Characterization of the Ligand Properties of Donor-stabilized Pnictogenyltrielanes

A general synthesis and the characterization of novel alkyl-substituted NHC-stabilized pnictogenylboranes NHC ⋅ BH2 ER2 (NHC=N-heterocyclic carbene, E=P, As; R2 =Me2 , Ph2 , t BuH, Cy2 , (SiMe3 )2 ) are reported. These compounds were reacted with Ni(CO)4 to the corresponding complexes of the type [(NHC ⋅ BH2 ER2 )Ni(CO)3 ] to determine their donor strength by Tolman Electronic Parameters (TEPs) and their steric demand as ligands compared to classical phosphines, superbasic phosphines and other commonly applied donor systems. The results show that the NHC-stabilized pnictogenyltrielanes can be considered as being highly basic, while their steric influence depends strongly on the organic residues as well as the donor attached to the {BH2 } moiety. Although weaker than commonly used superbasic phosphines, the donor strength of pnictogenyltrielanes in general can be classified as of similar strength as NHCs. The steric and electronic properties can easily be modified by alkyl substitution as evident from the TEP trends.

NHC-Stabilized Mixed Group 13/14/15 Element Hydrides

The syntheses of novel N-heterocyclic carbene (NHC) adducts of group 13, 14 and 15 element hydrides are reported. Salt metathesis reactions between NaPH2 and IDipp ⋅ GeH2 BH2 OTf (1) (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) led to mixtures of the two isomers IDipp ⋅ GeH2 BH2 PH2 (2 a) and IDipp ⋅ BH2 GeH2 PH2 (2 b); by altering the reaction conditions an almost exclusive formation of 2 b was achieved. Attempts to purify mixtures of 2 a and 2 b by re-crystallization from THF afforded a salt [IDipp ⋅ GeH2 BH2  ⋅ IDipp][PHGeH2 BH2 PH2 BH2 GeH2 ] (4) that contains the novel anionic cyclohexyl-like inorganic heterocycle [PHGeH2 BH2 PH2 BH2 GeH2 ]- . In addition, the borane adducts IDipp ⋅ GeH2 BH2 PH2 BH3 (3 a) and IDipp ⋅ BH2 GeH2 PH2 BH3 (3 b) as even longer chain compounds were obtained from reactions of 2 a/2 b with H3 B ⋅ SMe2 and were studied by NMR spectroscopy. Accompanying DFT computations give insight into the mechanism and energetics associated with 2 a/2 b isomerization as well as their decomposition pathways.

A General Pathway towards NHC ⋅ GaH2 (OTf) Adducts - The Key for the Synthesis of NHC-Stabilized Cationic 13/15 Chain Compounds of Gallium

A general pathway towards NHC (NHC=N-heterocyclic carbene)-stabilized galliummonotriflates NHC ⋅ GaH2 (OTf) (NHC=IDipp, 1 a; IPr2 Me2 , 1 b; IMes, 1 c; IDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene, IPr2 Me2 =1,3-bis-(diisopropyl)-4,5-dimethyl-imidazolin-2-ylidene, IMes=1,3-bis(2,4,6-trimethylphenyl)-imidazolin-2-ylidene) is reported. Quantum chemical calculations give detailed insight into the underlying reaction pathway. The obtained NHC ⋅ GaH2 (OTf) compounds were employed in reactions with donor-stabilized pnictogenylboranes to synthesize the elusive cationic parent 13/15/13 chain compounds [IDipp ⋅ GaH2 ER2 E'H2  ⋅ D][OTf] (3 a: D=IDipp, E=P, E'=B, R=H; 3 b: D=NMe3 , E=P, E'=B, R=H, 3 c: D=NMe3 , E=P, E'=B, R=Ph, 3 d: D=IDipp, E=P, E'=Ga, R=H). Supporting computational studies highlight the electronic features of the products.

Three- and Five-Membered Anionic Chains of Pnictogenylboranes

An unprecedented family of three- and five-membered substituted anionic derivatives of parent pnictogenylboranes is herein reported. Reacting various combinations of the pnictogenylboranes H₂ E'-BH₂ -NMe₃ (E'=P, As) with pnictogen-based nucleophiles MER1R2 (E=P, As; R1=H, R2=^t Bu; R1=R2=Ph; M=Na, K) allows for the isolation of the unsymmetrical products [Na(18-crown-6)][H₂ E'-BH₂ -EH^t Bu] (3: E=E'=P; 4: E=E'=As; 5: E=As, E'=P) and [M(C)][H₂ E'-BH₂ -EPh₂ ] (7: E=E'=P, M=Na, C=18-crown-6; 8: E=E'=As; M=K, C=[2.2.2]cryptand; 9: E=P, E'=As, M=Na, C=[2.2.2]cryptand; 10: E=As, E'=P, M=K, C=[2.2.2]cryptand). [Na(18-crown-6)][H₂ As-BH₂ -^t BuPH-BH₃ ] (6) is only accessible by a different pathway, using ^t BuPH₂ , BH₃  ⋅ SMe₂ and NaNH₂ as starting materials. Additionally, the synthesis of symmetrical diphenyl-substituted compounds [M(18-crown-6)][Ph₂ E-BH₂ -EPh₂ ] (11: E=P, M=Na; 12: E=As, M=K) is reported which can be regarded as isostructural inorganic, negatively charged analogs of dppm (1,1-bis(diphenylphosphino)methane) and dpam (1,1-bis(diphenylarsino)methane). Furthermore, an elongation of the pnictogen boron backbone in compounds 3, 7 and 9' (similar compound to 9, stabilized however by 18-crown-6), is attainable by reacting them with the pnictogenylboranes H₂ E'-BH₂ -NMe₃ leading to corresponding five-membered chain-like compounds [Na(18-crown-6)][H₂ E-BH₂ -R1R2P-BH₂ -E'H₂ ] (E=E'=P, R1=H, R2=^t Bu (13); E=E'=P, R1=R2=Ph (14); E=E'=As, R1=R2=Ph (15); E=P, E'=As, R1=R2=Ph (16)). Finally, the thermodynamics of the reaction pathways were evaluated by quantum chemical computations.

A convenient route to mixed cationic group 13/14/15 compounds

The formation of novel cationic mixed main group compounds is reported revealing a chain composed of different elements of group 13, 14, and 15. Reactions of different pnictogenylboranes R₂EBH₂·NMe₃ (E = P, R = Ph, H; E = As, R = Ph, H) with the NHC-stabilized compound IDipp·GeH₂BH₂OTf (1) (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene) were carried out, yielding the novel cationic, mixed group 13/14/15 compounds [IDipp·GeH₂BH₂ER₂BH₂·NMe₃]⁺ (2a E = P; R = Ph; 2b E = As; R = Ph; 3a E = P; R = H; 3b E = As; R = H) by the nucleophilic substitution of the triflate (OTf) group. The products were analysed by NMR spectroscopy and mass spectrometry and for 2a and 2b also by X-ray structure analysis. Further reactions of 1 with H₂EBH₂·IDipp (E = P, As) resulted in the unprecedented parent complexes [IDipp·GeH₂BH₂EH₂BH₂·IDipp][OTf] (5a E = P; 5b E = As), which were studied by X-ray structure analysis, NMR spectroscopy and mass spectrometry. Accompanying DFT computations give insight into the stability of the formed products with respect to their decomposition.

Coordination of Pnictogenylboranes Towards Tl(I) Salts and a Tl- Mediated P-P Coupling

The coordination chemistry of only Lewis-base (LB)-stabilized pnictogenylboranes EH₂ BH₂ ⋅NMe₃ (E=P, As) towards Tl(I) salts has been studied. The reaction of Tl[BAr^Cl ] (BAr^Cl =[B(3,5-C₆ H₃ Cl₂ )₄ ]^- ) with the corresponding pnictogenylborane results in the formation of [Tl(EH₂ BH₂ ⋅NMe₃ )][BAr^Cl ] (1 a: E=P; 1 b: E=As). Whereas the Tl ion in 1 a/b is monocoordinated, the exchange of the weakly coordinating anion (WCA) in the Tl(I) salt leads to the formation of a trigonal pyramidal coordination mode at the Tl atom by coordination of three equivalents of EH₂ BH₂  ⋅ NMe₃ in [Tl(EH₂ BH₂  ⋅ NMe₃ )₃ ][WCA] (2 a: E=P, WCA=TEF^Cl ; 2 b: E=As, WCA=TEF) (TEF=[Al{OC(CF₃ )₃ }₄ ]^- , TEF^Cl =[Al{(OC(CF₃ )₂ (CCl₃ )}₄ ]^- ). Furthermore, by using two equivalents of PH₂ BH₂ ⋅NMe₃ , a Tl(I)-mediated P-P coupling takes place in CH₂ Cl₂ as solvent resulting in [Me₃ N⋅BH₂ PH₂ PHBH₂ ⋅NMe₃ ][WCA] (WCA=TEF, 3 a; BAr^Cl , 3 b; TEF^Cl , 3 c). In contrast, for the arsenic derivatives 1 b and 2 b, no coupling reaction is observed. The underlying chemical processes are elucidated by quantum chemical computations.

Synthesis and Application of Alkali Metal Antimonide-A New Approach to Antimony Chemistry

Alkali metal dihydrogen-antimonides [M(L)_x SbH₂ ], short: alkali metal antimonides (M=Li, Na, K, Rb, Cs; 1: L=pmdta; 2: L=crown-ether), were prepared from stibine and n-Butyllithium, M(hmds) (hmds=hexamethyldisilazane) or MOtBu, respectively. We developed a generally applicable synthesis route for these compounds and the obtained compounds were examined on their stability depending on the alkali metal and stabilizing additives used, whereby the use of appropriate crown-ethers allowed their isolation and characterization at room temperature. Moreover, the 1,4-dioxane adduct [Na(dioxane)_x SbH₂ ] was the appropriate starting compound for the synthesis of the first primary silylstibane (Me₃ Si)₃ SiSbH₂ (3) which was characterized by NMR and IR spectroscopy. Reaction of 3 with (Dipp₂ NacNac)Ga (Dipp₂ NacNac=HC{C(Me)N(Dipp)}₂ ; Dipp=2,6-iPr₂ C₆ H₃ ) resulted in the formation of (Dipp₂ NacNac)GaH(SbHSi(SiMe₃ )₃ ) (4) which was furthermore characterized by single crystal x-ray diffraction.

An NHC-Stabilized H2 GeBH2 Precursor for the Preparation of Cationic Group 13/14/15 Hydride Chains

The synthesis, characterization and reactivity studies of the NHC‐stabilized complex IDipp ⋅ GeH₂BH₂OTf (1) (IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazolin‐2‐ylidene) are reported. Nucleophilic substitution of the triflate (OTf) group in 1 by phosphine or arsine donors provides access to the cationic group 13/14/15 chains [IDipp ⋅ GeH₂BH₂ERR¹R²]⁺ (2 E=P; R, R¹=H; R²=^tBu; 3 E=P; R=H; R¹, R²=Ph; 4 a E=P; R, R¹, R²=Ph; 4 b E=As; R, R¹, R²=Ph). These novel cationic chains were characterized by X‐ray crystallography, NMR spectroscopy and mass spectrometry. Moreover, the formation of the parent complexes [IDipp ⋅ GeH₂BH₂PH₃][OTf] (5) and [IDipp ⋅ GeH₃][OTf] (6) were achieved by reaction of 1 with PH₃. Accompanying DFT computations give insight into the stability of the formed chains with respect to their decomposition.

Molecular Main Group Metal Hydrides

This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.

Easy Access to Enantiomerically Pure Heterocyclic Silicon-Chiral Phosphonium Cations and the Matched/Mismatched Case of Dihydrogen Release

Phosphonium ions are widely used in preparative organic synthesis and catalysis. The provision of new types of cations that contain both functional and chiral information is a major synthetic challenge and can open up new horizons in asymmetric cation-directed and Lewis acid catalysis. We discovered an efficient methodology towards new Si-chiral four-membered CPSSi* heterocyclic cations. Three synthetic approaches are presented. The stereochemical sequence of anchimerically assisted cation formation with B(C6 F5 )3 and subsequent hydride addition was fully elucidated and proceeds with excellent preservation of the chiral information at the stereogenic silicon atom. Also the mechanism of dihydrogen release from a protonated hydrosilane was studied in detail by the help of Si-centered chirality as stereochemical probe. Chemoselectivity switch (dihydrogen release vs. protodesilylation) can easily be achieved through slight modifications of the solvent. A matched/mismatched case was identified and the intermolecularity of this reaction supported by spectroscopic, kinetic, deuterium-labeling experiments, and quantum chemical calculations.

A general method for the synthesis of covalent and ionic amine borane complexes containing trinitromethyl fragments

A general approach for the synthesis of covalent and ionic amine borane complexes containing trinitromethyl fragments has been developed through metathesis reactions between amine chloroborane complexes and potassium salt of trinitromethyl (K[C(NO₂)₃]). Five covalent and ionic trinitromethyl amine borane complexes have been synthesized in good yields with high purity and it is found that the ionic complex, [H₂B(NH₃)₂][C(NO₂)₃], might be a promising energetic material on the basis of the investigation of its thermal decomposition behaviour.

A general approach has been developed through which five covalent and ionic amine borane complexes containing trinitromethyl fragments were synthesized.

A new family of silver(i) complexes stabilised by the phosphanylborane (C6H5)2PBH2·N(CH3)3

By the reaction of the phosphanylborane Ph2PBH2·NMe3 with Ag[FAl{OC6F10(C6F5)}3] or Ag[BF4] first Ag(i) coordination compounds stabilized by phosphine-boranes were obtained.

Phosphanylalanes and Phosphanylgallanes Stabilized only by a Lewis Base

The synthesis and characterization of the first parent phosphanylalane and phosphanylgallane stabilized only by a Lewis base (LB) are reported. The corresponding substituted compounds, such as IDipp⋅GaH2 PCy2 (1) (IDipp=1,3-bis(2,6-diisopropylphenyl)-imidazolin-2-ylidene) were obtained by the reaction of LiPCy2 with IDipp⋅GaH2 Cl. However, the LB-stabilized parent compounds IDipp⋅GaH2 PH2 (3) and IDipp⋅AlH2 PH2 (4) were prepared via a salt metathesis of LiPH2 ⋅DME with IDipp⋅E'H2 Cl (E'=Ga, Al) or by H2 -elimination reactions of IDipp⋅E'H3 (E'=Ga, Al) and PH3 , respectively. The compounds could be isolated as crystalline solids and completely characterized. Supporting DFT computations gave insight into the reaction pathways as well as into the stability of these compounds with respect to their decomposition behavior.

Boron-Boron Dehydrocoupling of Boranes Initiated by Reaction with Iodine

A new boron-boron dehydrocoupling strategy was established, providing convenient access to some diborane(4) compounds starting from simple borane adducts under mild conditions. In contrast to the traditional pathway using a reducing reagent, the reduction from B^III to B^II was paradoxically initiated by the addition of the oxidation-reagent iodine. A reaction pathway for this unusual reaction was proposed based on quantum-chemical calculations.

Bidentate Phosphanyl- and Arsanylboranes

A new class of neutral bidentate ligands with pnictogenyl-functional sites has been obtained. The reaction of tmeda⋅(BH₂ I)₂ (1, tmeda=tetramethylethylendiamine) with different phosphanides yields the corresponding bidentate phosphanylboranes tmeda⋅(BH₂ PH₂ )₂ (2 a), tmeda⋅(BH₂ PPh₂ )₂ (2 b), and tmeda⋅(BH₂ tBuPH)₂ (2 c). This reaction strategy could be further extended to synthesize the first bidentate arsanylborane tmeda⋅(BH₂ AsPh₂ )₂ (3). Depending on the substituents on the phosphorus, these compounds form different Au^I complexes, to build either polymeric tmeda⋅(BH₂ PH₂ AuCl)₂ (4 a), or monomeric tmeda⋅(BH₂ PPh₂ AuCl)₂ (4 b) products. These compounds form also neutral oligomeric group 13/15 chain-like molecules by coordination to a boron moiety such as tmeda⋅(BH₂ PH₂ BH₃ )₂ (5 a) and tmeda⋅(BH₂ AsPh₂ BH₃ )₂ (5 b). DFT calculations provide insight into the differences between the syntheses of mono- and bidentate pnictogenylboranes.

Gold(I) Complexes Containing Phosphanyl- and Arsanylborane Ligands

The structural and photophysical properties of a series of new Au^I compounds have been studied. The reactions of AuCl(tht) with the phosphanyl- and arsanylboranes RR^' EBH₂ NMe₃ (E=P, As; R=H, Ph; R'=H, Ph, tBu) afford the complexes [AuCl(RR^' EBH₂ NMe₃ )]. In the solid state, [AuCl(H₂ PBH₂ NMe₃ )]₂ (2 a) is a dimer showing unsupported intermolecular aurophilic interactions with short Au⋅⋅⋅Au distances. In contrast, [AuCl(H₂ AsBH₂ NMe₃ )]_n (2 b) aggregates to form 1D chains. Organic substituents on the pnictogen atoms lead to discrete molecules in [AuCl(RR^' PBH₂ NMe₃ )] (2 c: R=H, R'=tBu; 2 d: R=R'=Ph). To increase the aurophilicity, the ionic homoleptic complexes [Au(RR^' EBH₂ NMe₃ )₂ ][AlCl₄ ] (3 a-d) have been synthesized, for which 3 a,b form chains in the solid state and exhibit luminescence. The emissions show a drastic redshift with temperature decrease, correlating with decreasing Au⋅⋅⋅Au distances. DFT calculations provide insight into the bonding situation of the products.

PBP bridged [3]ferrocenophane: a bisphosphanylborane with a redox trigger

Stereospecific access to the unprecedented P-B-P bridged [3]ferrocenophane Fe(C₅H₄PtBu)₂BMes is presented. In contrast to acyclic ferrocenylphosphanes, we find evidence for a shift of spin-density from Fe to P upon pyramidal inversion of the P centers in the mono-cation; the latter has a lifetime of τ = 0.31(4) s.

Iridium-catalysed dehydrocoupling of aryl phosphine-borane adducts: synthesis and characterisation of high molecular weight poly(phosphinoboranes)

The thermal dehydrogenative coupling of aryl phosphine-borane adducts with iridium complexes bearing a bis(phosphinite) pincer ligand is reported. This catalysis produces high molecular weight poly(phosphinoboranes) [ArPH-BH2]n (Ar = Ph, (p)Tol, Mes). Furthermore, we investigated the reactivity of these pincer complexes towards primary phosphines and their respective borane adducts on a stoichiometric scale.

Site-selectivity in the halogenation of titanium-functionalized polyoxovanadate–alkoxide clusters

Syntheses and site differentiated reactivity for titanium-functionalized polyoxovanadate–alkoxide clusters are presented. We present insights into the mechanism and electronic consequences metal oxide halogenation.

Depolymerization of Poly(phosphinoboranes): From Polymers to Lewis Base Stabilized Monomers

We report on depolymerization reactions of poly(phosphinoboranes). The cleavage of the polymers [H₂ PBH₂ ]_n (2 a), [tBuHPBH₂ ]_n (2 c), [PhHPBH₂ ]_n (2 e) and the oligomer [Ph₂ PBH₂ ]_n (2 b), with strong Lewis bases (LBs), in particular with NHCs, leads to the corresponding monomeric phosphanylboranes R¹ R² PBH₂ LB. It is observed that the depolymerization depends on the strength and stability of the LBs as well as on the substitution pattern of the poly(phosphinoboranes). The solid state structures of the monomeric phosphinoboranes H₂ PBH₂ NHC^Me (NHC=N-heterocyclic carbene) (4 a), H₂ PBH₂ NHC^dipp (5 a) and tBuHPBH₂ NHC^Me (4 c) were determined. DFT calculations support the experimentally observed reaction behavior.

Synthetic and structural studies of phosphine coordinated boronium salts

The reaction of BrH₂B·SMe₂ with primary and secondary phosphines affords a range of boronium salts of the form [H₂B(PR₃)₂]Br (PR₃ = PHCy₂1; PHPh₂, 2; PH₂Cy, 3), which have been fully characterised including solid-state determinations. Reactions of bulky tertiary phosphines, e.g., PCy₃ and PPh₃, with BrH₂B·SMe₂ do not proceed beyond the phosphine-stabilised bromoborane adducts, however, the smaller tertiary phosphine PMe₂Ph readily proceeds to form [H₂B(PMe₂Ph)₂]Br (4). The formation of the unsymmetrical boronium salts [H₂B(PH₂Cy)(PHCy₂)]Br (5) and [H₂B(PHCy₂)(PHPh₂)]Br (6) was observed by in situ NMR spectroscopy, however, the compounds were found to spontaneously disproportionate to their respective homophosphine boronium cations, even on prolonged storage in solution at -78 °C. Di- and triphosphines were found to form ring-closed boronium salts to afford [H₂B(κ²-P,P'-diphosphine)]Br (diphosphine = dppe, 7; dcpe, 8; dmpe, 9; dppf, 10; dppf with [AsF₆]^- counterion, 11; amphos, 12). The analogous methodology with Br₂HB·SMe₂ proved less generally applicable due to an accessible decomposition pathway being available to boronium salts bearing primary and secondary phosphines, leading to the formation of phosphonium salts, although [BrHB(dcpe)]Br (13), [BrHB(PMe₂Ph)₂]Br (14) and [BrHB(amphos)]Br (15) were synthesised with varying degrees of success. Reaction of BrH₂B·SMe₂ with diphars afforded the boronium salt [H₂B(κ²-P,P'-diphars)]Br (16), which featured two pendant arsine arms. Similarly, triphos was found to react with BrH₂B·SMe₂ to give [H₂B(κ²-P,P'-triphos)]Br (17), which featured a pendant phosphine arm. Substitution of the bromide counter anion with either hexafluoroarsenate or hexfluoroantimonate anions revealed weak hydrogen bonds between the P-H bonds of the boronium cations and the anions, that appeared through NMR studies to be retained in solution (where hydrogen bonding order was determined to be Br^- > [SbF₆]^-/[AsF₆]^-). This was further demonstrated by comparison of solid-state structures and solution NMR data of 1 with [H₂B(PHCy₂)₂][SbF₆] (18), 4 with [H₂B(PMe₂Ph)₂][AsF₆] (19) and 17 with [H₂B(triphos)][AsF₆] (20).

Group 14 inorganic hydrocarbon analogues

This Review article deals with the synthesis and properties of inorganic hydrocarbon analogues: binary chemical species that contain heavier Group 14 elements (Si, Ge, Sn or Pb) and hydrogen as components. Rapid advances in our general knowledge of these species have enabled the development of industrially relevant processes such as the hydrosilylation of unsaturated substrates and the chemical vapor deposition of semi-conducting films.

Metal-Free Addition/Head-to-Tail Polymerization of Transient Phosphinoboranes, RPH-BH2: A Route to Poly(alkylphosphinoboranes)

Mild thermolysis of Lewis base stabilized phosphinoborane monomers R(1)R(2)P-BH2⋅NMe3 (R(1),R(2)=H, Ph, or tBu/H) at room temperature to 100 °C provides a convenient new route to oligo- and polyphosphinoboranes [R(1)R(2)P-BH2]n. The polymerization appears to proceed via the addition/head-to-tail polymerization of short-lived free phosphinoborane monomers, R(1)R(2)P-BH2. This method offers access to high molar mass materials, as exemplified by poly(tert-butylphosphinoborane), that are currently inaccessible using other routes (e.g. catalytic dehydrocoupling).

Generation of aminoborane monomers RR'N=BH2 from amine-boronium cations [RR'NH-BH2L](+): metal catalyst-free formation of polyaminoboranes at ambient temperature

Protonation of MeRNH·BH3 (R = Me or H) with HX (X = B(C6F5)4, OTf, or Cl), followed by immediate, spontaneous H2 elimination, yielded the amine-boronium cation salt [MeRNH·BH2(OEt2)][B(C6F5)4] and related polar covalent analogs, MeRNH·BH2X (X = OTf or Cl). These species can be deprotonated to conveniently generate reactive aminoborane monomers MeRN=BH2 which oligomerize or polymerize; in the case of MeNH2·BH3, the two step process gave poly(N-methylaminoborane), [MeNH-BH2]n.

Donor-acceptor chemistry in the main group

This Perspective article summarizes recent progress from our laboratory in the isolation of reactive main group species using a general donor-acceptor protocol. A highlight of this program is the use of carbon-based donors in combination with suitable Lewis acidic acceptors to yield stable complexes of parent Group 14 element hydrides (e.g. GeH2 and H2SiGeH2). It is anticipated that this strategy could be extended to include new synthetic targets from throughout the Periodic Table with possible applications in bottom-up materials synthesis and main group element catalysis envisioned.