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

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 chapter (expenses) 2021 (lei) 2022 (lei) 2023 (lei) Total
1 Salaries 204,000 252,022 240,000 696,022
2 Logistics 156,941.31 42,494.04 74,862 274,297.35
2.1 Capital expenses 100.881,14 2,080.9 74,862 177.824,04
2.2 Stocks expenses 54,164.24 39,696.31 0 93,860,55
2.3 Services 1,895.93 716.83 0 2,612.76
3 Mobility 971.42 13,507.96 15,000 29,479.38
4 Overhead 60,037.27 65,326 72,870 198,233.27
5 Total 421,950 373,350 402,732 1,198,032


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.

Stage 2 (January 2022 – December 2022) in the implementation of the project

The main results obtained during stage 2 of the project are summarized bellow:

  • Starting from the oxide [2-(Me2NCH2)C6H4SbO]3 a series of mononuclear organoantimony(III) aryloxides were obtained: [2-(Me2NCH2)C6H4]Sb(OAr)2 [Ar = C6H3-2-tBu-6-Me (68), C6H3Cl3-2,4,6 (69)] together with a dinuclear derivative [{2-(Me2NCH2)C6H4}Sb(OC6H2Cl3-2,4,6)]2O (70). The studies were completed with the synthesis of mononuclear chiral compounds [2-(Me2NCH2)C6H4]Sb(Cl)[(E=PPh2)2N] [E = S (74), Se (75)], with a dynamic behaviour evidenced by a vt 31P NMR investigation. These compounds will be used as starting materials to obtain ionic species with weak or non-coordinating anions;
  • Studies regarding organoantimony(V) derivatives which were obtained in the first stage of the project by oxidation of the organoantimony(III) species with o-chloranil were extended to other compounds, i.e. [2-(Me2NCH2)C6H4]Sb(pinF)(o-C6Cl4O2) (76) [pinF = OC(CF3)2(CF3)2O]2-];
  • Investigation of the monoorganopnicogen(III) bis(aryloxides), RSb(OC6H3iPr-2,6)2 (50), RSb[OC6H3(OMe)2-2,6]2 (51) and RBi[OC6H3(OMe)2-2,6]2 (53), [R = 2,6-(Me2NCH2)C6H3], was finished with a manuscript which is in the final stage before submission.
  • The structural and spectroscopic characterization of organopnictogen(III) bis(arylthiolates), [2,6-(Me2NCH2)2C6H3]Pn(SC6H3Me2-2,6)2 [Pn = Sb, Bi], [2,6-{MeN(CH2CH2)2NCH2}C6H3]Pn(SC6H3Me2-2,6)2 [Pn = Sb, Bi] and [2,6-{O(CH2CH2)2NCH2}C6H3]Pn(SC6H3Me2-2,6)2 [Pn = Sb, Bi] was now accomplished as the synthesis of these compounds was reported in a previous project (PN-III-P4-ID-PCE-2016-0857). Reactivity studies over chalcogens were performed for these derivatives giving ciclo-[{2,6-(Me2NCH2)2C6H3}Pn(μ-O)]2 [Pn = Sb (77), Bi (78)] or ciclo-[{2,6-(Me2NCH2)2C6H3}Pn(μ-E)]2 [E = S (79), Se (80)] and the disulfide ArS–SAr (Ar = C6H3Me2-2,6) and over elemental iodine with the isolation of the diiodide [2,6-{O(CH2CH2)2NCH2}C6H3]BiI2 (81) and an adduct 81∙0.5I2 formed via halogen bonds. The results were included in the paper Dalton Trans., 2022, 51, 10406-10419 (DOI: 10.1039/d2dt01436j)
  • The siloxide [2-(Me2NCH2)C6H4]2Bi(OSiPh3) was successfully prepared as only the second member of the organopnicogen(III) siloxides family. The compound was characterized by multinuclear NMR and its molecular structure was established by single-crystal X-ray diffraction.
  • The following types of ionic chiral species were also synthesized and characterized: [{2,6-(Me2NCH2)2C6H3}Pn(Cl)]+[X]-, [{2-(Me2NCH2)C6H4}Pn]+[X]- [{2-{2',6'-(iPr2C6H3)N=CH}C6H4}2Pn]+[X]-. Some of these compound were also investigated for their Mannich catalytic activity.
  • Studies on the C-H activation in reactions of organopnicogen(III) dihalides with KOC6H3tBu2-2,6 were also continued, as well as, the reactivity of the [2,6-(Me2NCH2)2C6H3]Sb(C6H3tBu2-3,5-O-4) towards CE2 (E = O, S).
  • The catalytic activity of some organoantimony(III) compounds was investigated on Mannich reaction of the benzaldehyde, aniline and cyclohexanone in different organic solvents.
  • Most of the new compounds were characterized by multinuclear NMR spectroscopy, MS spectrometry and single-crystal X-ray diffraction.
  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

  2. Organopnictogen(III) bis(arylthiolates) containing NCN-aryl pincer ligands: from synthesis and characterization to reactivity,
    G. Duneş, A. Soran, C. Silvestru, Dalton Trans., 2022, 51, 10406-10419.
    DOI: 10.1039/d2dt01436j

  3. [2,6-{O(CH2CH2)2NCH2}2C6H3]SbCl2 – a new pincer ligand-containing organoantimony(III) compound. Molecular structure and supramolecular aspects,
    G. Duneş, A. Soran, C. Silvestru, Rev. Roum. Chim., 2022, 67, 385-392.
    DOI: 10.33224/rrch.2022.67.6-7.05

  4. NCN-pincer organopnictogen(III) bis(aryloxides),
    G. Duneş, C. Silvestru, 2022, to be submitted.

  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).

  4. Organometallic chemistry of heavy pnicogens (Sb, Bi) at CCSOOM – FCIC (1993 – present) – from unusual structures to potential uses,
    C. Silvestru,
    at The 18th International Conference Students for Students, Cluj-Napoca, April, 6th-10th, 2022 (invited plenary lecture).

  5. Chimia organometalică a pnictogenilor grei (Sb, Bi) – de la structuri neobișnuite la utilizări potențiale,
    C. Silvestru,
    at Simpozionul „120 de ani de la nașterea Academicianului Costin D. Nenițescu”, Academia Română, București, September, 22th-23th, 2022 (invited plenary lecture).

  6. Novel organoantimony(III) aryloxides. Synthesis and reactivity,
    M.-C. Afloarei, M. Mehring, C. Silvestru,
    at A XXXVI-a Conferință Națională de Chimie, Călimănești-Căciulata, October, 4th-7th, 2022 (oral presentation).

  7. Arylantimony(III) nicotinates and isonicotinates. Synthesis and structural characterization,
    A. Tomuță, C. Silvestru, C. I. Raț
    at A XXXVI-a Conferință Națională de Chimie, Călimănești-Căciulata, October, 4th-7th, 2022 (poster presentation).

  8. Lewis acidic organoantimony(V) compounds with pendant arms,
    R. G. Dornea, C. I. Raț
    at A XXXVI-a Conferință Națională de Chimie, Călimănești-Căciulata, October, 4th-7th, 2022 (poster presentation).

  9. Organopnicogen(III) compounds containing Pn−chalcogen (Pn = Sb, Bi) - structure and reactivity,
    C. Silvestru,
    at The 14th Symposium “New Trends and Strategies in the Chemistry of Advanced Materials with Relevance in Biological systems, techniques and Environmental Protection”, Timișoara, October, 21st-22nd, 2022 (invited plenary lecture).

  10. Hypercoordinated organopnicogen(III) compounds containing Pn−E (Pn = Sb, Bi; E = O, S, Se) – structure and reactivity,
    C. Silvestru,
    at The 10th Workshop of the Selenium and Sulfur Redox and Catalysis Network (WSeS-10), Niteroi, Brazil, November, 25th-26th, 2022 (invited lecture).

  11. Hypercoordinate organoantimony(III) compounds with antimony-chalcogen bonds
    A. L. Corjuc, A. Farris, E. Kapronczai, V. Lippolis, C. Silvestru,
    at The 15th International Conference on the Chemistry of Selenium and Tellurium (ICCST-15), Florianopolis, Brazil, November, 28th- December, 2nd, 2022 (poster).

PhD Thesis
  1. Hypercoordinated organopnictogen(III) (Sb, Bi) compounds − structure and reactivity −,
    Gabriel-Iulian Duneş
    Scientific advisor: Acad. Prof. Dr. Cristian Silvestru
    Defended on: September, 30th, 2022.


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