Themed collection Main Group Transformations

Welcome to this themed issue of Dalton Transactions focusing on main group transformations.

This short review describes the transition metal chemistry of cyclodiphosphazanes.

History, chemical properties and emerging biology of HSNO/SNO⁻, SSNO⁻ and [ONN(O)-SO₃]²⁻ and their role in the sulfide/nitric oxide cross talk.

The N-heterocyclic phosphines portrayed gain unusual chemical reactivity from the ionic polarization of exocyclic P–X bonds or low-energy P–P bond cleavage.

Expanding the belt! NHC ring expansion reactions and E–E activation from the 1960s till the present are summarized.

Metal-free hydrogenation of 3,6-diarylpyridaxines was realized for the first time to furnish 1,4,5,6-tetrahydropyridazine derivatives in 85–95% yields.

Reaction of the anionic NHDC ligand, [:C{[N(2,6-Prⁱ₂C₆H₃)]₂CHCLi}]_n (1), with SiCl₄ gives the trichlorosilyl-substituted NHC ligand (7). Abnormal carbene–SiCl₄ complex (8) can be conveniently synthesized by combining 7 with HCl·NEt₃. Meanwhile, 7 may react with CH₂Cl₂ in warm hexane, giving the abnormal carbene-complexed SiCl₃⁺ cation (9). The structure and bonding of 9 have also been probed by DFT computations.

Boron mono- and di-cations featuring a nucleophilic N-heterocyclic olefin and the pentamethylcyclopentadienyl substituent have been prepared and structurally characterized. Experimental and theoretical investigations show that [η⁵-Cp*B-NHO]²⁺ is considerably more Lewis acidic than [η⁵-Cp*B-IMes]²⁺ due to the steric congestion imposed by the bent geometry of NHO around the central boron atom.

The reaction of a terphenyl tin(II) compound bearing an η³ coordinating allyl ligand with adamantyl phosphaalkyne is reported.

Treatment of methyl (Z)-2-alken-4-ynoates with the strong Lewis acid tris(pentafluorophenyl) borane, B(C₆F₅)₃, yield 2,5,6-substituted zwitterionic pyrylium borate species via an intramolecular 6-endo-dig cyclisation reaction.

A sterically demanding N-aryl carbodiimide reacts with magnesium 1,4-dihydropyridides to initiate heterocyclic ring contraction and pyrrolide formation under unprecedentedly mild conditions.

The [(η⁶-arene)RuC₂B₉H₁₁] complexes (arene = p-cymene (2), biphenyl (3) and 1-Me-4-COOEt-C₆H₄ (4)) show cytotoxic activity and excellent selectivity towards specific tumour cells.

The reactivity of the heavier group 15 tribromides, SbBr₃ and BiBr₃, towards 1,3-bis(2,6-diisopropylphenyl)-imidazol-2-ylidene (IPr) is described.

Diberyllium hydride complex – not a diborane analogue: the diberyllium hydrides Be₂(CH₃)₂H₂L₂ (L = H⁻, CO, NHC and CN⁻) are isostructural to diborane but differ in the nature of the bonding interaction at the bridging H-atoms.

The binding mode of B-aryl substituted amine–boranes at {Rh(bisphoshine)}⁺ fragments can manipulated by variation of the P–Rh–P bite-angle.

Mono-, di- or triaminobismuthanes were synthesized depending on the sterical demand of the organic substituent. In one case, a C–C coupling product was observed as main product in the reaction of BiCl₃ with Mes*(SiMe₃)NLi.

Simple tin derivatives, Cp*₂SnCl₂ (1) and Ph₂SnCl₂ (2), catalyze the hydrophosphination of alkene substrates with diphenylphosphine.

N-Heterocyclic stannylenes containing a functionalised donor arm have been synthesised using a transamination strategy from [Sn{N(SiMe₃)₂}₂] and fluorenyl-tethered diamines.

The reaction between prestabilized group 13 metal hydrides and primary silylphosphines lead to the formation of rare, butterfly-like folded, four membered rings including free lone pairs on the phosphorus atoms, wherein the Lewis base can readily be substituted by N-heterocyclic carbenes.

Transmetallation of lithiodihydropyridines with Group 1 alkoxides provides facile access to reactive MH (M = Na, K) sources, which show significant structural diversity due in part to the distinct ways that Na/K engage with the σ (green) and π (red) donor systems of the DHP ligands.

Using commercially available 2-pyridyldiphenylphosphine (o-NC₅H₄)PPh₂, a family of electrophilic phosphonium cations [(o-NC₅H₄)PFPh₂]⁺ (2) and dications [(o-MeNC₅H₄)PRPh₂]²⁺ (R = F (4); Me (5)) were prepared.

Synthesis and structural characterization of novel tetra- and dinuclear organoantimony oxo-hydroxo clusters ligated by phosphonates and phosphonates/selininates are reported. Mass spectral studies reveal that the solid state molecular structures of these clusters were retained in solution as well.

Mixtures of hydrogen storage materials are examined to find a ‘fuel blend’ that remains a liquid phase throughout hydrogen release, maximizes hydrogen storage density, minimizes impurities and is thermally stable.

Amino group combined P/Ge FLPs Ph₂PN(R)GeCl₃ (R = 2,6-iPr₂C₆H₃ (1), 2,4,6-Me₃C₆H₂ (2), and C₆H₁₁ (3)) and Ph₂PN(2,6-iPr₂C₆H₃)GeMe₃ (4) as well as P/Sn FLP Ph₂PN(2,6-iPr₂C₆H₃)SnMe₃ (5) were prepared and utilized for reactions with alkyne and aldehyde molecules.

The blue, red and green spheres represent three different anions present within a series of novel hetero-trianionic sodium zincates. The syntheses and structures of the complexes are reported as well as their reactivities with important organic molecules.

We present a zwitterionic triphosphenium molecule which features dicoordinate, tricoordinate and tetracoordinate phosphorus centers in addition to a cyclopentadienyl moiety. Crystallographic, computational, electrochemical and spectroscopic data illustrate and rationalize the reactivity of this molecule as a multifunctional ligand for both transition metals and main group acceptors and suggest how the donor properties may be tuned.

Imidoselenium(II) chlorides ClSe[N(^tBu)Se]_nCl (n = 1–3) are intermediates in the formation of cyclic selenium imides by the reaction of SeCl₂ and ^tBuNH₂ in THF.

Structurally tracking the reaction of a sodium butylmagnesiate supported by a bulky silyl(bisamide) ligand towards quinoxaline, SET reactivity.

The s-block metal complex [K₂Ca{N(H)Dipp}₄] represents a suitable catalyst for the regioselective catalytic single and two-fold hydroamination of diphenylbutadiyne with N-methyl-anilines.

An Al–Cl functionalized germane with an activated Ge–Cl bond showed a ^tBu/Cl exchange via a transient germyl cation.

On the basis of the deprotonated bis-(4-methylbenzoxazol-2-yl)-methane ligand 1 a series of group 13 metal complexes was synthesised and fully characterised. A detailed comparison of solid state structures demonstrates clearly the similarity of methanide and the omnipresent nacnac ligand.

A series of functionalised bis-(benzothiazol-2-yl)-amine ligands and the related dimethylaluminium amides were synthesised and characterised. The solid state structural comparison reveals various coordination motifs, specific folding parameters and hydrogen bonding patterns in detail and guide the way to future Janus head ligand design.

Why are boron containing systems so effective at CO coupling? Full quantum chemical calculations with density functional theory (DFT) provide interesting insights into why recently reported CO coupling by diboryne systems is such a facile process.

The unsolvated Al(C₆F₅)₃ exists as a dimer in the solid state via double Al⋯(ortho-)F bridging and forms a stable adduct with Cp₂Fe through η¹-coordination.

Smallest chalcogenidometalate anions of the heaviest metals are presented alongside calculated energetics of these heaviest homologues of [NO_x]⁻, [PO₄]²⁻ and [CO₃]²⁻.

The FLP species bis(2-(TMP)phenyl)chloroborane was prepared as a monomeric Frustrated Lewis Pair displaying no B–N interaction. Species 1 reacts with H₂ to generate reversibly the zwitterionic H₂ activation product.

Microwave-irradiation accelerates FLP-catalyzed hydrogenations.

Cast from chlorobenzene, a light-emitting layer shows its best morphology and highest efficiency of 18.99 cd A⁻¹ in single-layer FIrpic-based OLEDs.

Dimesitylphosphinoisoprene reacts with a series of R-B(C₆F₅)₂ boron Lewis acids by isomerization and subsequent 1,4-P/B addition to give the corresponding heterocyclic phosphonium/borate zwitterionic products.

Lithio(thiocyanato)cuprates have been developed. These reveal planar, boat-shaped and chair-shaped Lipshutz-type dimers in the solid state, while Lipshutz-type and Gilman structures are seen in solution.

Nine homo- and hetero-tri(aryl)boranes related by stepwise aryl substitutions, are studied for H₂ cleavage as part of an FLP, and comparative Lewis acidity/electrochemical measurements discussed.

The reactivity of two 2,4,6-tris(trifluoromethyl)phenyl-substituted 2-(lutidinyl)organoboranes as intramolecular frustrated Lewis pairs was investigated.

A heteroleptic three coordinate germylene monochloride, its adduct with a Lewis acid, and germaacid-chloride & -ester derivatives with sulfur and selenium have been reported.

The main group element triggered C–H bond activation of a Rh-bound Cp ligand is reported. The key aspect of this transformation is the presence of a highly Lewis acidic Group 14 element site.

ArylBCl₂ and aryl and vinyl containing borocations synthesised by electrophilic borylation effect the carboboration of TMS-substituted alkynes and allenes.

Two different [As^VS₄]³⁻ linkage modes first coexist in 1-D organic hybrid lanthanoid thioarsenates.

The effectiveness of simple synthetic routes to access silylamide Hauser base (R₂NMgX; X = halogen) and amido-Grignard (R₂NMgR) complexes from commercially available Grignard reagents is explored herein.

A bulky NPN-substituted dichlorostibane was reduced with KC₈ to afford a distibenium compound with a [Sb₂]²⁺ ion which can be regarded as a dimerization product of a stiba-phospha-diazanediyl singlet biradicaloid. The intermediate formation of this singlet stiba-phospha-diazanediyl was proven by trapping experiments.

Three B{C₆H₃(CF₃)₂}₃ isomers have been studied, ortho-substituents quench FLP H₂ cleavage via steric blocking and electron donation to the boron centre.

The synthesis and electronic structure of bis(imino)pyridine (I₂P) complexes of the divalent metal ions, Zn(II) and Mg(II) are reported, and a correlation between the ligand C_im–C_py bond lengths with the ligand torsion angle is described. Structural comparison with a new complex of Al(III) and previously reported Al(III) complexes is included.

The insertion of an N-heterocyclic carbene into a P–H bond is the first step in a new synthesis of parent phosphinidene–carbene adducts from PH₃. These adducts are used to generate bis(phosphinidene)mercury(II) complexes.

The density functional theory (DFT) calculations reveal the potential of newly proposed main group germanium hydride systems to effect important chemical transformations, such as the catalytic cleavage of the O–H bond in water and alcohols, with significantly greater efficiency than the existing, state-of-the-art post-transition metal based systems.

New synthetic methods for preparing gram quantities BN analogs of polycyclic aromatic hydrocarbons are highlighted. Such methods are key to proper evaluation of these materials in device applications.