Proiect PN-III-P4-ID-PCE-2020-2651 :   Project timespan   Project team   Abstract   Budget   Results  
Contract: 224/2021

Title: Organopnicogen (antimony, bismuth) alkoxides and related compounds – from fundamental molecular design to applied catalysis

Project timespan
2021 -- 2023

Abstract
The present proposal is focused on the organometallic chemistry of heavy pnicogens (Pn = Sb, Bi) of high interest for their valuable potential in catalysis. The compounds envisaged are neutral or cationic, well defined molecular and/or cluster species from the less explored class of alkoxides and completely unexplored classes of related oxo ligands - boryloxides, siloxides and germyloxides. Our research objectives are focused on (i) preparation of molecular organopnicogen(III) alkoxides, including chiral ones, enough stable to be investigated both in solution and in solid state; (ii) preparation of first boryloxide, siloxide and germyloxide analogues; (iii) evaluation of the tetrel nature on the reactivity of Pn–O bond in the Pn–O–Tet unit (Tet = C, Si, Ge); (iv) preparation of monoorganopnicogen(alkoxo) cations stabilized through intramolecular coordination; (v) studies regarding the potential of the new organopnicogen(III) species with oxo ligands in catalysis, including C–H activation, and exploration of their active role in reversible CO2 fixation/activation.

Budget
Budget chapter (expenses) 2021 (lei) 2022 (lei) 2023 (lei) Total
1 Salaries 204.000 240.000 240.000 684.000
2 Logistics 156.941,31 69.000 60.854 286.795,31
2.1 Capital expenses 100.881,14 0 0 100.881,14
2.2 Stocks expenses 54.164,24 69.000 60.854 184.018,24
2.3 Services 1.895,93 0 0 1.895,93
3 Mobility 971,42 15.000 15.000 30.971,42
4 Overhead 60.037,27 69.000 69.196 198.233,27
5 Total 421.950 393.000 385.050 1.200.000

Results

Stage 1 (January 2021 – December 2021) in the implementation of the project
During the first stage of the project the performed activities (management and scientific ones) were dedicated to the development of the objectives detailed in the research plan, part of the approved proposal (contract 224/2021):
  • Several aromatic proligands with two pendant arms, 2,6-(R2NCH2)2C6H4, as well as triorganopnicogens(III), R3Pn, organopnicogen(III) halides, R2PnX and RPnX2 (X = Cl, Br), oxides and sulfides, (RPnE)n and (R2Pn)2E (E = O, S), oxy-chlorides, (RPnCl)2O [Pn = Sb, Bi; R = 2-(Me2NCH2)C6H4, 2,6-(R2NCH2)2C6H3] were prepared. All these compounds are non-commercial products and are raw materials necessary to carry out the proposed research within this project.
  • The new compounds RBi(Cl)(S2CNMe2) and Bi(S2CNMe2)2 [R = 2-(Me2NCH2)C6H4] were prepared and characterized by IR, Raman, multinuclear NMR spectroscopies, mass spectrometry, thermogravimetric studies, single crystal X-ray diffraction, and computational methods. The results were published (DOI: 10.1016/j.molstruc.2021.131335).
  • The new organopnicogen(III) amides, RPn[N(SiMe3)2]2 and R2Pn[N(SiMe3)2] [Pn = Sb, Bi; R = 2-(Me2NCH2)C6H4] were synthesized and characterized by multinuclear NMR spectroscopy. These compounds will be used in the next stages of the project as starting materials for the preparation of new organopnicogen(III) alkoxides.
  • Several organopnicogen(III) alkoxides and aryloxides, RPn(OR′)2 and R2Pn(OR′) [Pn = Sb, Bi; R′= akyl, aryl], as well as related compounds were synthesized and characterized spectroscopically (multinuclear NMR – including variable temperature studies, MS). For some compounds the molecular structure was established by single crystal X-ray diffraction studies. Computational methods were performed on selected compounds to investigate the noncovalent interactions observed in the crystal.
  • Related triorganopnicogen(V) aryloxides were also prepared and characterized spectroscopically (multinuclear NMR, MS).
  • Several boronic and borinic acids, i.e. RB(OH)2 and R2B(OH), were prepared and used for the synthesis of organopnicogen(III) species containing [RB(OH)O] or [R2BO] ligands.
  • Preliminary studies have been performed on the synthesis of non-coordinating anions as [B(C6F5)4] (or BArF) and [Al{OC(CF3)3}]. The compound [2-(Me2NCH2)C6H4Sb(O3SCF3)]2O, containing a fluorinated anion with low coordinating properties, was prepared and investigated by multinuclear NMR spectroscopy and mass spectrometry.
  • The reaction of RPnCl2 with potassium aryloxides was investigated and studies on the reactivity of the isolated compounds were performed.
The obtained results were so far disseminated through one published article; two other manuscripts are in the final stages of writing and will be sent for publication at beginning of 2022. In addition, part of the results obtained within this first stage of the project were within two oral presentations at international conferences.

Articles
  1. Synthesis, physicochemical properties, crystal molecular structure and DFT investigation of an organobismuth(III) bis(dimethyldithiocarbamate),
    A. Anton, A. Soran, C. Silvestru, J. Mol. Struct., 2021, 1247, 131335.
    DOI: 10.1016/j.molstruc.2021.131335
Conferences
  1. Aerobic decomposition of new NCN-type pincer organopnictogen(III) bis(arylthiolates),
    G. Duneș, C. Silvestru
    at The 24th Conference on Organometallic Chemistry (EuCOMC XXIV) (on-line), Alcala de Henares, Madrid, Spain, September 1st-3rd, 2021 (oral presentation).

  2. Hypercoordinated organopnicogen(III) (Sb, Bi) compounds - C-H bond activation and reactivity,
    A. Sava, G. Duneș, A. Pöllnitz, C. Silvestru
    at New trends and strategies in the chemistry of advanced materials, (on-line), Timișoara, Romania, October 7th-8th, 2021 (invited plenary lecture).

  3. Synthesis, physicochemical properties, crystal molecular structure and DFT investigation of an organobismuth(III) bis(dimethyldithiocarbamate),
    A. Anton, A. Soran, C. Silvestru
    at 13th International Conference Processes in Isotopes and Molecules (hybrid event), INCDTIM, Cluj-Napoca, September 22th-24th, 2021 (poster presentation).
Reports

For information about unpublished results contact Prof. Dr. Cristian Silvestru at cristian.silvestru (at) ubbcluj.ro.