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The trisulfide radical anion is well-known as the blur chromophore in ultramarines and it has a versatile role in materials chemistry, especially in the redox chemistry of alkali-metal-sulfur batteries, electrochemistry,...

The oxidative-addition reaction between an arylmethyl chloride (RCH2Cl; R = 1-C10H7, 2,4,6-Me3C6H2, 4-MeC6H4, 3-MeC6H4, C6H5, 4-ClC6H4) and tin powder in boiling toluene produces bis(arylmethyl)tin dichlorides, [(RCH2)2SnCl2] in good yields. At 160 °C in mesitylene bis(1-naphthylmethyl)tin dichloride undergoes Sn-C homolytic cleavage to generate two 1-naphthylmethyl radicals (1-C10H7CH2•) which were trapped by TEMPO (C9H8NO•). Subsequently, the radicals (RCH2•) produced in this manner were utilized for efficient substitution reactions with electron-rich arenes (R'H; R' = 2,4,6-Me3C6H2, 1,2,4,5-Me4C6H, 1,2,3,4,5-Me5C6) to obtain a variety of unsymmetrical diarylmethanes (RR´CH2). The addition of one equivalent of iodine (I2) to the reaction mixture resulted in a significant increase in the yields of coupled products.

Early theoretical and experimental investigations of inorganic sulfur-nitrogen compounds were dominated by (a) assessments of the purported aromatic character of cyclic, binary S,N molecules and ions, (b) the unpredictable reactions of the fascinating cage compound S4N4, and (c) the unique structure and properties of the conducting polymer (SN)x. In the last few years, in addition to unexpected developments in the chemistry of well-known sulfur nitrides, the emphasis of these studies has changed to include nitrogen-rich species formed under high pressures, as well as the selenium analogues of well-known S,N compounds. Novel applications have been established or predicted for many binary S/Se,N molecules, including their use for fingerprint detection, in optoelectronic devices, as high energy-density compounds or as hydrogen-storage materials. The purpose of this perspective is to evaluate critically these new aspects of the chemistry of neutral, binary chalcogen-nitrogen molecules and to suggest experimental approaches to the synthesis of target compounds. Recently identified ternary S,N,P compounds will also be considered in light of their isoelectronic relationship with binary S,N cations.

This work explores avenues toward PCP pincer complexes with acyclic diaminocarbene central moieties that are suitable for ligand-assisted reactivity involving the carbene carbon. For this purpose, diphosphine chelating ligands 1 and 2, with bis(imidazolyl)methyl and bis(pyrazolyl)methyl backbones, respectively, were prepared in two high-yield synthetic steps. Nickel(II) and platinum(II) dihalide complexes 3 and 6, incorporating 1, were prepared and converted into PCP pincer ligands 5 and 7 upon deprotonation with KHMDS. Chelated nickel(I) complex 4 was obtained as a byproduct to 3. Although the solid-state structures of 5 and 7 presented geometric strain at the diaminomethyl carbon, this moiety could not be converted into a diaminocarbene by proton or hydride abstraction. 7 could be converted into platinum(IV) analog 8 by oxidation with PhICl2. Ligand 2 proved more versatile than 1, or less dependable in its behavior, generating P,N-chelating cobalt(II) dibromide complex 9. Easily accessible ligands 1 and...

Reaction of potassium carbonate with elemental sulfur or selenium in acetone in the presence of [PPN]Cl (PPN = (Ph3P)2N) produces catena-[S12]2−, the longest structurally characterised polysulfide dianion, or spiro-[Se11]2− as ion-separated [PPN]+ salts.

The well-known tendency of sulfur to catenate is exemplified by an extensive series of polysulfide dianions [Sn]2- (n = 2-9) and related radical monoanions [Sn]˙-. The dianions can be isolated as crystalline salts with appropriate cations and structurally and spectroscopically characterized. Although the smaller radical monoanions may be stabilized in zeolitic matrices, they are usually formed in solution via disproportionation or partial dissociation of the dianions as well as by electrochemical reduction of elemental sulfur. An understanding of the fundamental chemistry of these homoatomic species is key to unravelling their behaviour in a broad variety of chemical environments. This review will critically evaluate the techniques used to characterize polysulfide dianions and radical anions both in solution and in the solid state, i.e. Raman, UV-visible, EPR, NMR and X-ray absorption spectroscopy, X-ray crystallography, mass spectrometry, chromatography and high-level quantum-chemical calculations. This is followed by a discussion of recent advances in areas in which these anionic sulfur species play a crucial role, viz. alkali-metal-sulfur batteries, organic syntheses, biological chemistry, geochemical processes including metal transport, coordination complexes, atmospheric chemistry and materials science.

Cyclocondensation is a major preparative route for the generation of inorganic heterocycles especially in the case of ring systems involving a Group 15 or 16 element linked to nitrogen. This Perspective will consider recent experimental and computational studies involving the reactions of primary amines (or their synthetic equivalents) with pnictogen and chalcogen halides. The major focus will be a discussion of the identity and role of acyclic intermediates in the reaction pathways to ring formation, as well as the nature of the heterocycles so formed. The similarities and differences between the chemistry of group 15 and 16 systems are emphasised with a view to providing signposts for further investigations.

The reaction of silver hexafluoridoantimonate with Ph2PCH2PPh2NSiMe3 (1) in dichloromethane produces the dimeric complex [Ag(μ-Ph2PCH2PPh2NSiMe3)]2[SbF6]2 (2), in which two heterobifunctional ligands 1 in the dication are N, P-chelated in a head-to-tail fashion to a [Ag···Ag]2+ unit that exhibits an Ag···Ag contact of 2.8530(6) A. Quantum theory of atoms-in-molecules (QTAIM) analysis of the bonding revealed an attractive interaction between the two silver atoms.

Correction for ‘Tellurium: a maverick among the chalcogens’ by Tristram Chivers and Risto S. Laitinen, Chem. Soc. Rev., 2015, 44, 1725–1739, DOI: 10.1039/C4CS00434E.

Silyl-substituted naphthalene derivatives, tris(1-napthyl)silicon (IV) chloride (1), tris(1-napthyl)silicon (IV) hydroxide (2) and tris(1-napthyl)silicon (IV)-n-butoxide (3) have been structurally characterized by single-crystal X-ray diffraction. The close intermolecular proximity of the naphthyl substituents groups in 1–3 results in a variety of C–H---π intermolecular interactions to form 2D assemblies. The UV–vis spectra of 1–3 display bathochromic (red)-shifts and the extinction coefficients increase with respect to unsubstituted naphthalene. Quantum yield calculations indicate that the fluorescence emission efficiency of 1–3 is significantly decreased with reference to 1-trimethylsilylnaphthalene. The absorptions in the solid-state spectra are broadened and approximately 45 nm red-shifted in comparison with the spectra of 1–3 in solution.

There are several commercial selenium and tellurium compounds that are useful in synthetic chemistry. The introduction of selenium and tellurium into both organic and inorganic compounds frequently begins with the elements. This chapter provides an overview of the main reactivity of the hexagonal allotropes of selenium and tellurium, which are the most stable form of the elements under ambient conditions. While the two elements have very similar chemical properties, there are also notable differences. Upon reduction, both elements form mono- and poly-chalcogenides, which are useful nucleophilic reagents in several reactions. The elements also react with many main group compounds as well as with transition metal complexes. They also form homopolyatomic cations upon oxidation. Both selenium and tellurium react with Grignard reagents and organyllithium compounds affording organylchalcogenolates, which upon oxidation form dichalcogenides that are themselves useful reagents in organic synthetic chemistry as well as in materials applications. This chapter provides a short introduction to the various topics that will be developed further in the subsequent chapters of this book. This article has previously been published in the journal Physical Sciences Reviews, Volume 4, Issue 4, 20180059, ISSN (Online) 2365-659X, DOI: https://doi.org/10.1515/psr-2018-0059.

The reactivity of the chalcogen–nitrogen bond toward main-group element or transition-metal halides, as well as electrophilic and nucleophilic reagents, is the source of a variety of applications of Se–N and Te–N compounds in both inorganic or organic chemistry. The thermal lability of Se–N compounds also engenders useful transformations including the formation of radicals via homolytic Se–N bond cleavage. These aspects of Se–N and Te–N chemistry will be illustrated with examples from the reactions of the binary selenium nitride Se4N4, selenium–nitrogen halides [N(SeCln)2]+ (n = 1, 2), the synthons E(NSO)2 (E = Se, Te), chalcogen–nitrogen–silicon reagents, chalcogen(IV) diimides RN=E=NR, the triimidotellurite dianion [Te(NtBu)3]2−, chalcogen(II) amides and diamides E(NR2)2 (E = Se, Te; R = alkyl, SiMe3), and heterocyclic systems.

Selenium and tellurium form binary halides in which the chalcogen can be in formal oxidation states (IV), (II) or (I). They are versatile reagents for the preparation of a wide range of inorganic and organic selenium and tellurium compounds taking advantage of the reactivity of the chalcogen–halogen bond. With the exception of the tetrafluorides, the tetrahalides are either commercially available or readily prepared. On the other hand, the low-valent species, EX2 (E = Se, Te; X = Cl, Br) and E2X2 (E = Se, Te; X = Cl, Br) are unstable with respect to disproportionation and must be used as in situ reagents. Organoselenium and tellurium halides are well-known in oxidation states (IV) and (II), as exemplified by REX3, R2EX2 and REX (R = alkyl, aryl; E = Se, Te; X = F, Cl, Br, I); mixed-valent (IV/II) compounds of the type RTeX2TeR are also known. This chapter surveys the availability and/or preparative methods for these widely used reagents followed by examples of their applications in synthetic inorganic and organic selenium and tellurium chemistry. For both the binary halides and their organic derivatives, the discussion is subdivided according to the formal oxidation state of the chalcogen.

A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn-S(C) and Zn-S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(ii) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S',S'') mode to the Ni(ii) centre with three distinctly different Ni-S bond lengths (2.3487(8), 2.4500(9) and 2.5953(10) Å). By contrast, in the red-brown square-planar complex 5b the two ligands are S,S'-chelated to Ni(ii) (d(Ni-S) = 2.165(2) and 2.195(2) Å) with one pendant PPh2S group. DFT calculations revealed that the energetic difference between singlet and triplet state octahedral and square-planar isomers of the Ni(ii) complex is essentially indistinguishable. Consistently, VT and (31)P CP/MAS NMR spectroscopic investigations indicated that a mixture of isomers exists in solution at room temperature, while the singlet state square-planar isomer 5b becomes favoured at -40 °C.

The Se,N ligand CH2(PPh2Se)(PPh2NSiMe3) (1e) was prepared in excellent yield by treatment of [CH2(PPh2)(PPh2NSiMe3)] with selenium in hot toluene. Reactions of 1e with a small excess of KH or with Mg[N(SiMe3)2] in a 2:1 molar ratio in boiling THF or toluene produced [K{CH(PPh2Se)(PPh2NSiMe3)}]2 (K3e) or Mg{CH(PPh2Se)(PPh2NSiMe3)}2 [Mg(3e)2], respectively. Compounds 1e, (K3e)2, and Mg(3e)2 were characterized by multinuclear (1H, 13C, 29Si, 31P, 77Se) NMR spectroscopy, and their X-ray structures were determined. In the solid state the N,Se-coordinated potassium salt forms a centrosymmetric dimer via weak K···Se interactions [3.269(1) A]; the K+ ions also engage in intramolecular (η3 and η6) interactions with neighboring phenyl groups. The homoleptic magnesium complex Mg(3e)2 is monomeric and exhibits a Se,C,N-bonding mode [Mg–C 2.480(5) and 2.442(5) A].

MRCI-SD/def2-QZVP and PBE0/def2-QZVP calculations have been employed for the analysis of geometries, stabilities, and bonding of isomers of the 18-electron anions N2S2−, NS2−, and NSO−. Isomers of the isoelectronic neutral molecules SO2, S2O, S3, and O3 are included for comparison. The sulfur-centered acyclic NSN2−, NSS−, and NSO− anions are the most stable isomers of their respective molecular compositions. However, the nitrogen-centered isomers SNS− and SNO− lie close enough in energy to their more stable counterparts to allow their occurrence. The experimental structural information, where available, is in good agreement with the optimized bond parameters. The bonding in all investigated species is qualitatively similar, though electron density analyses reveal important quantitative differences that arise from bond polarization. Most of the investigated systems can be described with a single configuration wave function, the two notable exceptions being isomers SSS and OOO that show some diradical character. The computed MRCI-SD/def2-QZVP absorption maxima for SNS− and NSS− are 342 and 327 nm, respectively. The corresponding PBE0/def2-QZVP values in acetonitrile are 353 and 333 nm. These data support the proposed initial formation of SNS− from electrochemical or chemical reduction of SSNS− based on experimental UV–vis spectra. The interconversion of SNS− and NSS− is calculated to be facile and reversible, leading to an equilibrium mixture that also includes the remarkably stable dianion SNSNSS2−. Thus, salts of either SNS− or NSS− with bulky organic cations represent feasible synthetic targets.

Binary S,N anions, e.g., NSN2- and SSNSS-, and related ternary S,N,O anions such as the structural isomers NSO-/SNO- and SSNO- are rarely mentioned in inorganic chemistry textbooks, despite the fact that their salts were synthesised and structurally characterised more than 30 years ago. These fundamentally important species and their conjugate acids, e.g. HNSO and HSNO, have been the focus of numerous investigations in recent years in view of their significance in disciplines as diverse as atmospheric chemistry and cell biology. This Tutorial Review provides a consolidated account of the fundamental chemistry including synthesis, spectroscopic characterisation, molecular and electronic structures, and properties of these intriguing species, and compares these aspects of their behaviour with those of isoelectronic sulfur oxides and N,O anions. A final section draws attention to the significance and applications of these simple S-N species in a broader context.

The reactions of Li2[C(PPh2S)2] with EI3 (E = As, P) have been investigated in order to determine the nature of the coordination mode between the methanediide ligand and lighter pnictogens. Treatment of this reagent in toluene with AsI3 in a 1:1 M ratio produces the heteroleptic complex AsI[C(PPh2S)2] (2a), which was characterized by multinuclear NMR spectra and by a crystal structure determination. Attempts to isolate the phosphorus analogue PI[C(PPh2S)2] (2b) were unsuccessful. The dianionic methanediide ligand [C(PPh2S)2]2− in 2a is S,C,S-coordinated to the AsIII centre. The lengths of the weak As–S bonds differ markedly (2.852(2) and 2.443(2) A) and the As–C bond distance 1.864(6) A falls midway between single and double bond values. DFT calculations for AsI[C(PPh2S)2] reveal that the structure with a symmetrically coordinated ligand is lower in energy than the experimental structure by only 8.3 kJ mol−1 suggesting that the stabilization of the latter in the solid state is due to packing effects. The calculated bond orders for the M–C bond in MI[C(PPh2S)2] are 1.23 (M = As) and 1.31 (M = P). The π M–C interaction is predicted to be significantly stronger in the corresponding cations [M{C(PPh2S)2}]+ with bond orders of 1.68 (M = As) and 1.75 (M = P).

Density functional theory (DFT) calculations for the six-membered ring 1,4-(CH2)2(PtBu)4 (1), the dimer (PtBu2)2 (2) and the 2,5-chalcogenated derivatives of 1, 3a (E = S) and 3b (E = Se), and the corresponding cation radicals and dications predict significant structural changes upon oxidation. The formation of a transannular P–P single bond (ca. 2.25 A) in the three cyclic dications 12+, 3a2+, and 3b2+ is indicated by geometry and consideration of the frontier orbitals. The calculations also indicate a weak transannular interaction in the cyclic cation radicals. The nature of these transannular P–P bonding interactions is analyzed through a consideration of the molecular orbitals involved. Cyclic Voltammetry studies of 1 and 2 reveal two well-separated oxidation processes. Both processes are irreversible for 1 at normal scan rates, whereas for 2 the first process is quasi-reversible. The cation radical 1+• could not be detected by in situ electron paramagnetic resonance studies of the first electrochemical oxidation, but a spectrum for the radical cation 2+• could be observed. The difference in the redox behavior of 1 and 2 is considered with respect to the structural parameters and DFT calculations. Chemical oxidation of 1 with NO+[Al(ORF)4]− (RF = C(CF3)3) in CH2Cl2 led to a complex mixture; the protonated cation H1+ (1,4-(CH2)2(PtBu)3(HPtBu)+) was identified as one of the major products on the basis of multinuclear NMR spectra.

While exploring the chemistry of tellurium-containing dichalcogenidoimidodiphosphinate ligands, the first all-tellurium member of a series of related square-planarEII(E′)4complexes (EandE′ are group 16 elements), namely bis(P,P,P′,P′-tetraphenylditelluridoimidodiphosphinato-κ2Te,Te′)tellurium(II) (systematic name: 2,2,4,4,8,8,10,10-octaphenyl-1λ3,5,6λ4,7λ3,11-pentatellura-3,9-diaza-2λ5,4λ5,8λ5,10λ5-tetraphosphaspiro[5.5]undeca-1,3,7,9-tetraene), C48H40N2P4Te5, was obtained unexpectedly. The formally TeIIcentre is situated on a crystallographic inversion centre and isTe,Te′-chelated to two anionic [(TePPh2)2N]−ligands in ananticonformation. The central TeII(Te)4unit is approximately square planar [Te—Te—Te = 93.51 (3) and 86.49 (3)°], with Te—Te bond lengths of 2.9806 (6) and 2.9978 (9) Å.

The metathetical reactions between SnBr4 and Li2[E'C(PPh2E)2] in toluene produce the homoleptic tin(IV) complexes Sn[E′C(PPh2E)2]2 [E = E′ = S (1b); E = S, E′ = Se (1c)], which were isolated as red crystals and structurally characterized by X-ray crystallography. The metrical parameters of these octahedral complexes are compared with those of the all-selenium analog Sn[E′C(PPh2E)2]2 (E = E′ = Se, 1a), which was prepared previously by a different route.

The reactions of K[HC(PPh2NSiMe3)2] (K[1]) and MI3 (M = As, Sb) or TeI4 gave as the major products the complexes [{MIn}{C(PPh2NSiMe3)(PPh2NHSiMe3)}] (MIn = trans-AsI2, trans- or cis-SbI2, TeI3), which feature the ligand [C(PPh2NSiMe3)(PPh2NHSiMe3)]− (2). This anion, the NH tautomer of [HC(PPh2NSiMe3)2]−, is formally generated by a 1,3-hydrogen shift to give complexes in which the ligand is N,C-chelated to the main-group-metalloid center. The M–C distances are slightly longer than the sum of the covalent radii for M and C in the case of the group 15 metalloids but significantly shorter for M = Te. The arsenic derivative [{t-AsI2}2] is monomeric in the solid state, with As–I distances that differ by ca. 0.55 A, whereas the antimony analogues [{t-SbI2}2] and [{c-SbI2}2] are dimeric through bridging iodide ligands and the disparity in Sb–I distances of the SbI2 units is 0.10 and 0.33 A, respectively. The tellurium derivative [{TeI3}2] is monomeric with a distorted-square-pyramidal geometry at the Te center an...

The reaction of H2C(PCl2)2 with four equivalents of iPrMgCl produces H2C(PiPr2)2, which was treated with tellurium in boiling toluene, or selenium in toluene at room temperature, to give the monochalcogenides EPiPr2CH2PiPr2 (E = Te, 4a; E = Se, 4b) in high yields. X-ray structural determinations show that 4a and 4b exist as the CH2 tautomers in the solid state with E–P–C–P dihedral angles of 56.1(2)° and 56.7(1)°, respectively. DFT calculations were carried out for the isolectronic series EPR2CH2PR2 and EPR2NHPR2 (E = Se, Te; R = Me, iPr, tBu, Ph) and for their non-chalcogenated precursors in order to elucidate the factors that determine the preference for PH tautomers in some PNP-bridged systems. Compounds 4a and 4b were also characterized by multinuclear (1H, 13C, 31P, 77Se, 125Te) NMR spectroscopy. In solution, 4a exhibits fluxional behavior, which has been investigated by variable-temperature and variable-concentration multinuclear NMR spectroscopy. The observed behavior is consistent with an intermolecular tellurium transfer with an activation energy of 21.9 ± 3.2 kJ mol–1; consideration of selenium exchange in 4b indicates a much higher energetic barrier. DFT calculations provide insights into the pathway for the chalcogen exchange process in 4a (ΔE = 20.4 kJ mol–1). The outcome of reactions of 4a with selenium and nBuLi reflects the lability of the P-Te functionality.

The reaction of Li2[C(PPh2NSiMe3)2] with elemental tellurium in THF was carried out in an attempt to generate the tellurocarbonyl dianion [TeC(PPh2NSiMe3)2]2− as the dilithium derivative. This thermally unstable tridentate ligand was characterized by 31P and 7Li NMR spectroscopy. Attempted recrystallization gave yellow crystals, which were shown by X-ray crystallography to be a neutral, centrosymmetric complex comprised of two molecules of the novel telluroketone [TeC(PPh2NSiMe3)2] stabilized by N,Te,N coordination to LiOLi units of the rhombic dodecahedral cluster [Li8(μ5-O)2(μ5-OH)4(C4H8O)4].

The electronic structures of tetrachalcogen tetranitrides, E4N4, and octachalcogen dications, E8(2+), and the nature of their intramolecular E···E interactions (E = S, Se) was studied with high-level theoretical methods. The results reveal that the singlet ground states of both systems have a surprisingly large correlation contribution which functions to weaken and therefore lengthen the cross-ring E-E bond. The observed correlation effects are primarily static in E4N4, whereas in E8(2+) the dynamic part largely governs the total correlation contribution. The presented description of bonding is the first that gives an all-inclusive picture of the origin of cross-ring interactions in E4N4 and E8(2+); not only does it succeed in reproducing all experimental structures but it also offers a solid explanation for the sporadic performance of different computational methods that has been reported in previous studies. Furthermore, the theoretical data demonstrate that E···E bonds in E4N4 and E8(2+) are unique and fundamentally different from, for example, dispersion that plays a major role in weak intermolecular chalcogen···chalcogen contacts.

The complexes [Na{HC(PPh2S)2}] (Na3a), [Na{HC(PPh2Se)2}] (Na3b), [K{HC(PPh2S)2}]∞ (K3a), [K{HC(PPh2Se)2}]∞ (K3b), [Mg{HC(PPh2S)2}2] (Mg(3a)2), [Mg{HC(PPh2Se)2}2] (Mg(3b)2), and [Zn{HC(PPh2S)2}2] [Zn(3a)2] have been prepared in good yields (69–92 %) by treatment of the neutral ligands H2C(PPh2E)2 (1a, E = S; 1b, E = Se) with [Na{N(SiMe3)2}] (Na3a), NaNH2 (Na3b), [K{N(SiMe3)2}] (K3a and K3b), [Mg{N(SiMe3)2}2] [Mg(3a)2 and Mg(3b)2], or Me2Zn [Zn(3a)2] as base in THF/toluene. These compounds were characterized in solution by multinuclear (1H, 13C, 31P, and 77Se) NMR spectroscopy and the X-ray structures of K3a, K3b, Mg(3a)2, Mg(3b)2, and Zn(3a)2 were determined. In the solid state, the E,E′-chelated ligands in K3a and K3b also engage in potassium–chalcogen interactions with adjacent molecules to form one-dimensional ladder structures. With K3a, both sulfur atoms of the ligand are involved in chelation leading to four-membered K2S2 rings, whereas only one selenium atom is tricoordinated in K3b; significant potassium···aryl interactions are also observed in both structures. In the homoleptic magnesium complexes Mg(3a)2 and Mg(3b)2, the E,E′ chelation by the methanide ligands is supplemented by weak, unequal Mg···C interactions [2.781(10) and 3.199(7) A for Mg(3a)2; 3.331(8) and 3.217(7) A for Mg(3b)2]. The zinc complex Zn(3a)2 is isostructural with the previously reported selenium analogue Zn(3b)2. The X-ray structures of the S,S′-chelated complex [(TMEDA)Li3a] as well as new polymorphs of 1a and 1b are also reported.

The reactions of Li2[C(Ph2PS)2] with tellurium tetrahalides in a 1:1 molar ratio in toluene afford the complexes {TeX2[C(Ph2PS)2]}2 (7a, X = Cl; 7b, X = Br; 7c, X = I). These complexes dimerize through halide bridges in the solid state, and the tridentate ligand is S,C,S-coordinated to the tellurium center with a Te–C bond length of 2.024(3), 2.030(6), and 2.045(8) A, respectively. In the case of TeBr4, small amounts of the complex TeX2[SC(Ph2PS)2] (8b, X = Br) were isolated and shown by X-ray analysis to be the result of formal sulfur insertion into the Te–C bond of 7b. Complex 8b and the corresponding dichloride and diiodide, 8a (X = Cl) and 8c (X = I), may be prepared in good yields by the metathetical reactions of Li2[SC(Ph2PS)2] with TeX4 in toluene. The complex TeI2[(I2)C(Ph2PS)2] (9) was isolated as a minor product from the reaction of Li2[C(Ph2PS)2] and TeI4 and identified by X-ray crystallography. Complex 9 is constructed from the insertion of an iodine atom of an I2 molecule into the Te–C bond o...

Correction for ‘The role of polysulfide dianions and radical anions in the chemical, physical and biological sciences, including sulfur-based batteries’ by Ralf Steudel et al., Chem. Soc. Rev., 2019, 48, 3279–3319.

The formation and structural characterization of the first coordination complex of the tellurophosphorane [tBu(H)NP(μ-NtBu)2P(Te)N(H)tBu] are presented. The silver(I) iodide complex {(I)Ag[tBu(H)NP(μ-NtBu)2P(Te)N(H)tBu]3} (2) was isolated from the reaction of [Li(TMEDA)]2[tBuN(Te)P(μ-NtBu)2P(Te)NtBu)] (1) with AgI in toluene and characterized by X-ray analysis and multinuclear NMR spectroscopy. Complex 2 is comprised of three tellurophosphorane ligands coordinated to AgI in a distorted tetrahedral arrangement [102.90(3)–114.51(5)o]. The P=Te bond lengths of 2.3883(13)–2.4043(17) A in 2 are slightly elongated compared to those in the free ligand.

The reaction of Li2[PhbamDipp] (PhbamDipp = PhB(NDipp)2; Dipp = 2,6-iPr2C6H3) with lanthanum(III) triiodides LnI3(THF)3.5 (Ln = La, Sm) in THF produces complexes of the type [Li(THF)4]2[(PhbamDipp)2LnI], which were characterized in solution by multinuclear NMR spectroscopy and in the solid state by single-crystal X-ray structural determinations. The ion-separated complexes are comprised of a spirocyclic anion in which two PhbamDipp ligands and an iodide ion are linked to the five-coordinate metal atom; charge balance is provided by two tetrasolvated lithium ions [Li(THF)4]+.

The first examples of the incorporation of the boraamidinate ligand into lanthanide complexes have been prepared by reaction of equimolar amounts of [Li(2)][PhB(NDipp)(2)] and LnCl(3) in tetrahydrofuran (THF), which produces "ate" complexes of the form {[Li(THF)(4)][bamLnCl(2)(THF)]}(2) [Ln = Y (9a), Pr (9b), Nd (9c), Sm (9d), Ho (9e), Er (9f), Yb (9g)] through the inclusion of the LiCl by-product. The isostructural complexes 9a-g were characterized in the solid state by X-ray crystallography, which revealed ion-separated complexes composed of a dimeric anion with a terminal and a bridging chloride ligand on each metal center and a tetrasolvated cation, [Li(THF)(4)](+). In solution, the yttrium complex 9a was characterized by multinuclear ((1)H, (13)C, (7)Li, and (11)B) NMR spectroscopy. The (1)H and (7)Li NMR spectra of the paramagnetic complexes 9b-9d showed broad resonances, but NMR spectra could not be obtained for 9e-g. The complexes 9a-g are readily soluble in THF, but insoluble in diethyl ether and hexane. The reaction of {[Li(THF)(4)][bamLnCl(2)(THF)]}(2) (Ln = Y, Sm) with an excess of trimethysilyl trifluoromethanesulfonate (TMSOTf) generates the dimeric neutral complexes {bamLnCl(THF)(2)}(2), which have been characterized by (1)H NMR and X-ray crystallography.

[CoCl2{N,N′-Te2(NtBu)4}] (1) was obtained in good yields by the reaction of equimolar amounts of (tBu)NTe(μ-NtBu)2TeN(tBu) and CoCl2 in toluene under an argon atmosphere. The crystal structure of 1·CH2Cl2 showed that the dimeric tellurium diimide ligand is N,N′-chelated to cobalt. The related reaction of Se(NtBu)2 and CoCl2 affords a green product tentatively identified as a 1:1 adduct [CoCl2{N,N′-Se(NtBu)2}] (CHN analysis). However, recrystallization from thf produces the ion-separated complex [Co2(μ-Cl)3{N,N′-Se(NtBu)2}2(thf)2][CoCl3{NH2(tBu)}]·1½thf (2·1½thf), in which the monomeric selenium diimide ligand is N,N′-chelated to cobalt in the cation. A pathway for the formation of 2 from [CoCl2{N,N′-Se(NtBu)2}] in thf is proposed.

After a brief reflection on the important discoveries in main group chemistry during the past century, this article provides some suggestions concerning areas in which studies of s- and p-block element compounds are likely to have a major impact on the discipline of chemistry and upon society in general in the context of significant advances that have been made in the last decade. These areas range from fundamental to applied aspects of the subject. In the former category, novel aspects of chemical bonding and new reagents for synthetic applications are considered. From a more practical perspective alternative energy sources (especially hydrogen storage), new materials (notably nanomaterials and chemical sensors), catalysis (in the context of green chemistry), and medicinal chemistry (both diagnostic and therapeutic applications) are discussed.

Selenium- and tellurium-containing bis(diphenylphosphinoyl)methane monoanions were prepared by oxidation of the anion [HC(PPh2)2]− with elemental chalcogens. The selenium-containing isopropyl derivative was synthesized by generating [H2C(PiPr2)2] via a reaction between [H2C(PCl2)2] and 4 equiv of iPrMgCl prior to in situ oxidation with selenium followed by deprotonation with LiNiPr2. The solid-state structures of the lithium salts of the monochalcogeno anions TMEDA·Li[HC(PPh2E)(PPh2)] (E = Se (Li7a), E = Te (Li7b)) and the dichalcogeno anions TMEDA·Li[HC(PR2Se)2] (R = Ph (Li8a), iPr (Li8c)) revealed five- and six-membered LiEPCP and LiSePCPSe rings, respectively. The homoleptic group 12 complexes {M[HC(PPh2Se)2]2} (M = Zn (9a), Hg (9b)) were prepared from Li8a and MCl2 and shown to have distorted-tetrahedral structures; the nonplanarity of the carbon center in the PC(H)P unit of the Zn complex 9a is attributed to crystal-packing effects. The complexes Li7a, Li7b, Li8a, TMEDA·Li[HC(PPh2Te)2] (Li8b), Li8c, ...

Voltammetric studies of S2N2 employing both cyclic voltammetry (CV) and rotating disk electrode (RDE) methods on GC electrodes at room temperature (RT) revealed two irreversible reduction processes at about −1.4 V and −2.2 V in CH3CN, CH2Cl2, and tetrahydrofuran (vs ferrocene) and no observable oxidation processes up to the solvent limit when the scan is initially anodic. However, after cycling the potential through −1.4 V, two new couples appear near −0.3 V and −1.0 V due to [S3N3]−/0 and [S4N4]−/0 respectively. The diffusion coefficient D for S2N2 was determined to be 9.13 × 10−6 cm2 s−1 in CH2Cl2 and 7.65 × 10−6 cm2 s−1 in CH3CN. Digital modeling of CVs fits well to a mechanism in which [S2N2]−• couples rapidly with S2N2 to form [S4N4]−•, which then decomposes to [S3N3]−. In situ electron paramagnetic resonance (EPR) spectroelectrochemical studies of S2N2 in both CH2Cl2 and CH3CN resulted in the detection of strong EPR signals from [S4N4]−• when electrolysis is conducted at −1.4 V; at more negative vol...

Voltammetric studies of S4N4 employing both cyclic (CV) and rotating disk (RDE) methods in CH2Cl2 at a glassy carbon electrode reveal a one-electron reduction at −1.00 V (versus ferrocene/ferrocenium), which produces a second redox couple at −0.33 V, confirmed to be the electrochemically generated [S3N3]− by CV studies on its salts. Diffusion coefficients (CH2Cl2/0.4 M [nBu4N][PF6]) estimated by RDE methods: S4N4, 1.17 × 10−5 cm2 s−1; [S3N3]−, 4.00 × 10−6 cm2 s−1. Digital simulations of the CVs detected slow rates of electron transfer for both couples and allowed for a determination of rate constants for homogeneous chemical reaction steps subsequent to electron transfer. The common parameters (kf1 = 2.0 ± 0.5 s−1, ks1 = 0.034 ± 0.004 cm s−1 for [S4N4]−/0; kf2 = 0.4 ± 0.2 s−1, ks2 = 0.022 ± 0.005 cm s−1 for [S3N3]−/0 at T = 21 ± 2 °C) fit well to a “square-scheme” mechanism over the entire range of data with first order decay of both redox products. An alternate model could also be fit wherein [NS]• liber...

The solid-state structures of the complexes M[PhB(μ-N-t-Bu)2]2 (1a, M= Ge; 1b, M = Sn) were determined to be spirocyclic with two orthogonal boraamidinate (bam) ligands N,N′-chelated to the group 14 centre. Oxidation of 1b with SO2Cl2 afforded the thermally unstable, blue radical cation {Sn[PhB(μ-N-t-Bu)2]2}•+, identified by electron paramagnetic resonance (EPR) spectroscopy supported by density functional theory (DFT) calculations, whereas the germanium analogue 1a was inert towards SO2Cl2. The reaction between Li2[PhB(μ-N-t-Bu)2]2 and SnCl2 or PbI2 in 2:1 molar ratio in diethyl ether produced the novel heterotrimetallic complexes Li2Sn[PhB(μ-N-t-Bu)2]2 (2b) and (Et2O·Li)LiPb[PhB(μ-N-t-Bu)2]2 (2c·OEt2), respectively. By contrast, treatment of Li2[PhB(μ-N-t-Bu)2]2 with C4H8O2·GeCl2 yielded the germanium(IV) complex 1a via a redox process. The X-ray structures of 2b and 2c·THF revealed polycyclic arrangements in which one bam ligand is N,N′-chelated to the Sn(II) or Pb(II) atom and one of the Li+ cations, while the second bam ligand exhibits a unique bonding mode, bridging all three metal centres. The fluctional behaviour of 2b was investigated by variable temperature, multinuclear NMR spectroscopy.

The reaction of (THT)AuCl with (TMEDA)Na[N(TePR2)2] (R = Ph, i-Pr, t-Bu) produces a series of gold (III) complexes of the type [{R2PNP(Te)R2}Au(µ-Te)]2 (4a, R = i-Pr; 4b, R = Ph; 4c, R = t-Bu) rather than the expected homoleptic Au(I) complexes of the ditelluridoimidodiphosphinate ligands. A combination of solution- and solid-state NMR studies shows that both cis and trans isomers of 4a–4c are formed in these reactions. X-ray structural determinations of the trans isomers of 4a–4c reveal a centrosymmetric arrangement with a central four-membered Au2Te2 ring formed by the formal insertion of gold into a P–Te bond; this insertion process was shown to be reversible upon addition of PPh3 to 4a to give the monomeric gold(I) complex Ph3PAu[N{TeP(i-Pr)2}2]. The X-ray structure of cis-4b is also described.Key words: gold, tellurium, redox, X-ray structures, imidodiphosphinate.

The metathesis of [PhB(μ-NtBu)2]AsCl and tBuN(H)Li in 1:1 molar ratio in diethyl ether produced the amido derivative [PhB(μ-NtBu)2AsN(tBu)H] (1) in good yield. The lithiation of 1 with one equivalent of nBuLi afforded the lithium salt [PhB(μ-NtBu)2AsN(tBu)Li] (2a). Both 1 and 2a were characterized by multinuclear NMR spectroscopy. The crystal structure of 2a is comprised of a U-shaped, centrosymmetric dimer in which the monomeric [PhB(μ-NtBu)2AsN(tBu)]−Li+ units are linked by Li-N interactions to give a six-rung ladder. Oxidation of 2a with one-half equivalent of I2 in diethyl ether resulted in hydrogen abstraction from the solvent to give the dimeric lithium iodide adduct {[PhB(μ-NtBu)2AsN(tBu)H]LiI}2 (1·LiI) with a central Li2I2 ring.

Reactions of ((BuHN)-Bu-t)(3)PNSiMe3 (1) with the alkyl-metal reagents dimethylzinc, trimethylaluminum and di-n-butylmagnesium yield the monodeprotonated complexes [MeZn{((NBu)-Bu-t)(NSiMe3)P((NHBu)-Bu-t)(2)}] (2), [Me2Al((NBu)-Bu-t)(NSiMe3)P((NHBu)-Bu-t)2}] (3) and [Mg{((NBu)-Bu-t)(NSiMe3)P((NHBu)-Bu-t)(2)}(2)] (4), respectively. Attempts to further deprotonate complex 2 with n-butyllithium or di-n-butylmagnesium result in nucleophilic displacement of the methylzinc fragment by lithium or magnesium. The two remaining amino protons of 3 are removed by reaction with di-n-butylmagnesium to give a heterobimetallic complex in which the coordination sphere of magnesium is completed by two molecules of THF (5 center dot 2THF) or one molecule of TMEDA (5 center dot TMEDA). Reaction of complex 3 with 1 equiv. of n-butyllithium followed by treatment of the product with di-n-butylmagnesium yields the complex {Me2Al[((NBu)-Bu-t)(NSiMe3)P((NBu)-Bu-t)(2)]MgBu} Li center dot 4THF (6 center dot 4THF), the first example of a triply deprotonated complex of 1 containing three different metals. Reaction of complex 5 with iodine results in cleavage of an Al-Me group to give {MeIAI[((NBu)-Bu-t)(NSiMe3)P((NBu)-Bu-t)(2)Mg]} (7). Complexes 5 center dot 2THF, 5 center dot TMEDA, 6 center dot 4THF and 7 have been characterized in solution by multinuclear (H-1, C-13, P-31 and Li-7) NMR spectroscopy, while the solid-state structures of 2, 4 and 5 center dot 2THF have been determined by X-ray crystallography. (c) 2007 Elsevier B.V. All rights reserved.