Aluminium(I)

Last updated January 01, 2021

In chemistry, aluminium(I) refers to monovalent aluminium (+1 oxidation state) in both ionic and covalent bonds. Along with aluminium(II), it is an extremely unstable form of aluminium.

While late Group 3 elements such as thallium and indium prefer the +1 oxidation state, aluminium(I) is rare. Unlike late Group XIII elements, aluminium does not experience the inert pair effect, a phenomenon where valence s electrons are poorly shielded from nuclear charge due to the presence of filled d and f orbitals.^[1] As such, aluminium (III) ( ${\ce {Al^3+}}$ ) is the much more common oxidation state for aluminium.

Aluminium(I) compounds are both prone to disproportionation and difficult to prepare.^[2] At standard conditions, they readily oxidize to the aluminium(III) form.

Characteristics

Al(I) appears to be red, as solutions of AlBr and AlCl in organic solvents are both red.^[4] The presence of this color implies a relatively small HOMO/LUMO gap that is accessible by green light.^[5]

The geometry of compounds can be determined by analysis of the fine structure of the electronic spectra.^[2] Matrix isolation spectroscopy prevents disproportionation of aluminium monohalides and thus allows for the measuring of transitional vibrations as well as reactivity with molecules such as O₂.^[2]^[6]

Analysis by ²⁷Al NMR spectroscopy of AlCl, AlBr, and AlI in toluene/diethyl ether at room temperature reveal two signals: one very broad signal at δ = 100-130 ppm (regardless of the halogen), and one at higher field strength (AlCl: δ = + 30, AlBr: δ = + 50, AlI: δ = + 80).^[2] The first signal corresponds to a donor-stabilized four-coordinate aluminium species, while the identity of the latter is inconclusive.^[2]

Monohalides

The aluminium(I) cation reacts with hydrogen halides to form the following aluminium monohalides:^[1]

These compounds are only thermodynamically stable at high temperatures and low pressures in the singlet ground state.^[7] However, decomposition can be prevented by making disproportionation kinetically unfavorable. Under cold temperatures (below 77 K), disproportionation is slow enough that the AlCl solid can be kept for long periods of time.^[1]

Synthesis

AlCl is synthesized by reaction of liquid aluminium with gaseous HCl at 1200 K and 0.2 mbar to yield gaseous AlCl and hydrogen gas.^[1] At 77 K, AlCl is a dark red solid which turns black upon disproportionation at temperatures higher than 180 K. At temperatures under 77 K and dissolved in a matrix of polar and non-polar solvents, it exists as a metastable solution whose reactivity can be studied. AlBr, a red oil, is prepared similarly from liquid aluminium metal and gaseous HBr.^[4]

${\ce {Al (l) + HCl (g) -> AlCl (g) + 1/2 H2 (g)}}$

Due to the nature of HF, which possesses a bond much stronger than that of its congeners,^[8] AlF is synthesized instead by the comproportionation of Al and AlF₃ which are pressed and mixed into pellets.^[9] The pellets are then loaded into a graphite furnace and heated to 1050 K.^[9]

${\ce {2 Al (s) + AlF3 (s) -> 3 AlF (g)}}$

Stability increases with mass: while AlCl decomposes at 77 K or above, AlBr remains stable up to 253 K.^[1]^[4] Remarkably, it has been discovered that at any given temperature, the vapor pressure of AlF is orders of magnitude lower than that of other aluminium monohalides.^[9]

Disproportionation

At room temperature, AlX compounds tend to disproportionate to Al and AlX₃. When dark red, solid AlCl is allowed to warm up, it turns black to yield aluminium metal and the more stable aluminium (III) chloride salt.^[1]

${\ce {2 AlCl (s)-> Al (s) +AlCl3 (s)}}$

Dohmier et. all documented that the exception is AlBr. AlBr is stable enough at temperatures under -30 C that it comproportionates to AlBr₂ in the presence of AlBr₃.^[2]

${\ce {AlBr (s) + AlBr3 (s) -> 2 AlBr2 (s)}}$

Oligomerization

In Lewis basic solutions, AlX compounds have a tendency to oligomerize.^[2]

Complex Chemistry

Aluminium is not only the most abundant metal in the earth's crust, but also an element of low toxicity. As such, aluminium (I) complexes attract considerable interest. These complexes can be supported by various ligands and used to activate small molecules.

β-Diketiminato Systems

In 2018, Liu et. al reviewed the chemistry of aluminium (I) with β-diketiminato ligands,^[10] widely used ligands with immense versatility in electronic and steric properties. These aluminium (I) complexes have immense potential for small molecule activation.^[10]

Synthesis

β-diketiminato aluminium alkyls and aluminium halides are synthesized by adding a trialkyl aluminium compound to the initial β-diketiminate ligands, adding iodine, and the reducing with potassium.^[10]

[1+2] Cycloadditions

Al(I) compounds exhibit behavior analogous to that of singlet carbenes.^[10] Like carbenes, they undergo [1+2] cycloadditions with alkynes and azides to afford three membered ring derivatives such as dialuminacyclohexadiene.^[1]^[10]

Similarly to the nucleophilic carbon center in the carbene, the lone pair on the aluminium center binds to the first azide equivalent. Nitrogen gas is liberated. With the second equivalent of azide, a five-member ring is formed.

Reactions with Other Small Molecules

Such aluminium (I) complexes can activate water as well as elemental phosphorus, oxygen, and sulfur to yield bridged dimers. This occurs via partial reduction of the elemental small molecule.^[10]

AlCp*

AlCp*, consisting of aluminium (I) bonded with the pentamethylcyclopentadiene anion ((CCH3)₅⁻), was first synthesized in 1991 by Dohmier et al.^[12] (AlCp*)_4, a yellow crystalline solid, is first produced from the combination of AlCl and MgCp*_2.^[6] When vaporized, the long Al-Al bonds (276.9 pm)^[12] split, and monomeric molecules of [AlCp*] are created.

As revealed through Schnockel's work, [AlCp*] reacts by inserting itself into other bonds. Reaction with Al₂I₆ yields subvalent halide species; reaction with As₄tBu₄ yields As-Al bonds.^[6] When reacted with transition metal-cyclopentadienyl complexes such as NiCp₂, it offers a straightforward pathway to compounds containing aluminium-transition metal bonds, which has great potential for important catalytic reactions.^[2]

The LUMO orbitals of CO are shown here. These orbitals are antibonding p orbitals. Carbon-monoxide-LUMO-phase-3D-balls.png — The LUMO orbitals of CO are shown here. These orbitals are antibonding π orbitals.

As with other AlR ligands, [AlCp*] can be regarded as a CO analogue, as it possesses 2 empty π orbitals and engages in similar coordination modes (terminal and bridging).^[6] This similarity implies the possibility of pi backbonding interactions between AlCp*and metals it complexes to.

Metalloidal Clusters

Work in aluminium clusters has been done by Linti and Schnockel. These metalloidal clusters can be formed from Al(I) compounds, namely aluminium monohalides. These clusters are termed "metalloidal clusters" because the number of unbridged metal-metal bonds is greater than the number of localized metal-ligand bonds. On the way to metal formation, intermediates are trapped in the presence of the bulky ligands which substitute the halide atoms.^[6]^[1] As a result, metal-rich clusters such as Al₇₇R₂₀ are possible and offer insight into solid bulk metal formation.^[6]

Tetrahedral aluminium is available from the reaction between aluminium(I) species and organometallic species.^[6] These clusters can be made through combinations such as AlCp* and LiR, AlBr and Li(THF)₃(SiMe₃)_3, and AlI and NaSiBu₃.^[6]

Formation of tetrahedral aluminium. Alcptet.png — Formation of tetrahedral aluminium.

This method of cluster formation created the only known incidence of an octahedral aluminium cluster, [Al₆(tBu)₆]⁻, which was formed by reaction between AlCl and ^tBuLi.^[6] Similarly, AlCl and LiN(SiMe₃)₂ react to form the first known example of a cluster where two M₄ tetrahedra are connected by a common center.^[6]

Natural Occurrence

Aluminium is rarely found in its +1 oxidation state in nature due to the immense stability of the +3 oxidation state.

Rotational transitions of AlF and AlCl have been detected in circumstellar shells near IRC +10216.^[9]^[13] The presence of AlF suggests that fluorine is produced in helium shell flashes instead of explosive nucleosynthesis.^[13]

Related Research Articles

An interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.

Aluminium chloride (AlCl₃), also known as aluminium trichloride, describe compounds with the formula AlCl₃(H₂O)_n (n = 0 or 6). They consist of aluminium and chlorine atoms in a 1:3 ratio, and one form also contains six waters of hydration. Both are white solids, but samples are often contaminated with iron(III) chloride, giving a yellow color.

A superatom is any cluster of atoms that seem to exhibit some of the properties of elemental atoms.

In chemistry, an atom cluster is an ensemble of bound atoms or molecules that is intermediate in size between a simple molecule and a nanoparticle; that is, up to a few nanometers (nm) in diameter. The term microcluster may be used for ensembles with up to couple dozen atoms.

Aluminium bromide is any chemical compound with the empirical formula AlBr_x. Aluminium tribromide is the most common form of aluminium bromide. It is a colorless, sublimable hygroscopic solid; hence old samples tend to be hydrated, mostly as aluminium tribromide hexahydrate (AlBr₃·6H₂O).

Aluminium monofluoride is the chemical compound with the formula AlF. This elusive species is formed by the reaction between aluminium trifluoride and metallic aluminium at elevated temperatures but quickly reverts to the reactants when cooled. Clusters derived from related aluminium(I) halides can be stabilized using specialized ligands.

Aluminium iodide is a chemical compound containing aluminium and iodine. Invariably, the name refers to a compound of the composition $AlI 3$ , formed by the reaction of aluminium and iodine or the action of $HI$ on $Al$ metal. The hexahydrate is obtained from a reaction between metallic aluminum or aluminum hydroxide with hydrogen iodide or hydroiodic acid. Like the related chloride and bromide, $AlI 3$ is a strong Lewis acid and will absorb water from the atmosphere. It is employed as a reagent for the scission of certain kinds of C-O and N-O bonds. It cleaves aryl ethers and deoxygenates epoxides.

Organoaluminium chemistry is the study of compounds containing bonds between carbon and aluminium bond. It is one of the major themes within organometallic chemistry. Illustrative organoaluminium compounds are the dimer trimethylaluminium, the monomer triisobutylaluminium, and the titanium-aluminium compound called Tebbe's reagent. The behavior of organoaluminium compounds can be understood in terms of the polarity of the C−Al bond and the high Lewis acidity of the three-coordinated species. Industrially, these compounds are mainly used for the production of polyolefins.

There are three sets of Indium halides, the trihalides, the monohalides, and several intermediate halides. In the monohalides the oxidation state of indium is +1 and their proper names are indium(I) fluoride, indium(I) chloride, indium(I) bromide and indium(I) iodide.

Polysilicon halides are silicon-backbone polymeric solids. At room temperature, the polysilicon fluorides are colorless to yellow solids while the chlorides, bromides, and iodides are, respectively, yellow, amber, and red-orange. Polysilicon dihalides (perhalo-polysilenes) have the general formula (SiX₂)_n while the polysilicon monohalides (perhalo-polysilynes) have the formula (SiX)_n, where X is F, Cl, Br, or I and n is the number of monomer units in the polymer.

Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. Covalently bonded metal halides may be discrete molecules, such as uranium hexafluoride, or they may form polymeric structures, such as palladium chloride.

Molecular oxohalides (oxyhalides) are a group of chemical compounds in which both oxygen and halogen atoms are attached to another chemical element A in a single molecule. They have the general formula AO_mX_n, X = F, Cl, Br, I. The element A may be a main group element, a transition element or an actinide. The term oxohalide, or oxyhalide, may also refer to minerals and other crystalline substances with the same overall chemical formula, but having an ionic structure.

Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.

A borylene is the boron analogue of a carbene. The general structure is R-B: with R an organic residue and B a boron atom with two unshared electrons. Borylenes are of academic interest in organoboron chemistry. A singlet ground state is predominant with boron having two vacant sp² orbitals and one doubly occupied one. With just one additional substituent the boron is more electron deficient than the carbon atom in a carbene. For this reason stable borylenes are more uncommon than stable carbenes. Some borylenes such as boron monofluoride (BF) and boron monohydride (BH) the parent compound also known simply as borylene, have been detected in microwave spectroscopy and may exist in stars. Other borylenes exist as reactive intermediates and can only be inferred by chemical trapping.

An N-Heterocyclic Silylene (NHSi) is an uncharged heterocyclic chemical compound consisting of a divalent silicon atom bonded to two nitrogen atoms. The isolation of the first stable NHSi, also the first stable dicoordinate silicon compound, was reported in 1994 by Michael Denk and Robert West three years after Anthony Arduengo first isolated an N-heterocyclic carbene, the lighter congener of NHSis. Since their first isolation, NHSis have been synthesized and studied with both saturated and unsaturated central rings ranging in size from 4 to 6 atoms. The stability of NHSis, especially 6π aromatic unsaturated five-membered examples, make them useful systems to study the structure and reactivity of silylenes and low-valent main group elements in general. Though not used outside of academic settings, complexes containing NHSis are known to be competent catalysts for industrially important reactions. This article focuses on the properties and reactivity of five-membered NHSis.

(Pentamethylcyclopentadienyl)aluminium(I) is an organometallic compound with the formula Al(C₅Me₅) ("Me" is a methyl group; CH₃). The compound is often abbreviated to AlCp* or Cp*Al, where Cp* is the pentamethylcyclopentadienide anion (C₅Me₅⁻). Discovered in 1991 by Dhmeier et al., AlCp* serves as the first ever documented example of a room temperature stable monovalent aluminium compound. In its isolated form, Cp*Al exists as the tetramer [Cp*Al]₄, and is a yellow crystal that decomposes at temperatures above 100 °C but also sublimes at temperatures above 140 °C.

Aluminium (or aluminum) combines characteristics of pre- and post-transition metals. Since it has few available electrons for metallic bonding, like its heavier group 13 congeners, it has the characteristic physical properties of a post-transition metal, with longer-than-expected interatomic distances. Furthermore, as Al³⁺ is a small and highly charged cation, it is strongly polarizing and aluminium compounds tend towards covalency; this behaviour is similar to that of beryllium (Be²⁺), an example of a diagonal relationship. However, unlike all other post-transition metals, the underlying core under aluminium's valence shell is that of the preceding noble gas, whereas for gallium and indium it is that of the preceding noble gas plus a filled d-subshell, and for thallium and nihonium it is that of the preceding noble gas plus filled d- and f-subshells. Hence, aluminium does not suffer the effects of incomplete shielding of valence electrons by inner electrons from the nucleus that its heavier congeners do. Aluminium's electropositive behavior, high affinity for oxygen, and highly negative standard electrode potential are all more similar to those of scandium, yttrium, lanthanum, and actinium, which have ds² configurations of three valence electrons outside a noble gas core: aluminium is the most electropositive metal in its group. Aluminium also bears minor similarities to the metalloid boron in the same group; AlX₃ compounds are valence isoelectronic to BX₃ compounds (they have the same valence electronic structure), and both behave as Lewis acids and readily form adducts. Additionally, one of the main motifs of boron chemistry is regular icosahedral structures, and aluminium forms an important part of many icosahedral quasicrystal alloys, including the Al–Zn–Mg class.

Metal cluster compounds are a molecular ion or neutral compound composed of three or more metals and featuring significant metal-metal interactions.

Aluminium(I) nucleophiles are a group of inorganic and organometallic nucleophilic compounds containing at least one aluminium metal center in the +1 oxidation state with a lone pair of electrons strongly localized on the aluminium(I) center.

“GaI” is a low-valent gallium species that acts as a reactive intermediate for many gallium-based products. Gallium(I) halides were first crystallographically characterized by Schnöckel and coworkers and have allowed a synthetic route to many low-valent gallium species. However, chemical syntheses that employ “GaI” rather than gallium(I) halide precursors have been increasingly investigated given the ease of synthesis of this reagent. While the synthetic method of Schnöckel and coworkers to synthesize gallium(I) halides require extraordinarily high temperatures, the straightforward preparation of “GaI” at near room temperature has allowed for the exploration of new gallium-based chemistries.

References

1 2 3 4 5 6 7 8 Tacke, Matthias; Schnoeckel, Hansgeorg (1989-07-01). "Metastable aluminum chloride, AlCl, as a solid and in solution". Inorganic Chemistry. 28 (14): 2895–2896. doi:10.1021/ic00313a039. ISSN 0020-1669.
1 2 3 4 5 6 7 8 9 Dohmeier, Carsten; Loos, Dagmar; Schnöckel, Hansgeorg (1996-02-02). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition in English. 35 (2): 129–149. doi:10.1002/anie.199601291. ISSN 0570-0833.
↑ van der Woerd, Mark J.; Lammertsma, Koop; Duke, Brian J.; Schaefer, Henry F. (1991-07-15). "Simple mixed hydrides of boron, aluminum, and gallium: AlBH6, AlGaH6, and BGaH6". The Journal of Chemical Physics. 95 (2): 1160–1167. doi:10.1063/1.461146. ISSN 0021-9606.
1 2 3 Mocker, Mario; Robl, Christian; Schnöckel, Hansgeorg (1994-05-02). "Donor-Stabilized Aluminum(II) Bromide". Angewandte Chemie International Edition in English. 33 (8): 862–863. doi:10.1002/anie.199408621. ISSN 0570-0833.
↑ Bohren, Craig (2006). Fundamentals of Atmospheric Radiation: An Introduction with 400 Problems . Wiley-VCH. pp. 214. ISBN 978-3-527-40503-9.
1 2 3 4 5 6 7 8 9 10 11 Schnockel (2000-09-01). "Low valent aluminium and gallium compounds — structural variety and coordination modes to transition metal fragments". Coordination Chemistry Reviews. 206–207: 285–319. doi:10.1016/S0010-8545(00)00339-8. ISSN 0010-8545.
↑ Nagendran, Selvarajan; Roesky, Herbert W. (2008-02-05). "The Chemistry of Aluminum(I), Silicon(II), and Germanium(II)". Organometallics. 27 (4): 457–492. doi:10.1021/om7007869. ISSN 0276-7333.
↑ Benson, Sidney W. (1965). "III - Bond energies". Journal of Chemical Education. 42 (9): 502. doi:10.1021/ed042p502. ISSN 0021-9584.
1 2 3 4 Dyke, J.M.; Kirby, C.; Morris, A.; Gravenor, B.W.J.; Klein, R.; Rosmus, P. (1984-08-01). "A study of aluminium monofluoride and aluminium trifluoride by high-temperature photoelectron spectroscopy". Chemical Physics. 88 (2): 289–298. Bibcode:1984CP.....88..289D. doi:10.1016/0301-0104(84)85286-6. ISSN 0301-0104.
1 2 3 4 5 6 7 Liu, Yashuai; Li, Jia; Ma, Xiaoli; Yang, Zhi; Roesky, Herbert W. (2018-11-01). "The chemistry of aluminum(I) with β-diketiminate ligands and pentamethylcyclopentadienyl-substituents: Synthesis, reactivity and applications". Coordination Chemistry Reviews. 374: 387–415. doi:10.1016/j.ccr.2018.07.004. ISSN 0010-8545.
↑ Cui, Chunming; Roesky, Herbert W.; Schmidt, Hans‐Georg; Noltemeyer, Mathias; Hao, Haijun; Cimpoesu, Fanica (2000-12-01). "Synthesis and Structure of a Monomeric Aluminum(I) Compound [{HC(CMeNAr)2}Al] (Ar=2,6–iPr2C6H3): A Stable Aluminum Analogue of a Carbene". Angewandte Chemie International Edition. 39 (23): 4274–4276. doi:10.1002/1521-3773(20001201)39:23<4274::AID-ANIE4274>3.0.CO;2-K. ISSN 1521-3773.
1 2 Dohmeier, Carsten; Robl, Christian; Tacke, Matthias; Schnöckel, Hansgeorg (1991). "The Tetrameric Aluminum(I) Compound[{Al(η5-C5Me5)}4]". Angewandte Chemie International Edition in English. 30 (5): 564–565. doi:10.1002/anie.199105641. ISSN 0570-0833.
1 2 Ziurys, L. M.; Apponi, A. J.; Phillips, T. G. (1994-04-07). "Exotic fluoride molecules in IRC +10216: Confirmation of AlF and searches for MgF and CaF". The Astrophysical Journal. 433: 729–732. Bibcode:1994ApJ...433..729Z. doi:10.1086/174682. ISSN 0004-637X.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[Tacke_1989-1] 1 2 3 4 5 6 7 8 Tacke, Matthias; Schnoeckel, Hansgeorg (1989-07-01). "Metastable aluminum chloride, AlCl, as a solid and in solution". Inorganic Chemistry. 28 (14): 2895–2896. doi:10.1021/ic00313a039. ISSN 0020-1669.

[Dohmeier_1996-2] 1 2 3 4 5 6 7 8 9 Dohmeier, Carsten; Loos, Dagmar; Schnöckel, Hansgeorg (1996-02-02). "Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions". Angewandte Chemie International Edition in English. 35 (2): 129–149. doi:10.1002/anie.199601291. ISSN 0570-0833.

[3] van der Woerd, Mark J.; Lammertsma, Koop; Duke, Brian J.; Schaefer, Henry F. (1991-07-15). "Simple mixed hydrides of boron, aluminum, and gallium: AlBH6, AlGaH6, and BGaH6". The Journal of Chemical Physics. 95 (2): 1160–1167. doi:10.1063/1.461146. ISSN 0021-9606.

[Mocker_1994-4] 1 2 3 Mocker, Mario; Robl, Christian; Schnöckel, Hansgeorg (1994-05-02). "Donor-Stabilized Aluminum(II) Bromide". Angewandte Chemie International Edition in English. 33 (8): 862–863. doi:10.1002/anie.199408621. ISSN 0570-0833.

[5] Bohren, Craig (2006). Fundamentals of Atmospheric Radiation: An Introduction with 400 Problems . Wiley-VCH. pp. 214. ISBN 978-3-527-40503-9.

[Schnockel_2000-6] 1 2 3 4 5 6 7 8 9 10 11 Schnockel (2000-09-01). "Low valent aluminium and gallium compounds — structural variety and coordination modes to transition metal fragments". Coordination Chemistry Reviews. 206–207: 285–319. doi:10.1016/S0010-8545(00)00339-8. ISSN 0010-8545.

[7] Nagendran, Selvarajan; Roesky, Herbert W. (2008-02-05). "The Chemistry of Aluminum(I), Silicon(II), and Germanium(II)". Organometallics. 27 (4): 457–492. doi:10.1021/om7007869. ISSN 0276-7333.

[8] Benson, Sidney W. (1965). "III - Bond energies". Journal of Chemical Education. 42 (9): 502. doi:10.1021/ed042p502. ISSN 0021-9584.

[Dyke_1984-9] 1 2 3 4 Dyke, J.M.; Kirby, C.; Morris, A.; Gravenor, B.W.J.; Klein, R.; Rosmus, P. (1984-08-01). "A study of aluminium monofluoride and aluminium trifluoride by high-temperature photoelectron spectroscopy". Chemical Physics. 88 (2): 289–298. Bibcode:1984CP.....88..289D. doi:10.1016/0301-0104(84)85286-6. ISSN 0301-0104.

[Liu_2018-10] 1 2 3 4 5 6 7 Liu, Yashuai; Li, Jia; Ma, Xiaoli; Yang, Zhi; Roesky, Herbert W. (2018-11-01). "The chemistry of aluminum(I) with β-diketiminate ligands and pentamethylcyclopentadienyl-substituents: Synthesis, reactivity and applications". Coordination Chemistry Reviews. 374: 387–415. doi:10.1016/j.ccr.2018.07.004. ISSN 0010-8545.

[11] Cui, Chunming; Roesky, Herbert W.; Schmidt, Hans‐Georg; Noltemeyer, Mathias; Hao, Haijun; Cimpoesu, Fanica (2000-12-01). "Synthesis and Structure of a Monomeric Aluminum(I) Compound [{HC(CMeNAr)2}Al] (Ar=2,6–iPr2C6H3): A Stable Aluminum Analogue of a Carbene". Angewandte Chemie International Edition. 39 (23): 4274–4276. doi:10.1002/1521-3773(20001201)39:23<4274::AID-ANIE4274>3.0.CO;2-K. ISSN 1521-3773.

[Dohmeier_1991-12] 1 2 Dohmeier, Carsten; Robl, Christian; Tacke, Matthias; Schnöckel, Hansgeorg (1991). "The Tetrameric Aluminum(I) Compound[{Al(η5-C5Me5)}4]". Angewandte Chemie International Edition in English. 30 (5): 564–565. doi:10.1002/anie.199105641. ISSN 0570-0833.

[Ziurys_1994-13] 1 2 Ziurys, L. M.; Apponi, A. J.; Phillips, T. G. (1994-04-07). "Exotic fluoride molecules in IRC +10216: Confirmation of AlF and searches for MgF and CaF". The Astrophysical Journal. 433: 729–732. Bibcode:1994ApJ...433..729Z. doi:10.1086/174682. ISSN 0004-637X.

[1]

[2]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[12]

[13]