A regioselectively 1, 1',3 ,3'-tetrazincated ferrocene complex displaying core and peripheral reactivity

Honeyman, Gordon W. and Armstrong, David R. and Clegg, William and Hevia, Eva and Kennedy, Alan R. and McLellan, Ross and Orr, Samantha A. and Parkinson, John A. and Ramsay, Donna L. and Robertson, Stuart D. and Towie, Stephen and Mulvey, Robert E. (2020) A regioselectively 1, 1',3 ,3'-tetrazincated ferrocene complex displaying core and peripheral reactivity. Chemical Science, 11 (25). pp. 6510-6520. ISSN 2041-6520 (https://doi.org/10.1039/D0SC01612H)

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Abstract

Regioselective 1,1′,3,3′-tetrazincation [C-H to C-Zn(tBu)] of ferrocene has been achieved by reaction of a fourfold excess of di-t-butylzinc (tBu2Zn) with sodium 2,2,6,6-tetramethylpiperidide (NaTMP) in hexane solution manifested in the trimetallic iron-sodium-zinc complex [Na4(TMP)4Zn4(tBu)4{(C5H3)2Fe}], 1. X-ray crystallographic studies supported by DFT modelling reveal the structure to be an open inverse crown in which two [Na(TMP)Zn(tBu)Na(TMP)Zn(tBu)]2+ cationic units surround a {(C5H3)2Fe}4- tetraanion. Detailed C6D6 NMR studies have assigned the plethora of 1H and 13C chemical shifts of this complex. It exists in a major form in which capping and bridging TMP groups interchange, as well as a minor form that appears to be an intermediate in this complicated exchange phenomenon. Investigation of 1 has uncovered two distinct reactivities. Two of its peripheral t-butyl carbanions formally deprotonate toluene at the lateral methyl group to generate benzyl ligands that replace these carbanions in [Na4(TMP)4Zn4(tBu)2(CH2Ph)2{(C5H3)2Fe}], 2, which retains its tetrazincated ferrocenyl core. Benzyl-Na π-arene interactions are a notable feature of 2. In contrast, reaction with pyridine affords the crystalline product {[Na·4py][Zn(py∗)2(tBu)·py]}∞, 3, where py is neutral pyridine (C5H5N) and py∗ is the anion (4-C5H4N), a rare example of pyridine deprotonated/metallated at the 4-position. This ferrocene-free complex appears to be a product of core reactivity in that the core-positioned ferrocenyl anions of 1, in company with TMP anions, have formally deprotonated the heterocycle.

  • Item type:Article
    ID code:71934
    Dates:
    Date
    Event
    7 July 2020
    Published
    27 March 2020
    Published Online
    26 March 2020
    Accepted
    Subjects:Science > Chemistry
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:31 Mar 2020 10:09
    Last modified:09 Apr 2024 01:24
    URI:https://strathprints.strath.ac.uk/id/eprint/71934
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