Molybdenum

Young, Charles G.

doi:10.1016/b0-08-043748-6/03033-4

Cited by 22 publications

(10 citation statements)

References 1,205 publications

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“…It was suggested that the higher ionic radii facilitate decomposition via seven-coordinate intermediates or that decomposition may be catalyzed by byproducts with different oxidation states [162]. In general, intermediate oxidation states like + III are more difficult to stabilize in 5d and 6d transition metal complexes resulting in complexes sensitive to oxidation [163,164].…”

Section: -Mo III Wiii Vii Mn Iv and Re Ivmentioning

confidence: 99%

Spin-flip luminescence

Kitzmann

Moll

Heinze

2022

Photochem Photobiol Sci

149

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In molecular photochemistry, charge-transfer emission is well understood and widely exploited. In contrast, luminescent metal-centered transitions only came into focus in recent years. This gave rise to strongly phosphorescent CrIII complexes with a d3 electronic configuration featuring luminescent metal-centered excited states which are characterized by the flip of a single spin. These so-called spin-flip emitters possess unique properties and require different design strategies than traditional charge-transfer phosphors. In this review, we give a brief introduction to ligand field theory as a framework to understand this phenomenon and outline prerequisites for efficient spin-flip emission including ligand field strength, symmetry, intersystem crossing and common deactivation pathways using CrIII complexes as instructive examples. The recent progress and associated challenges of tuning the energies of emissive excited states and of emerging applications of the unique photophysical properties of spin-flip emitters are discussed. Finally, we summarize the current state-of-the-art and challenges of spin-flip emitters beyond CrIII with d2, d3, d4 and d8 electronic configuration, where we mainly cover pseudooctahedral molecular complexes of V, Mo, W, Mn, Re and Ni, and highlight possible future research opportunities. Graphical abstract

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Section: -Mo III Wiii Vii Mn Iv and Re Ivmentioning

confidence: 99%

Spin-flip luminescence

Kitzmann

Moll

Heinze

2022

Photochem Photobiol Sci

149

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“…, 3 ) followed by rupture of a MoO–R bond; the resulting oxo-molybdenum complexes of type [O=MoCl 3 ] ( 4 ) dimerize and can lead to adducts such as 5 or even complex polynuclear arrays. 10 − 13 The ease of formation of the [Mo=O] group manifest in these examples is a hallmark of (high-valent) molybdenum chemistry; 10 , 14 , 15 this prevalent functionality dominates the field and plays a pivotal role in biological and industrial catalysis alike. 16 , 17 Only highly fluorinated alcohols were found to subsist to such degradation: trifluoroethanol, for example, on treatment with MoCl 5 , affords the stable heteroleptic complex 6 .…”

Section: Introductionmentioning

confidence: 99%

“…The reaction is thought to proceed by partial ligand exchange with formation of transient Mo(V) alkoxides ( e.g. , 3 ) followed by rupture of a MoO–R bond; the resulting oxo-molybdenum complexes of type [OMoCl 3 ] ( 4 ) dimerize and can lead to adducts such as 5 or even complex polynuclear arrays. − The ease of formation of the [MoO] group manifest in these examples is a hallmark of (high-valent) molybdenum chemistry; ,, this prevalent functionality dominates the field and plays a pivotal role in biological and industrial catalysis alike. , Only highly fluorinated alcohols were found to subsist to such degradation: trifluoroethanol, for example, on treatment with MoCl 5 , affords the stable heteroleptic complex 6 . , The fact that even the electron-poor O atom of trifluoroethoxide serves as a bridging ligand highlights the very strong bias for dimerization, which is yet another characteristic trait of the coordination chemistry of molybdenum. A closely related binuclear molybdenum(V) alkoxide 7 was prepared by salt metathesis between MoCl 5 and NaOMe, but complete ligand exchange could not be accomplished either. , Analogous reactions with electron-rich alkoxides are unlikely in view of the ease of reduction of MoCl 5 even by much milder agents; in any case, no follow-up investigation describing the preparation of analogues of 7 has been published.…”

Section: Introductionmentioning

confidence: 99%

Isolation of a Homoleptic Non-oxo Mo(V) Alkoxide Complex: Synthesis, Structure, and Electronic Properties of Penta-tert-Butoxymolybdenum

et al. 2020

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Treatment of [MoCl 4 (THF) 2 ] with MO t Bu (M = Na, Li) does not result in simple metathetic ligand exchange but entails disproportionation with formation of the well-known dinuclear complex [( t BuO) 3 Mo≡Mo(O t Bu) 3 ] and a new paramagnetic compound, [Mo(O t Bu) 5 ]. This particular five-coordinate species is the first monomeric, homoleptic, all-oxygen-ligated but non-oxo 4d 1 Mo(V) complex known to date; as such, it proves that the dominance of the Mo=O group over (high-valent) molybdenum chemistry can be challenged. [Mo(O t Bu) 5 ] was characterized in detail by a combined experimental/computational approach using X-ray diffraction; UV/vis, MCD, IR, EPR, and NMR spectroscopy; and quantum chemistry. The recorded data confirm a Jahn–Teller distortion of the structure, as befitting a d 1 species, and show that the complex undergoes Berry pseudorotation. The alkoxide ligands render the disproportionation reaction, leading the formation of [Mo(O t Bu) 5 ] to be particularly facile, even though the parent complex [MoCl 4 (THF) 2 ] itself was also found to be intrinsically unstable; remarkably, this substrate converts into a crystalline material, in which the newly formed Mo(III) and Mo(V) products cohabitate the same unit cell.

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“…Molybdenum–cyano complexes have been reviewed recently . No structural reports for binuclear molybdenyl (MoO) sulfur-bridged complexes with terminal cyano ligands (Mo/O/S/CN) were found to date in a structural database search.…”

Section: Introductionmentioning

confidence: 99%

Reaction Chemistry of the syn-[Mo₂O₂(μ-S)₂(S₂)(DMF)₃] Complex with Cyanide and Catalytic Thiocyanate Formation

et al. 2020

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Removal of cyanide as nontoxic thiocyanate under physiological conditions may serve as a catalytic detoxification route in vivo. Aqueous catalytic reaction conditions were explored where at the conditions employed the reaction proceeded to exhaustion in 1 h. The complex, syn-[Mo 2 O 2 (μ-S) 2 (S 2 )(DMF) 3 ] 1, participates in a ligand exchange reaction of the dimethylformamide ligands and cyanide. Simultaneous sulfur abstraction reaction from the terminal disulfide group forms thiocyanate and terminal sulfido ligand. Respective reaction rates for the two reactions appear competitive where different products were isolated solely based on change of reaction temperature. The approach to determine the number of cyanide ligands participating in the ligand exchange reaction by varying the stoichiometry and reaction temperature led to identification and isolation of tetranuclear complexes 2 and 5 and dinuclear complexes 3, 4, and 6. A synthesized and fully characterized thiocyanate analog of 6 (7) supports spectroscopic characterization of 6. The tetranuclear anion, [Mo 4 O 4 (μ-S) 6 (CN) 4 ] 4− , 2, was crystallized from a reaction at ambient temperature. The dinuclear anion, [Mo 2 O 2 (μ-S) 2 (S)(CN) 3 ] 3− , 3, was crystallized from similar reaction conditions at lower temperature. The reaction yield of thiocyanate obtained at pH of 7.4 and at 9.2 as a function of time, for several ratios of cyanide, favors the sulfur abstraction reaction at elevated pH. The sulfur abstraction reaction is the first step in a proposed mechanism of the reaction of cyanide and thiosulfate to form thiocyanate and sulfite by 1.

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Molybdenum

Cited by 22 publications

References 1,205 publications

Spin-flip luminescence

Spin-flip luminescence

Isolation of a Homoleptic Non-oxo Mo(V) Alkoxide Complex: Synthesis, Structure, and Electronic Properties of Penta-tert-Butoxymolybdenum

Reaction Chemistry of the syn-[Mo₂O₂(μ-S)₂(S₂)(DMF)₃] Complex with Cyanide and Catalytic Thiocyanate Formation

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Molybdenum

Cited by 22 publications

References 1,205 publications

Spin-flip luminescence

Spin-flip luminescence

Isolation of a Homoleptic Non-oxo Mo(V) Alkoxide Complex: Synthesis, Structure, and Electronic Properties of Penta-tert-Butoxymolybdenum

Reaction Chemistry of the syn-[Mo2O2(μ-S)2(S2)(DMF)3] Complex with Cyanide and Catalytic Thiocyanate Formation

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Reaction Chemistry of the syn-[Mo₂O₂(μ-S)₂(S₂)(DMF)₃] Complex with Cyanide and Catalytic Thiocyanate Formation