Fe Hg Research Articles

Tracing anthropogenic mercury in soils from Fe–Hg mining/smelting area: Isotopic and speciation insights

Mercury (Hg) stable isotope ratios supplemented by Hg solid speciation data were determined in soils in a former Fe–Hg mining/smelting area (Jedová hora, Czech Republic, Central Europe). The dominant Hg phase in the studied soils was found to be cinnabar (HgS). A secondary form of soil Hg(II) was represented by Hg weakly and strongly bound to mineral (micro)particles, as revealed by thermo-desorption analysis. These Hg species probably play a key role in local soil Hg processes and biogeochemical cycling. The Hg isotopic data generally showed small differences between HgS (−1.1 to −0.8‰; δ202Hg) and the soil samples (−1.4 to −0.9‰; δ202Hg), as well as limited isotopic variability within the two studied soil profiles. On the other hand, the detected negative δ202Hg shift (∼0.4‰) in organic horizons compared to mineral soils in the highly contaminated profile suggests the presence of secondary post-depositional Hg processes, such as sorption or redox changes. For the less contaminated profile, the observed Hg isotopic variation (∼0.3‰; δ202Hg) in the subsurface mineral soil compared to both overlying and underlying horizons is likely due to cyclic redox reactions associated with Hg isotopic fractionation. We assume that the adsorption of Hg(II) to secondary Fe(III)/Mn(III,IV)-oxides could be of major importance in such cases.

Single and mixture toxicity of As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, and Zn to the rotifer Proales similis under different salinities.

Aquatic organisms that inhabit coastal environments are generally exposed to multiple mixtures of chemicals. The single and mixture toxicity of nine trace metals (As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, and Zn) to the rotifer Proales similis were examined at four different salinities (5, 15, 25, and 35ppt). Chronic toxicity reproductive tests were performed using an application factor (AF) of 0.05, 0.1, 0.2, and 0.4 by multiplying the 24-h LC50 values of each metal. The metal mixture treatments were: T1, As-Cd-Cr-Cu-Fe-Hg-Ni-Pb-Zn; T2, As-Cd-Hg-Pb and; T3, Cr-Cu-Fe-Ni-Zn. The LC50 values ranged between 5 and 4140μgL-1 in the following order: Hg>Cu>Fe>Pb>Cd>Zn>As>Cr>Ni in low salinity and Hg>Cu>Fe>Pb>Zn>As>Cd>Cr>Ni in high salinity conditions. In all cases, acute toxicity was higher at a salinity of 5ppt compared to 35ppt. Chronic toxicity tests indicated that single metal toxicity intensified as the AF increased and as salinity decreased. Regardless of salinity, Pb at 0.4 AF was the most toxic metal. Proales similis evidenced a higher growth in the As treatments (0.1 and 0.2 AF) at 35ppt compared to controls. Furthemore, the T1 and T2 treatments were the most toxic, and in most cases, they induced a synergistic effect. Antagonism effects were detected in the T3 treatment at 25 and 35ppt. The present data highlights the importance of the examination of pollution in natural environmental conditions in which many aquatic invertebrates endure.

Crystal face-dependent methylmercury adsorption onto mackinawite (FeS) nanocrystals: A DFT-D3 study

• Facet-dependent MeHg adsorption onto mackinawite (FeS) was calculated by DFT-D3. • The (0 1 1) surface is more favorable than (0 0 1) and (1 1 1) surfaces for MeHg adsorption. • MeHg adsorbs preferentially onto Fe sites of FeS surfaces relative to the S sites. Reactions occurring at mackinawite (FeS) surfaces play an important role in controlling methylmercury (MeHg) bioavailability and mobility. MeHg adsorption onto FeS is morphology dependent, and the mineral surface structure imparts distinct interfacial chemical properties to individual facets and can control the adsorption capacity at these interfaces. However, the underlying mechanisms for facet-specific adsorption of MeHg remain poorly understood at the molecular scale. A systematic first-principles study of MeHg adsorption onto the (0 0 1), (0 1 1), and (1 1 1) surfaces of FeS was conducted using density functional calculations, and the preferred adsorption sites and adsorption mechanisms were determined. MeHg binds preferentially with Fe sites relative to S sites on the FeS surface, with stronger adsorption onto the FeS (0 1 1) and FeS (1 1 1) surfaces compared to the FeS (0 0 1) surface. MeHg displays a variety of chemisorption geometries on each of the FeS surfaces. The most stable configuration on the FeS (0 0 1) surface is a monodentate S–Hg complex. In contrast, the most stable configuration on the FeS (0 1 1) surface is a monodentate Fe–Hg complex, and a bidentate Fe–Hg–Fe complex was found to be the most stable configuration on the FeS (1 1 1) surface. This work provides an important stepping stone in understanding facet effects and bonding mechanisms of MeHg adsorption on FeS surfaces at the molecular level and provides a framework to guide experimental studies that optimize the use of FeS as a scavenger material for MeHg in groundwater and soil systems.

Concentration of some heavy metals (Cd, Co, Fe Hg) in soil and edible vegetables in Ogoja urban area of Cross River State, Nigeria

The concentration of heavy metals (Cd,Co,Fe & Hg) in soil and some edible vegetables was determined during the rainy and dry seasons of the year, using Atomic Absorption Spectrometer (AAS) after the samples were digested. Forty samples of the eight edible vegetables and forty soil samples, where they were planted, were also collected at the root level of the vegetables. The eight most common edible vegetables considered were Telfairia occidentalis , Amaranthus spp, Corchorus olitorius , Ocimum grattissimum (scent leaf), Solanum melongena (yellow garden egg leaf), Talinum triangulare , Murraya koenigi and Vernonia amygdalina . The result of the analysis revealed that Co and Hg were stringed variables as they were not detected in the soil or vegetables in both seasons of the year. Cd ranged from 0.005-0.043 mgkg -1 in the soil and 0.005-0.042 mgkg -1 for rainy and dry season respectively while Fe ranged from (0.015-0.051) mgkg -1 and (0.019-0.050) mgkg -1 for rainy and dry season respectively. The mean concentration of Cd accumulated by the vegetable ranged from 0.005-0.010 mgkg -1 in both seasons, while that of Fe ranged from (0.013-0.034) mgkg -1 and (0.009-0.033) mgkg -1 for rainy and dry seasons respectively. From the data, it shows that Fe was more in the soil than Cd, and it was also accumulated by the vegetables more than Cd. The metal’s concentration in the vegetables is still low and within the permissible limits of FAO/WHO. The amount of metal accumulated is directly proportional to that in the soil. There is no significant difference between the results of the dry and rainy season. There is need to maintain this low level of heavy metals in the soil and vegetables through adequate awareness on the proper disposal of waste and environmental monitoring/evaluation by relevant agencies of the state. Keywords: Heavy Metals, Concentration, Soil, Edible Vegetables

Lead and sulfur isotope constraints on the genesis of the polymetallic mineralization at Oued Maden, Jebel Hallouf and Fedj Hassene carbonate-hosted Pb–Zn (As–Cu–Hg–Sb) deposits, Northern Tunisia

The Oued Maden, Jebel Hallouf and Fedj Hassene Pb–Zn (Ba–Sr–F–Fe–Hg) hydrothermal ore deposits are located in the Nappe zone of Northern Tunisia. These ore deposits occur as epigenetic veins, karst and stockwork fillings in Upper Cretaceous limestones. The ore mineralogy consists mainly of galena and sphalerite, accompanied by minor amounts of jordanite, pyrite, chalcopyrite, orpiment, realgar, and other sulfosalts. Sulfur isotope data from sphalerite and galena indicate that the reduced sulfur was derived through thermochemical and/or bacterial reduction of dissolved sulfate resulting in metal precipitation. Lead isotope ratios and corresponding calculated age models indicate that the Pb in galenas has been derived from a homogenous crustal source during Upper Miocene time.

Experimental investigations and thermodynamic description of the PbO–Fe 2O 3 system

The knowledge of the quinary Pb–Bi–O–Fe–Hg is necessary for understanding the degradation mechanisms of the T91 steel used as structure material in future ADS nuclear reactors. In this device, the steel will be in direct contact with the liquid spallation target (which is constituted by lead or lead-bismuth eutectic) surrounded by a reduced oxygen pressure atmosphere. In the present work, the characterization of the pseudo-binary PbO–Fe 2O 3 cut has been performed. In order to complete the available data in the literature, some experimental investigations by differential thermal analysis (DTA), isothermal annealing, powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) have been done. These results have allowed proposing a thermodynamic assessment using the Calphad method.

Corrosion of T91 Steel in LBE: Contribution to the Study of the Pb–Bi–O–Fe–Hg System - Thermodynamic Description of PbO–Fe<sub>2</sub>O<sub>3</sub>

The knowledge of the quinary Pb–Bi–O–Fe–Hg is necessary for understanding the degradation mechanisms of the T91 steel used as structural material in future ADS nuclear reactors. In this device, the steel will be in direct contact with the liquid spallation target (which is constituted by lead or lead-bismuth eutectic) surrounded by a reduced oxygen pressure atmosphere. In the present work, the characterization of the pseudo-binary PbO–Fe2O3 cut has been performed. In order to complete the available data in the literature, some experimental investigations by DTA, isothermal annealing, SEM and EPMA have been done. These results have allowed proposing a thermodynamic assessment using the Calphad method by the ThermoCalc software.

Fe–Hg Interactions and 31P Chemical Shifts in [Fe(CO) 3 (PPh 2R) 2(HgCl 2)] (R=pym, fur, py, thi)

In order to study the effects of R group on Fe–Hg interactions and 31P chemical shifts, the structures of mononuclear complexes Fe(CO) 3(PPh 2R) 2 (R=pym: 1, fur: 2, py: 3,thi: 4; pym=pyrimidine, fur=furyl, py=pyridine, thi=thiazole) and binuclear complexes [Fe(CO) 3(PPh 2R) 2(HgCl 2)] (R=pym: 5, fur: 6, py: 7, thi: 8) were studied using the density functional theory (DFT) PBE0 method. The 31P chemical shifts were calculated by PBE0-GIAO method. Nature bond orbital (NBO) analyses were also performed to explain the nature of the Fe–Hg interactions. The conclusions can be drawn as follows: (1) The complexes with nitrogen donor atoms are more stable than those with O or S atoms. The more N atoms there are, the higher is the stabilility of the complex. (2) The Fe–Hg interactions play a dominant role in the stabilities of the complexes. In 5 or 6, thereisa σ-bond between Fe and Hg atoms. However, in 7 and 8, the Fe–Hg interactions act as σ P–Fe→ n Hg and σ C–Fe→ n Hg delocalization. (3) Through Fe→Hg interactions, there is charge transfer from R groups towards the P, Fe, and Hg atoms, which increases the electron density on P nucleus in binuclear complexes. As a result, compared with their mononuclear complexes, the 31P chemical shifts in binuclear complexes show some reduction.

Bis[dicarbonyl(cyclopentadienyl)ferrio]mercury(II)

Crystals of Hg[Fe(CO)2(η5–C5H5)]2 contain discrete mol­ecules with crystallographically imposed twofold symmetry, Hg—Fe 2.5546 (10) A and an Fe—Hg—Fe angle of 156.34 (6)°, the most acute yet found for a simple Hg[MLn]2 species.

The reaction of ferrocene with mercuric chloride revisited: ‘Cp 2Fe*2HgCl 2’=[(C 5H 5)Fe(C 5H 4HgCl)] 2[Hg 2Cl 6], comparison of its molecular structure with that of chloromercuriferrocene

The ‘blue adduct’ formed from the decomposition of the red ‘Cp 2Fe*7HgCl 2’ and formulated as ‘Cp 2Fe*2HgCl 2’ was characterized by X-ray crystallography as the ring-mercurated ferricenium salt [(C 5H 5)Fe(C 5H 4HgCl)] 2[Hg 2Cl 6]. For comparison, the neutral [(C 5H 5)Fe(C 5H 4HgCl)] was also studied by single-crystal diffractometry. Both compounds have the HgCl group within the plane of the cyclopentadienyl ring with no Fe–Hg interaction.

Molecular Structure of Hg-Bridged Tetramethyl[2]ferrocenophane Salt ([{C5H4(CH3)2}2Fe–Hg–Fe{C5H4(CH3)2}2]2+ (BF4−)2) and Related Salts

Abstract The crystal form of the salt [{C5H4(CH3)2}2Fe–Hg–Fe{C5H4(CH3)2}2Hg(BF4)2, 1], prepared by a reaction of tetramethyl[2]ferrocenophane and Hg(CN)2 in ethanol containing HBF4, is triclinic, space group , a = 9.315(3), b = 12.823(4), c = 14.108(5) Å, α = 106.055(2), β = 100.253(2), γ = 94.460(2)°, Z = 2 and the final R = 0.059 and Rw = 0.072. Two ferrocene moieties are coordinated to the Hg atom from the opposite side, and the previously proposed Fe–Hg–Fe bridged structure has been verified. The structural feature of the cation is found in the conformation of the ferrocene moiety around the Fe–Hg–Fe bond. In order to reduce the steric hindrance between the Hg and ferrocene moieties, each moiety rotates largely with respect to the other (the torsion angle of the Cpcnt–Fe(1)···Fe(2)–Cpcnt is 75(1)° and Cpcnt is defined as the centroid of the Cp-ring). The mean Fe–Hg distance is 2.598(8) Å and the Fe–Hg–Fe bond angle is 176.4(1)°. The two C5H4 rings are greatly tilted, the mean tilting angle between them being 33.72°. Analogous Hg(II) salts of ruthenocene (2) and osmocene (3) were prepared by a similar method. Crystal 2 is monoclinic, space group P21/a, a = 9.633(1), b = 18.864(3), c = 13.388(1) Å, β = 94.161(9)°, Z = 4 and the final R = 0.058 and Rw = 0.072. The mean Ru–Hg distance is 2.661(2) Å and the Ru–Hg–Ru bond angle is 174.4(1)°; the mean tilting angle between the C5H4-planes is 27.39°. The structure of the cation is very similar to that of 1 (the torsion angle of the Cpcnt–Ru(1)···Ru(2)–Cpcnt is 70(1)°). The crystal form of 3 is triclinic, space group , a = 9.823(1), b = 11.194(1), c = 12.241(1) Å, α = 113.822(8), β = 95.828(8), γ = 90.104(8)°, Z = 2 and the final R = 0.030 and Rw = 0.032. The mean Os–Hg distance is 2.69(2) Å and the Os–Hg–Os angle is 170.1(3)°. The most interesting structural difference of 3 compared with 1, 2 is found to be the conformation of the osmocene moieties around the Os–Hg–Os bond. The two moieties are coordinated to Hg in parallel, and the torsion angle of Cpcnt–Os(1)···Os(2)–Cpcnt is negligible (2(1)°) so as to reduce the steric hindrance between the cations and the PF6− anions.

Coordination chemistry of organometallic polydentate ligands. syntheses of Fe-M complexes using Fe(CO)4(Ph2Ppy-P)[Ph2Ppy = 2-(Diphenylphosphino)Pyridine] and TRANS-Fe(PhPMepy)2(CO)3[PhPMepy = 2-(Phenylmethylphosphino) Pyridine] AS A Neutral BI- OR Tridentate Ligand

Fe(CO)4(Ph2Ppy-P) (1), prepared by the oxygen-atom transfer reaction, reacted as an organometallic bidentate ligand with HgX2 (X = Cl, I) to form binuclear complexes containing a Fe—Hg bond and treatment of the organometallic tridentate ligand trans-Fe (PhPMepy)2(CO)3 (2) with M(CO)6 (M = Cr, Mo), M(SCN)2 (M = Zn, Cd, Co, Ni, Mo), HgX2 (X = Cl, I) and CdCl2 also afforded binuclear complexes including a Fe—M bond. The crystal and molecular structures of the Fe-Hg complexes (CO)4Fe(μ-Ph2Ppy)Hg(μ-Cl) 2HgCl2 (3), (CO)3Fe(μ-PhPMepy)2Hg(μ-Cl)2HgCl2·1/2CH2Cl2 (5) and (CO)3Fe(μ-PhPMepy) 2Hg(μ-I)2HgI2· 3CH2Cl2 (6) have been determined. Copyright © 1996 Elsevier Science Ltd

Coordination chemistry of organometallic polydentate ligands Studies on the syntheses and properties of FeM binuclear complexes prepared from organometallic tridentate ligand trans-Fe(CO) 3(Ph 2Ppy) 2 (Ph 2Ppy = 2-(diphenylphosphino)pyridine)

The binuclear complexes (CO) 3Fe( μ-Ph 2Ppy) 2MX n (Ph 2Ppy = 2-(diphenylphosphino)pyridine, MX n = Mn(SCN) 2, Co(SCN) 2, CoCl 2, NiCl 2, Mo(CO) 3, Zn(SCN) 2, ZnCl 2, Cd(SCN) 2, CdCl 2, HgCl 2, HgI 2, AgClO 4, and SnCl 2) were prepared from the new type of organometallic tridentate ligand, trans-Fe(CO) 3(Ph 2Ppy) 2 ( 1), which contains both a basic metal center and bridging phosphine ligands. The crystal structure of the benzene solvate of 1 was determined by X-ray diffraction. The compound 1·1/2C 6H 6 crystallizes in the monoclinic space group P2 1/ c with a = 17.560(5), b = 12.110(1), c = 18.176(4) A ̊ ; β = 101.27(2)° and Z = 4 . The structure was refined to a conventional R value of 0.077 by using 2670 significant reflections and parameters. The structure of one of the binuclear complexes, namely, (CO) 3Fe(μ-Ph 2Ppy) 2HgI 2 ( 14), has also been determined by X-ray diffraction. The compound 14 crystallizes in the monoclinic space group P2 1/ n, with a = 13.829(2), b = 14.175(2), c = 19.514(3) A ̊ , β = 120.27(1)°, V = 3738(2) A ̊ 3 and Z = 4 . The structure was refined to a conventional R values of 0.032 by using 3279 significant reflections and parameters. The FeHg distance is 2.678 Å, indicative of a metal-metal bond. Results of Mössbauer and electron-absorption spectra suggested the presence of metal to metal interactions in these binuclear complexes.

Insertion of mercury into iron-iodine bonds leading to dinuclear (FeHg) mixed isonitrile-phosphine complexes

The binuclear complexes trans-[Fe(HgI 2)(PPh 3)(CNR) 4] R  Ph, 4-MeC 6H 4, or tBu), trans- [Fe(HgI 2)(dppm- P)(CNR) 4] (RPh or 4-MeC 6H 4), and mer-[Fe(HgI 2)(dppe)(CNR) 3] (R  Ph or 4-MeC 6H 4)were obtained by the reaction of metallic mercury with [FeI 2(CNR) 4] in the presence of phosphines such as PPh 3, Ph 2PCH 2PPh 2 (dppm) and Ph 2PCH 2CH 2PPh 2 (dppe); this process yields adducts of the Lewis acid Hgl 2 with the metallic bases“FeL(CNR) 4” (L  PPh 3 or dppm- P) or “Fe(dppe)(CNR) 3”. Spectroscopic data and conductivity measurements suggest a sequence for the strength of these metallic fragments acting as bases.

Studies on binuclear complexes. Synthesis and catalytic behaviour of Fe-M complexes (M  Mo, Ni, Rh, Cu, Hg) using trans- Fe(Ph2Ppy)2(CO)3 [Ph2Ppy = 2-(diphenylphosphino) pyridine] as a neutral tridentate ligand. Molecular structure of FeHg(μ-Ph2Ppy)2(CO)3(SCN)2

trans-Fe(Ph2Ppy)2(CO)3 reacts as a neutral tridentate ligand with Mo(CO)6, Ni(NCS)2, [Rh(CO)2Cl]2, CuX (Cl, Br, I) and Hg(SCN)2 to form binuclear complexes including an FeM bond. Crystal and molecular structures of the FeHg complex has been determined by X-ray diffraction. The FeHg bond distance is 2.648 Å. The effects have been evaluated of these complexes as homogeneous catalysts on the carbonylation of ethanol to ethyl propionate. The FeRh complex possesses very high activity and selectivity.

Übergangsmetall-silyl-komplexe: XLII. Einfluβ des phosphan-liganden auf bildung, struktur und stabilität der hetero-zweikernkomplexe (CO) 3(R′ 3P)(R 3Si)Fe—ML n (M  Cu, Ag, Au, Hg)

The anionic silyl complexes Na[Fe(CO) 3(PR′ 3)SiR 3] (PR′ 3  PMe 3: SiR 3  SiMePh 2, SiMe 3; PR′ 3  P nBu 3: SiR 3  SiMePh 2; PR′ 3  PPh 2H: SiR 3  SiPh 3, SiMePh 2, SiMe 2Ph) were prepared by deprotonation of the corresponding hydrido silyl complexes. They react with CH 3I or Me 3SnCl to give mer-(CO) 3(R′ 3P)(R 3Si)FeER 3 (PR′ 3  PMe 3 and PPh 2H; ER 3  CH 3, SnMe 3), while with metal complex halides XML n , (ML n ,  AuPR 3, AgPPh 2Tol, CuPR 3 Cudppe, HgPh) the hetero-binuclear complexes mer-(CO) 3(R′ 3P)R 3Si) FeML n are obtained, which contain unbridged metal—metal bonds. Upon reaction of [Fe(CO) 3(PR′ 3)SiR 3] − with HgBr 2 in THF the trinuclear complexes [ fac-(CO) 3(R′ 3P)(R 3Si)Fe] 2Hg are obtained, from which the binuclear complexes mer-(CO) 3(R′ 3P)(R 3Si)FeHgX are formed in toluene with a second equivalent of HgX 2. X-Ray structure analyses of the octahedral complexes mer-(CO) 3(Me 3P)(Ph 2MeSi)(FAuPPh 2Tol (FeAu 252.7(3) pm), mer(CO) 3(Me 3P)(Ph 2MeSi)FeAgPh 2Tol (FeAg 258.1(1) pm) and mer-(CO) 3(Me 3P)-(Ph 2MeSi)FeHgBr) (FeHg 251.5(3) pm) show that the Fe-metal bond is cis to both the PMe 3 and the SiMePh 2 ligand. The comparison of the Fe-Si, Fe-P and Fe-M bond distances indicates that the polarity of the Fe-M bond increases from M  Hg and M  Au to M  Ag. The Fe-Hg compound is loosely dimerized via unsymmetrical Br bridges (Hg-Br 253.5(3) and 306.3(1) pm).

Synthesis and structural studies of bis(1,10-phenanthrolinethiocyanatemercury) tetracarbonyliron

The bis(1,10-phenanthrolinethiocyanatemercury)tetracarbonyliron was prepared from bis(thiocyanatemercury)tetracarbonyliron and 1,10-phenanthroline and crystallized from hot acetone solution as [Fe(CO) 4(HgSCN) 2(phen) 2]·C 3H 6O, which was subjected to a full IR and X-ray crystallographic characterization. The iron atom is octahedrally coordinated by four carbonyl groups and two mercury atoms in cis positions. The coordination geometry of the mercury atoms is a distorted square-based pyramid since each one is coordinated to one iron, one sulphur, one mercury and two nitrogen atoms. The FeHg distances are 2.549(3) and 2.564(3) Å, and the HgFeHg angle is 78.01(9)°.

Synthesis of dppm-stabilized Si–Fe–M (M = Zn, Cd, Hg or Tl) complexes and crystal structure of a heterotetranuclear Fe2Cd2complex (dppm = Ph2PCH2PPh2)

Treatment of K[Fe(CO)3{Si(OMe)3}(dppm-P)](dppm = Ph2PCH2PPh2) with CdX2(X = Cl or Br) in tetrahydrofuran (thf) in a 1 : 1 ratio afforded the tetranuclear iron–cadmium complexes mer-[{[(MeO)3Si](OC)3[graphic omitted](µ-X)}2]2a(X = Cl) and 2b(X = Br) in 78 and 65% isolated yield, respectively. Each Fe–Cd bond is supported by a dppm ligand. The reaction of the ketophosphine-substituted metalate K[Fe(CO)3{Si(OMe)3}{Ph2PCH2C(O)Ph}] with CdCl2 in a 1 : 1 ratio similarly afforded mer-[{[(MeO)3Si](OC)3[graphic omitted](µ-Cl)}2]2c, in which a bridging mode for the functional (P,O) ligand is assumed for the first time. Reaction of K[Fe(CO)3{Si(OMe)3}(dppm-P)] with ZnCl2 afforded the Fe–Zn analogue 3, which is very labile. Similarly, Fe–Hg complexes of the type mer-[{(MeO)3Si}(OC)3[graphic omitted]X](R = Et, X = Ph; R = Me, X = C6Cl5 or Cl) were prepared. The chloride bridges of 2a are easily split by nucleophiles. Using Ph2PCH2C(O)Ph, mer-[{(MeO)3Si}(OC)3[graphic omitted]Cl{Ph2PCH2C(O)Ph}] and mer-[{(MeO)3Si}(OC)3[graphic omitted]gCl{Ph2PCH2C(O)Ph}] were obtained. They reacted with Tl[PF6] to yield cationic complexes in which the ketophosphine acts as a chelating ligand. The synthesis of the Fe–TlIII complex mer-[{(MeO)3Si}(OC)3[graphic omitted](lC6F5)2]9 is also described. The 31P-{1H} NMR resonance due to the phosphorus bound to thallium consists of a doublet of doublets at δ–14.0 with 1J(P–203Tl/205Tl)= 6765 Hz. The molecular structure of complex 2a was determined by X-ray diffraction. Crystals of the hexane solvate are orthorhombic, space group Pbcn, with a= 23.498(9), b= 16.856(8), c= 18.220(8)A, and Z= 4. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.0653 for 2906 observed reflections. In the dimeric complex, having an imposed C2 symmetry, the two Fe–Cd distances, 2.624(2)A, are indicative of metal–metal bonds and the two Cd atoms are joined by a double nearly symmetrical chloride bridge. A phosphorus atom of the dppm ligand completes the co-ordination of the Cd atom. Each Fe atom is octahedrally co-ordinated by three carbonyl groups in a meridional arrangement, by a phosphorus atom of the dppm ligand, by the Si atom of the Si(OMe)3 ligand and by the Cd atom.

Qualitative interpretation of Mössbauer data for some [1] ferrocenophanes; Fe–Pd dative bonding in [(SC5H4)2FePd (PPh3)] and Fe–Hg and Fe–H+bonding in ferrocene

The Mössbauer data for a number of ferrocene complexes in which the Fe is directly bonding to or interacting with an additional atom are discussed. For weak ferrocenyl Fe–X (X = Ge, Si, P, or Pd) interactions in [1]ferrocenophanes or 1,2,3-trithia[3] ferrocenophanes quadrupole splittings (Δ) around 0.4 mm s–1 smaller than that of ferrocene are observed. These are explained by the interactions of the ferrocene electrons with the X atom. Exalted Δ values relative to ferrocene are found for ferrocenyl Fe (and substituted ferrocenophanes) bonded to mercury, and for ferrocenyl Fe bonded to H+. These are explained by ring tilt altering the molecular orbital bonding scheme relative to ferrocene, causing the 3dz2 orbital to partake in the bonding. This orbital makes a negative contribution to Δ so that if electron density is removed from it then Δ will increase. Compounds of PdII and PtII trichalcogeno[n] ferrocenophanes (n= 7 or 9) which show little variation in quadrupole splitting from ferrocene (but do differ by having higher isomer shifts) are also explained as having metal–iron bonds.

Anionic trimetallic compounds containing FeEM skeletons (E = Zn, Cd, Hg; M = Fe, Mo, W). Crystal structure of [N(PPh 3) 2] 2[(OC) 4FeHgFe(CO) 4

Dichlorides of group 12 elements react with (NEt 4)[HFe(CO) 4] in tetrahydrofuran to give the di-hydrides [(OC) 4HFeEFeH(CO) 4] (E = Zn, Cd, Hg) in good yields. These compounds undergo proton abstraction by nBuLi to give di-anions [(OC) 4FeEFe(CO) 4] 2-, stabilized as their bis(triphenylphosphine)nitrogen(+) (PPN +) salts. (PPN) 2[(OC) 4FeHgFe(CO) 4] crystallizes in the triclinic system, space group P 1 with a 20.382(3), b 15.328(2), and c 13.420(2) Å; α 115.96(3), β 108.89(2), and γ 87.09(2) o, and Z = 2. The anion consists of an almost linear spine (FeHgFe angle 178.7(1) o), with an average FeHg bond distance of 2.546(2) Å. The Fe atoms display a trigonal bipyramidal geometry, and the equatorial CO groups linked to the iron atoms are in an eclipsed conformation, resulting in an idealized D 3 h symmetry. The existence of two conformers for this anion and the presence of Hg · · · CO backbonding are discussed on the basis of qualitative molecular orbital theory. The [(OC) 4FeHgFe(CO) 4] 2- anion undergoes redistribution reactions with [M(CO) 3(η-C 5H 5)] 2 Hg (M = Mo, W) to give the new unsymmetrical anions [(OC) 4FeHgM(CO) 3(η-C 5H 5)] -.