 ) 3 (NCMe) (2) [28], were prepared according to literature procedures. Mesitylene, diphenylacetylene, and chlorotitanium tri-isopropoxide were obtained from Acros.…”