Simultaneous Fenton‐like Ion Delivery and Glutathione Depletion by MnO2‐Based Nanoagent to Enhance Chemodynamic Therapy

Chemodynamic therapy (CDT) utilizes iron‐initiated Fenton chemistry to destroy tumor cells by converting endogenous H₂O₂ into the highly toxic hydroxyl radical (^.OH). There is a paucity of Fenton‐like metal‐based CDT agents. Intracellular glutathione (GSH) with ^.OH scavenging ability greatly reduces CDT efficacy. A self‐reinforcing CDT nanoagent based on MnO₂ is reported that has both Fenton‐like Mn²⁺ delivery and GSH depletion properties. In the presence of HCO₃^?, which is abundant in the physiological medium, Mn²⁺ exerts Fenton‐like activity to generate ^.OH from H₂O₂. Upon uptake of MnO₂‐coated mesoporous silica nanoparticles (MS@MnO₂ NPs) by cancer cells, the MnO₂ shell undergoes a redox reaction with GSH to form glutathione disulfide and Mn²⁺, resulting in GSH depletion‐enhanced CDT. This, together with the GSH‐activated MRI contrast effect and dissociation of MnO₂, allows MS@MnO₂ NPs to achieve MRI‐monitored chemo–chemodynamic combination therapy.     

A Smart DNAzyme–MnO2 Nanosystem for Efficient Gene Silencing

DNAzymes hold promise for gene‐silencing therapy, but the lack of sufficient cofactors in the cell cytoplasm, poor membrane permeability, and poor biostability have limited the use of DNAzymes in therapeutics. We report a DNAzyme–MnO₂ nanosystem for gene‐silencing therapy. MnO₂ nanosheets adsorb chlorin e6‐labelled DNAzymes (Ce6), protect them from enzymatic digestion, and efficiently deliver them into cells. The nanosystem can also inhibit ¹O₂ generation by Ce6 in the circulatory system. In the presence of intracellular glutathione (GSH), MnO₂ is reduced to Mn²⁺ ions, which serve as cofactors of 10–23 DNAzyme for gene silencing. The release of Ce6 generates ¹O₂ for more efficient photodynamic therapy. The Mn²⁺ ions also enhance magnetic resonance contrast, providing GSH‐activated magnetic resonance imaging (MRI) of tumor cells. The integration of fluorescence recovery and MRI activation provides fluorescence/MRI bimodality for monitoring the delivery of DNAzymes.     

Tumor microenvironment-responsive MnSiO3-Pt@BSA-Ce6 nanoplatform for synergistic catalysis-enhanced sonodynamic and chemodynamic cancer therapy

Compared with traditional photodynamic therapy （PDT）,ultrasound （US） triggered sonodynamic therapy （SDT） has a wide application prospect in tumor therapy because of its deeper penetration depth.Herein,a novel MnSiO₃-Pt （MP） nanocomposite composed of Mn Si O₃nanosphere and noble metallic Pt was successfully constructed.After modification with bovine serum albumin （BSA） and chlorine e6 （Ce6）,the multifunctional nanoplatform Mn Si O₃-Pt@BSA-Ce6 （MPBC） realized the m...     

Degradable nanocatalyst enables antitumor/antibacterial therapy and promotion of wound healing for diabetes via self-enhanced cascading reaction

Diabetic patients often have problems such as residual tumor and wound infection after tumor resection, causing severe clinical problems. It is urgent to develop effective therapies to reach oncotherapy/anti-infection/promotion of wound healing combined treatment. Herein, we propose CS/MnO₂-GOx (CMGOx) nanocatalysts for the specific catalytic generation of ^•OH to inhibit tumors and bacteria in a hyperglycemic environment. The good biocompatible chitosan (CS), as a carrier for the catalyst, exhibits excellent antibacterial effect as well as promotes wound healing. Glucose oxidase (GOx) is loaded on the surface of CS nanoparticles to generate H₂O₂ and gluconic acid by consuming glucose (starvation therapy, ST) and O₂. The MnO₂ depletes glutathione (GSH) to produce Mn²⁺, amplifying oxidative stress and further promoting the activity of Mn²⁺-mediated Fenton-like reaction to produce ^•OH (chemodynamic therapy, CDT) in weak acidic environment. Moreover, the produced gluconic acid lowers the pH of the environment, enhancing chemodynamic therapy (ECDT). The tumor cells and bacteria are efficiently eliminated by the synergistic effect of ST and ECDT. The MnO₂ nanoparticles at neutral environment decomposes H₂O₂ into O₂, which cooperate with CS to promote healing. The self-enhanced cascade reaction of CMGOx in situ exhibits excellent effects of antitumor/antibacterial therapy and promotion of wound healing, offering a promising integrated treatment for diabetic patients after tumor surgical resection.     

Self-Immolative Amphiphilic Poly(ferrocenes) for Synergistic Amplification of Oxidative Stress in Tumor Therapy

Amphiphilic self-immolative polymers (SIPs) can achieve complete degradation solely through one triggerable event, which potentially optimize the blood clearance and uncontrollable/inert degradability for therapeutic nanoparticles. Herein, we report self-immolative amphiphilic poly(ferrocenes), BP ^nbs -Fc , composed by self-immolative backbone and aminoferrocene (AFc) side chains as well as end-capping poly(ethylene glycol) monomethyl ether. Upon triggering by tumor acidic milieu, the BP ^nbs -Fc nanoparticles readily degrade to release azaquinone methide (AQM) moieties, which can rapidly deplete intracellular glutathione (GSH) to cascade release AFc. Furthermore, both AFc and its product Fe²⁺ can catalyze intracellular hydrogen peroxide (H₂O₂) into highly reactive hydroxyl radicals (⋅OH), thus amplifying the oxidative stress of tumor cells. Rational synergy of GSH depletion and ⋅OH burst can efficiently inhibit tumor growth by the SIPs in vitro and in vivo. This work provides an elegant design to adopt innate tumor milieu-triggerable SIPs degradation to boost cellular oxidative stress, which is a promising candidate for precision medicine.     

Programmed Release of Dihydroartemisinin for Synergistic Cancer Therapy Using a CaCO3 Mineralized Metal–Organic Framework

Dihydroartemisinin (DHA) has attracted increasing attention as an anticancer agent. However, using DHA to treat cancer usually depends on the synergistic effects of exogenous components, and the loss of DHA during delivery reduces its effectiveness in cancer therapy. Reported herein is a programmed release nanoplatform of DHA to synergistically treat cancer with a Fe‐TCPP [(4,4,4,4‐(porphine‐5,10,15,20‐tetrayl) tetrakis(benzoic acid)] NMOF (nanoscale MOF) having a CaCO₃ mineralized coating, which prevents DHA leakage during transport in the bloodstream. When the nanoplatform arrives at the tumor site, the weakly acidic microenvironment and high concentration of glutathione (GSH) trigger DHA release and TCPP activation, enabling the synergistic Fe²⁺‐DHA‐mediated chemodynamic therapy, Ca²⁺‐DHA‐mediated oncosis therapy, and TCPP‐mediated photodynamic therapy. In vivo experiments demonstrated that the nanoplatform showed enhanced anticancer efficiency and negligible toxicity.     

MnO2‐Modified Persistent Luminescence Nanoparticles for Detection and Imaging of Glutathione in Living Cells and In Vivo

Persistent luminescence nanoparticles (PLNPs) hold great promise for the detection and imaging of biomolecules. Herein, we have demonstrated a novel nanoprobe, based on the manganese dioxide (MnO₂)‐modified PLNPs, that can detect and image glutathione in living cells and in vivo. The persistent luminescence of the PLNPs can be efficiently quenched by the MnO₂ nanosheets. In the presence of glutathione (GSH), MnO₂ was reduced to Mn²⁺ and the luminescence of PLNPs can be restored. The persistent luminescence property can allow detection and imaging without external excitation and avoid the background noise originating from the in situ excitation. This strategy can offer a promising platform for detection and imaging of reactive species in living cells or in vivo.     

A mechanistic investigation of the decacarbonyldimanganese-catalyzed carbonylation of amines

The Mn₂(CO)₁₀-catalyzed reactions of n-butylamine and cyclohexylamine with CO to give the corresponding ureas have been examined under a variety of conditions of temperature, CO pressure, reaction time, solvent and potential co-catalysts. With the diamines, ethylenediamine and 1,4-diaminobutane, there was no catalyzed reaction with CO. On the other hand, 1,3-diaminopropane gave 1,4,5,6-tetrahydropyrimidine, and 1,6-diaminohexane yielded a polyurea. In an effort to elucidate the mechanism of these reactions, several stoichiometric reactions were carried out. The reaction of Mn₂(CO)₁₀ with primary aliphatic amines proceeds to give a carbamoyl complex as follows: Mn₂(CO)₁₀ + 3 RNH₂ ? cis-Mn(CO)₄(NH₂R)(CONHR) + RNH₃⁺ + Mn(CO)₅^? Under CO pressure the isolated carbamoyl complex reacted to give the urea as follows: cis-Mn(CO)₄(NH₂R)(CONHR) + CO → (RNH)₂CO + HMn(CO)₅ The mechanism of this latter reaction is proposed to involve the intermediate formation of the organic isocyanate RNCO. These reactions are discussed as part of an overall mechanism for the Mn₂(CO)₁₀-catalyzed formation of ureas. The mechanism successfully accounts for factors which affect the yields of the reaction. Other metal carbonyl complexes, Re₂(CO)₁₀, (η-CH₃C₅H₄)Mn(CO)₃ and [η-C₅H₅Cr(CO)₃]₂, did not catalyze the reactions.     

Reactions of diazoles with manganese and iron carbonyls

The compounds of two types were isolated in the reactions of dimanganese decacarbonyl with diazoles. The compounds with an unaltered oxidation state of the metal were formed as a result of nucleophilic substitution of a carbonyl ligand of Mn₂(CO)₁₀. The compounds with an altered oxidation state of the central atom were produced in redox-transformations of Mn₂(CO)₁₀. The substances were characterized by the data of mass-, IR-, ¹H-NMR-spectra. The EPR-data were obtained for paramagnetic Mn²⁺ salts. The reactions of Mn₂(CO)₁₀ with diazoles are compared with those of iron carbonyls.     

Paramagnetic organometallic molecules : III. Photolysis of dimanganese decacarbonyl

The photolysis of Mn₂(CO)₁₀ has been investigated over a range of solvents and temperatures and found to be more complicated than hitherto reported. Homolysis of the metal—metal bond in Mn₂(CO)₁₀ is the dominant photochemical process in all solvents are evidenced by trapping the Mn(CO)_5^. radical. A temperature dependent bifunctionality of the spin-trap 2,4,6-tri-t-butylnitrosobenzene was observed. The unstable adduct Mn(CO)₅O_2^., previously characterised in the solid state, is formed in non-polar solvents in the absence of a trap. A paramagnetic species giving rise to a broad, structureless signal at ambient temperatures is the major product in basic solvents; in certain polar solvents at low temperatures, hyperfine coupling to manganese (A(Mn) 88 G) could be distinguished. Both spectra are believed to derive from the solvated manganese(II) ion.The controversial six-line spectrum found on photolysis of Mn₂(CO)₁₀ in tetrahydrofuran also results from a manganese(II) species. The unusual properties of the Mn₂(CO)₁₀/THF system may be explained in terms of ion-pair formation between the Mn²⁺ and Mn(CO)_5^? ions in solution.     

State of manganese ions in the structure of corundum synthesized in supercritical water fluid

The kinetics and formation mechanism of doped corundum (α-Al₂O₃) from hydrargillite (γ-Al(OH)₃) in supercritical water fluid (SCWF) in the presence of manganese ions are studied. It was ascertained that due to the reversible dehydroxylation in an aqueous medium, solid-phase transformation of hydrargillite into boehmite (γ-AlOOH) and then into corundum occurs with the formation of well-faceted corundum micro-crystals that are uniformly doped with manganese. It was found that when Mn²⁺ or MnO₄⁻ ions are introduced into the reaction medium, Mn⁵⁺, Mn⁴⁺, Mn³⁺, and Mn²⁺ ions are observed in the synthesized corundum. Meanwhile, the manganese ions form a complex defect in the corundum structure, which comprises oxygen vacancies and hydroxyl groups. The defects in corundum that emerge upon doping with manganese in SCWF are different from those in corundum doped during high-temperature synthesis.     

Redox Dyshomeostasis Strategy for Hypoxic Tumor Therapy Based on DNAzyme-Loaded Electrophilic ZIFs

Redox homeostasis is one of the main reasons for reactive oxygen species (ROS) tolerance in hypoxic tumors, limiting ROS-mediated tumor therapy. Proposed herein is a redox dyshomeostasis (RDH) strategy based on a nanoplatform, FeCysPW@ZIF-82@CAT Dz, to disrupt redox homeostasis, and its application to improve ROS-mediated hypoxic tumor therapy. Once endocytosed by tumor cells, the catalase DNAzyme (CAT Dz) loaded zeolitic imidazole framework-82 (ZIF-82@CAT Dz) shell can be degraded into Zn²⁺ as cofactors for CAT Dz mediated CAT silencing and electrophilic ligands for glutathione (GSH) depletion under hypoxia, both of which lead to intracellular RDH and H₂O₂ accumulation. These “disordered” cells show reduced resistance to ROS and are effectively killed by ferrous cysteine-phosphotungstate (FeCysPW) induced chemodynamic therapy (CDT). In vitro and in vivo data demonstrate that the pH/hypoxia/H₂O₂ triple stimuli responsive nanocomposite can efficiently kill hypoxic tumors. Overall, the RDH strategy provides a new way of thinking about ROS-mediated treatment of hypoxic tumors.     

A radiochemical study of the kinetics of exchange between manganese oxides and some cations in solution

The kinetics of the exchange between⁵⁶Mn-labelled manganese dioxide and cations in aqueous solution was studied by measuring the β⁻ activity acquired by the solution. The results of the exchange between a chemical γ MnO₂ and a divalent M²⁺ ion (M=Mn, Co, Cu or Zn) or a trivalent M³⁺ ion (M=Ga, Fe, In, Rh or Al) indicate a fast initial process followed by a diffusion—controlled exchange. It is assumed that M²⁺ ions exchange with Mn²⁺ ions and M³⁺ ions exchange with Mn³⁺ ions in MnO₂. The process depends on the radii of the host and substituent ions and on consideration of crystal field stabilisation energies. It seems that the γ MnO₂ studied contains more Mn³⁺ than Mn²⁺ ions. The possibility of the exchange between Mn ions and cations of a different charge cannot be ruled out. The exchange between Co²⁺ ions and MnO₂ was enhanced in presence of pyrophosphate, which stabilises Mn(III) as a complex. The fraction of Mn in different samples of MnO₂ exchanged with a given cation depends on the type and not on the surface area of the sample.     

Metal‐catalyzed reversible conversion between chemical and electrical energy designed towards a sustainable society

Proton dissociation of an aqua‐Ru‐quinone complex, [Ru(trpy)(q)(OH₂)]²⁺ (trpy = 2,2′ : 6′,2″‐terpyridine, q = 3,5‐di‐t‐butylquinone) proceeded in two steps (pK_a = 5.5 and ca. 10.5). The first step simply produced [Ru(trpy)(q)(OH)]⁺, while the second one gave an unusual oxyl radical complex, [Ru(trpy)(sq)(O^?.)]⁰ (sq = 3,5‐di‐t‐butylsemiquinone), owing to an intramolecular electron transfer from the resultant O^2? to q. A dinuclear Ru complex bridged by an anthracene framework, [Ru₂(btpyan)(q)₂(OH)₂]²⁺ (btpyan = 1,8‐bis(2,2′‐terpyridyl)anthracene), was prepared to place two Ru(trpy)(q)(OH) groups at a close distance. Deprotonation of the two hydroxy protons of [Ru₂(btpyan)(q)₂(OH)₂]²⁺ generated two oxyl radical Ru‐O^?. groups, which worked as a precursor for O₂ evolution in the oxidation of water. The [Ru₂(btpyan)(q)₂(OH)₂](SbF₆)₂ modified ITO electrode effectively catalyzed four‐electron oxidation of water to evolve O₂ (TON = 33500) under electrolysis at +1.70 V in H₂O (pH 4.0). Various physical measurements and DFT calculations indicated that a radical coupling between two Ru(sq)(O^?.) groups forms a (cat)Ru‐O‐O‐Ru(sq) (cat = 3,5‐di‐t‐butylcathechol) framework with a μ‐superoxo bond. Successive removal of four electrons from the cat, sq, and superoxo groups of [Ru₂(btpyan)(cat)(sq)(μ‐O₂^?)]⁰ assisted with an attack of two water (or OH^?) to Ru centers, which causes smooth O₂ evolution with regeneration of [Ru₂(btpyan)(q)₂(OH)₂]²⁺. Deprotonation of an Ru‐quinone‐ammonia complex also gave the corresponding Ru‐semiquinone‐aminyl radical. The oxidized form of the latter showed a high catalytic activity towards the oxidation of methanol in the presence of base. Three complexes, [Ru(bpy)₂(CO)₂]²⁺, [Ru(bpy)₂(CO)(C(O)OH)]⁺, and [Ru(bpy)₂(CO)(CO₂)]⁰ exist as an equilibrium mixture in water. Treatment of [Ru(bpy)₂(CO)₂]²⁺ with BH₄^? gave [Ru(bpy)₂(CO)(C(O)H)]⁺, [Ru(bpy)₂(CO)(CH₂OH)]⁺, and [Ru(bpy)₂(CO)(OH₂)]²⁺ with generation of CH₃OH in aqueous conditions. Based on these results, a reasonable catalytic pathway from CO₂ to CH₃OH in electro‐ and photochemical CO₂ reduction is proposed. A new pbn (pbn = 2‐pyridylbenzo[b]‐1,5‐naphthyridine) ligand was designed as a renewable hydride donor for the six‐electron reduction of CO₂. A series of [Ru(bpy)_3‐n(pbn)_n]²⁺ (n = 1, 2, 3) complexes undergoes photochemical two‐ (n = 1), four‐ (n = 2), and six‐electron reductions (n = 3) under irradiation of visible light in the presence of N(CH₂CH₂OH)₃. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 169–186; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200800039     

Effect of the Atmospheric Conditions on the Thermal Behaviour of the Sarkinite Mineral,Mn2(OH)AsO4

The sarkinite, Mn₂(OH)AsO₄, mineral has been synthesized in laboratory as pure phase under mild hydrothermal conditions. The decomposition process of the hydroxiarsenate compound is strongly dependent on the atmospheric conditions. The results of the thermal treatment in air or argon are quite different. In this way, a new black phase appears in air atmosphere in the 400‐630 °C temperature range whereas under inert atmosphere the structure of Mn₂(OH)AsO₄ at room temperature is maintained up to 560 °C. The weight loss is attributed to the partial decomposition of Mn₂(OH)AsO₄ above 400 °C with removal of OH groups and the oxidation of Mn^II to Mn^III that occur simultaneously. Above 650 °C, the structures of the intermediate compounds are broken and the evolution of the inorganic residues gives rise to the formation of arsenates and oxides of Mn^II and Mn^III in inert and air atmospheres.     

TiO2晶相对MnOx/TiO2催化剂催化NO氧化性能的影响

以浸渍在不同晶相TiO₂ （金红石型（R）、锐钛矿型（A）和P25型（P））上的锰基催化剂为对象,研究了TiO₂晶相对MnO_x/TiO₂催化剂催化NO氧化活性的影响。 结果表明,MnO_x/TiO₂（P）催化剂活性最高,NO转化率在300℃及GHSV = 20000 h^-1条件下可达83%。 各催化剂活性顺序为MnO_x/TiO₂（P）>MnO_x/TiO₂（A）>MnO_x/TiO₂（R）。采用X射线粉末衍射、场发射扫描电子显微镜、X射线光电子能谱、H₂程序升温还原和O₂程序升温脱附等手段研究了TiO₂晶相影响MnO_x/TiO₂催化剂催化活性的作用机理。结果表明,相比于A和R型TiO₂,P型TiO₂能够增加MnO_x在其表面的分散度并抑制催化剂颗粒的团聚和粘连,且更有利于Mn₂O₃的生成,而后者催化NO氧化活性比其它MnO_x更高;此外,P型TiO₂可以增加MnO_x尤其是Mn₂O₃的还原性,并可促进O₂^-从M³⁺-O键的脱附。     

Complexes of distibinomethane ligands: 3. Manganese and rhenium carbonyl complexes

Photolysis of Mn₂(CO)₁₀ with the distibinomethanes Ph₂SbCH₂SbPh₂ (dpsm) and Me₂SbCH₂SbMe₂ (dmsm) yields [Mn₂(CO)₆(dpsm)₂] and [Mn₂(CO)₈(dmsm)], respectively, which have been characterised by IR, ¹H, ¹³C{¹H} NMR spectroscopies and fast atom bombardment (FAB) mass spectrometry. Similar photolysis of the ligands with Re₂(CO)₁₀ yields axially substituted [Re₂(CO)₉(η¹-distibinomethane)]. The X-ray crystal structure of [Mn₂(CO)₆(dpsm)₂] reveals two dpsm ligands, each bonding to the two metal centres [Mn–Mn 3.098(2), Mn–Sb 2.487(2)–2.500(2) Å].     

Tetranuclear Manganese Complex Incorporating 2‐Pyridyloximate Ligand: Synthesis,Crystal Structure and Magnetic Property

A tetranuclear manganese complex of the composition {Mn₄[(Py)C(Ph)NO]₄(CH₃CH₂OH)₃(CH₃CH₂O)Cl₃}·2H₂O ( 1 ) was synthesized by solvothermal reaction, and characterized by X‐ray single crystal diffraction, IR spectroscopy, and elemental analysis. X‐ray analysis revealed that complex 1 contains a [Mn₄(NO)₄]⁴⁺ core with three Mn^II atoms displaying distorted octahedral arrangements and one Mn^II ion exhibiting a trigonal bipyramidal arrangement. Low‐temperature magnetic susceptibility measurement for the solid sample of 1 revealed antiferromagnetic Mn^II ··· Mn^II interactions.     

Chemistry of iridium carbonyl : I. Chemical and structural characterization of the tetranuclear anions [Ir4(μ-CO)3(CO)8(COOR)]-

1 The anions [Ir₄(CO)₁₁(COOR)^- (R  Me, Et) have been prepared by reacting Ir₄(CO)₁₂ with alkali alkoxides in dry alcohol and under an atmosphere of carbon monoxide. The reaction of [Ir₄(CO)₁₁(COOMe)]^- with primary and secondary alcohols (EtOH, PrⁱOH) gives rise to specific alcoholysis. The anions [Ir₄(CO)₁₁(COOR)^- react with acids in THF solution to give quantitatively Ir₄(CO)₁₂. The chemical, spectroscopic and crystallographic characterization of the tetranuclear anions are reported.     

Deprotonierung von Mn2(μ-H)(μ-PR2)(CO)8 (R=Ph,Cy) zur Synthese von Heteronuklearen Mangan—Gold Clustern mit Mn2Aun-Kernen (n = 1 – 3)

Deprotonation of Mn₂(μ-H)(μ-PR₂)(CO)₈ (R = Ph Cy) for Synthesis of Heteronuclear Manganese-Gold Clusters with Mn₂Au_n Cores (n = 1–3) The dimanganese complexes Mn₂(μ-H)(μ-PR₂)(CO)₈ (R = Ph, Cy) have been deprotonated with 1,8-diazabicyclo[5.4.0]undec-7-en (DBU) in tetrahydrofuran solution at 20^°C to give the anions [Mn₂(μ-PR₂)(CO)₈]^?, which were isolated as tetraethylammonium salts. Both dimanganese complexes and the related anions were measured by cyclic voltammetry. The treatment of the aforementioned dimanganese complexes in thf solution with Lir' (R =Me, Ph) and subsequently with PPh₃AuCl gave at 20^°C three types of products: Mn₂(μ-PR₂(CO)₈(AuPPh₃),Mn₂(μ-PR₂)(μ-C(R′)O)(CO)₆-(AuPPh₃)₂ and Mn₂(μ-PR₂)(CO)₆(AuPPh₃)₃. The newly prepared substances were characterized by means of IR-, UV/VIS, ³¹P NMR data. The results of single X-ray analyses showed for the three-membered metal ring compound Mn₂(μ-PPh₂)(CO)₈(AuPPh₃) an uni-fold bridged σ(Mn? Mn) bond length of 306.7(3) pm, the metallatetrahedron complex Mn₂(μ-PPh₃)(μ-C(Ph)O(CO)₆(AuPPh₃)₂ a twofold bridged σ(Mn? Mn) bond length of 300.6(4) pm and the trigonal-bipyramidal cluster Mn₂(μ-Pph₂)(CO)₆(AuPPh₃)₃ an uni-fold bridged π(Mn? Mn) bond length of 274.7(3) pm. The Mn? Au bonds of these substances are accompanyied by semi-bridging CO ligands which are signified through short Au…C contact lengths in the range of 251 to 270 pm. In the substance with the Mn₂Au₂ metallatetrahedron core exists, additionally, such a contact with the acylic C atom of C(Ph)O bridging group of 263.4(18) pm. Such contact lengths were compared for corresponding dimanganese and dirhenium complexes.