skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • The synthesis and characterization of a bidentate complex of 1,1′-(1,3-phenylene)bis(3-butylimidazolium) pincer proligand with molybdenum – A non-pincer binding mode
Title: The synthesis and characterization of a bidentate complex of 1,1′-(1,3-phenylene)bis(3-butylimidazolium) pincer proligand with molybdenum – A non-pincer binding mode
The synthesis of the bidentate Mo complex tetrachlorido[6-(3’-butylimidazolium-1’-yl)-2-(3’’-butylimidazol-1’’-yl-2’’-idene-κC2)phenyl-κC1]molybdenum(IV) 3 was carried out using the metalation followed by transmetalation methodology. The transmetallation process led to a bidentate complex after reaction of DCM with HNMe2 formed an acidic ammonium ion that protonated the bidentate complex. Optimization of the synthetic methodology provided the tetrachlorido[6-(3’-butylimidazolium-1’-yl)-2-(3’’-butylimidazol-1’’-yl-2’’-idene-κC2)phenyl-κC1]molybdenum(IV) complex in high yield. The crystal structure of the bidentate complex, 3, is reported herein. Attempts to avoid the acidic reaction conditions with different solvents or starting materials produced the bis-ligated Mo complex bis[2,6-bis(3’-butylimidazol-1’-yl-2’-idene-κC2)phenyl-κC1]molybdenum(IV) dichloride based on MS analysis. Electronic and coordinative unsaturation in the resulting bidentate complex, 3, open new possibilities for coordination of incoming substrates while also allowing access to the pincer-like motif via oxidative addition. Access to the interconversion of a NHC to/from imidazolium opens new avenues of non-innocent ligand pathways for proton shuttling in reactions such as nitrogen reduction to ammonia.  more » « less
Award ID(s):
1539035
PAR ID:
10493365
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Elsevier Ltd.
Date Published:
Journal Name:
Polyhedron
Volume:
247
Issue:
C
ISSN:
0277-5387
Page Range / eLocation ID:
116714
Subject(s) / Keyword(s):
bidentate phenyl-NHC molybdenum, CCC-NHC ligand, N-heterocyclic carbene, pincer compound
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; ; (, Dalton Transactions)
    The importance of electron deficient Tp ligands motivates the introduction of electron-withdrawing substituents into the scorpionate framework. Since perfluorophenyltris(pyrazol-1-yl)borate affects significant anodic shifts in half-cell potentials in their metal complexes relative those of phenyltris(pyrazol-1-yl)borate analogues, the tuning opportunities achieved using 3,4,5-trifluorophenyl- and 3,5-bis(trifluoromethyl)phenyl(pyrazol-1-yl)borates were explored. Bis(amino)boranes ((3,4,5-F)C 6 H 2 )B(NMe 2 ) 2 and ((3,5-CF 3 )C 6 H 3 )B(NMe 2 ) 2 are precursors to fluorinated tris(pyrazol-1-yl)phenylborates. Thallium salts of these scorpionates exhibit bridging asymmetric κ 3 - N , N , N coordination modes consistent with the reduced π-basicity of the fluorinated phenyl substituents relative those of other structurally characterized tris(pyrazol-1-yl)phenylborates. While a comparative analysis of the spectral and X-ray crystallographic data for classical Mo(0), Mo( ii ), Mn( i ), Fe( ii ) and Cu( ii ) complexes of [((3,4,5-F)C 6 H 2 )Bpz 3 ] − and [((3,5-CF 3 )C 6 H 3 )Bpz 3 ] − could not differentiate these ligands with respect to their metal-based electronic impacts, cyclic voltammetry suggests that 3,4,5-trifluorophenyl- and 3,5-bis(trifluoromethyl)phenyl(pyrazol-1-yl)borates affect similar anodic shifts within their metal complexes, with coordination of [((3,5-CF 3 )C 6 H 3 )Bpz 3 ] − rendering metal centers more difficult to oxidize, and sometimes even more difficult to oxidize than their [C 6 F 5 Bpz 3 ] − analogues. These data suggest that the extent of phenyl substituent fluorination necessary to minimize metal center electron-richness in phenyltris(pyrazol-1-yl)borate complexes cannot be confidently predicted. 
    more » « less
  2. ; ; ; ; (, Acta Crystallographica Section E Crystallographic Communications)
    Two cis -dioxomolybdenum complexes based on salan ligands with different backbones are reported. The first complex, dioxido{2,2′-[l,2-phenylenebis(iminomethylene)]bis(phenolato)}molybdenum(VI) dimethylformamide disolvate, [Mo(C 20 H 18 N 2 O 2 )O 2 ]·2C 3 H 7 NO ( Ph LMoO 2 , 1b ), features a phenyl backbone, while the second complex, (6,6′-{[(cyclohexane-1,2-diyl)bis(azanediyl)]bis(methylene)}bis(2,4-di- tert -butylphenolato))dioxidomolybdenum(VI) methanol disolvate, [Mo(C 36 H 56 N 2 O 2 )O 2 ]·2CH 3 OH ( Cy LMoO 2 , 2b ), is based on a cyclohexyl backbone. These complexes crystallized as solvated species, 1b ·2DMF and 2b ·2MeOH. The salan ligands Ph LH 2 ( 1a ) and Cy LH 2 ( 2a ) coordinate to the molybdenum center in these complexes 1b and 2b in a κ 2 N ,κ 2 O fashion, forming a distorted octahedral geometry. The Mo—N and Mo—O distances are 2.3475 (16) and 1.9567 (16) Å, respectively, in 1b while the corresponding measurements are Mo—N = 2.3412 (12) Å, and Mo—O = 1.9428 (10) Å for 2b . A key geometrical feature is that the N—Mo—N angle of 72.40 (4)° in Cy LMoO 2 is slightly less than that of the Ph LMoO 2 angle of 75.18 (6)°, which is attributed to the flexibility of the cyclohexane ring between the nitrogen as compared to the rigid phenyl ring in the Ph LMoO 2 . 
    more » « less
  3. ; ; ; ; ; ; (, Chemical Communications)
    null (Ed.)
    The reactivity of alkali metal capped Ce( iv ) imido compounds [M(DME) 2 ][CeNAr F (TriNOx)] ( 1-M with M = K, Rb, Cs and Ar F = 3,5-bis(trifluoromethyl)phenyl) with CO 2 and organic isocyanates has been evaluated. 1-Cs reacted with CO 2 to yield an organocarbamate complex. Reaction of 1-K and 1-Rb with organic isocyanates yielded organoureate Ce( iv ) complexes. 
    more » « less
  4. ; ; (, European Journal of Inorganic Chemistry)
    Abstract Catalysis ofO‐atom transfer (OAT) reactions is a characteristic of both natural (enzymatic) and synthetic molybdenum‐oxo and ‐peroxo complexes. These reactions can employ a variety of terminal oxidants, e. g. DMSO,N‐oxides, and peroxides, etc., but rarely molecular oxygen. Here we demonstrate the ability of a set of Schiff‐base‐MoO2complexes (cy‐salen)MoO2(cy‐salen=N,N’‐cyclohexyl‐1,2‐bis‐salicylimine) to catalyze the aerobic oxidation of PPh3. We also report the results of a DFT computational investigation of the catalytic pathway, including the identification of energetically accessible intermediates and transition states, for the aerobic oxidation of PMe3. Starting from the dioxo species, (cy‐salen)Mo(VI)O2(1), key reaction steps include: 1) associative addition of PMe3to an oxo‐O to give LMo(IV)(O)(OPMe3) (2); 2) OPMe3dissociation from2to produce mono‐oxo complex (cy‐salen)Mo(IV)O (3); 3) stepwise O2association with3via superoxo species (cy‐salen)Mo(V)(O)(η1‐O2) (4) to form the oxo‐peroxo intermediate (cy‐salen)Mo(VI)(O)(η2‐O2) (5); 4) theO‐transfer reaction of PMe3with oxo‐peroxo species5at the oxo‐group, rather than the peroxo unit leading, after OPMe3dissociation, to a monoperoxo species, (cy‐salen)Mo(IV)(η2‐O2) (7); and 5) regeneration of the dioxo complex (cy‐salen)Mo(VI)O2(1) from the monoperoxo triplet37or singlet17by a concerted, asynchronous electronic isomerization. An alternative pathway for recycling of the oxo‐peroxo species5to the dioxo‐Mo1via a bimetallic peroxo complex LMo(O)‐O−O‐Mo(O)L8is determined to be energetically viable, but is unlikely to be competitive with the primary pathway for aerobic phosphine oxidation catalyzed by1. 
    more » « less
  5. ; ; ; ; ; (, Molecules)
    Complexes consisting of earth-abundant main group metals such as silicon with polypyridine ligands are of interest for a variety of optical and electronic applications including as electrochromic colorants. Previous spectroelectrochemical studies with tris(2,2′-bipyridyl)silicon(IV) hexafluorophosphate, [Si(bpy)3](PF6)4, demonstrated an ability to control the color saturation of the potential electrochromic dye, with the intensity of the dye’s green color increasing as the charge state sequentially reduces from 4+ to 1+. In this study, the synthesis of bis(4′-(4-tolyl)-2,2′:6′,2″-terpyridine)silicon(IV) hexafluorophosphate, [Si(ttpy)2](PF6)4, is reported along with electrochemical and spectroelectrochemical analyses. Computational modeling (density functional theory) is used to further elucidate the electrochromic properties of previously reported Si(bpy)3n+ species and the new Si(ttpy)2n+ species. While the homoleptic tris(bidentate)silicon(IV) complexes are attractive as electrochromic dyes for tunable color saturation, the bis(tridentate)silicon(IV) complexes are attractive as polychromatic electrochromic dyes. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email