116232-38-3Relevant academic research and scientific papers
Synthesis, characterization, and some chemical properties of unusual 16-electron dialkyl(η5-cyclopentadienyl)nitrosylmolybdenum and -tungsten complexes
Legzdins, Peter,Rettig, Steven J.,Sánchez, Luis
, p. 2394 - 2403 (2008/10/08)
Novel 16-electron dialkyl complexes of molybdenum and tungsten, CpM(NO)R2 [(Cp = η5-C5H5; M = Mo or W; R = CH2SiMe3, CH2CMe3, CH2CMe2Ph, or CH2Ph], result in high yields from the sequential treatment of [CpM(NO)I2]2 first with a Grignard reagent, RMgCl, and then water. When R = CH2SiMe3, the intermediate complexes [CpM(NO)R2]2MgI2·Et2O are isolable as red crystalline solids prior to the addition of H2O. The final CpM(NO)R2 compounds possess monomeric, piano-stool molecular structures, a fact that has been established for CpW(NO)(CH2SiMe3)2 in the solid state by a single-crystal, X-ray crystallographic analysis. This compound crystallizes in the monoclinic space group P21/c with cell dimensions a = 12.070 (2) A?, b = 12.4360 (7) A?, c = 13.5742 (15) A?, and β = 104.856 (6)°. The most chemically interesting feature of the molecular structure involves the essentially linear (169.5 (6)°) WNO group in which the short W-N (1.757 (8) A?) and long N-O (1.226 (10) A?) bond lengths indicate the existence of considerable W→NO back-bonding. Consistently, the IR spectra of all the CpM(NO)R2 complexes as Nujol mulls exhibit single, strong νNO'S in the relatively low-energy range of 1540-1587 cm-1. The chemical properties of these dialkyl compounds are exemplified by the reactions of CpW(NO)(CH2SiMe3)2 with various substrates. Thus, this complex incorporates small Lewis bases such as PMe3 directly at the tungsten center, 1:1 adducts resulting. Other Lewis base adducts undergo subsequent intramolecular transformations involving one of the alkyl groups. Hence, reaction of CpW(NO)(CH2SiMe3)2 with t-BuNC affords the insertion product CpW-(NO)(CH2SiMe3)[η2-C(CH 2SiMe3)=N-t-Bu] in 94% isolated yield. [Hydrolysis of this iminoacyl complex cleanly produces the corresponding methyl derivative, CpW(NO)(CH2SiMe3)[η22-C(CH 3)=N-t-Bu].] Similarly, treatment of the tungsten dialkyl complex in hexanes with NO gas affords quantitatively the N-alkyl-N-nitrosohydroxylaminato compound CpW(NO)(CH2SiMe3)(η2-O2N 2{CH2SiMe3}), which exists in nonpolar solvents as a mixture of two isomers. Finally, reaction of CpW(NO)(CH2SiMe3)2 with elemental sulfur or selenium results in the occurrence of the unprecedented sequential transformations (Equation Presented) where M = CpW(NO), R = CH2SiMe3, and E = S or Se. When E = S, all three product complexes are isolable as analytically pure solids, but when E = Se, only CpW(NO)(CH2SiMe3)(SeCH2SiMe3) and CpW(NO)(SeCH2SiMe3)2 may be so obtained. All new complexes isolated during this investigation have been fully characterized by conventional spectroscopic methods.
