Misplaced Pages

This is an old revision of this page, as edited by Hritwik1 (talk | contribs) at 02:06, 9 December 2024. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

This article, Stibinidene, has recently been created via the Articles for creation process. Please check to see if the reviewer has accidentally left this template after accepting the draft and take appropriate action as necessary. Reviewer tools: Inform author

Stibinidenes represent a class of organoantimony compounds in which the antimony center exhibits a formal oxidation state of +1. Structurally, stibinidenes adopt the general formula R–Sb, with the antimony center possessing two lone pairs of electrons and a vacant 5p orbital (Figure 1). Due to the unusual low oxidation state of antimony, stibinidenes are highly reactive and prone to oxidation, often transitioning to the more stable +3 oxidation state. Historically, stibinidenes were only known in their oligomeric forms or in coordination complexes with transition metal centers. In such coordination states, the reactive lone pair centers are effectively blocked, limiting the potential applications of these compounds. However, the use of sterically bulky ligands, such as 2,4,6-trisphenyl, 2,6-bis--4-phenyl, and various m-terphenyl ligands, has enabled the isolation of stable heavier-element dipnictenes of the general formula RSb=SbR. So, the synthesis of monomeric stibinidene molecules necessitates the combined application of kinetic and thermodynamic stabilization strategies. This approach has successfully yielded stabilized monomeric stibinidenes with carbene ligands , bulky N,C,N-pincer ligands, phosphine based and gallium based ligand. Based on computational studies, ⲡ-donating substituents, such as nitrogen- and phosphorus-based anionic ligands attached to the pnictogen atom, significantly stabilize the singlet ground state of stibinidenes. In this state, the molecule features one stereochemically inactive lone pair with predominantly s-character and another lone pair with predominantly p-character, accompanied by a vacant p orbital, making stibinidenes ambiphilic (Figure 1). In contrast, σ-type ligands, such as hydride and alkyl groups, favor the triplet ground state, where two unpaired electrons occupy two 5p orbitals and one lone pair resides in the 5s orbital. Notably, the isolation of a triplet stibinidene was achieved only recently using a highly bulky σ-type ligand, hydrindacene.

Synthesis

Transition metal-stabilized stibinidne

The earliest examples of stibinidene complexes involved the use of transition metal centers to stabilize the Sb(I) center. These methods typically utilized simple Sb(I) halides, alkyl, or aryl compounds coordinated to tungsten, manganese, iron, or chromium carbonyl complexes. One of the first reported transition metal stabilized stibinidenes, PhSb₂, was synthesized by Huttner et al. in 1978 from diiodostibane. Based on its unusual bond lengths, angles, and the trigonal planar geometry around the antimony atom, the authors proposed the presence of Sb–Mn π-bonding in this complex.  In 1984, the same group reported the synthesis of the first chloro substituted stibinidene complex, , which features a three-center, four-π-electron bond across both Sb–Cr bonds. Trigonal planar stibinidene complexes of the type (A, where M = Cr, Mo, W) are typically prepared via salt-elimination reactions between Na₂ and SbCl₃ (Scheme 1). However, these complexes are highly unstable due to the vacant p orbital on the antimony center and, in the case of M = Mo or W, cannot easily be isolated. To stabilize these complexes, they can be trapped using Lewis bases (LB), forming stable adducts with the general formula (B) (Scheme 1).  Interestingly, Huttner and colleagues also identified distibene complexes of the type ₃ as side products during stibinidene synthesis, particularly when non-donor solvents were used.  This observation highlights the critical role of donor molecules in stabilizing these compounds.

N,C,N-coordinated stibinidene

Monomeric stibinidenes were not stabilized in the absence of transition metal complexes until 2010, when Libor Dostál's research group reported the isolation of a formal Sb(I) center stabilized solely by an N,C,N-pincer ligand. The ligand employed was L = 2,6-bisphenyl. The synthesis of this complex was achieved by reacting the precursor molecule LSb(III)Cl₂ with two equivalents of the reducing agent K, resulting in the formation of isolable crystals of the stable monomeric stibinidene Sb via dihydrogen elimination (Scheme 2). In this system, coordination from the nitrogen centers provides thermodynamic stabilization to the Sb(I) center by delocalizing electron density, while the bulky N,C,N ligand introduces significant steric hindrance, which kinetically stabilizes the monomeric stibinidene by preventing dimerization or further reactions. Subsequently, other N,C,N-coordinating ligands were developed to produce stibinidenes, such as ArSb (where Ar = C₆H₃-2,6-(CH=NBu)₂ & Ar = C₆H₃-2,6-(CH=NDipp)₂) which gained prominence in studies on stibinidene reactivity. These compounds are occasionally referred to as "Dostál's stibinidene" due to their pivotal role in this area of chemistry. Dostál's stibinidene has found widespread application as a ligand for transition metal compounds and in catalysis, significantly advancing the utility of stibinidenes in modern organometallic chemistry.

Carbene stabilized stibinidene

In 2014, Hudnall et al. reported the isolation of a novel diamidocarbene (DAC)-stabilized stibinidene containing a monomeric Sb(I) center. The synthesis involved the reaction of phenylantimony dichloride, stabilized by a DAC, with magnesium powder in THF at room temperature (Scheme 3). This process yielded stable, isolable, fluorescent red crystals of the carbene-stabilized stibinidene, (DAC)Sb-Ph. Despite the exocyclic Sb(I) center being exposed, the compound exists as a monomer, with its stability attributed to the strong backbonding between the DAC and the antimony center. The steric bulk of the mesityl group in the carbene further contributes to the compound's kinetic stability. Density functional theory (DFT) calculations revealed that the stability of the compound arises from partial double bond character between the carbene carbon and the Sb(I) center. This is attributed to backbonding from the antimony center into the vacant p orbital of the carbene. In the same year, Guy Bertrand's group achieved the stabilization of a chloro-substituted stibinidene using a cyclic alkyl(amino)carbene (CAAC) ligand. The synthesis started with a CAAC-coordinated SbCl₃, which was reduced with two equivalents of KC₈ to yield the desired stibinidene complex. More recently, the first phosphine stabilized stibinidene, (o-PPh₂)C₆H₄(Ar*)Ge(Cl)Sb (E, where Ar* = 2,6-Trip₂C₆H₃), was reported. This unique compound was obtained by the reduction of a cyclic SbCl₂ germylene-phosphine complex.

Reactivity

Theoretically, singlet stibinidenes are ambiphilic due to the presence of both empty and filled 5p orbitals, which respectively confer Lewis acidic and Lewis basic character. However, N,C,N-pincer-coordinated stibinidenes exhibit diminished Lewis acidity because of n_N → p*_Sb donor-acceptor interactions. Despite this reduction in Lewis acidity, Dostál’s stibinidene remains widely utilized in reactivity studies. In contrast, carbene-stabilized stibinidenes show significantly reduced reactivity as strong electron donation from the carbene ligand diminishes the Lewis acidic nature, while strong back-donation from the Sb center to the carbene weakens their Lewis basicity. Due to their ambiphilic nature, Dostál’s stibinidenes are capable of activating small molecules, like disulfides, through oxidative addition. This reactivity arises from their ability to donate electron density to the LUMO of small molecules while simultaneously accepting electron density into the vacant 5p orbital. Dostál's N,C,N-coordinated stibinidene ArSb (where Ar = C₆H₃-2,6-(CH=NtBu)₂) has been reported to act as a catalyst in the hydroboration of disulfides (Scheme 5). This reactivity exploits the ability of the stibinidene to reversibly interconvert between Sb(I) and Sb(III) oxidation states under the reaction conditions. The catalytic cycle involves the oxidative addition of disulfides to the Sb(I) center, followed by reductive elimination to regenerate the active species, enabling efficient hydroboration. As of 2024, this is the only reported example of catalysis involving stibinidene, demonstrating its potential in organometallic catalysis. Notably, triplet stibinidenes exhibit a distinct mode of reactivity. Acting as diradicals, they can react with small molecules such as alkynes and butadienes, forming antimony-substituted heterocycles, including three-membered and five-membered rings respectively (Scheme 4).

Small molecule activation and catalysis

As discussed, Dostál’s stibinidenes demonstrate significant potential for small molecule activation. The first example was reported in 2017 by Stephan Schulz and co-workers. In this study, the stibinidene ArSb (where Ar = C₆H₃-2,6-(CH=NtBu)₂) reacted with E₂Ph₂ (E = S, Se), resulting in the oxidative addition product ArSb(EPh)₂ via cleavage of the E–E bond in E₂Ph₂ (Scheme 5). Building on this work, Jiliang Zhou's group developed a catalytic cycle using this oxidized product (Scheme 5). They reacted it with pinacolborane at 70°C in benzene-d₆ to produce sulfidoborates and thiophenol derivatives. These products were subsequently utilized in situ with α,β-unsaturated carbonyl compounds to facilitate Michael addition reactions, with the stibinidene acting as a base catalyst. In situ generated transient stibinidene, formed from the dissociation of a sterically distorted distibene stabilized by the bulky MFluind ligand and reported by Cornella et al., exhibits remarkable small molecule activation. Under a 1.2 bar atmosphere of H₂ or ethylene at 60°C, the distibene was converted into the corresponding antimony dihydride or stibacyclopropane, respectively, via a transient stibinidene intermediate. NMR studies confirmed that this transient stibinidene adopts a triplet electronic configuration, allowing it to activate small molecules in a diradical fashion. Similarly, the reactivity of an isolated triplet stibinidene was observed by G. Tan's group. Acting as diradicals, this stibinidene react with small molecules such as 2,3-dimethyl-1,3-butadiene and 4-tetrabutylphenylacetylene, leading to the formation of antimony-substituted heterocycles, including five-membered and three-membered rings.

Hetero Diels-Alder reaction with alkynes

The Dostál group demonstrated that N,C,N-pincer-coordinated stibinidenes can act as masked heterocyclic dienes. When treated with the electron-deficient alkyne dimethyl acetylenedicarboxylate (DMAD), these stibinidenes undergo a hetero Diels–Alder cycloaddition reaction (Scheme 6). This transformation yields a CO₂Me-disubstituted 1-stiba-1,4-dihydro-iminonaphthalene, effectively converting one of the pendant imine arms of the stibinidene into a nitrogen-bridged stibacyclohexadiene. In this product, the Sb(III) atom serves as a bridgehead, while the second imine arm loses coordination with the Sb(III) center. Additionally, similar cycloaddition reactions were observed between Dostal's stibinidene and other substrates, such as methyl propiolate and N-alkyl/aryl-maleimides, RN(C(O)CH)₂ (R = Me, Bu, Ph).  These findings highlight the reactivity of stibinidenes as dienes, expanding their utility in cycloaddition chemistry.

Transition chemistry

The presence of exposed lone pairs in N,C,N-coordinated stibinidenes grants these compounds significant potential as ligands for transition compounds, where they can act as 2-electron (2e) or 4-electron (4e) L-type donors (Scheme 7). Initial studies on their coordination properties focused on Group 6 transition metals and iron carbonyls, leading to the formation of 1:1 complexes. DFT analysis revealed that N,C,N-chelated stibinidene, function exclusively as 2e σ-donors through their p-type lone pairs. This unique electronic behavior is reflected in their perpendicular coordination geometry, which markedly differs from coordination chemistry of the traditional trivalent Sb(III) analogs such as R₃Sb. Subsequent investigations utilizing manganese and cobalt carbonyl complexes allowed the isolation of 2:1 coordination compounds. However, the ligands coordination mode, involving the p-type orbital, remained unchanged. Further exploration extended the study to Rh(I) and Ir(I) complexes, broadening the scope of these ligands coordination versatility. Among Group 10 metals, Pd(II) and Pt(II) complexes featuring stibinidenes as ancillary ligands have also been synthesized. An intriguing outcome was observed with allyl palladium complexes, ₂, treated with the stibinidene ligand. This reaction produced both 1:1 and dinuclear complexes, the latter featuring two palladium fragments bridged by a single antimony atom. In these dinuclear species, the stibinidene functions as a 4e donor via two nearly equivalent sp hybrid orbitals, highlighting its ability to switch between 2e and 4e coordination modes depending on stoichiometry. The coordination chemistry of gold(I) has also been investigated. While many of the resulting complexes exhibited lability and decomposition into elemental gold, a few stable complexes were isolated, particularly with AuCl and IPr-stabilized Au(I) cations. These findings demonstrate the adaptability and multifaceted coordination behavior of N,C,N-coordinated stibinidenes across various transition metal systems.

Stibinidene cation:

A significant advancement in the field of pnictogen chemistry was achieved when the first stable stibinidene cation, isoelectronic with carbones, was isolated by Herbert W. Roesky group (Scheme 8) in 2021. The stibinidene cation features a formal +1 oxidation state at the antimony center and an overall molecular charge of +1. The synthesis was carried out using one equivalent of SbX₃ (X = F, Cl), two equivalents of the reducing agent KC₈, and one equivalent of LiOTf, with stabilization provided by the addition of an IPr CAAC ligand. This process resulted in the formation of a CAAC-stabilized Sb(I) cation. Previously, attempts to stabilize Sb(I) cations were made using a bis(diisopropylamino)cyclopropenylidene ligand. However, the resulting species was obtained in low yield and exhibited significant instability, undergoing decomposition. Subsequently, Majumdar et al. reported the isolation of an Sb(I) cation stabilized with a diphosphine ligand. In this synthesis, SbCl₃, the bis(phosphine) ligand, and trimethylsilyl trifluoromethanesulfonate were reacted in a 1:2:3 ratio at room temperature. The bis(phosphine) ligand was found to act as both a reductant and a supporting ligand. Despite the overall positive charge of the Sb(I) site, it was observed to bind metal centers, forming complexes with Au(I), Ag(I), and Cu(I). Further progress was made by Zhenbo et al., who isolated an Sb(I) cation stabilized by a bis-silylene ligand. The lone pair on the Sb(I) center in this species was shown to coordinate with Cr and Mo carbonyls. Additionally, the group led by Ingo Krossing succeeded in isolating an Sb(I) cation supported by a bisiminopyridine ligand. These findings underscore the versatility of Sb(I) cations and their capacity to form diverse coordination complexes.

References

1. ^ Šimon, Petr; de Proft, Frank; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2010). "Monomeric Organoantimony(I) and Organobismuth(I) Compounds Stabilized by an NCN Chelating Ligand: Syntheses and Structures". Angewandte Chemie International Edition. 49 (32): 5468–5471. doi:10.1002/anie.201002209. ISSN 1521-3773.
2. ^ Wu, Mengyuan; Li, Hao; Chen, Wang; Wang, Dongmin; He, Yuhao; Xu, Lei; Ye, Shengfa; Tan, Gengwen (2023-09-14). "A triplet stibinidene". Chem. 9 (9): 2573–2584. doi:10.1016/j.chempr.2023.05.005. ISSN 2451-9294.
3. Breunig, Hans Joachim; Rösler, Roland (2000). "New developments in the chemistry of organoantimony and -bismuth rings". Chemical Society Reviews. 29 (6): 403–410. doi:10.1039/a908785k.
4. ^ Rummel, Lena; Seidl, Michael; Timoshkin, Alexey Y.; Scheer, Manfred (2022). "Reactivity of the stibinidene complex [ClSbCr(CO)52(thf)]". Zeitschrift für anorganische und allgemeine Chemie. 648 (13): e202200014. doi:10.1002/zaac.202200014. ISSN 1521-3749.
5. Roller, Clara A.; Doler, Berenike; Steller, Beate G.; Saf, Robert; Fischer, Roland C. (2024). "A Distibene with Extremely Long Sb=Sb Distance and Related Heavier Dipnictenes from Salt-Free Metathesis Reactions". European Journal of Inorganic Chemistry. 27 (10): e202300586. doi:10.1002/ejic.202300586. ISSN 1099-0682.
6. ^ Dorsey, Christopher L.; Mushinski, Ryan M.; Hudnall, Todd W. (2014). "Metal-Free Stabilization of Monomeric Antimony(I): A Carbene-Supported Stibinidene". Chemistry – A European Journal. 20 (29): 8914–8917. doi:10.1002/chem.201403578. ISSN 1521-3765.
7. ^ Kretschmer, Robert; Ruiz, David A.; Moore, Curtis E.; Rheingold, Arnold L.; Bertrand, Guy (2014). "One-, Two-, and Three-Electron Reduction of a Cyclic Alkyl(amino)carbene–SbCl3 Adduct". Angewandte Chemie International Edition. 53 (31): 8176–8179. doi:10.1002/anie.201404849. ISSN 1521-3773.
8. ^ Raiser, Dominik; Eichele, Klaus; Schubert, Hartmut; Wesemann, Lars (2021). "Phosphine-Stabilized Pnictinidenes". Chemistry – A European Journal. 27 (56): 14073–14080. doi:10.1002/chem.202102320. ISSN 1521-3765. PMC 8518042. PMID 34291518.{{cite journal}}: CS1 maint: PMC format (link)
9. Krüger, Julia; Wölper, Christoph; Auer, Alexander A.; Schulz, Stephan (2022). "Formation and Cleavage of a Sb−Sb Double Bond: From Carbene-Coordinated Distibenes to Stibinidenes". European Journal of Inorganic Chemistry. 2022 (3): e202100960. doi:10.1002/ejic.202100960. ISSN 1099-0682.
10. ^ von Seyerl, Joachim; Huttner, Gottfried (1978). "C6H5Sb[Mn(CO)2C5H5]2—The first Compound Containing Trigonal-Planar Coordinated Antimony(I)". Angewandte Chemie International Edition in English. 17 (11): 843–844. doi:10.1002/anie.197808431. ISSN 1521-3773.
11. Weber, Ute; Zsolnai, Laszlo; Huttner, Gottfried (1984-01-17). "Stibinidenkomplexe: Verbindungen mit trigonal planar koordiniertem antimon". Journal of Organometallic Chemistry. 260 (3): 281–291. doi:10.1016/S0022-328X(00)99477-4. ISSN 0022-328X.
12. ^ Sigwarth, Beate; Weber, Ute; Zsolnai, Laszlo; Huttner, Gottfried (1985). "Abfangreaktionen für Arsiniden- und Stibiniden-Komplexe: Addition von Lewisbasen an [(CO)5M]2XR (XAs, Sb; MCr, Mo, W)". Chemische Berichte (in German). 118 (8): 3114–3126. doi:10.1002/cber.19851180810. ISSN 1099-0682.
13. Weber, Ute; Huttner, Gottfried; Scheidsteger, Olaf; Zsolnai, Laszlo (1985-07-09). "Valenztautomerie an stibiniden-komplexen. Synthese von stiban und distiben-komplexen". Journal of Organometallic Chemistry. 289 (2): 357–366. doi:10.1016/0022-328X(85)87412-X. ISSN 0022-328X.
14. Vránová, Iva; Alonso, Mercedes; Jambor, Roman; Růžička, Aleš; Erben, Milan; Dostál, Libor (2016). "Stibinidene and Bismuthinidene as Two-Electron Donors for Transition Metals (Co and Mn)". Chemistry – A European Journal. 22 (22): 7376–7380. doi:10.1002/chem.201601272. ISSN 1521-3765.
15. Zechovský, Jan; Kertész, Erik; Erben, Milan; Hejda, Martin; Jambor, Roman; Růžička, Aleš; Benkő, Zoltán; Dostál, Libor (2024). "Palladium(II) and Platinum(II) Bis(Stibinidene) Complexes with Intramolecular Hydrogen-Bond Enforced Geometries". ChemPlusChem. 89 (5): e202300573. doi:10.1002/cplu.202300573. ISSN 2192-6506.
16. ^ Ganesamoorthy, Chelladurai; Wölper, Christoph; Dostál, Libor; Schulz, Stephan (2017-09-15). "Syntheses and structures of N,C,N-stabilized antimony chalcogenides". Journal of Organometallic Chemistry. Organometallic Chemistry of Pincer Complexes. 845: 38–43. doi:10.1016/j.jorganchem.2017.01.007. ISSN 0022-328X.
17. ^ Huang, Minghao; Li, Kunlong; Zhang, Zichen; Zhou, Jiliang (2024-07-24). "Antimony Redox Catalysis: Hydroboration of Disulfides through Unique Sb(I)/Sb(III) Redox Cycling". Journal of the American Chemical Society. 146 (29): 20432–20438. doi:10.1021/jacs.4c05905. ISSN 0002-7863.
18. ^ Pang, Yue; Leutzsch, Markus; Nöthling, Nils; Cornella, Josep (2023). "Dihydrogen and Ethylene Activation by a Sterically Distorted Distibene". Angewandte Chemie International Edition. 62 (32): e202302071. doi:10.1002/anie.202302071. ISSN 1521-3773.
19. ^ Kořenková, Monika; Kremláček, Vít; Hejda, Martin; Turek, Jan; Khudaverdyan, Raffi; Erben, Milan; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2020). "Hetero Diels–Alder Reactions of Masked Dienes Containing Heavy Group 15 Elements". Chemistry – A European Journal. 26 (5): 1144–1154. doi:10.1002/chem.201904953. ISSN 1521-3765.
20. ^ Kremláček, Vít; Hejda, Martin; Rychagova, Elena; Ketkov, Sergey; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2021). "Probing Limits of a C=C Bond Activation by N-Coordinated Organopnictogen(I) Compounds". European Journal of Inorganic Chemistry. 2021 (38): 4030–4041. doi:10.1002/ejic.202100648. ISSN 1099-0682.
21. ^ Vránová, Iva; Kremláček, Vít; Erben, Milan; Turek, Jan; Jambor, Roman; Růžička, Aleš; Alonso, Mercedes; Dostál, Libor (2017). "A comparative study of the structure and bonding in heavier pnictinidene complexes [(ArE)M(CO) n ] (E = As, Sb and Bi; M = Cr, Mo, W and Fe)". Dalton Transactions. 46 (11): 3556–3568. doi:10.1039/C7DT00095B. ISSN 1477-9226.
22. ^ Dostál, Libor; Jambor, Roman; Aman, Michal; Hejda, Martin (2020). "(N),C,N-Coordinated Heavier Group 13–15 Compounds: Synthesis, Structure and Applications". ChemPlusChem. 85 (10): 2320–2340. doi:10.1002/cplu.202000620. ISSN 2192-6506.
23. ^ Vránová, Iva; Alonso, Mercedes; Jambor, Roman; Růžička, Aleš; Erben, Milan; Dostál, Libor (2016). "Stibinidene and Bismuthinidene as Two-Electron Donors for Transition Metals (Co and Mn)". Chemistry – A European Journal. 22 (22): 7376–7380. doi:10.1002/chem.201601272. ISSN 1521-3765.
24. ^ Kořenková, Monika; Kremláček, Vít; Erben, Milan; Jambor, Roman; Růžičková, Zdeňka; Dostál, Libor (2017-09-15). "Reactions of N,C,N-chelated pnictinidenes with Rh(I) and Ir(I) complexes: Coordination vs. Transmetalation". Journal of Organometallic Chemistry. Organometallic Chemistry of Pincer Complexes. 845: 49–54. doi:10.1016/j.jorganchem.2017.02.022. ISSN 0022-328X.
25. ^ Kořenková, Monika; Hejda, Martin; Štěpnička, Petr; Uhlík, Filip; Jambor, Roman; Růžička, Aleš; Dostál, Libor (2018). "Synthesis and non-conventional structure of square-planar Pd( ii ) and Pt( ii ) complexes with an N , C , N -chelated stibinidene ligand". Dalton Transactions. 47 (16): 5812–5822. doi:10.1039/C8DT00714D. ISSN 1477-9226.
26. ^ Kořenková, Monika; Hejda, Martin; Jirásko, Robert; Block, Theresa; Uhlík, Filip; Jambor, Roman; Růžička, Aleš; Pöttgen, Rainer; Dostál, Libor (2019). "Antimony( i ) → Pd( ii ) complexes with the (μ-Sb)Pd 2 coordination framework". Dalton Transactions. 48 (31): 11912–11920. doi:10.1039/C9DT02340B. ISSN 1477-9226.
27. ^ Kořenková, Monika; Kremláček, Vít; Erben, Milan; Jirásko, Robert; De Proft, Frank; Turek, Jan; Jambor, Roman; Růžička, Aleš; Císařová, Ivana; Dostál, Libor (2018). "Heavier pnictinidene gold( i ) complexes". Dalton Transactions. 47 (41): 14503–14514. doi:10.1039/C8DT03022G. ISSN 1477-9226.
28. Siddiqui, Mujahuddin M.; Sarkar, Samir Kumar; Nazish, Mohd; Morganti, Massimiliano; Köhler, Christian; Cai, Jiali; Zhao, Lili; Herbst-Irmer, Regine; Stalke, Dietmar; Frenking, Gernot; Roesky, Herbert W. (2021-01-27). "Donor-Stabilized Antimony(I) and Bismuth(I) Ions: Heavier Valence Isoelectronic Analogues of Carbones". Journal of the American Chemical Society. 143 (3): 1301–1306. doi:10.1021/jacs.0c12084. ISSN 0002-7863.
29. Zhou, Jiliang; Kim, Hyehwang; Liu, Liu Leo; Cao, Levy L.; Stephan, Douglas W. (2020). "An arene-stabilized η 5 -pentamethylcyclopentadienyl antimony dication acts as a source of Sb + or Sb 3+ cations". Chemical Communications. 56 (85): 12953–12956. doi:10.1039/D0CC02710C. ISSN 1359-7345.
30. Kumar, Vikas; Gonnade, Rajesh G.; Yildiz, Cem B.; Majumdar, Moumita (2021). "Stabilization of the Elusive Antimony(I) Cation and Its Coordination Complexes with Transition Metals". Angewandte Chemie International Edition. 60 (48): 25522–25529. doi:10.1002/anie.202111339. ISSN 1521-3773.
31. Wang, Xuyang; Lei, Binglin; Zhang, Zhaoyin; Chen, Ming; Rong, Hua; Song, Haibin; Zhao, Lili; Mo, Zhenbo (2023-05-23). "Isolation and characterization of bis(silylene)-stabilized antimony(I) and bismuth(I) cations". Nature Communications. 14 (1). doi:10.1038/s41467-023-38606-2. ISSN 2041-1723. PMC 10206093. PMID 37221189.{{cite journal}}: CS1 maint: PMC format (link)
32. Schorpp, Marcel; Tamim, Razan; Krossing, Ingo (2021). "Oxidative addition, reduction and reductive coupling: the versatile reactivity of subvalent gallium cations". Dalton Transactions. 50 (42): 15103–15110. doi:10.1039/D1DT02682H. ISSN 1477-9226.

• Pending AfC submissions
• Pending AfC submissions in article space
• AfC submissions by date/09 December 2024