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.


Title: Lewis Acid Supported Nickel Nitrenoids
Abstract Metalation of the polynucleating ligandF,tbsLH6(1,3,5‐C6H9(NC6H3−4‐F−2‐NSiMe2tBu)3) with two equivalents of Zn(N(SiMe3)2)2affords the dinuclear product (F,tbsLH2)Zn2(1), which can be further deprotonated to yield (F,tbsL)Zn2Li2(OEt2)4(2). Transmetalation of2with NiCl2(py)2yields the heterometallic, trinuclear cluster (F,tbsL)Zn2Ni(py) (3). Reduction of3with KC8affords [KC222][(F,tbsL)Zn2Ni] (4) which features a monovalent Ni centre. Addition of 1‐adamantyl azide to4generates the bridging μ3‐nitrenoid adduct [K(THF)3][(F,tbsL)Zn2Ni(μ3‐NAd)] (5). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state (S=). Cyclic voltammetry of5reveals two fully reversible redox events. The dianionic nitrenoid [K2(THF)9][(F,tbsL)Zn2Ni(μ3‐NAd)] (6) was isolated and characterized while the neutral redox isomer was observed to undergo both intra‐ and intermolecular H‐atom abstraction processes. Ni K‐edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn2Ni] nitrenoid complexes. However, DFT analysis suggests Ni‐borne oxidation for5.  more » « less
Award ID(s):
1834750 2247817 2216066
PAR ID:
10491536
Author(s) / Creator(s):
; ; ; ; ; ; ; ;
Publisher / Repository:
John Wiley & Sons, Ltd
Date Published:
Journal Name:
Angewandte Chemie International Edition
Volume:
62
Issue:
50
ISSN:
1433-7851
Page Range / eLocation ID:
e202313156
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, European Journal of Inorganic Chemistry)
    Abstract Exploration of the reduction chemistry of the 2,2’‐bipyridine (bipy) lanthanide metallocene complexes Cp*2LnCl(bipy) and Cp*2Ln(bipy) (Cp* = C5Me5) resulted in the isolation of a series of complexes with unusual composition and structure including complexes with a single Cp* ligand, multiple azide ligands, and bipy ligands with close parallel orientations. These results not only reveal new structural types, but they also show the diverse chemistry displayed by this redox‐active platform. Treatment of Cp*2NdCl(bipy) with excess KC8resulted in the formation of the mono‐Cp* Nd(III) complex, [K(crypt)]2[Cp*Nd(bipy)2],1, as well as [K(crypt)][Cp*2NdCl2],2, and the previously reported [K(crypt)][Cp*2Nd(bipy)]. A mono‐Cp* Lu(III) complex, Cp*Lu(bipy)2,3, was also found in an attempt to make Cp*2Lu(bipy) from LuCl3, 2 equiv. of KCp*, bipy, and K/KI. Surprisingly, the (bipy)1−ligands in neighboring molecules in the structure of3are oriented in a parallel fashion with intermolecular C⋅⋅⋅C distances of 3.289(4) Å, which are shorter than the sum of van der Waals radii of two carbon atoms, 3.4 Å. Another product with one Cp* ligand per lanthanide was isolated from the reaction of [K(crypt)][Cp*2Eu(bipy)] with azobenzene, which afforded the dimeric Eu(II) complex, [K(crypt)]2[Cp*Eu(THF)(PhNNPh)]2,4. Attempts to make4from the reaction between Cp*2Eu(THF)2and a reduced azobenzene anion generated instead the mixed‐valent Eu(III)/Eu(II) complex, [K(crypt)][Cp*Eu(THF)(PhNNPh)]2,5, which allows direct comparison with the bimetallic Eu(II) complex4. Mono‐Cp* complexes of Yb(III) are obtained from reactions of the Yb(II) complex, [K(crypt)][Cp*2Yb(bipy)], with trimethylsilylazide, which afforded the tetra‐azido [K(crypt)]2[Cp*Yb(N3)4],6, or the di‐azido complex [K(crypt)]2[Cp*Yb(N3)2(bipy)],7 a, depending on the reaction stoichiometry. A mono‐Cp* Yb(III) complex is also isolated from reaction of [K(crypt)][Cp*2Yb(bipy)] with elemental sulfur which forms the mixed polysulfido Yb(III) complex [K(crypt)]2[Cp*Yb(S4)(S5)],8 a. In contrast to these reactions that form mono‐Cp* products, reduction of Cp*2Yb(bipy) with 1 equiv. of KC8in the presence of 18‐crown‐6 resulted in the complete loss of Cp* ligands and the formation of [K(18‐c‐6)(THF)][Yb(bipy)4],9. The (bipy)1−ligands of9are arranged in a parallel orientation, as observed in the structure of3, except in this case this interaction is intramolecular and involves pairs of ligands bound to the same Yb atom. Attempts to reduce further the Sm(II) (bipy)1−complex, Cp*2Sm(bipy) with 2 equiv. of KC8in the presence of excess 18‐crown‐6 led to the isolation of a Sm(III) salt of (bipy)2−with an inverse sandwich Cp* counter‐cation and a co‐crystallized K(18‐c‐6)Cp* unit, [K2(18‐c‐6)2Cp*]2[Cp*2Sm(bipy)]2 ⋅ [K(18‐c‐6)Cp*],10. 
    more » « less
  2. ; ; ; (, Chemistry – A European Journal)
    Abstract Affinities of six anions (mesylate, acetate, trifluoroacetate,p‐toluenecarboxylate,p‐toluenesulfonate, and perfluorooctanoate) for three related Pt2+‐linked porphyrin nanocages were measured to probe the influence of different noncovalent recognition motifs (e. g., hydrogen bonding, electrostatics, π bonding) on anion binding. Two new hosts of M6L312+(1b) and M4L28+(2) composition (M=(en)Pt2+, L=(3‐py)4porphyrin) were prepared in a one‐pot synthesis and allowed comparison of hosts that differ in structure while maintaining similar N−H hydrogen‐bond donor ability. Comparisons of isostructural hosts that differ in hydrogen‐bonding ability were made between1band a related M6L312+nanoprism (1a, M=(tmeda)Pt2+) that lacks N−H groups. Considerable variation in association constants (K1=1.6×103 M−1to 1.3×108 M−1) and binding mode (exovs.endo) were found for different host–guest combinations. Strongest binding was seen betweenp‐toluenecarboxylate and1b, but surprisingly, association of this guest with1awas only slightly weaker despite the absence of NH⋅⋅⋅O interactions. The high affinity betweenp‐toluenecarboxylate and1acould be turned off by protonation, and this behavior was used to toggle between the binding of this guest and the environmental pollutant perfluorooctanoate, which otherwise has a lower affinity for the host. 
    more » « less
  3. ; ; ; ; ; (, Angewandte Chemie International Edition)
    Abstract Herein, the first report on the isolated and unambiguously proven benzene radical trianion is presented. This unprecedented radical oxidation state of benzene is stabilized through two trivalent rare earth (RE) metal cations each supported by a bis(guanidinate) scaffold. Specifically, the one‐electron chemical reduction of the neutral inverse‐sandwich yttrium complex [[{(Me3Si)2NC(NiPr)2}2Y]2(μ–ƞ6:ƞ6–C6H6)]1, containing a benzene dianion, with potassium graphite (KC8) in the presence of [2.2.2]‐cryptand yielded the title complex [K([2.2.2]‐cryptand)][[{(Me3Si)2NC(NiPr)2}2Y]2(μ–ƞ6:ƞ6–C6H6•)]2, featuring a benzene radical trianion. Analyses through single‐crystal X‐ray diffraction, EPR and UV–vis spectroscopy, elucidated its molecular structure and revealed strong [YIII–(C6H6)3–•–YIII] metal–radical interactions. Although the Y centers remain in the +3 oxidation state, the spin density of the unpaired electron resides primarily on the benzene trianion moiety and extends toward the YIIIions. Density functional theory (DFT) calculations on2corroborate this assignment and further suggest weak aromaticity for the benzene radical trianion. 
    more » « less
  4. ; ; ; ; (, Angewandte Chemie International Edition)
    Abstract Reaction of Tl(OTf) with 2 equiv of bis(diisopropylamino)cyclopropenylidene (BAC) in THF results in formation of [Tl(BAC)2(OTf)] (1) in moderate yields. Subsequent reaction of1with [K][H2‐9‐BBN] ([H2‐9‐BBN]− = dihydrido 9‐boratabicyclo[3.3.1]nonane) in THF results in formation of [Tl(BAC)(μ‐H2‐9‐BBN)]2(3), also in moderate yield. Complex3is the first reported thallium borohydride. We attribute its thermal stability to the strong donor ability of the BAC co‐ligand. Both1and3exhibit trigonal pyramidal geometries about Tl+in the solid‐state, indicative of the presence of stereochemically active lone pairs. The hydride environment in3is calculated to exhibit a 3.9 ppm downfield shift attributed to spin‐orbit effects from the adjacent Tl center. 
    more » « less
  5. ; ; ; ; ; ; ; ; (, Chemical Science)
    In polynuclear biological active sites, multiple electrons are needed for turnover, and the distribution of these electrons among the metal sites is affected by the structure of the active site. However, the study of the interplay between structure and redox distribution is difficult not only in biological systems but also in synthetic polynuclear clusters since most redox changes produce only one thermodynamically stable product. Here, the unusual chemistry of a sterically hindered trichromium complex allowed us to probe the relationship between structural and redox isomerism. Two structurally isomeric trichromium imides were isolated: asymmetric terminal imide ( tbs L)Cr 3 (NDipp) and symmetric, μ 3 -bridging imide ( tbs L)Cr 3 (μ 3 –NBn) (( tbs L) 6− = (1,3,5-C 6 H 9 (NC 6 H 4 - o -NSi t BuMe 2 ) 3 ) 6− ). Along with the homovalent isocyanide adduct ( tbs L)Cr 3 (CNBn) and the bisimide ( tbs L)Cr 3 (μ 3 –NPh)(NPh), both imide isomers were examined by multiple-wavelength anomalous diffraction (MAD) to determine the redox load distribution by the free refinement of atomic scattering factors. Despite their compositional similarities, the bridging imide shows uniform oxidation of all three Cr sites while the terminal imide shows oxidation at only two Cr sites. Further oxidation from the bridging imide to the bisimide is only borne at the Cr site bound to the second, terminal imido fragment. Thus, depending on the structural motifs present in each [Cr 3 ] complex, MAD revealed complete localization of oxidation, partial localization, and complete delocalization, all supported by the same hexadentate ligand scaffold. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email