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The synthesis and structural characterization of a new coordination polymer [Pb(OH)]n[Ag(SCN)(CN)]n, formed by an anionic layer [Ag(CN)(μ3-SCN)]nn− linked to the 1D cationic fragment [Pb(OH)]n through a bridging cyanide, is reported. We have obtained a rational combination of the pattern of laurionite-type structures (Pb(OH)X, with X = halogen, SCN) with the 2D hexagonal pattern of the silver thiocyanate. The title compound shows luminescent behaviour, and the analysis of the computed band structure allows us to describe the electronic transitions.

The reactions of Fe3(CO)12 with 2-methyl-3-butyn-2-ol and 3-pentyn-1-ol in CH3OH/KOH solution lead, respectively, to the binuclear complex Fe2(CO)6(μ-CO)(μ-η2-[HCC{ C(CH3)2}C( O)(OCH3)]) (as the main product) and to the closed trinuclear hydridic complex (μ-H)Fe3(CO)9(μ3-η3-[H3CCC(CH2)(CH2)CO]) (as the unique product). The oxygenated ligands of these complexes are formed, respectively, by coupling of a formerly coordinated CO with a methoxy group and by coupling of a formerly coordinated CO with a deoxygenated alkynic residual.

The thermal reactions of 2-methyl-1-hexen-3-yne [CH3CH2C≡CC(=CH2)CH3, metey] with Fe3(CO)12 have been studied: cluster opening or fragmentation and alkyne dimerization occur. Main products are the open triangular isomers [Fe3(CO)6(μ-CO)2{CH3(=CH2)CC(Et)C(Et)C(=CH2)CH3}] (complex 3a) and [Fe3(CO)6(μ-CO)2{C(Et)CCH3(=CH2)C(Et)CCH3(=CH2)}] (complex 3b). The structure and isomerism of the complexes has been confirmed by X-ray studies. The minor products of the reaction have been characterized by spectroscopic techniques. An attempt at exploiting the reactivity of the “free” C=C bonds of the coordinated ene-yne was made: complex 3a was reacted with styrene under thermal conditions. Unexpectedly considerable yields of the closed triangular cluster [Fe3(CO)6{EtC2C(=CH2)CH3}2] (complex 5) have been obtained. This behaviour had not been previously observed. The unprecedented structure of complex 5 has been confirmed with an X-ray study.

The title complex is the main product of the reaction of Fe3(CO)12 with isopropenylacetylene in basic methanolic solution (followed by acidification); it is obtained upon carbon–carbon bond forming and dimerization of the alkyne. The same complex is also obtained by reacting Fe3(CO)12 in CH3OH/KOH solution with 2-methyl-hex-1-en-3-yne; carbon–carbon bond cleavage presumably occurs to form isopropenylacetylene, which then reacts with the iron carbonyl. The unprecedented structure of the complex has been determined with a X-ray diffraction analysis.

The reactions of Fe3(CO)12 with but-2-yn-1,4-diol (BUD), 1,4-dichloro-but-2-yne (DCB), propargyl alcohol (PA) and propargyl chloride (PC) in KOH/CH3OH solutions (followed by acidification with HCl) and under thermal conditions have been examined. The complex Fe2(CO)6{H2CCCCH2} is the main product of the reactions with BUD or DCB in all conditions. The complexes Fe2(CO)6{H2CCC(H)C(OMe)O} and Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH3}CCH2} are the main products obtained respectively in the reactions with propargyl chloride (PC) or propargyl alcohol (PA) in basic methanolic solution. The structures of the three complexes have been determined by means of X-ray analysis. Complex Fe2(CO)6{H2CCCCH2} contains a butatrienyl ligand in an uncommon structural arrangement. The formation of complex Fe2(CO)6{H2CCC(H)C(OMe)O} requires CO and methanol activation; its ferrole like structure contains a coordinated acetate group. Complex Fe3(CO)10{H2CCC(H)C(O)C{CH2(O)CH 3}CCH2} contains one Fe(CO)4 and one Fe2(CO)6 fragments linked through a carbon atom chain derived from the insertion of CO and dimerization of propargyl alcohol (with substitution of OCH3 from methanol in the place of OH). Comments on the syntheses and on the reaction pathways leading to the complexes are made.

The title complex is obtained by reacting Ru3(CO)12 with 1,4-dichloro-but-2-yne (ClCH2C CCH2Cl, DCB) in CH3OH/KOH solution (followed by acidification with HCl). The X-ray structure analysis shows that (μ-H)2Ru3(CO)9{μ3-η2-[H2C C(H)CCC( O)OCH3]} complex contains a “parallel” ene-yne acetyl substituent, H2C C(H)C CC( O)OCH3; the formation of such a ligand starting from DCB is – to our knowledge – unprecedented. The synthesis of complex (μ-H)2Ru3(CO)9{μ3-η2-[H2C C(H)CCC( O)OCH3]} occurs through the activation of CO and methanol. This process has been found for other reactions of functionalized alkynes with M3(CO)12 carbonyls (M = Fe, Ru) under basic methanolic conditions. The known hydridic cluster, (μ-H)Ru3(CO)9[μ3-η3-(MeCCHCH)] has been identified as the minor reaction product.

Ene–yne molecules are found as natural products. Natural and synthetic ene–ynes are actively studied and partly used as anticancer drugs. Conjugated and non-conjugated ene–yne molecules are widely used as synthons in organic reactions promoted by organometallic compounds. Surprisingly, the coordination of ene–ynes to transition metal clusters has not been fully rationalized up to now; the same happens for the (not very many) examples of their reactivity and of their potentials uses. In this paper the synthetic routes leading to (and the structures of) transition metal clusters containing ene–yne ligands are described. Comparisons with the chemistry of di-ynes coordinated to transition metal clusters are made.

The reaction of Co4(CO)12 with the dipropargylamine [(HCCCMe2)2NMe] (ligand A) leads to moderate yields of the title complex (complex 4). An X-ray analysis has shown that this tetranuclear complex is a ‘spiked’ (or metallo-ligated) triangular cluster containing one molecule of ligand A partially cyclized and coordinated to all four metal atoms. Complex 4 is the first tetracobalt cluster showing this type of structure which was previously found only for two M2Ni2 (M=Fe, Ru) isopropenylacetylene derivatives. Reaction pathways leading to the formation of complex 4 are discussed.

The reactions of Co2(CO)8 with 1-ethynylcyclohexanol (HCCC6H10OH, ECY) in benzene led mainly to Co2(CO)6(ECY) 1 and to smaller amounts of the methylidyne complex Co3(CO)9[μ3-CCH2(C6H10OH)] 2. The reactions of Fe3(CO)12 with ECY in the same solvent led to binuclear metallacyclic derivatives Fe2(CO)6(ECY)2 (isomers 3a, 3b) or Fe2(CO)6[(ECY)2 − H2O] 3c as the main products; small yields of trinuclear complexes Fe3(CO)9(μ-CO)[μ3-η2-1,2-HCC(C6H10OH)] 4, Fe3(CO)9(μ-CO)[μ3-η2-1,2-CC(C6H10)] 5 and Fe3(CO)7[μ3-η7-(C6H10OH)CCHCHC(C6H9)] 6 {containing respectively a parallel alkynol, an allenylidene and a dimeric metallacyclic ligand} were also obtained, together with 7, a thermal decomposition product of 6. Finally, when Co2(CO)8 was treated with ECY in benzene, and Fe3(CO)12 was added, the heterometallic complex Co2Fe(CO)6(μ-CO)[μ3-η7-(C6H9)CC(H)C(H)C(H)(C6H10)] 8 was obtained in low yields. The complexes have been characterized by means of IR and 1H NMR spectroscopies and by mass spectrometry. The structures of 2, 5, 8 have been determined by X-ray diffraction. Complex 2 contains an “hydrogenated” ECY ligand, 5 an allenylidene ligand formed upon dehydration of ECY (loss of the OH and of the terminal hydrogen), whereas 8 contains a ligand formed by tail-to-tail coupling of two ECY molecules, with loss of water and oxygen and shift of hydrogen. The elemental analysis of complex 8 gave a Co ∶ Fe ratio of 2 ∶ 1; on the basis of this analysis, the refinement of the diffraction data allowed a hypothesis on the distribution of the metal atoms in the cluster. Reaction pathways for the formation of these clusters are proposed and dehydration mechanisms for the ligand discussed.

The compound [Ru3(CO)9[mu-P(NPri2)2]3][Ru6(CO)15(mu 6-C)[mu-P(NPri2)2]] (1), obtained via the addition of PCl(NPri2)2 to K2[Ru4(CO)13], crystallizes in the monoclinic space group P2l/c with a = 15.537(8) A, b = 36.151(16) A, c = 19.407(5) A, beta = 91.14(2) degrees, Z = 4, and R = 0.069 for 8006 observed reflections. The unit cell is unusual in that it contains both a typical octahedral Ru6 cluster anion (1a), featuring an encapsulated carbide, and a symmetrical phosphido bridge, in addition to a 50-electron trinuclear cluster cation [Ru3(CO)9[mu-P(NPri2)2]3]+ (1c). The latter, with approximate D3h symmetry, exhibits long Ru-Ru distances (> or = 3.15 A). Among the family of clusters with M3(mu-PR2)3 cores and different numbers of both electrons (TEC) and terminal ligands (LxLyLz), 1c is unique in that it is a 333 stereotype with 50 valence electrons. MO calculations permit us to predict the existence of redox congeners of 1c clusters and related 48e Re3 clusters. This work also presents a summary of the relationships between the electronic and the geometric structures for all known M3LxLyLz(mu-PR2)3 species. The basic stereochemical features are influenced by the total-electron count and, hence, by the degree of M-M bonding, as well as the remarkable flexibility of the phosphido bridging ligands. The mu-PR2 ligands need not necessarily lie in the M3 plane, and a wide range of M-P-M angles (as small as 72 degrees or as large as 133 degrees) have been observed.

The complexes Co3(CO)9(μ3-X) (X=S, Se) can be reduced to the corresponding anionic species [Co3(CO)9(μ3-X)]−, which react with allyl bromide to give Co3(CO)7(μ-η3-C3H5)(μ3-X) (X=S, Se). These are the first two cobalt complexes containing the bridging μ-η3-allyl ligand. The structure of the selenium complex was determined by X-ray crystallography. Crystal data for Co3(CO)7(μ-η3-C3H5)(μ3-Se) are as follows: space group P21/c, a=9.051(2) A, b=8.102(2) A, c=21.27(4) A, β=93.82(3)°, Z=4, and R=0.0565 for 2491 observed reflections.

The paramagnetic Co3(CO)9(μ3−S) cluster (1) reacts with organic compounds containing S−H, S−S, or P−H bonds to give diamagnetic Co3(CO)7(μ-X)(μ3−S) (μ-X = (μ-L, μ-(1,2-η)-L, and μ-(1,3-η)-L) complexes. The reaction was used to prepare the derivatives with μ-L = SR (2a−h; R = Et, t-Bu, CH2Ph, allyl, Ph, C6F5, 2-naphthyl, CH2CH2OH) and PPh2 (7), μ-(1,2-η)-L = P(S)Ph2 (8), and μ-(1,3-η)-L = S2CR (R = SMe (4), OMe (5), Ph (6)). The reaction results in an increase of the oxidation state of cobalt and may be therefore called an oxidative substitution. It is the first successful and rational way to prepare derivatives of Co3(CO)9(μ3-S), a fundamental cluster molecule described in 1961. The crystal structures of the triphenylphosphine-substituted derivative of 2b, Co3(CO)4(PPh3)3(μ-S-t-Bu)(μ3-S) (3), and of 4, 6, and 8 were determined. A new, high-yield synthesis of 1 is described.

The disubstituted clusters[Ir4(CO)10(μ2-LL)] with one edge-bridging ligand have a ground-state geometry with all COs terminal (LL = (MeS)2CHMe, cluster 1) or with three edge-bridging COs (LL = (Ph2P)2CHMe, cluste 2; LL =Ph2P(CH2)3PPh2, cluster 3) in the solid state and in solution. A comparative 13C-NMR study of 1–3 shows that their respective ground-state geometries are merely relative minima of energy in the same kinetic profile of successive fluxional processes consisting of a merry-go-round of six COs about a unique trangular face and the rotation of terminal COs about one Ir-atom. The factors affecting the activation energy of the merry-go-round result from the relative bites of the bidentate ligands in the ground-state geometry, as shown by a comparison of the molecular structures of 2 and 3.

Dicobalt octacarbonyl reacts with an excess of (MeSCS2)2 to form several sulfur-containing cobalt carbonyl derivatives; on addition of PPh3, the complex Co2(CO)2(PPh3)2(1,3-η-S2CSMe)(μ-1,2-η-SCSMe) (1) could be isolated from the reaction mixture. The structure of complex 1 was determined by X-ray crystallography; it contains a methyl dithioformate ligand in which the ligand donates five electrons to the cluster and the CS group is bound perpendicular to the Co2 core.

Dicobalt octacarbonyl and perfluoro diphenyl disulfide react to form Co3(μ3-S) (C6F5)(CO)8 (1), an unusual cobalt carbonyl cluster containing an aryl-metal sigma bond. The structure of complex 1 was determined by X-ray crystallography; it crystallizes in triclinic P-1 space group with a = 8.218(2), b = 13.379(2), c = 18.864(2) A, α = 106.96(2), β = 96.91(2), γ = 97.39(2)°. The final R is 0.0376 for 5286 observed reflections (F0>4.0σF0).

The complex (1) has been prepared and its structure determined. Complex1 is the first stable thioether derivative of a metal carbonyl containing only cobalt as metal. It crystallizes in the monoclinic P21/c space group, witha = 13.975( 4 ),b = 11.363( 3 ),c = 14.686(2)A,β = 112.25(2)°,V = 2158.5(7)A3.Z = 4. The solution using direct methods and the anisotropic refinement of all nonhydrogen atoms led toR = 0.039,wR = 0.041 for 3296 reflections with F> 4.0σ(F) Analogous but less stable complexes are formed with 1,6-diphenyl-2,5-dithiahexane and the crown thioether 1,4,7-trithiacyclonane, the latter functioning either as a bidenlate or a tridentate ligand.

The structures of CHI3 and of its adduct with quinoline have been analyzed using X-ray single crystal diffraction at low (106 K, CHI3) and room temperature (adduct CHI3⋅3(C9H7N)). The disorder of the molecule is removed at low temperature and the non centrosymmetric structure in P63 space group allows a deep examination of the halogen bondings in the crystal. The iodine atom clearly shows in the both compounds its electrophilic and nucleophilic behavior. It is noteworthy that when iodoform forms adducts involving the three iodine atoms with Lewis bases, it gives raise to non centrosymmetric crystals, and it is a good candidate for obtaining new materials.

The synthesis of homoleptic 1,2:5,6- di -O- isopropylidene -α- d - glucofuranose (HL) complexes bound to metal triple bond moieties was achieved by their reaction with the corresponding molybdenum and tungsten dimethylamido derivatives. The products [Mo2L6] (1) and [W2L6] (2) were characterized by 1H, 13C NMR and IR spectroscopy; optical rotation values were measured and are briefly discussed. The X-ray structures of 1 and 2, determined at 118 and 293 K, respectively, are reported. Crystallographic details: [Mo2L6], monoclinic, space group P2 1 , a = 14.448(11), b = 21.749(12), c = 15.819(9) A , β = 115.07(5)°, Z = 2 and R = 0.0391 for 13 367 independent reflections; [W2L6], orthorhombic, space group P22 1 2 1 , a = 15.993(2), b = 16.127(3), c = 19.260(4) A , Z = 2 and R = 0.067 for 6215 independent reflections.

Several diamine-substituted cobalt carbonyl butenolide complexes of the type Co2(H,R,C4O2)(μ2-CO)(CO)4(LL) [R = H or nBu; (LL) = N,N,N′,N′-tetramethylethylenediamine (tmeda), 1,2-diamino cyclohexane (dach) cis- and trans-isomers, o-phenylene diamine (opda), 1,10-phenanthroline (phen), or 2,2′-dipyridyl (dipy)] have been prepared. The structures of three representatives [R = H, (LL) = tmeda (1); R = nBu, (LL) = phen (8b) and dipy (9)] have been determined. Complexes 1, 8b and 9 crystallise in triclinic P1 (a = 7.442(2), b = 9.159(2), c = 14.182(3) A, α = 79.34(3), β = 82.34(3), γ = 7.07(3)°), monoclinic P21/c (a = 10.953(2), b = 16.464(4), c = 14.537(3) A, β = 110.47(2) °) and monoclinic P21/n (a = 9.698(6), b = 15.508(6), c = 15.966(8), A, β = 79.30(4)°) space groups, respectively. The complexes with tmeda and trans-dach are the first stable cobalt carbonyl derivatives containing saturated aliphatic amines as ligands.

The Cp)2Ni2Fe(CO)3(µ3-C2H2) and Cp)2Ni2Fe(CO)3(µ3-C2H2) (B) complexes have been synthesized and spectroscopically characterized. An accurate X-ray study and a comparison with related structures shows that the substituents of the alkyne ligands exert considerable effects on the bonding parameters.

The monosubstituted [Ir4(CO)11L] clusters (L = P(OPh)3, 1; L = P(OMe)3, 2; L = P(OCH2)3CEt, 3) were obtained in good yields by the reaction of [Ir4(CO)11I]− with the corresponding phosphite. In the solid state, cluster 3 has a Cs geometry with all terminal ligands as shown by an X-ray analysis. Three isomers are present in solution: one with terminal ligands (A) and two with three edge-bridging CO's and with L in axial (B) or radial (C) position (see Scheme). The thermodynamic and kinetic parameters of isomerisations B ⇌ A and A ⇌ C were determined by simulation of the variable-temperature 31P-NMR spectra. The three isomers correspond to three minima on the kinetic pathway of CO scrambling, whose relative energies vary independently within a small range (1–9 kJ mol−1 at 298 K). At low temperature, isomer C is always the least stable and is not observed for 1 which bears the most bulky phosphite ligand. The isomerisations are due to two intramolecular merry-go-rounds of CO groups about two unequivalent faces of the unbridged species A.

[Ir4(CO)12] reacts with oxirane in the presence of Br− to give [Ir4(CO)12−x( COCH 2 CH 2 O )x] (x=1, 2, 3). The structures of three products were established by X-ray diffraction studies. All ligands are in terminal positions in [Ir4(CO)11( COCH 2 CH 2 O )]. The di- and tri-substituted cluster compounds have 3 edge-bridging COs and dioxycarbene ligands in axial positions. The fluxional behaviour of these Ir4 clusters, as studied by 2D 13C NMR spectroscopy, is due to CO site exchanges localised on one or on three Ir atoms.

Co 6 C(CO) 12 Se 2 crystallizes in the monoclinic system, space group Cc with a = 16.365(4) A, b = 9.429(2) A, c = 17.479(5) A, β = 122.75(2)°, Z = 4 and (Mo — K a ) = 0.71070 A. The final reliability indices are R = 0.051 and R W = 0.048 for 2081 observed reflections having F > 4.0σ( F ). The molecule consists of a Co 6 trigonal prism with the triangular faces capped by selenium atoms. Each cobalt is bonded to two terminal CO groups. A carbon atom is embedded at the centre of the Co 6 prism. The Raman spectra of polycrystalline samples of this compound and of the sulphur analogue have been recorded. These, together with the corresponding infrared data, can only be understood in terms of a dominant intermolecular coupling on the ν(Co—E) modes (E = S, Se). The origin of this coupling is the close contact between neighbouring clusters in one distinct direction which gives rise to a chain of molecules in the crystal. The significant effect of these oriented close contacts on the vibrational modes is demonstrated.

The reaction of [Co 2 (CO) 8 ] with 1-phenylbut-1-yn-3-one in refluxing toluene yields [Co 2 (CO) 6 {μ-PhCCC(O)CH 3 }, the symmetrical trimer {PhC 2 C(O) CH 3 } 3 , which were characterized by spectroscopic techniques, and the title complex, the structure of which has been elucidated by X-ray analysis. The crystals are monoclinic P 2 1 / c with a = 10.640(2), b = 17.741(4), c = 17.845 (4) A, β = 90.50(3)°, Z = 4. The molecule has a CoCo bond and the {PhC 2 C(O)CH 3 } 3 chain links the cobalt atoms in a “flyover” arrangement. To our knowledge, this is the first example of stepwise formation of a symmetrical benzene from an asymmetrical, internal alkyne via this type of intermediate.

X-ray analyses of [Fe3(CO)9SSe], [Fe3(CO)9STe] and of [Fe3(CO)9SeTe] was performed. The three compounds are isomorphous and belong to the trielinic space group P 1 with a = 6.835(1), 6.996(1), 6.964(1) A, b = 9.186(2), 9.367(1), 9.360(2) A, c = 13.121(3), 13.058(2), 13.189(2) A, α = 93.79(3), 93.23(1), 94.09(2)°, β = 94.21(3), 94.03(1), 94.54(2)° γ = 110.89(3), 111.14(1), 110.67(2)° for the SSe, STe and SeTe complexes, respectively. The structures were refined anisotropically to R = 0.026, 0.042, 0.030 for 3127 3465, 2564 observed reflections for the SSe, STe and SeTe complexes, respectively. They belong to the well known series of [Fe3(CO)9XY] complexes formed by an open triangle of iron atoms each linked to three terminal CO groups, with two faces capped by a chalcogen atom. The bond distances and angles of these mixed complexes are well within the ranges imposed due to the different dimensions of the chalcogen atoms. Intermolecular contacts occur when at least one chalcogen atom is tellurium. Examining some relevant geometrical features of the complexes with X,Y = S, Se, Te, NR, PR, AsR… a regular trend of the Fe-Fe distances is found, depending on the dimensions of the capping atoms; an asymmetry of the Fe-Fe distances is attributed to steric factors.

The tellurium complex [Fe3(CO)9Te2] reacts with CO to give [Fe3(CO)10Te2]. The reaction occurs via attack of CO on a peripheral iron atom of the open triangle of [Fe3(CO)9Te2] with consequent rupture of an iron—iron bond. The complex lies on a crystallographic two-fold axis and contains an iron—iron bond between two Fe atoms each linked to three terminal carbonyl groups: a third Fe atom, linked to four terminal CO groups, is connected to the Fe2 unit by two bridging Te atoms.

The title complex is the main product of the room-temperature reaction between Co 2 (CO) 8 and sulfur. Its crystals are monoclinic, space group C2/c

The reaction of 2-methyl-1-buten-3-yne (isopropenylacetylene, IPA) with triiron dodecacarbonyl in refluxing benzene leads to medium yields of four main derivatives. Two of them are the trinuclear open-cluster isomers Fe3(CO)10[H2CC(CH3)CC(H)C(H)C(CO)C(CH3)CH2] (complex 1a) and Fe3(CO)10[HCC(CH3)C(H)C(H)C(H)C(CO)C(CH3)CH2] (complex 1b) containing an organic ligand formed upon tail-to-tail dimerization of the alkyne. In both complexes one isolated iron atom is part of a metallacyclic five-membered ring formed by three carbon atoms of one alkyne molecule and a carbon belonging to a CO. The other two iron atoms are linked together; however their bonding to the organic moiety is different in complexes 1a and 1b. This type of isomerism and the coordination mode of the unique iron atom are unprecedented in alkyne-cluster chemistry. The other two complexes are binuclear and have been identified, respectively, as Fe2(CO)5[C15H18(CO)] (2) and Fe2(CO)6L3 [L = IPA] (3). Complex 2 contains an unprecedented organic ligand formed by three alkyne molecules and one CO; this is different from other L3CO (troponic) ligands found in the literature. The structures of complexes 1a, 1b and 2 have been studied by X-ray crystallography. Complex 3 did not give crystals suitable for X-ray analysis. Reaction pathways leading to new complexes are hypothesized.

The diacetone glucose (DAGH, 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose) monoanion DAG binds as a terminal alkoxo ligand to a variety of transition metals. When it is used in excess, with respect to the oxidation state of the metal, homoleptic anionic complexes [M'(DAG)(6)](3)(-) are formed. Such complexes contain oxygen-rich cavities between pairs of DAG ligands appropriate for binding alkali metal cations. The anionic complexes have been obtained by using [Li(DAG)], 1, and [Na(DAG)], 2, whose syntheses and characterization are reported here. The reaction of 1 and 2 with [V(DAG)(3)] gave [V(DAG)(6)Li(3)], 3, and [V(DAG)(6)Na(3)], 4, respectively. An alternative synthesis of 3 and 4 involves the metathesis reaction of 1 and 2 with [VCl(3)(thf)(3)]. This strategy also led to the synthesis of [Cr(DAG)(6)Li(3)], 5, and [Ti(DAG)(6)Li(3)], 6. Three pairs of DAG shape a cavity appropriate for three lithium cations in the case of complexes 3, 5, and 6; a cavity is formed for three sodium cations in the case of 4, where the alkali cation is in a tetrahedral O(4) environment. In the anionic manganese derivative [Mn(Cl)(DAG)(4)](3)(-), the four DAG units arrange in such a way as to bind four Li cations, which form a cationic cage [Mn(Cl)(DAG)(4)Li(4)](+), and Cl(-) is bound inside as [Mn(Cl)(DAG)(4)Li(4)(mgr;(4)-Cl)], 7. Crystallographic details: 4, prism, P2(1), a = 14.735(10) Å, b = 15.033(9) Å, c= 21.021(10) Å, beta = 107.34(2) degrees, V= 4445(5) Å(3), Z = 2, and R = 7.60; 5, prismatic, C2, a = 22.671(9) Å, b = 18.785(5) Å, c = 13.886(4) Å, beta = 126.39(2) degrees, V= 4761(3) Å(3), Z = 2, and R = 7.32; 6, prismatic, P2(1), a= 13.888(5) Å, b = 18.750(5) Å, c= 17.933(5) Å, beta = 91.84(2) degrees, V = 4667(2) Å(3), Z = 2, and R = 8.75; 7, prismatic, P2(1), a = 13.306(7) Å, b= 21.311(11) Å, c = 13.376(6) Å, beta = 95.01(2) degrees, V = 3779(3) Å(3), Z = 2, and R = 9.33.

The experimental electron density (ED) of the triclinic phase of Co2(CO)6(μ-CO)(μ-C4O2H2), μ-carbonyl-μ-5-oxo-2,5-dihydrofuran-2-ylbis(tricarbonylcobalt), has been determined through X-ray diffraction at 120 K. The presence of a `closed shell' Co—Co bond in the title compound, found in an experimental ED study of its orthorhombic form, is confirmed by the Quantum Theory of Atoms in Molecules. However, the two phases show a significant Co—Co bond length difference [triclinic: 2.4402 (2) Å; orthorhombic: 2.4222 (3) Å]. The flat distribution of the experimental ED along the Co—Co bond path and on the two Co2C rings allows for variations of the Co—Co bond length which may be easily induced by the different packing arrangements of the two forms.

The reaction of [Fe3(CO)12] with RNO2(R = Et or PrI) gives, among complexes of well known structures, many other iron–nitrogen–carbonyl complexes which are indicative of novel reaction paths, such as reduction of a nitro-to a nitroso-group, hydrogen abstraction, and N–C bond breakage. The complexes have been fully characterized by means of i.r., mass, and 1H and 13C n.m.r. spectroscopy. The crystal structure of the title complex has been determined by X-ray diffractometry from 2 446 reflections (R 0.037). Crystals are triclinic, space group P, with Z= 2 in a unit cell of dimensions a= 12.008(5), b= 9.827(4), c= 8.580(4), A, α= 120.53(4), β= 99.29(1), and γ= 96.80(1)°. The structure consists of two Fe(CO)3 units linked by an Fe–Fe bond and doubly bridged by the nitrogen of the isopropylamido-ligand and the nitrogen and oxygen of the oximato-ligand. The n.m.r. study shows the presence of a substantial torsional barrier about the N–Fe and N–O bonds and localized carbonyl interchange.

The paper reports the synthesis, spectroscopic properties and structural characterization of a new di-iron carbonyl compound Fe 2 (CO) 6 (μ-OCCH 2 C 6 H 5 )(μ-NC(CH 3 ) 2 ), obtained in the reaction between Fe 3 (CO) 12 and 2-nitropropane in toluene solution. The complex crystallizes in the monoclinic P2 1 /n space group with a = 19.70(5), b = 11.62(4), c = 16.78(4) A and β = 95.19(2)°, Z = 8 and shows the presence of two independent molecules in the unit cell. The mlecular structure consists basically of two Fe(CO) 3 unites, joined by a FeFe bond and bridged by the benzylcarboxy and isopropylene amido ligands. The presence of the former ligand represents a proof of activation of the solvent, which probably occurs via an unstable hydrido alkyl iron intermediate.

The title compound has been prepared in reasonable yield by reaction of a methanolic solution of CoCl2 and MeOCS2K with CO. I.r. spectra have been analyzed both in the C-O stretching region and in the region of the main vibrations of the xanthate ligand: an explanation of the appearance of only 4 out of 7 i.r.-active ν(CO) modes is proposed. The structure of the triphenylphosphine derivative has been solved by x-ray diffraction analysis: [SCo3(CO)6(PPh3)(S2COMe)] crystallizes in the triclinic space group P¯1, witha = 10.710(3),b = 10.199(3) andc = 16.208(4) A, α = 113.57(2)°, β = 98.14(2)°, γ = 104.32(2)°, Z = 2, λ(MoKα) = 0.7107 A. The final R value is 0.045 [4461 reflections with F > 6 σ(F)]. The molecule is formed by an SCo3 cluster, in which each Co atom coordinates two CO groups. The chelating xanthate ligand is equatorially bonded to two cobalt atoms forming a nonplanar pentaatomic ring; the phosphine is equatorially bonded to the other cobalt atom.

The compound [Co8(CO)21(µ5-CS2)(µ5-C2S)], a minor product of the reaction between [Co2(CO)8] and CS2, has been characterized by X-ray diffraction analysis. The crystals are monoclinic, space group Cc, with a= 9.208(4), b= 15.864(6), c= 25.36(1), β= 96.39(3)°, and Z= 4. The Co atoms were located by the Patterson method, the S, C, and O atoms by Fourier difference maps. The final R was 0.0899 for 3 206 reflections with F > 6σ(F). The structure consists of an assembly of three cobalt clusters, the central one being the most interesting part of the complex, as it shows an unprecedented Co2(µ-SC) fragment. The compound is formally derived from a previously reported one by isolobal substitution of a Co(CO)3 group by a C–R group [R = CCo3(CO)9].

Co6C(CO)12S2 (I) has been isolated in crystalline form from the mixture of more than a dozen of carbonyl products formed when Co2(CO)8 reacts at room temperature with CS2. Crystals of I are monoclinic with space group Cc, and lattice constants a  16.250(5), b  9.413(4), c  16.036(5) A, β  116.77(4)°. Structure refinement gave R  0.034 for 1974 reflections. The CCo6S2 core of the molecule possesses idealized D3h geometry. It is composed of a Co6 trigonal prism, enclosing a C atom in the centre, and the triangular faces are capped symmetrically by the two S atoms. The core contains two sorts od CoCo distances: short one (2.432 A) along the triangular edges, and long ones (2.669 A) along the lateral edges. The average CoC distance is 1.94 A, and the average CoS distance 2.192 A. 13CO-enriched samples were prepared photochemically and their IR spectra used in the assignment of the CO stretching frequencies. The CO stretching force constant was calculated to be 1670(2) Nm-1. By the use of 13CS2, I has also been obtained in a selectively carbido-13C-labelled form. The vibrational frequencies of the carbide atom were observed, and that at 819 cm-1 (13C: 790 cm-1) assigned to the species , and that at 548 cm-1 (13C: 535.5 cm-1) to species E′. For the Co-C(carbide) force constant a value of 155 Nm-1 was calculated. The cobalt—sulphur stretching frequencies were found at 309 cm-1 ( ) and 239 cm-1 (E′). The CoS stretching force constant, 78 Nm-1, is considerably lower than that obtained for SCo3-(CO)9, viz. 112 Nm-1.

Several carbonyl derivatives of iron(II) thiolates containing N-donor ligands with the general formula FeS2N2(CO)2 were prepared in methanol solution starting from FeSO4·7H2O, the appropriate thiol (S) and nitrogen-donor ligand (N), carbon monoxide and a base. The structures of two representatives Fe(SC6H4- NH2-o)2(CO)2 (1) and Fe(SPh)2(H2NC2H4NH2)- (CO)2 (2) were determined. Complex 1 crystallizes with one molecule of THF in the triclinic space group P1, a=5.659(3), b=8.960(6), c=10.624(6) A, α= 105.15(5), β=103.23(5), γ=94.35(5)°, V=500.86 A3, Z=1, Dcalc=1.43 g cm−3. Complex 2 crystallizes in the monoclinic space group P21/c, a=11.739(2), b=9.725(2), c=15.868(2) A, β=101.583(8)°, V= 1774.6 A3, Z=4, Dcalc=1.44 g cm−3. Final agreement factors, R=0.0300, Rw=0.0304 (1787 reflections) for 1; R=0.0368, Rw=0.0369 (2147 reflections) for 2; the absolute configuration of 1 was determined. The octahedral complexes contain the two CO ligands in cis position and the coordinated N atoms are trans to the CO groups. A necessary condition for the stability of such complexes is the presence of at least one chelating ligand; all complexes lose CO on heating and this reaction is (in part) reversible.

Cristallisation dans le groupe P2 1 2 1 2 1 (Affinement jusqu'a R=0,045). Les six Co sont disposes en forme de bateau. Les quatre Co de la base forment un carre regulier, avec des liaisons Co-Co des 4 cotes. Les deux Co situes au sommet sont lies de la facon suivante: Co-C-C-Co. Les 6 Co portent des CO. Un pont sulfuro est etabli entre les 4 Co de base

The reaction of the title complexes with phosphine-like ligands proceeds by two competing path, one, first order in [complex] and (L), the other first order in [complex] and second order in (L). The mechanism can be explained by a rate-determining formation of an intermediate Fe2(CO)6L(μX)2, which can lose CO or react further with another L prior to decomposition. The effect of both X and L on the rate of the two paths is discussed. The values of the rate constants show a large discriminating ability of the substrate versus the ligand, and this is tentatively explained by a facile coordination of the ligand on the complex via a low-energy empty M.O.

The title complex was obtained in a reversible reaction by treating Ru3(CO)6(C12H20)(C13H20O) with excess t-butylacetylene in hydrocarbon solvents. From the two isomers of the starting product, the corresponding isomers of the new complex were obtained. The structure of one of the isomers has been determined by X-ray methods; crystals are triclinic, space group P1, with two molecules in a unit cell of dimensions a = 11.830(8), b = 17.096(7), c = 10.368(9) A, α = 102.31(4), β = 113.61(5), γ = 96.23(5)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 5.0% for 2299 observed reflections. The complex consists of a nearly equilateral triangle of ruthenium atoms bonded to five terminal carbonyls; two independent organic moieties interact with all the metals of the cluster. The former is formed by two oligomerized alkynes and is responsible for the isomerism of the complex, the latter is an heterocyclic organic ring obtained by the insertion of one carbonyl into three molecules of alkyne. The formation mechanism of the complex, starting from Ru3(CO)12 and alkynes, is discussed on the basis of deuteration experiments and of the structures of intermediate derivatives.

Le compose du titre cristallise dans le systeme orthorhombique, groupe d'espace Pna2 1 et sa structure est affinee jusqu'a R=0,058. Coordination plane autour du platine

sym-(CO)9Co3C(CS2)Co3(CO)7S has been isolated from the mixture formed in the reaction of Co2(CO)8 with CS2. This is the fifth member of the CmSnCop(CO)q family identified by X-ray diffraction studies. The molecular structure of the title compound is discussed and briefly compared with that of the asymmetric isomer and related compounds.

The X-ray analyses of some neutral and cationic derivatives of 2-(4-methylpyridin-2-yl)-1H-benzimida-zole are reported and the structural data tentatively correlated to relative UV-visible properties. A rotation of the γ-picoline ring with respect to the benzimidazole moiety may be responsible of the spectral behavior.

Homoleptic metal−sugar complexes were obtained in the form of MnII− and FeII−diacetoneglucose derivatives. The protolysis of [Mn3Mes6] and [Fe2Mes4] (Mes = 2,4,6-Me3C6H2) with DAGH (1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, diacetoneglucose) led to [M(DAG)2] [M = Mn (1), Fe (2)]. Although monomeric in solution, they showed a different degree of aggregation in the solid state, iron being monomeric and manganese oligomeric (see magnetic properties). Dimeric complexes from 1 and 2 were obtained in the reaction with 9,10-phenanthroline [phen], leading to [(phen)2M(μ-DAG)2M(DAG)2] [M = Mn (3), Fe (4)]. The organometallic functionalization of 1 and 2 was achieved via a ligand redistribution reaction mixing them with [Mn3Mes6] and [Fe2Mes4], respectively. The reaction led to mixed alkoxo aryl trinuclear complexes in the form of [(Mes)2M2(μ-DAG)2M(μ-Mes)2] [M = Mn (5), Fe (6)]. Both have a linear trimetallic skeleton with Mn···Mn and Fe···Fe average distances of 2.93 and 2.88 A, respectively. The crystal dat...

The molecular structure of the title compound obtained from the reaction of Os3(CO)12 with phenylacetylene reveals the unique feature of two alkyne molecules linked through a carbon and an oxygen atom derived from opening of the CO bond of a carbonyl group; two five-membered rings are formed with σ and π bonds to the Os3 cluster, and a highly asymmetrical bridging carbonyl group is present.

Preparation et breve presentation de l'etude de radiocristallographique du complexe du titre

X-Ray analysis of µ-(isopropylamino)-µ-(propanone oximato)-bis(tricarbonyliron)(Fe–Fe), the main product of the reaction between [Fe3(CO)12] and 2-nitropropane, shows an unusual structure with an Fe–N–O–Fe ring, which can be related to the nature of novel intermediates in the reduction of nitro-compounds by iron carbonyls.

The kinetics of 14CO exchange and CO replacement in [FeCo2(CO)9S] have been studied with a variety of ligands. The rate equation is Kobs.=k1+k2[L], in which the ligand-independent path is often negligible, except with very poor nucleophiles such as CO or AsPh3. The ligand-dependent path indicates the very high electrophilicity and great discriminating power among the ligands of the co-ordination site, suggesting that bond making plays an important role in the transition state. The probable mechanism is discussed in terms of steric accessibility of the co-ordination site and in terms of a bonding model for the cluster complex. The rates of the successive CO substitutions with PBu3 indicate that the ligand already bonded to the cluster affects the reactivity of the adjacent metal atom, i.e. CO dissociation is practically unaffected, whereas ligand co-ordination is greatly decreased.

X-Ray study of [Fe4(CO)11(NEt)(ONEt)], obtained by the reaction of [Fe3(CO)12] with nitroethane, has revealed the presence of a slightly distorted tetrairon square cluster with two organic ligands face-bridging the cluster, with eight terminal, two asymmetrical, and one symmetrical bridging carbonyl groups.