Electrochemical analysis of cyclopentadienylmetal carbonyl dimer complexes: Insight into the design of hydrogen-producing electrocatalysts

Chromium, molybdenum and tungsten

“…The trans isomer 10 was crystallized as the major product, and the molecular structure was determined by X-ray analysis. 67 The trans isomer 10 was isomerised by heating in solution to give a 1 : 1 mixture of trans and cis isomers (10,11). 67 Oxidation of these isomers by Me 3 NO afforded [Et 4 N] 2 [Mo VI O 2 (1,2-S 2 -3-t-BuNH-COC 6 H 3 ) 2 ] 12 1 H NMR analysis revealed that the dioxomolybdenum(VI) complex existed as a single isomer where both oxo ligands were trans to each of the two hydrogen-bonded thiolate ligands.…”

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This chapter reviews the literature reported during 2012 on some important advances in the areas of catalysis, bioinorganic, and organometallic chemistry for the chromium triad.Research highlights for each metal during the year are also given.

Highlights(I) Molecular and electronic structures and photophysical properties of quadruply bonded binuclear complexes, 1 (II) quadruply bonded dimolybdenum complexes of the terphenyl ligand Ar Xyl 2 (Ar Xyl 2 = C 6 H 3 -2,6-(C 6 H 3 -2,6-Me 2 ) 2 ), 2 (III) the effects of supplemental chromium(III) picolinate and chromium(III) histidinate on nuclear factor-kappa B (NF-kB p65) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling pathway in diabetic rat brain, 3 (IV) the first examples of trivacant Keggin-type metal carbonyl derivatives, 4 (V) the near infrared absorption properties of (NH 4 ) x WO 3 nanorods for application as a solar light control filter, 5 (VI) the first 3d-4f-5d heterotrinuclear [Cu II Ln III W V ] (Ln = Gd, Ho, or Tb) complexes, 6 (VII) MoO 2 (acac)@amine-MWCNTs for epoxidation of olefins, 7 (VIII) (Co 9 (H 2 O) 6 (OH) 3 (HPO 4 ) 2 (PW 9 O 34 ) 3 ) 16À as a homogeneous catalyst for water oxidation, 8 and other catalysis featuring a novel SiO 2 -supported inorganic and organic hybrid chromium-based catalyst for ethylene polymerisation, 9 the production of hydrogen [10][11][12] and photoinduced water oxidation. 13,14

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“…76 Exciting research involving either Mo or W featured the following catalysis: molybdenyl acetylacetonate supported on multi-wall carbon nanotubes, MoO 2 (acac)@amine-MWCNTs for epoxidation of olefins, 7 (Co 9 (H 2 O) 6 (OH) 3 (HPO 4 ) 2 (PW 9 O 34 ) 3 ) 16À as a homogeneous catalyst for water oxidation, 8 copper molybdenum sulphide (Cu 2 MoS 4 ) as a new efficient electrocatalyst for hydrogen production from water, 77 the demonstration of the ability to utilize sunlight to produce hydrogen from a potentially low-cost and abundant biomass derivative, glucose, using a WO 3 -based tandem photoelectrochemical cell, 78 the catalytic activity of a tin(IV)porphyrin-hexamolybdate hybrid material was investigated in the acetylation of alcohols and phenols with acetic anhydride (the reusability of this catalyst was also investigated). 79 Catalysis featuring a novel SiO 2 -supported inorganic and organic hybrid chromium-based catalyst for ethylene polymerisation, 9 the production of hydrogen [10][11][12] and photoinduced water oxidation 13,14 was also reported.…”

Molybdenum-Containing Metalloenzymes and Synthetic Catalysts for Conversion of Small Molecules

“…It was shown that anionic cyclopentadienyl (Cp) ligand has a similar electronic property as the Ni ligation sphere of the [NiFe]-hydrogenase active site[157]. Felton and Donovan reported that [(η 5 -C5H5)Mo(CO)3]2 (Scheme 17) (35) complex promoted the reduction of acetic acid in acetonitrile with 0.9 V overpotential[158]. Fan and Hu utilized polyhapto ligands to prepare Mo-carbonyl complexes of (η3 -C3H5)Mo(CO)2(CH3CN)2Br (36), (η 3 -C3H5)Mo(CO)2(dppe)Br (37), (η 5 -C5H5)Mo(CO)3I(38), and (η5 -C5H5)Mo(CO)2PPh3I (39) (Scheme 17) [159].…”

Unraveling Confined Dynamics of Guests Trapped in Self-Assembled Pd6L4 Nanocages by Ultrafast Mid-IR Polarization-Dependent Spectroscopy

“…Metal-directed self-assembled coordination cages can form nanosized cavities that can act to trap and stabilize guest molecules through noncovalent interactions. − The physical and chemical properties of these host–guest complexes are dictated by the interplay of many factors including steric restrictions, electrostatics, and weak interactions such as π-stacking. − , One such example of the self-assembled coordination cages is the octahedral Pd 6 L 4 nanocage first synthesized by Fujita and coworkers . This nanocage has been successfully employed over the last two decades to carry out selective ground and excited reactions and trap and stabilize reactive species. − Recently, Fujita and coworkers have demonstrated that the Pd 6 L 4 nanocages can trap group-VIII diruthenium carbonyl complexes. , The group-VIII dimetal carbonyl complexes are well known for their interesting photochemistry − and catalytic properties in addition to their fluxional behavior, where they exist as multiple isomers in dynamic equilibrium. − When encapsulated by the Pd 6 L 4 nanocage, the diruthenium carbonyl complexes were stabilized in their cis-bridging isomeric form and were shown to undergo carbonyl photosubstitution without cleavage of the metal–metal bond . From analysis of the X-ray crystal structures, the stabilization was attributed to π-stacking interactions between the triazine walls of the cage and the cyclopentadienyl ligands of the metal carbonyl complexes, and the photochemical products were suggested to arise from the restricted dynamics of the guests within the cage .…”