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Cytoreductive surgery followed by platinum based systemic chemotherapy is an effective treatment for advanced ovarian epithelial carcinoma, resulting in up to 80% complete response (CR) rate; however only 30% of patients reaches 5-year survival. The low extra-abdominal relapse attitude leads to consider the opportunity of treatment intensification combining aggressive cytoreductive surgery with locoregional chemotherapy for FIGO stage III/IV ovarian carcinoma recurrent after the first-line chemotherapy, having still a curative intent.An "open" intra-abdominal hyperthermic perfusion with 25 mg/m(2)/lt cisplatin of perfusate or 50 mg/m(2)cisplatin plus 15 mg/m(2)doxorubicin was carried out throughout the abdomino-pelvic cavity on 42 patients affected by peritoneal carcinomatosis from ovarian primary, soon after tumor removal en bloc with regional involved peritoneum. Clinical and oncologic data have been prospectively recorded on a dedicated database.Forty-two patients, submitted to peritonectomy, achieved no residual macroscopic disease in 83% of the cases. Hyperthermic chemoperfusion was performed in 95% of the patients. Major complications were observed in 21.4%, being directly correlated to the duration of the surgical procedure (p=0.03). The operative mortality was 4.7%. At a mean follow up of 22 months, the overall 3-year survival was 61.4%, with a median survival of 41 months.Complete cytoreduction is possible for the majority of patients, allowing encouraging survival to be reached. Careful selection of patients could reduce surgical risk and further improve survival.

Under pressure, metals exhibit increasingly shorter interatomic distances. Intuitively, this response is expected to be accompanied by an increase in the widths of the valence and conduction bands and hence a more pronounced free-electron-like behaviour. But at the densities that can now be achieved experimentally, compression can be so substantial that core electrons overlap. This effect dramatically alters electronic properties from those typically associated with simple free-electron metals such as lithium and sodium, leading in turn to structurally complex phases and superconductivity with a high critical temperature. But the most intriguing prediction - that the seemingly simple metals Li and Na will transform under pressure into insulating states, owing to pairing of alkali atoms - has yet to be experimentally confirmed. Here we report experimental observations of a pressure-induced transformation of Na into an optically transparent phase at 200 GPa (corresponding to 5.0-fold compression). Experimental and computational data identify the new phase as a wide bandgap dielectric with a six-coordinated, highly distorted double-hexagonal close-packed structure. We attribute the emergence of this dense insulating state not to atom pairing, but to p-d hybridizations of valence electrons and their repulsion by core electrons into the lattice interstices. We expect that such insulating states may also form in other elements and compounds when compression is sufficiently strong that atomic cores start to overlap strongly., Comment: Published in Nature 458, 182-185 (2009)

Background: The Peritoneal Cancer Index (PCI) may be used in the intraoperative evaluation of peritoneal surface malignancies to estimate the feasibility of peritonectomy with intraperitoneal hyperthermic chemotherapy perfusion. Although radiologic imaging techniques detect liver and other distant metastases, they do not accurately image small cancer implants on small bowel and its mesentery, thus making a CT-PCI classification impossible. Results: We used videolaparoscopy to stage 97 cases of peritoneal carcinomatosis, and achieved full laparoscopic PCI assessment in 96/97 cases, while only 2/96 cases were understaged. In all our cases where peritonectomy followed diagnostic laparoscopy, we found good correlation between the open surgery data and the laparoscopic PCI. There was no mortality and no neoplastic colonization at the trocar port site. We excluded patients from peritonectomy if the staging laparoscopy showed a massive involvement of their small bowel or mesentery. Conclusion: Laparoscopy is a useful tool in peritoneal surface malignancies; it allows direct visualization even of small cancer nodules and provides a reliable assessment of the feasibility of peritonectomy. 2006 Published by Elsevier Ltd.

The application visualization system (AVS) product line saw several versions of the tool that were eventually refined and improved in a fully object-oriented modular environment introduced in 1994 called AVS/Express. Thus, this chapter concentrates on this latest instance of the software product. The chapter reviews the design goals of AVS/Express, based on some of the limitations of AVS. The chapter continues with a quick user tour to help illustrate AVS/Express' user interface environment and user-level functionalities. A detailed description of the most fundamental architecture aspects of AVS/Express, focusing on four areas (the object model, the execution model, the unified data model, and the rendering subsystem structure) follows. With recent additions such as batch-mode rendering (off-screen rendering), multipipe rendering for immersive rendering, illuminated lines, volume rendering, two-pass transparency, and a CAVElib integration, AVS/Express is a modern programming environment with an advanced usage and prototyping environment based on object technology. Its customer base includes thousands of users worldwide in academic and industrial positions.

An assessment method to quantify and qualify unsteady state collected data was developed through the use of a pressure change rate matching technique. This method allowed us to improve the reliability of the estimation of heterogeneous hydraulic property derived from various crosshole tests, such as hydropulse. Adjoint state method efficiently calculated gradients of a modified objective function, introduced in this paper as the conventional objective function type plus an additional pressure change rate term to reflect information of unsteady state data. A modified bootstrap method, a type of Monte Carlo method, was used to objectively evaluate the difference in reliability of estimation derived from the inversion method. Various types of pumping rate patterns were changed systematically and compared with their reliability indexes, such as confidence intervals of estimation, calculated for a 1-D simple model. The objective function, proposed in this paper for matching rate of pressure change with respect to time, has proved to be effective for estimation of adequately heterogeneous permeability distributions under certain conditions, assuming two cycle pulse tests. Different flow rate patterns cause clearly different reliability of estimations. The optimum pulse test (pumping rate pattern) to characterize hydraulic properties under certain conditions is also estimated for the 1-D hypothetical model.

We explore whether the topology of energy landscapes in chemical systems obeys any rules and what these rules are. To answer this and related questions we use several tools: (i)Reduced energy surface and its density of states, (ii) descriptor of structure called fingerprint function, which can be represented as a one-dimensional function or a vector in abstract multidimensional space, (iii) definition of a ''distance'' between two structures enabling quantification of energy landscapes, (iv) definition of a degree of order of a structure, and (v) definitions of the quasi-entropy quantifying structural diversity. Our approach can be used for rationalizing large databases of crystal structures and for tuning computational algorithms for structure prediction. It enables quantitative and intuitive representations of energy landscapes and reappraisal of some of the traditional chemical notions and rules. Our analysis confirms the expectations that low-energy minima are clustered in compact regions of configuration space ("funnels") and that chemical systems tend to have very few funnels, sometimes only one. This analysis can be applied to the physical properties of solids, opening new ways of discovering structure-property relations. We quantitatively demonstrate that crystals tend to adopt one of the few simplest structures consistent with their chemistry, providing a thermodynamic justification of Pauling's fifth rule., Published in J. Chem. Phys. 130, 104504 (2009)

The reaction of PhCN with Ru3 (CO)12 in the presence of acetic acid gives H4Ru4(CO)12, (I), (μ-H)Ru3(CO)10(μ-NCHPh) (II) and (μ-H)Ru3(CO)10(μ-NH-CH2Ph) (III) as the main products. Reaction under 110 atm of H2 gives more III and also gives benzylamine. Replacement of acetic acid by H2 at atmospheric pressure gives only II. When H4Ru4CO)12 reacts with PhCN alone or in the presence of NaOH, II is formed as the only product. The structures of II and III have been fully elucidated by X-ray methods. The nitrogen atom of the NCHPh ligand in II and that of the NHCH2Ph ligand in III, interact with the isosceles-triangular metal cluster, symmetrically bridging the shortest Ru(1)-Ru(2) edge. A hydride ligand in both II and III bridges the same Ru(1)-Ru(2) edge of the cluster. Under mild conditions acetic acid is an essential requirement for the activation of Ru3(CO)12 for reaction with PhCN to give III, which cannot be obtained under these conditions from II.

The reaction between Ru3(C0)12 and 1,3-cyclohexadiene has been carried on under different conditions: contrary to previous findings Ru3(CO)12 does not catalyze the cleavage and the hydrogenation of 1,3-cyclohexediene. The products of the reaction have been characterized by i.r., n.m.r. and mass spectrometry. The crystal structure of the novel complex Ru4(CO)9(C6H6)(C6H8) has been determined by X-ray methods. Crystals are monoclinic, space group P21/2c with Z = 4 in a unit cell of'dimensions: a = 15.167(15), b = 10.114(9), c = 15.517(12) A, β = 87.1(1)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R = 0.058 for 3828 observed reflections. A four metal atom cluster, in a “butterfly” arrangement, is coordinated by nine terminal CO groups, by a benzene molecule and a 1-cyelohexen-1,2-ylene unit obtained, respectively, by dehydrogenation and isomerization of two diene molecules.

Hydrogenation under mild conditions (1 atm H 2 and 60–80°C) of trans 1,3-pentadiene catalysed by Rh 2 Cl 2 (CO) 4 in toluene solution and by Rh 2 Cl 2 (CO)4 anchored on γ-Al 2 O 3 has been investigated. Both the homogeneous and the heterogenised catalysts display a good specificity towards hydrogenation of the external double bond of the conjugated diene system. A slow inactivation of the supported catalyst occurs during the hydrogenation, but it cannot be attributed to reaction of the catalyst with the substrate since it occurs also when Rh 2 Cl 2 (CO) 4 is heated at 70°C under 1 atm H 2 . Partial substitution of CO ligands of Rh 2 Cl 2 (CO) 4 by triphenylphosphine leads to a reduction of the activity of the homogeneous catalyst but does not alter its specificity. Triphenylphosphine can either increase or decrease the activity of the heterogenised catalyst depending on whether its introduction into the system precedes or follows the anchorage of Rh 2 Cl 2 (CO) 4 on Al 2 O 3 .

13C n.m.r. spectra of hydrido olefinic carbonyl clusters of ruthenium show that localized scrambling of the carbonyls occurs with different energy barriers which depend on the nature of the bonding between the ligand and the metal cluster and on the nature of the substituents in the olefinic chain. Resonances of carbons “sigma” bonded to one ruthenium and “pi” bonded to a second one are in the lowfield region (198-162 ppm).

The catalytic activities of Rh 4 (CO) 12 and Rh 2 (CO) 4 Cl 2 for the homogeneous hydrogenation of pentynes in toluene have been studied and compared with those of these complexes anchored on γ-Al 2 O 3 . Rh 4 (CO) 12 and Rh 2 (CO) 4 Cl 2 interact strongly with γ-Al 2 O 3 , and the resulting species give identical IR spectra in the CO stretching region characterised by absorptions at 2080 cm −1 and 1997 cm −1 , suggesting that the same carbonylrhodium active centres are formed upon binding of both metal carbonyls. However, Rh 4 (CO) 12 /Al 2 O 3 and Rh 2 (CO) 4 Cl 2 /Al 2 O 3 show completely different behaviour as catalysts in the hydrogenation of pentynes; Rh 2 (CO) 4 Cl 2 /Al 2 O 3 is more active than Rh 2 (CO) 4 Cl 2 in solution, while the activity of Rh 4 (CO) 12 is not substantially altered upon going from the homogeneous to the heterogenised system. Complete hydrogenation to give pentane is favored when Rh 2 (CO) 4 Cl 2 and Rh 4 (CO) 12 are bound to Al 2 O 3 , and occurs much more slowly when the complexes are used as homogeneous catalysts.

Reactions of Ru3(CO)12 with p-methoxybenzonitrile and p-nitrobenzonitrile have been studied in refluxing cyclohexane and the complexes formed were characterized by IR, 1H NMR spectroscopy and mass spectrometry. In the presence of acetic acid and p-methoxybenzonitrile, (μ-H)Ru3(CO)10(μ-NHCH2- C6H4OMe) is the main reaction product, whilst when acetic acid is replaced by H2 at atmospheric pressure the main reaction products are (μ-H)Ru3(CO)10 (μ- NCHC6H4OMe) and (μ-H)2Ru3(CO)9(μ3-NCH2C6H4OMe). The crystal structure of (μ-H)2Ru3(CO)9(μ3- NCH2C6H4OMe) has been determined by X-ray diffraction methods. Crystals are triclinic, space group P 1 , with a=11.255(6), b=12.205(8), c=8.831(6) A, α=108.98(2), β=99.43(2), γ=95.78(2)°, V= 1116(1) A3, Z=2. Full-matrix least-squares refinement (324 variables, 2938 observed reflections) converged to give R and Rw values of 0.0318 and 0.0435 respectively. The structure consists of an isosceles triangular cluster of Ru atoms (with the longer edges bridged by hydrides) bound to nine terminal carbonyls and triply bridged by the NCH2C6H4OMe group. Reaction of Ru3(CO)12 with p-nitrobenzonitrile and acetic acid only leads to decomposition. Addition of H2 at atmospheric pressure to a cyclohexane solution of Ru3- (CO)12 and p-nitrobenzonitrile leads to (μ-H)Ru3- (CO)10(μ-NCHC6H4NO2) and (μ-H)2Ru3(CO)9- (μ3-NCH2C6H4NO2). In refluxing cyclohexane, (μ-H)- Ru3(CO)10(μ-NCHC6H4X) complexes (X=H, OMe, NO2) are slowly converted into (μ-H)2Ru3(CO)9- (μ3-NCH2C6H4X) (X=H, OMe, NO2), and in n-octane at 100 °C, besides (μ-H)2Ru3(CO)9(μ3- NCH2C6H4X), minor amounts of (μ-H)Ru3(CO)10- (μ-NHCH2C6H4X) are also formed. These results are discussed in terms of possible reaction pathways and of the role of acetic acid in the reaction of Ru3- (CO)12 with benzonitrile and its substituted derivatives.

Catalytic isomerisation of 1-pentene to 2- cis and 2- trans -pentene with H 4 Ru 4 (CO) 12 in toluene at 70.4 °C is described. Carbon monoxide, hydrogen, weak acids and polar substances, such as ethyl acetate, decrease the isomerisation rate. Reactions of H 4 Ru 4 (CO) 12 with trans -C 2 H 2 D 2 and [1,2-D 2 ] 1-pentene and of D 4 Ru 4 (CO) 12 with 1-pentene suggest the operation of a metal-hydride addition-elimination mechanism involving σ-alkyl intermediates. The active species is supposed to be mainly originated by loss of CO to give H 4 Ru 4 (CO) 11 . Catalytic hydrogenation of the pentene isomers occurs at the approaching of the equilibrium and is largerly enhanced by addition of hydrogen to the reaction system.

The catalytic hydrogenation under mild conditions of 1-pentyne and 2-pentyne in the presence of phosphine and phosphite substituted derivatives of H4Ru4(CO)12 has been investigated. The initial rates of hydrogenation of both 1- and 2-pentyne with the monosubstituted derivatives were found to follow the trend: P(OPh)3 ≅ P(OEt)3 < PPh3 ≅ P(n-Bu)3. The initial rates of hydrogenation of 2-pentyne decrease with increasing substitution of the catalyst, while the opposite trend is observed for 1-pentyne. The specificity of all the catalysts investigated, towards the formation of cis-2-pentene and 1-pentene from 2-pentyne and 1-pentyne respectively, is similar and is improved as compared with that observed in the presence of H4Ru4(CO)12. The experimental results are interpreted on the basis of the stability of the alkyne carbonylmetal intermediates and of the influence which increasing substitution on H4Ru4(CO)12 plays on the formation of active sites. The complexity of this multistep process, however, does not allow a comprehensive rationalisation of the experimental data.

Positive chemical ionization mass spectra of arenetricarbonylchromium compounds with propene, benzene and toluene, at about 0.5 torr, are reported. Protonation, charge exchange, fragmentation and CO substitution processes occur for all these complexes. The abundances of the [M + H]+ and substituted ions strongly depend on the reagent gas and, for any given gas, on the coordinated arene. The effects of the nature of the reagent gas and of the coordinated arene on the ion abundances are discussed and reaction mechanisms suggested.

Doubly charged ions observed in the mass spectra of trimetal carbonyl compounds of the iron group and of their derivatives at different ionizing energy are reported. In the case of Os 3 (CO) 12 , Ru 3 (CO) 12 , RuOs 2 (CO) 12 and Ru 2 Os(CO) 12 the abundances of the doubly charged ions decrease gradually when osmium atoms are substituted by ruthenium atoms and when ionizing electrons energy is decreased. They follow a characteristic trend in which the highest charge is transported by fragments containing a number of carbonyl groups which increases with decreasing ionizing energy. The mass spectrum of Fe 3 (CO) 12 contains very weak doubly charged species. H 2 Os 3 (CO) 12 exhibits a behaviour similar to that of Os 3 (CO) 12 , while Os 3 (CO) 10 Br 2 and Os 3 (CO) 12 Br 2 show that different structures do not appreciably affect the occurrence of doubly charged ions. The strong increase of the stabilization of doubly charged species, observed in the mass spectra of Fe 3 (CO) 8 [C 2 (C 6 H 5 ) 2 ] 2 , Ru 3 (CO) 8 [C 2 (C 6 H 5 ) 2 ] 2 and Os 3 (CO) 8 [C 2 (C 6 H 5 ) 2 ] 2 , shows a drastic influence of the organic ligands superimposed to that of the nature of metal atoms. In the mass spectrum of Os 3 (CO) 8 [C 2 (C 6 H 5 ) 2 ] 2 at 70 eV a rather strong [M  8CO] 3+ is observed.

The ionization potentials of the compounds Co2(CO)6C2H2, Co2(CO)6C2(CH3)2, Co2(CO)6C2(CF3)2, Co2(CO)6C2(CH2Cl)2 and Co2(CO)6C2CH3C6H5 have been determined by electron impact measurements and found to show a good correlation with the Taft σ★ constants of the substituent groups on the ligand. The average ionic dissociation energies of the CoCO bonds are mainly dependent on the π acceptor ability of the ligand, and exhibit the sequence (CF3)2 < H2 < (CH3)2. Suggestions concerning the Coligand bond strengths are discussed in connection with the relative kinetic reactivities of such compounds in exchange and carbonyl group substitution reactions.

The catalytic activity of H 4 Ru 4 (CO) 11 L (where is PPh 3 , P(OEt) 3 , P(OPh) 3 ), H 4 Ru 4 (CO) 10 [P(OEt) 3 ] 2 and H 4 Ru 4 (CO) 8 [P(OEt) 3 ] 4 in the isomerisation of pentenes in toluene at 70.4 °C is described. The initial conversion rate is proportional to the catalyst concentration, decreases with increasing CO pressure, while the addition of the free ligand causes a decrease of the conversion rate, in the initial steps, ascribed to its preferential coordination on the active sites. For H 4 Ru 4 (CO) 11 L, the isomerisation rate decreases with L in the sequence P(OEt) 3 > (P(OPh) 3 > PPh 3 > CO. The conversion rate, moreover, decreases with n in the series H 4 Ru 4 (CO) 12−n [P(OEt) 3 ] n (n = 1, 2, 4). The results are interpreted by suggesting that the RuCO bonds are mainly involved in the active site formation and that the phosphorus-donor ligands cause a weak increase of the activity of the carbonyl groups. However, the free sites formed by RuCO bond cleavage of Ru(CO) 2 L units are considered to give a little contribution to the isomerisation for the steric hindrance of L.

The negative ion electron impact mass spectra, at 70 eV, of (η6-C6H5R)Cr(CO)3 (R = CH3, CH2OH, Cl) [η6-1,3,5-(CH3)3C6H3]Cr(CO)3, (η6-C6H5COR)Cr(CO)3 (R = CH3, C2H5, C3H7, C(CH3)3), [η6-(o-CH3C6H4COC3H7)]Cr(CO)3, (η6-C6H5CH2COR)Cr(CO)3 (R = C2H5, C3H7), (η6-C6H5COOCH3)Cr(CO)3, [η6-(p-CH3C6H4COOCH3)] Cr(CO)3,(η6-C6H5R)W(CO)3 (R = CH3, Cl) and η6-C6H5COOCH3W(CO)3 are reported. The negative molecular ion is present in the spectra of the compounds containing the carbonyl function in the ligand, while [MCO]−??? is the highest mass ion in the spectra of the other compounds. The most abundant fragments are the species [MnCO]−??? (n = 1,2,3,). The intensity of the molecular peak is mainly affected by the nature of the moiety bonded to the carbonyl function of the ligand, while the nature of the metal seems to play a minor role. The comparison of the abundances of [M]−??? in the negative ion mass spectra of the metal complexes and of the corresponding free ligands shows that in the gas phase the tricarbonylchromium and tricarbonyltungsten units display a strong electron withdrawing ability, similar to the behaviour shown in solution.

Hydrogenation under mild conditions of 1- and 2-pentyne and of 1,3-cis- and 1,3-trans-pentadiene catalysed by Ru3(CO)12, FeRu2(CO)12, Fe2Ru(CO)12 and Fe3(CO)12 in toluene solutions or anchored on γ-Al2O3 has been studied. For all the systems examined, catalytic activity was highest for Ru3(CO)12-containing catalysts and lowest for Fe3(CO)12-containing ones. For mixed metal catalysts, activity decreased with increasing number of Fe atoms in the dodecacarbonyls. Anchorage of the clusters to γ-Al2O3 produced catalysts which were less active towards hydrogenation of 1- and 2-pentyne and more active towards hydrogenation of 1,3-cis- and 1,3-trans-pentadiene, but had no effect on product distribution.

The activation of the CN triple bond of benzonitrile in the presence of acetic acid and of Os3(CO)12 or H2Os3(CO)10 has been studied. When Os3(CO)12 reacts with PhCN and acetic acid in refluxing n-octane the three main products are (μ-H)Os3(CO)10(μ-O2CCH3) (I), (μ-H)Os3(CO)10(μ-NCHPh) (II) and (μ-H)Os3(CO)10(μ-NHCH2Ph) (III); II and III are analogues of (μ-H)Ru3(CO)10(μ-NCHPh) and (μ-H)Ru3(CO)10(μ-NHCH2Ph) obtained from PhCN, Ru3(CO)12 or H4Ru4(CO)]12, and acetic acid. In contrast to the reaction with ruthenium clusters, Os3(CO)12 and H2Os3(CO)10 also give the adduct Os3(CO)10(CH3COOH) (I). The structure of I has been fully elucidated by X-ray diffraction. Crystals of I are monoclinic, space group P21/m, with unit cell parameters a 7.858(6), b 12.542(8), c 9.867(6) A, β 109.92(2)°, Z = 2. In I an edge of the triangular cluster of osmium atoms is doubly bridged by a hydride and an acetate ligand. Ten terminal carbonyl groups are bonded to the metal atoms.

The complexes (η-C5H5)NiOs3(CO)9(μ2-H)3 and (η-C5H5)3 Ni3Os3(CO)9 can be obtained in high yield by treating Os3(CO)12 or H2Os3(CO)10 with [(η-C5H5)-Ni(CO)]2 in refluxing hydrocarbons. The course of the reactions and the yields of the products can be modified by carrying out the reaction under nitrogen, hydrogen or carbon monoxide atmospheres. A preliminary report of an X-ray study of the hexametallic, 87 e− cluster was presented. The new tetrametallic derivative was characterized by spectroscopic techniques; a tetrahedral, tri-hydridic structure is proposed for this complex. The reactions of the heterometallic nickel-osmium complexes towards ligands, in particular alkenes and alkynes, are discussed. A preliminary investigation of homogeneous hydrogenation of these substrates is reported.

Etude des reactions des complexes du titre avec benzonitrile, diphenylamine, phosphines, arsine, stibene, phosphinoacetylenes, bis(diphenylphosphino) methane

Isomerization and rearrangement of ligands L, such as 1,4-trans,trans-diphenyl-1,3-butadiene, hexadiene isomers, isoprene and 1,3-butadiene, occur in the reactions with Ru3(CO)12 to give trimetallic complexes of molecular formula HRu3(O)9(L-H), in addition to bi- and monometallic complexes of known structure. On the contrary the diene skeleton is always maintained when L is 2,3-dimethyl-1,3-butadiene. Structures of HRu3(CO)9(L-H) complexes are suggested and some novel features in their proton n.m.r. spectra are described.

The reactions between trinuclear acetylenic carbonyls of ruthenium or iron and an excess of diphenylacetylene or carbon monoxide have been studied in an attempt to determine the order in which the trinuclear intermediates are formed in the reaction between Ru 3 (CO) 12 and diphenylacetylene. The differences in the behaviour of the two carbonyls are discussed.

Following a report of different results obtained by other workers, our previous studies of the reaction between Ru3(CO)12 and tetraphenylcyclopentadienone have been extended to cover a wider range of concentrations and solvents. The results provided explanations of the differing reports, and permit a general reaction scheme to be drawn up. Preliminary studies of the reaction between Os3(CO)12 and tetraphenylcyclopentadienone are also reported.

The mass spectra of the following acetylenic derivatives of Co2(CO)8 are reported: Co2(CO)6C2H2Co2(CO)6C 2,(CH3)2, Co2(CO)6 C2(CH2Cl)2, Co2(CO)6C2 (CF3)2, Co2(CO)2C2(C6H5)2 and Co2(CO)6C2(COOCH3)2. The effect of different C2RR′ on fragmentation modes is investigated. When R and R′ are aromatic groups, the major controlling factor is the stability of charged fragments; in other cases, it seems to be the loss of a stable neutral moiety. Transfer processes of alkoxylic groups are observed in Co2(CO)6C2(COOCH3)2, as well as in Co3(CO),9CCOOCH3, and Co3(CO)9CCOOC2H5. It is suggested that both cobalt and carbon atoms may be the migration sites.