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  • A Cationic Pt(II) Dinitrogen Adduct: Synthesis and Characterization of a CCC-aNHC Pincer Pt Complex with Abnormal N -Heterocyclic Carbene Donor Arms
Title: A Cationic Pt(II) Dinitrogen Adduct: Synthesis and Characterization of a CCC-aNHC Pincer Pt Complex with Abnormal N -Heterocyclic Carbene Donor Arms
In contrast to the reported CCC-NHC pincer ligands that contain normal N-heterocyclic carbenes (NHC), herein we report an imidazole-based abnormal NHC (aNHC) pincer ligand, CCC-aNHC. The CCC-aNHC pincer Pt complex with two aNHC donors was synthesized via the in situ metalation and transmetalation methodology. The 1,3-phenylene(bis-2-phenyl-3-butyl imidazolium) diiodide salt was reacted with Zr(NMe2)4 to generate a CCC-aNHC pincer zirconium complex in situ. It was transmetalated to Pt using [Pt(COD)Cl2]. Electrospray ionization of the Pt pincer complex [(BuCa‑iCa‑iCBu)-PtI] in acetonitrile generated an intense peak at m/z = 696.2375, which was assigned to the dinitrogen adduct [M−I+N2]+ of the cationic CCC-aNHC pincer Pt(II) complex [(BuCa‑iCa‑iCBu)Pt− N2]+, representing a rare example of the platinum dinitrogen organometallic complex. The super electron-donating ability of the pincer ligands with abnormal NHC enabled the cationic CCC-aNHC pincer Pt(II) complex to selectively bind N2 over MeCN in a first-order analysis. A collision-induced dissociation (CID) study was conducted on the N2 and MeCN adducts, suggesting that more energy was required to dissociate N2 than MeCN. A computational study suggested that the N2 adduct was kinetically stable in the gas phase whereas the MeCN adduct was thermodynamically preferred. The computational results reconciled the mass spectral data experiment with an attempt to isolate the N2 adduct. DFT computation suggested that N2 dissociation is more challenging due to higher energy transition states, and there is a competitive pathway of N2 tumbling within the coordination sphere of the Pt. This tumbling path is not available from the MeCN ligand due to ligand structural differences.  more » « less
Award ID(s):
1539035 1827686
PAR ID:
10493361
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
Organometallics
Volume:
43
Issue:
4
ISSN:
0276-7333
Page Range / eLocation ID:
467 to 480
Subject(s) / Keyword(s):
Adducts, Ligands, Nitrogen, Pincer complexes, Platinum
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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