Synthesis, Characterization and Crystal Structure of [Na2(APZC)2(μ-H2O)2(μ3-H2O)]n

The synthesis and spectroscopic properties of a Na^＋ complex with ligand 3-aminopyrazine-2-carboxylic acid were described. The resulting complex was characterized by elemental analysis, IR, UV-Vis, NMR spectroscopy and single crystal X-ray diffraction method. The title compound crystallizes in the triclinic system with space group . The crystalline structure of this compound consists of supramolecular architectures involving strong intramolecular N—H…O in pyrazine molecules and intermolecular O—H…N, O—H…O, and N—H…N hydrogen bonds between substituted pyrazine and water molecules.     

Nitrosyl derivatives of the unsaturated dihydrides [Mn2(μ-H)2(CO)6(μ-L2)] (L2 = Ph2PCH2PPh2, (EtO)2POP(OEt)2)

The title dimanganese complexes react with NO (5% in N₂) at room temperature to give as major products the corresponding hexanitrosyl derivatives [Mn₂(NO)₆(μ-L₂)] in moderate yields, and they react rapidly with NO₂ to give the corresponding hydride derivatives [Mn₂(μ-H)(μ-NO₂)(CO)₆(μ-L₂)], these having a nitrite ligand bridging the dimetal centre through the N and O atoms. The dppm-bridged dihydride also reacts selectively at 273 K with (PPN)NO₂ to give first the nitro derivative (PPN)[Mn₂(μ-H)(H)(NO₂)(CO)₆(μ-dppm)], which then transforms into the nitrosyl complex (PPN)[Mn₂(μ-CO)(CO)₅(NO)(μ-dppm)] at room temperature or above (dppm = Ph₂PCH₂PPh₂; PPN⁺ = [N(PPh₃)₂]⁺). The latter anion reacts with (NH₄)PF₆ to give the hydride-bridged nitrosyl complex [Mn₂(μ-H)(μ-NO)(CO)₆(μ-dppm)] and with [AuCl(PPh₃)] to give the trinuclear cluster [AuMn₂(μ-NO)(CO)₆(μ-dppm)(PPh₃)] (Mn-Au = ca. 2.68 Å; Mn-Mn = 2.879(2) Å). Both products are derived from the addition of the added electrophile at the intermetallic bond and rearrangement of the nitrosyl ligand into a bridging position. In contrast, methylation of the anion with CF₃SO₃Me takes place at the nitrosyl ligand to yield the unstable methoxylimide derivative [Mn₂(μ-NOMe)(CO)₆(μ-dppm)]. Analogous reactions at the nitrosyl ligand take place upon the addition of HBF₄·OEt₂ to the nitrosyl-bridged hydrides [Mn₂(μ-H)(μ-NO)(CO)_n(μ-dppm)_m] (n = 6, m = 1; n = 4, m = 2) to give the corresponding hydroxylimide derivatives [Mn₂(μ-H)(μ-NOH)(CO)_n(μ-dppm)_m]BF₄, which were also thermally unstable and could not be isolated nor fully characterized.     

Diverse coordination of two ligands in ferromagnetic [Cu(μ-HCO2)2(3-pyOH)]n and [Cu2(μ-HCO2)2(μ-3-pyOH)2(3-pyOH)2(HCO2)2]n

Two novel polynuclear complexes with methanoate anions and 3-hydroxypyridine ligands [Cu(μ-HCO₂)₂(3-pyOH)]_n (1) and [Cu₂(μ-HCO₂)₂(μ-3-pyOH)₂(3-pyOH)₂(HCO₂)₂]_n (2), respectively, were synthesized and characterized. The central copper atom in 1 is surrounded by four methanoates and a 3-pyOH molecule, forming a square-pyramidal CuO₃NO chromophore. All the methanoates are bidentate and serve as bridges between the adjacent copper ions via syn-anti and anti–anti coordination. The basal square coordination axes are formed by O(syn), N(3-pyOH) (1.974(2), 2.016(2) Å) and O(anti), O(anti) (1.945(2), 1.960(2) Å), while the third O(anti) (2.247(2) Å) is on the top of the pyramid. A ferromagnetic transition with an exchange constant 2J/k_B = 9.2 cm⁻¹ is found for 1 below 20 K. This interaction probably takes place through two syn-anti methanoates extended in a chain through the 2D structure. On the other hand, two monoatomic Cu–O–Cu intra-dinuclear asymmetric (1.986(2), 2.415(2) Å) bridges of two methanoates in [Cu₂(HCO₂)₄(3-pyOH)₄] (2) are present. An elongated distorted octahedral coordination sphere around each copper(II) atom is completed by an additional monodentate terminal methanoate (1.975(2) Å), two N-coordinated 3-pyOH (2.005(2), 2.002(2) Å) and the third weakly O-coordinated 3-pyOH (2.732(2) Å). Although a shorter Cu?Cu distance is noticed in 2 than in 1 (4.690(1) Å 1, 3.442(1) Å 2), much weaker ferromagnetism is found in 2.     

Pyridine-2-thione (pySH) derivatives of silver(I): Synthesis and crystal structures of dinuclear [Ag2Cl2(μ-S-pySH)2(PPh3)2] and [Ag2Br2(μ-S-pySH)2(PPh3)2] complexes

Reaction of silver(I) halides with PPh₃ in acetonitrile and then with pyridine-2-thione (pySH) chloroform (1:1:1 molar ratio) has yielded sulfur bridged dimers of general formula, [Ag₂X₂(μ-S-pySH)₂(PPh₃)₂] (X = Cl, 1, Br, 2). Both these complexes have been characterized using analytical data, NMR spectroscopy and single crystal X-crystallography. The central Ag₂S₂ cores form parallelograms with unequal Ag–S bond distances (2.5832(8), 2.7208(11) Å) in 1 and (2.6306(4), 2.6950(7) Å) in 2, respectively. The Ag?Ag contacts of compounds 1 and 2 are 3.8425(8) and 3.8211(4) Å, respectively. The angles around Ag (in the range 87.19(2)–121.71(2)° in 1 and 87.81(2)–121.53(2)° in 2) reveal highly distorted tetrahedral geometry. There are inter dimer π–π stacking interactions between pyridyl rings (inter ring distances of 3.498 and 3.510 Å in complexes 1 and 2, respectively). The solution state ³¹P NMR spectroscopy has shown the existence of both monomers and dimers. The studies reveal relatively weaker intramolecular –NH?Cl hydrogen bonding in case of AgCl vis-à-vis that in CuCl which favored both a monomer and a dimer with AgCl, and only a monomer with CuCl.     

Crystal and molecular structure of tetraaquabarium Di-μ-tartrato-di-μ-hydroxodigermanate(IV) pentahydrate [Ba(H2O)4][Ge2(μ-Tart)2(μ-OH)2] · 5H2O

A new heteronuclear germanium barium complex with D-tartaric acid [Ba(H₂O)₄][Ge₂(μ-Tart)₂(μ-OH)₂]·5H₂O (I) (H₄Tart is tartaric acid) was synthesized. The identity of compound I and its com- position were determined by elemental analysis and X-ray diffraction. The thermal stability of the compound was studied; the coordination centers of the ligand were found from IR spectroscopy. The structure of I was determined by X-ray crystallography. Crystals I are tetragonal: a = 8.5033(2) ?, c = 30.9393(11) ?, V = 2237.10(11) ?³, Z = 4, space group P4₁, R1 = 0.0301 based on 4215 reflections with I > 2σ(I). In crystals I, neutral [Ge₂(μ-Tart)₂] dimers are linked in pairs by double hydroxyl bridges to form {[Ge₂(μ-Tart)₂(μ-OH)₂]²⁻}_∞ polymeric chains. Hydrated Ba²⁺ cations and crystal water molecules are in between the anionic chains. Polymeric complex anions, hydrated barium cations, and H₂O molecules are bound by a system of hydrogen bonds to form a framework.     

Synthesis,structure characterization and thermal properties of [Zr6(μ3-O)4(μ3-OH)4(OOCCH2Bu)9(μ2-OH)3]2

Oxo/hydoxo zirconium(IV) complex of the general formula [Zr₆(μ₃-O)₄(μ₃-OH)₄(OOCCH₂^tBu)₉(μ₂-OH)₃]₂ has been isolated, when Zr(OⁱPr)₄ reacted with a 2-fold excess of 3,3-dimethylbutyric acid. Single crystal X-ray diffraction data, collected at 103 and 153 K, showed that the studied compound crystallizes in hexagonal system (P6₃/m (no. 176)). Structure consists of dimers composed of [Zr₆(μ₃-O)₄(μ₃-OH)₄(OOCCH₂^tBu)₉] sub-units, linked by six μ₂-OH bridges. Infrared spectroscopic studies proved the presence of hydroxo groups in the structure of studied clusters and formation of different types of oxo/hydroxo bridges. The application of variable temperature infrared spectroscopy and differential scanning calorimetry revealed that the structure of this complex undergoes the phase transitions at 143–183 and 203–293 K. Comparison of spectral and crystallographic data suggests that these phase transitions might be related to changes in the strength of Zr–O bonds of μ₂-OH bridges linking complex sub-units, and change in symmetry of the crystal lattice (from hexagonal to trigonal). Analysis of thermogravimetric data showed that decomposition of [Zr₆(μ₃-O)₄(μ₃-OH)₄(OOCCH₂^tBu)₉(μ₂-OH)₃]₂ proceeds with complete conversion to ZrO₂ (monoclinic form) between 603 and 803 K.     

Synthesis and crystal structure of new one-dimensional copper(II) complex [Cu4(En)2(μ1,1-N3)4(μ1,1,1-N3)2(μ1,3-N3)2]n

A new polymer azido-bridged copper(II) complex [Cu₄(En)₂(μ_1,1-N₃)₄(μ_1,1,1-N₃)₂(μ_1,3-N₃)₂] _n (I) (En = ethylenediamine) has been synthesized and crystallography characterized. Complex I shows one-dimensional coordination polymeric structure based on a tetranuclear cluster unit [Cu₄(En)₂(μ_1,1-N₃)₄(μ_1,1,1-N₃)₂(μ_1,3-N₃)₂], in which the azido ions display three different bridging modes.     

Stepwise addition of CuBr at [(dtc)2Mo2(S)2(μ-S)2] (dtc=diethyldithiocarbamate): syntheses and crystal structures of two Mo/Cu/S clusters [(dtc)2Mo2(μ3-S)(μ-S)3(CuBr)] and [(dtc)2Mo2(μ3-S)4(CuBr)2]

Reactions of [(dtc)₂Mo₂(S)₂(μ-S)₂] with one or two equivalents of CuBr in CH₂Cl₂ afforded two new heterobimetallic sulfide clusters, [(dtc)₂Mo₂(μ₃-S)(μ-S)₃(CuBr)] (1) and [(dtc)₂Mo₂(μ₃-S)₄(CuBr)₂] (2). Both compounds were characterized by elemental analysis, IR, UV-vis and X-ray analysis. Compound 1 contains a butterfly-shaped Mo₂S₄Cu core in which one CuBr unit is coordinated by one bridging S and two terminal S atoms of the [(dtc)₂Mo₂(S)₂(μ-S)₂] moiety. In the structure of 2, one [(dtc)₂Mo₂(S)₂(μ-S)₂] moiety and two CuBr units are held together by six Cu-μ₃-S bonds, forming a cubane-like Mo₂S₄Cu₂ core.     

Synthesis and molecular structures of the Co3(μ-OOCPh)4(μ,η2-OOCPh)2[OC(Ph)OHNEt3]2 and Co(Hdmpz)2(OOCPh)2 complexes (Hdmpz = 3,5-dimethylpyrazole)

The product of the thermal reaction between cobalt acetate hydrate and benzoic acid reacts with a triethylamine excess to form the trinuclear complex Co₃(μ-OOCPh)₄(μ,η²-OOCPh)₂[OC(Ph)OHNEt₃]₂, and its reaction with 3,5-dimethylpyrazole yields the mononuclear complex Co(Hdmpz)₂(OOCPh)₂. The compound structures are discussed on the basis of X-ray crystallographic data.     

Cu2(μ-dppb)2(μ-Cl)2的合成、晶体结构及非线性光学性质

The complex Cu₂(μ-dppb)₂(μ-Cl)₂ has been synthesized from the reaction of CuCl， dppb and (n-Bu)₄NCl. The crystal belongs to the triclinic with space group P1. The unit cell parameters are: a=9.939(4)?， b=10.083(6)?， c=14.104(5)?， α=76.46(3)°， β=71.02(2)°， γ=70.87(5)°. The single crystal X-ray diffraction analysis reveals that it has a bi-ring structure with a symmetry center at the middle of two Copper atoms. The outer ring is a 14-membered ring of Cu-dppb-Cu-dppb， and the inner ring is a 4-membered ring composed of two Cl^- and two Cu(Ⅰ). Investigation of third-order optical nonlinearity shows that it exhibits considerable nonlinear absorptive and self-defocusing effect with α₂=1.75×10^-13m·W^-1 and n₂=3.19×10^-18m²·W^-1. CCDC: 193113.     

Synthesis of electronically and coordinatively unsaturated complexes [Ru2(CO)4(μ-H)(μ-PBu2)(μ-L2)] (L2 = biphosphanes)

A convenient synthesis and the characterization of six new electronically and coordinatively unsaturated complexes of the formula [Ru₂(CO)₄(μ-H)(μ-P^tBu₂)(μ-L₂)] (2b-g) (RuRu) is described exhibiting a close relation to the known [Ru₂(CO)₄(μ-H)(μ-P^tBu₂)(μ-dppm)] (2a). The complexes 2b-g were obtained in a kind of one-pot synthesis starting from [Ru₃(CO)₁₂] and P^tBu₂H in the first step followed by the reaction with the bidentate bridging ligand in the second step. The method was developed for the following bridging ligands (μ-L₂): dmpm (2b, dmpm = Me₂PCH₂PMe₂), dcypm (2c, dcypm = Cy₂PCH₂PCy₂), dppen (2d, dppen = Ph₂PC(=CH₂)PPh₂), dpppha (2e, dpppha = Ph₂PN(Ph)PPh₂), dpppra (2f, dpppra = Ph₂PN(Pr)PPh₂), and dppbza (2g, dppbza = Ph₂PN(CH₂Ph)PPh₂). The molecular structures of all new complexes 2b−g were determined by X-ray diffraction.     

Relativistic scalar and spin-orbit density functional calculations of the electronic structure, NICS index and ELF function of the [Re2(CO)8(μ-BiPh)2] and [Re2(CO)8(μ-BiPh2)2] clusters

Relativistic scalar and spin-orbit density functional calculations of the electronic structure, Nucleus-Independent Chemical Shift (NICS) index and ELF function of the [Re₂(CO)₈(μ-BiPh)₂] and [Re₂(CO)₈(μ-BiPh₂)₂] clusters are reported. We show here that the [Re₂(CO)₈(μ-BiPh)₂] cluster has large negative NICS values in the region defined by the Re-Bi-Re-Bi four-membered ring and the ELF function shows significant electron delocalization density in the center of the metallic ring, thus indicating an aromatic cluster. In contrast the Re-Bi-Re-Bi four-membered ring in the [Re₂(CO)₈(μ-BiPh₂)₂] cluster has negligible paratropic ring currents and the ELF function shows a low-density region within the metallic ring indicating that aromaticity is switched off. However, the phenyl ligands in both clusters show the expected aromatic character.     

Oxidative addition of the Mo-Cl bond to the Pt0 complex. Synthesis and structure of Cp′Mo(μ-CO)2(C2Ph2)Pt2(PPh3)2(CO)Cl

A reaction of Cp′Mo(CO)₃Cl(Cp′ = MeC₅H₄) with (PPh₃)₂Pt(C₂Ph₂) gave the heterometallic cluster Cp′Mo(μ-CO)₂(C₂Ph₂)Pt₂(PPh₃)₂(CO)Cl (I) as the sole product. According to X-ray diffraction data, complex I contains single Pt-Mo bonds (2.7962(5) and 2.7699(5) ?) but no Pt-Pt bond (Pt…Pt 2.9746(3) ?). The coordinated diphenylacetylene molecule forms two Pt-C σ-bonds (2.054(6) and 2.083(5) ?) and a π-bond to the Mo atom (Mo-C 2.265(6) and 2.272(5) ?; C≡C 1.387(8) ?). Original Russian Text ? A.A. Pasynskii, I.V. Skabitskii, Yu.V. Torubaev, S.S. Shapovalo, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 6, pp. 410–413.     

Reactivity of the unsaturated manganese dihydrides [Mn2(μ-H)2(CO)6(μ-L2)] [L2 = (EtO)2POP(OEt)2, Ph2PCH2PPh2, Me2PCH2PMe2] toward silicon and tin hydrides

The dimanganese hydride complexes [Mn₂(μ-H)₂(CO)₆(μ-L₂)] [L₂ = (EtO)₂POP(OEt)₂ (tedip), Ph₂PCH₂PPh₂ (dppm)] react with primary and secondary silanes H₂SiPhR (R = Ph, Me, H) to give the corresponding derivatives [Mn₂(μ-H₂SiPhR)(CO)₆(μ-L₂)] having a silane molecule displaying a relatively unusual μ-κ²:κ² coordination mode (averaged values are ca. Mn-H = 1.59 Å, H-Si = 1.69 Å and Mn-Si = 2.381 Å, when R = Ph and L₂ = tedip). These complexes display in solution cis and/or trans arrangement of the bridging silane relative to the diphosphorus ligands (and facial and/or meridional arrangements of the corresponding carbonyl ligands), depending on the bridging groups. The novel unsaturated dihydride [Mn₂(μ-H)₂(CO)₆(μ-dmpm)] (dmpm = Me₂PCH₂PMe₂) has been prepared through the reaction of [Mn₂(μ-Cl)₂(μ-dmpm)(CO)₆] and 5 equiv of Li[BH₂Me₂] in tetrahydrofuran followed by addition of water. The dihydride complexes [Mn₂(μ-H)₂(CO)₆(μ-L₂)] (L₂ = tedip, dppm, dmpm) react with HSnPh₃ to give different mixtures of products strongly dependent on the particular reaction conditions. We have thus been able to isolate and characterize five new types of dimanganese-tin derivatives: [Mn₂(μ-SnPh₂)₂(CO)₆(μ-L₂)], [Mn₂(μ-H)(μ-Ph₂SnO(H)SnPh₂)(CO)₆(μ-L₂)] (average values are Mn-Sn = 2.54 Å, Sn-O = 2.11 Å, when L₂ = tedip), [Mn₂(μ-H)(μ-κ¹:κ²-HSnPh₂)(CO)₆(μ-L₂)], [Mn₂(μ-H)(μ-κ¹:κ¹-O(H)SnPh₂)(CO)₆(μ-L₂)], and [Mn₂(μ-H)(SnPh₃)(CO)₇(μ-L₂)] (Mn-Mn = 3.237(1) Å, Mn-Sn = 2.642(1) Å, when L₂ = dppm).     

A comparison between the reaction of P2Ph4 with [{Co2(CO)6}2(μ-η:μ-η-HOCH2CCCCCH2OH)] and the reaction of [Co2(μ-PPh2)2(CO)6] with HOCH2CCCCCH2OH

Reaction of P₂Ph₄ with the diyne-diol complex [{Co₂(CO)₆}₂(μ-η²:μ-η²-HOCH₂CCCCCH₂OH)] in toluene at 65 °C gives [{Co₂(μ-P₂Ph₄)(CO)₄}{Co₂(CO)₆}(μ-η²:μ-η²-HOCH₂CCCCCH₂OH)] (1). Thermolysis of 1 at 95 °C leads to [{Co₂(CO)₅}₂(μ-P₂Ph₄)(μ-η²:μ-η²-HOCH₂CCCCCH₂OH)](2) and (μ₂-PPh₂)(μ₂-CO)(CO)₇] (3). The structures of 1-3 have been established by X-ray crystallography. In 1, a pseudoequatorial P₂Ph₄ ligand bridges the cobalt-cobalt bond of a Co₂(CC)(CO)₄ unit. By contrast, in isomeric 2, a pseudoaxial P₂Ph₄ ligand spans two Co₂(CC)(CO)₅ units, a new coordination mode for [{Co₂(CO)₅L}₂(μ-η²:μ-η²-diyne)] complexes. Complex 3 arises from dehydration-cyclocarbonylation of the diyne-diol in 1 to give a 2(5H)-furanone, a process that has not been previously reported. Reaction of HOCH₂CCCCCH₂OH with [Co₂(μ-PPh₂)₂(CO)₆] at 80 °C in toluene gave [Co₃(μ-PPh₂)₃(CO)₆], [Co₂(CO)₆(μ-η²-HOCH₂CCCCCH₂OH)] and [Co₂{μ-η⁴-PPh₂C(CCCH₂OH)C(CH₂OH)CO}(μ-PPh₂)(CO)₄] (4). The regiochemistry of 4 was confirmed by X-ray crystallography.     

Reactions of a phosphido-bridged unsymmetrical diiron complex (η-C5Me5)Fe2(CO)4(μ-CO)(μ-PPh2) with various alkynes

A phosphido-bridged unsymmetrical diiron complex (η⁵-C₅Me₅)Fe₂(CO)₄(μ-CO)(μ-PPh₂) (1) was synthesized by a new convenient method; photo-dissociation of a CO ligand from (η⁵-C₅Me₅)Fe₂(CO)₆(μ-PPh₂) (2) that was prepared by the reaction of Li[Fe(CO)₄PPh₂] with (η⁵-C₅Me₅)Fe(CO)₂I. The reactivity of 1 toward various alkynes was studied. The reaction of 1 with ^tBuCCH gave a 1:1 mixture of two isomeric complexes (η⁵-C₅Me₅)Fe₂(CO)₃(μ-PPh₂)[μ-CHC(^tBu)C(O)] (3) containing a ketoalkenyl ligand. The reactions of 1 with other terminal alkynes RCCH (R=H, CO₂Me, Ph) afforded complexes incorporating one or two molecules of alkynes and a carbonyl group. The principal products were dinuclear complexes bridged by a new phosphinoketoalkenyl ligand, (η⁵-C₅Me₅)Fe₂(CO)₃(μ-CO)[μ-CR¹CR²C(O)PPh₂] (4a: R¹=H, R²=H; 4b: R¹=CO₂Me, R²=H; 4c: R¹=H, R²=Ph). In the cases of alkynes RCCH (R=H, CO₂Me), dinuclear complexes having a new ligand composed of two molecules of alkynes, a carbonyl group, and a phosphido group; i.e. (η⁵-C₅Me₅)Fe₂(CO)₃[μ-CRCHCHCRC(O)PPh₂] (5a: R=H; 5b: R=CO₂Me), were also obtained. In all cases, mononuclear complexes, (η⁵-C₅Me₅)Fe(CO)[CR¹CR²C(O)PPh₂] (6a: R¹=H, R²=H; 6b: R¹=H, R²=CO₂Me; 6c: R¹=H, R²=Ph) were isolated in low yields. The structures of 1, 4c, 5b, and 6a were confirmed by X-ray crystallography. The detailed structures of the products and plausible reaction mechanisms are discussed.     

Synthesis, characterization, and structural study of iron-sulfur core {Cp2Fe2(μ-SEt)2} complexes

The known complexes [Cp₂Fe₂(μ-SEt)₂(MeCN)₂](PF₆)₂ (1) and Cp₂Fe₂(μ-SEt)₂(CN)₂ (2) are prepared to investigate their reactivity. The reaction of complex 2 with equimolar amounts of MeOTf yields a monomethylation product [Cp₂Fe₂(μ-SEt)₂(CN)(CNMe)](OTf) (3). Dimethylation of complex 2 by 2 equiv. MeOTf gives a complex [Cp₂Fe₂(μ-SEt)₂(CNMe)₂](OTf)₂ (4). Complex 1 containing two labile MeCN ligands reacts with several bidentate phosphine ligands, such as dppm, dppa, and dppf, to afford complexes [Cp₂Fe₂(μ-SEt)₂(dppm)](PF₆)₂ (5), [Cp₂Fe₂(μ-SEt)₂(dppa)](PF₆)₂ (6), and [Cp₂Fe₂(μ-SEt)₂(dppf)](PF₆)₂ (7), respectively. The spectroscopic, electrochemical, and reactivity studies of iron-sulfur core complexes are performed. The structures of complexes 1-7 were confirmed by X-ray crystallography.     

Synthesis,structure and catalase activity of the [TPA2Mn2(μ-Cl)2] complex

The dinuclear Mn complex (Et₃NH)₂[TPA₂Mn₂(μ-Cl)₂](ClO₄)₄ (I) was synthesized and characterized. Complex I was obtained from the reaction between MnCl₂ and [H₃TPA](ClO₄)₃ in MeOH. Structural analysis of I showed the two Mn(II) atoms are bridged by two chloride ligands, forming a bis(μ-chloro)dimanganese core. The [Mn₂(μ-Cl)₂]²⁺ core, with a Mn–Mn distance of 3.521(2) Å, is similar to the active site found in chloride-inhibited Mn catalase. EPR and temperature-dependent magnetic susceptibility measurements of complex I showed an antiferromagnetic interaction between the two S = 5/2 Mn centers with an exchange parameter J = −8.8 cm⁻¹. Catalytic activity of H₂O₂ dismutation was measured for complex I and compared with other related complexes. Kinetic parameters of H₂O₂ dismutation were obtained and a possible catalytic mechanism of complex I, related to chloride-inhibited Mn catalase, was suggested.     

Disulfido iron-manganese carbonyl cluster complexes: Synthesis, structure, bonding and properties of the radical CpFeMn2(CO)7(μ3-S2)2

Two new compounds CpFeMn₂(CO)₇(μ₃-S₂)₂ (2) and Cp₃Fe₃Mn(CO)₄(μ₃-S₂)₂(μ₃-S) (3) were obtained by the treatment of [CpFeMn(CO)₅(μ₃-S₂)]₂ (1) with CO at room temperature in the presence of room light. Compound 2 contains two triply bridging disulfido ligands on opposite sides of an open FeMn₂ triangular cluster. EPR and temperature-dependent magnetic susceptibility measurements show that it is paramagnetic with one unpaired electron per formula equivalent. The electronic structure of 2 was established by DFT and Fenske-Hall (FH) molecular orbital calculations which show that the unpaired electron occupies a low lying antibonding orbital that is located principally on the iron atom. The cyclic voltammogram of 2 exhibits one reversible one-electron oxidation wave at +0.34 V and one irreversible one-electron reduction wave at −0.66 V vs. Ag/AgCl. Compound 3 contains three iron atoms and one manganese atom with two triply bridging disulfido ligands and one triply bridging sulfido ligand and has no unpaired electrons. The molecular structures of compounds 2 and 3 were established by single crystal X-ray diffraction analyses.