Cluster intermediates in an organometallic synthesis of palladium telluride PdTe

Manganese Telluride Carbonyl Complexes: Facile Syntheses and Exotic Properties-Reversible Transformations, Hydrogen Generation, Paramagnetic, and Semiconducting Properties

A novel family of five Mn-Te-CO complexes was prepared via facile syntheses: mono spirocyclic [Mn₄Te(CO)₁₆]^2- (1), four-membered Mn₂Te₂ ring-type [Mn₂Te₂(CO)₈]^2- (2), hydride-containing square pyramidal [HMn₃Te₂(CO)₉]^2- (3), and dumbbell-shaped [Mn₆Te₆(CO)₁₈]^4- (4) and [Mn₆Te₁₀(CO)₁₈]^4- (5). Electron-precise complexes 4 and 5 exhibit unusual paramagnetism arising from two types of Mn atoms in different oxidation states, as determined by X-ray photoelectron spectroscopy, electron paramagnetic resonance, and density functional theory (DFT) calculations. The structural transformations from small-sized Mn₄Te 1 and Mn₂Te₂ 2 to the largest Mn₆Te₁₀ 5 were controllable, the off/on magnetic-switched transformation between HMn₃Te₂ 3 and 5 was reversible, and the magnetic transformation between Mn₆Te₆ 4 and 5 was observed. Interestingly, the reversible dehydridation and hydridation between the HMn₃Te₂-based cluster 3 and [Mn₃Te₂(CO)₉]^- were successfully accomplished, in which the release of a high yield of H₂ was detected by gas chromatography. In addition, upon the addition of CO, cluster 3 first forms a carbonyl-inserted intermediate [HMn₃Te₂(CO)₁₀]^2- (3'), detected by the high resolution ESI-MS, which is readily transformed to a dimeric dihydrido cluster [{HMn₃Te₂(CO)₁₀}₂]^2- (6) with the introduction of O₂. These low- to high-nuclearity complexes exhibit rich redox properties with semiconducting behavior in solids, possessing low but tunable energy gaps (1.06-1.62 eV) due to efficient electron transport via nonclassical C-H···O(carbonyl) interactions. The structural nature, reversible structural transformations, controllable on/off magnetic switches, electron communication networks, and associated chemical properties for hydrogen generation are discussed in detail and supported by DFT calculations, density of states, band structures, and noncovalent interaction analyses.

Applications of metal selenium/tellurium compounds in materials science

Metal chalcogenides are technologically important materials. Physical, chemical, electrical and mechanical properties of these materials can be fine-tuned by manipulating their shape, size and composition. Although several methods are employed for their synthesis, single-source molecular precursor route has emerged as a versatile strategy for their synthesis and in controlling shape, size and composition of the material under moderate conditions. This chapter gives a brief coverage on the design and development of single-source molecular precursors which have been employed for the preparation of metal selenide/telluride nanocrystals and for deposition of thin films. The discussion includes synthesis of transition-, main group and f-block metal chalcogenolate and/or chalcogenide clusters as precursors and their conversion into metal chalcogenides in the form of thin films and nanostructures. Precursors for ternary metal chalcogenides are also included.

Introduction of selenium and tellurium into reaction systems

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.

Emerging trends in organotellurolate chemistry derived from platinoids

This perspective begins with the discussion of various basic synthetic approaches applied for the synthesis of several organotellurium ligands, their chemistry derived from platinum group metals, and the reactivity difference among them.

Synthesis and Properties of Molecular Fragments of Metal Chalcogenides

In this manuscript we describe several approaches to the preparation of molecule-sized fragments of inorganic solids. The first is the arrested precipitation of metal selenides in reverse micelles; the second is the arrested pyrolysis of molecular precursors to II–VI compounds; and the third is the chemical moderation of molecules-to-solids reactions.

Bis(μ(2)-phenyl-tellurolato)bis-(phenyl-tellurolato)tetra-μ(3)-tellurido-hexa-kis(triphenyl-phosphine)hexa-palladium(II) benzene nona-solvate

The centrosymmetric title complex, [Pd₆(C₆H₅Te)₄Te₄(C₁₈H₁₅P)₆]·9C₆H₆, contains two Pd₃Te₂ cores that are joined into a cyclic hexa­nuclear complex by two bridging PhTe⁻ groups. Each Pd^II atom is coordinated by one triphenyl­phosphine ligand, one phenyl­tellurolate mol­ecule and two telluride ligands: two of the PhTe⁻ ligands act as terminal ligands and two as bridging ligands. The three distinct Pd^II atoms each show a slightly distorted PdPTe₃ square-planar coordination. The asymmetric unit also contains four and a half benzene solvent mol­ecules. Two of the benzene mol­ecules are disordered: one mol­ecule is distributed over two positions with site-occupancy factors of 0.529 (7) and 0.471 (7), while the other occupies two orientations about a centre of symmetry.

Chalcogen−Chalcogen Bonds in Edge-Sharing Square-Planar d8 Complexes. Are They Possible?

A theoretical study of the formation of X-X bonds in complexes with the general formula [M(2)(mu-X)(2)L(4)] (M = group 10 and X = group 16 elements) having d(8) transition-metal atoms is presented. The existence of two energy minima for some complexes, with short and long X-X distances, is shown by density functional theory calculations, and the factors responsible for it are analyzed, including a strong influence of the nature of the metals and ligands on the relative stability of the two isomers. The influence of the bite angle of chelating terminal ligands and the nature of the donor atom on the relative stabilities of the two isomers are also discussed.

Electrochemical and theoretical study of the redox properties of transition metal complexes with {Pt2S2} cores

The oxidation processes undergone by the [Pt2(mu-S)2] core in [Pt2(P[intersection]P)2(mu-S)2](P[intersection]P = Ph2P(CH2)nPPh2, n= 2,3) complexes have been analysed on the basis of electrochemical measurements. The experimental results are indicative of two consecutive monoelectronic oxidations after which the [Pt2(mu-S)2] core evolves into [Pt2(mu-S2)]2+, containing a bridging disulfide ligand. However, the instability of the monoxidised [Pt2(P[intersection]P)2(mu-S)2]+ species formed initially, which converts into [Pt3(P[intersection]P)3(mu-S)2]2+, hampered the synthesis and characterisation of the mono and dioxidised species. These drawbacks have been surpassed by means of DFT calculations which have also allowed the elucidation of the structural features of the species obtained from the oxidation of [Pt2(P[intersection]P)2(mu-S)2] compounds. The calculated redox potentials corresponding to the oxidation processes are consistent with the experimental data obtained. In addition, calculations on the thermodynamics of possible processes following the degradation of [Pt2(P[intersection]P)2(mu-S)2]+ are fully consistent with the concomitant formation of monometallic [Pt(P[intersection]P)S2)] and trimetallic [Pt3(P[intersection]P)3(mu-S)2]2+ compounds. Extension of the theoretical study on the [Pt2Te2] core and comparisons with the results obtained for [Pt2S2] have given a more general picture of the behaviour of [Pt2X2](X = chalcogenide) cores subject to oxidation processes.

Trialkylphosphine-stabilized copper-phenyltellurolate complexes: from small molecules to nanoclusters via condensation reactions

Reactions of CuCl with Te(Ph)SiMe3 and solublizing trialkylphosphine ligands afford a series of polynuclear copper-phenyltellurolate complexes that has been structurally characterized. The formation of the complexes is found to be highly dependent on the ancillary phosphine ligand used. The synthesis and structures of [Cu2(mu-TePh)2(PMe3)4] 1, [Cu4(mu3-TePh)4(PPr(i)3)3] 2, [Cu5(mu-TePh)3(mu3-TePh)3(PEt3)3][PEt3Ph] 3, and [Cu12Te3(mu3-TePh)6(PEt3)6] 4 are described. The telluride (Te(2-)) ligands in 4 arise from the generation of TePh2 in the reaction mixtures. The subsequent co-condensation of clusters 3 and 4 leads to the generation of the nanometer sized complex [Cu29Te9(mu3-TePh)10(mu4-TePh)2(PEt3)8][PEt3Ph] 5 in good yield, in addition to small amounts of [Cu39(mu3-TePh)10(mu4-TePh)Te16(PEt3)13] 6. These complexes are formed via the photo elimination of TePh2. The cyclic voltammogram of 5 in THF solution exhibits two oxidation waves, assigned to the oxidation of the Cu(I) centers.

Framework Bonding and Coordination Sphere Rearrangement in the M(2)X(2) Cores of Synthetic Analogues of Oxyhemocyanin and Related Cu and Pt Complexes

The electronic structures of oxo- and peroxo-bridged binuclear copper compounds analogous to the active site of oxyhemocyanin are analyzed in terms of their framework electron counts with the help of density functional and extended Hückel calculations. Through-ring bonding in the Cu(2)O(2) framework is discussed by means of a topological analysis of the electron density for the model compounds [(NH(3))(3)Cu(&mgr;-eta(2):eta(2)-O(2))Cu(NH(3))(3)](2+), [(NH(3))(3)Cu(&mgr;-O)(2)Cu(NH(3))(3)](2+), and [(PH(3))(2)Cu(&mgr;-H)(2)Cu(PH(3))(2)]. The existence of isomeric peroxo- and bis(oxo)-bridged Cu complexes can be rationalized in light of the framework electron counting rules by taking into account that two electrons can be localized in the metal 3d orbitals in the former but delocalized through framework bonding molecular orbitals in the latter. An analysis of the theoretical and experimental structural data indicates that a reorganization of the Cu coordination sphere that can be affected by the nature of the terminal ligands is important for the relative stability of the two isomeric forms. In particular, the peroxo-bridged structure is favored by tridentate ligands, whereas the oxo-bridged isomer is favored by bidentate ones. The stability of the two isomers is also compared for analogous complexes with different metal or bridging atoms for which only one isomeric form is known.