Organometallics alkylthiolate-bridged manganese cubanes

Chirality-Guided Isomerization of Mn2S2 Diamond Core Complexes: A Mechanistic Study

Occasioned by the discovery of a ligand transfer from M(N₂S₂) to Mn^I in Mn(CO)₅Br, the resulting H₂N₂S₂ ligand-tethered dimanganese complex, (μ₄-N,N'-ethylenebis(mercaptoacetamide))[Mn₂(CO)₆], was found to have myriad analogues of the type (μ-S-E)₂[Mn₂(CO)₆], making up an under-studied class containing Mn₂S₂ rhombs. The attempt to synthesize a nontethered version resulted in a solid-state structure in an anti-conformation. However, a direct comparison of the Fourier-transform infrared spectra of the tethered versus nontethered complexes in combination with theoretical frequency calculation suggested the coexistence of syn- and anti-isomers and their interconversion in solution. Analysis of the syn- versus anti-version of the dimanganese components led to the understanding that whereas the anti-form exists as centrosymmetric RS isomers, the syn-form is restricted by C₂ symmetry to be either RR or SS. Molecular scrambling experiments indicated monomeric, pentacoordinate, 16-e^- (S-O)Mn(CO)₃ intermediates with lifetimes sufficiently long to sample R and S monomers. Density functional theory analysis of the mechanistic pathway and a kinetic study corroborated that the proposed isomerization involves the cleavage and reformation of the dimeric structures.

Remote-controlled delivery of CO via photoactive CO-releasing materials on a fiber optical device

Although carbon monoxide (CO) delivery materials (CORMAs) have been generated, remote-controlled delivery with light-activated CORMAs at a local site has not been achieved. In this work, a fiber optic-based CO delivery system is described in which the photoactive and water insoluble CO releasing molecule (CORM) manganese(i) tricarbonyl [(OC)3Mn(μ3-SR)]4 (R = nPr, 1) has been non-covalently embedded into poly(l-lactide-co-d/l-lactide) and poly(methyl methacrylate) non-woven fabrics via the electrospinning technique. SEM images of the hybrid materials show a porous fiber morphology for both polymer supports. The polylactide non-woven fabric was attached to a fiber optical device. In combination with a laser irradiation source, remote-controlled and light-triggered CO release at 405 nm excitation wavelength was achieved. The device enabled a high flexibility of the spatially and timely defined application of CO with the biocompatible hybrid fabric in aqueous media. The rates of liberated CO were adjusted with the light intensity of the laser. CO release was confirmed via ATR-IR spectroscopy, a portable electrochemical CO sensor and a heterogeneous myoglobin assay.

Electrocatalytic hydrogen generation by a trithiolato-bridged dimanganese hexacarbonyl anion with a turnover frequency exceeding 40 000 s−1

Electrocatalytic proton reduction based on a dimanganese hexacarbonyl anion.

Syntheses and X-ray Structures of a Series of Chalcogen-Containing Manganese Carbonylates [E(2)Mn(3)(CO)(9)](-), [E(8)C(2)Mn(2)(CO)(6)](2-), and [E(2)Mn(4)(CO)(12)](2-) (E = Se, S)

The reaction of SeO(2) with Mn(2)(CO)(10)/KOH in methanol solution forms a trigonal bipyramid cluster anion [Se(2)Mn(3)(CO)(9)](-) (Ia). Cluster Ia can also be synthesized from the treatment of Se powder with Mn(2)(CO)(10)/KOH in 2:1 molar ratio in methanol solution. If Se is reacted with Mn(2)(CO)(10)/KOH in a molar ratio of 8:1, the deoxygenation occurs to produce a novel cluster [Se(8)C(2)Mn(2)(CO)(6)](2)(-) (IIa). Cluster IIa can readily transform into a new octahedral cluster [Se(2)Mn(4)(CO)(12)](2)(-) (IIIa) by further treatment with Mn(2)(CO)(10)/KOH in CH(2)Cl(2)/MeOH solutions, and the use of a molar ratio of 1:1 of Se powder to Mn(2)(CO)(10)/KOH in methanol also can yield complex IIIa. In the sulfur-manganese system, the synthesis of the analogous complexes [S(2)Mn(3)(CO)(9)](-) (Ib), [S(8)C(2)Mn(2)(CO)(6)](2)(-) (IIb), and [S(2)Mn(4)(CO)(12)](2)(-) (IIIb) also can be accomplished from the reactions of S powder with Mn(2)(CO)(10)/KOH in similar fashions. Clusters Ia-IIIa and Ib-IIIb are fully characterized by spectroscopic methods or/and X-ray analyses. The novel clusters [E(8)C(2)Mn(2)(CO)(6)](2)(-) (E = Se, IIa; E = S, IIb) each consist of two separate Mn(CO)(3) groups which are doubly bridged by two CE(4) fragments. Clusters Ia and Ib each display a trigonal bipyramid framework with two chalcogen atoms in the axial positions, while clusters IIIa and IIIb each exhibit an octahedral metal skeleton.