An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Tripod ligands RC(CH2X)(CH2Y)(CH(2)Z) (X, Y, Z = NR2, PR2) are accessible from a,p-unsaturated esters R(=CH2)COOR'. The key steps in this synthetic approach are Michael additions of amines and phosphanes to produce RCH(COOR')(CH2X) (X = NR2, PR2) (2 and 3), followed by hydroxymethylation with paraformaldehyde to result in RC(COOR')(CH2OH)(CH2X) (X = NR2) (4). Standard transformations of this Cl-symmetric precursor allow for the synthesis of tripod ligands such as PhC(CH(2)PZ)(CH2PPh2)(CH(2)PMes) (11). Coordination of these ligands with d(8)-metal ions [nickel(ii), palladium(a), rhodium(i)] results in square-planar complexes with the chelate cycles in half-chair, twist-boat or boat conformations, depending on the specific substitution pattern. Coordination through two phosphane donors with the nitrogen donor acting as a dangling arm is generally preferred throughout. Detail preparative procedures and complete characterisation by analytical methods, including X-ray analysis of the coordination compounds, are given. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The synthesis of a series of tripod ligands MeOCH2C(CH2X)-(CH2Y)(CH(2)Z) (X = PR2; Y, Z = PR'(2) or pz; pz = 1-pyrazolyl) based on the 3,3-difunctionalized oxetane O-a[CH2](2)C-a-(CH2OMS)(CH2Br)(O-a-C-a) as the starting material is described. With their mixed donor sets these ligands coordinate to d(8)-metal ions in a bidentate binding mode. One of the three donors remains uncoordinated in each case. Coordination of phosphane donors is generally preferred over coordination of pyrazole donors. With bulky phosphanes such as -CH2PMeS2, however, pyrazole may compete with PR2, depending on the kind of the d(8) fragment. Dynamic exchange between coordinated and noncoordinated pyrazole donors is observed. Tetracoordinate complexes of the general type L2MR2 are formed (L-2 symbolizes the tripod ligand in its bidentate chelate binding mode with two donors functions coordinating and the third one serving as a dangling arm; M = Ni-II, Pd-II, Pt-II). With nickel(II) as the d(8) species, tetrahedral or square-planar coordination geometries ensue, depending on the kind of donor functions and on the kind of co-ligands R. With palladium(II) and platinum(II) as the d(8) centres, square-planar coordination is observed throughout. The size of the chelate cycles varies from six to eight depending on the number of pyrazole entities within the cycle. The conformations and the conformational flexibility characterizing the chelate cycles have been analysed by X-ray analyses and by variable -temperature NMR. The classes of conformations observed may be formally reduced to chair, half-chair and twist-boat conformations. Dynamic exchange between these conformations is observed. In one case, the same compound forms two different types of crystals that differ by the conformation adopted by their chelate cycles. All compounds have been fully characterized by standard analytical techniques including X-ray structure analysis of 14 chelate compounds. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

A novel route to reactive In(I)-complexes [{(CO)(5)M}InX.THF] (M = Cr, X = Cl, Br; M = Mo, X = Cl; M = Mo, X = Cl) is described. With an excess of tetraphenylphosphonium halides [Ph4P]X (X = Cl, Br) these compounds react to give trihaloindate-complexes [Ph4P](2). [{(CO)(5)M}InX3] (M = Cr, X = Cl: 1a, X = Br: 1b; M = Mo, X = Cl: 2; M = W, X = Cl: 3), which contain indium in a formal oxidation state of +I. The reaction of equimolar ammounts of [{(CO)(5)Cr}InBr.THF] and bromide ions gives the bridged, dinuclear compound [{(CO)(5)Cr}InBr(mu(2)-Br)](2)(2-) (4). 4 is an intermediate in the reaction of [{(CO)(5)Cr}InBr.THF] to[{(CO)(5)Cr}InBr3](2-), 1b. Reaction of sodium-8-hydoxychinolate and [{(CO)(5)Cr}InCl.THF] produces the anion [{(CO)(5)Cr}In(oxinat)(2)](-) (5) which contains In(+I) in a square pyramidal coordination geometry. [{(CO)(5)Cr}GeI3](-), which is isoelectronic to 1-3, reacts with 8-hydroxyquinoline to produce [{(CO)(5)Cr}Ge(oxinat)(2)] (6) which is isoelectronic to 5. All new compounds have been characterized by X-ray analysis and by the usual analytic and spectroscopic techniques. (115)Ih NMR spectra of M(CO)(5) substituted indium species (M = Cr, Mo, W) are reported for the first time.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A novel route to reactive In(I)-complexes [{(CO) 5 M}InXּTHF] (M = Cr, X = Cl, Br; M = Mo, X = Cl; M = Mo, X = Cl) is described. With an excess of tetraphenylphosphonium halides [Ph 4 P]X (X = Cl, Br) these compounds react to give trihaloindate-complexes [Ph 4 P] 2 ּ [{(CO) 5 M}InX 3 ] (M = Cr, X = Cl: 1a, X = Br: 1b; M = Mo, X = Cl: 2; M = W, X = Cl: 3), which contain indium in a formal oxidation state of +I. The reaction of equimolar ammounts of [{(CO) 5 Cr}InBrּTHF] and bromide ions gives the bridged, dinuclear compound [{(CO) 5 Cr}InBr(μ 2 -Br)] 2 2- (4). 4 is an intermediate in the reaction of [{(CO) 5 Cr}InBrּTHF] to [{(CO) 5 Cr}InBr 3 ] 2- , 1b. Reaction of sodium-8-hydoxychinolate and [{(CO) 5 Cr}InClּTHF] produces the anion [{(CO) 5 Cr}In(oxinat) 2 ] - (5) which contains In(+I) in a square pyramidal coordination geometry. [{(CO) 5 Cr}GeI 3 ] - , which is isoelectronic to 1-3, reacts with 8-hydroxyquinoline to produce [{(CO) 5 Cr}Ge(oxinat) 2 ] (6) which is isoelectronic to 5. All new compounds have been characterized by X-ray analysis and by the usual analytic and spectroscopic techniques. 115 In NMR spectra of M(CO) 5 substituted indium species (M = Cr, Mo, W) are reported for the first time.

The disodium salt Na-2[{(CO)(5)Cr}(2)Pb(NO3)(2)], Na-2.1, which contains a lead center in a (4+2) coordination mode, reacts with tetraphenylphosphonium halides [Ph4P]X to give the tetrahedral compounds [Ph4P](2)[{(CO)(5)Cr}(2)PbX2] (X = Cl: 2a; X=Br: 2b; X = I: 2c). Substitution of the nitrate groups of Na-2.1 by alcoxides leads to binuclear compounds of the type [{(CO)(5)Cr}(2)Pb(mu(2)-OR)(2)Pb{Cr(CO)(5)}(2)](2-) (R = Et: 3a; R=n -Pr: 3b; R=i-Pr: 3c; R = Allyl: 3d). NMR experiments show that these dimeric compounds are in equilibrium with the monomeric species [{(CO)(5)Cr}(2)PbR](-). Trialkylphosphanes react with Na-2.1 to give the neutral phosphane complexes [{(CO)(5)Cr}(2)Pb(PR3)(2)] (R = Me: 4a; R = Et: 4b; R=n-Bu: 4c), which show dynamic behaviour in solution, All of the novel compounds have been characterized by X-ray analysis, as well as by the usual analytic and spectroscopic techniques. Pb-207-NMR data of Cr(CO)(5)-bound lead species are reported for the first time.

Improved syntheses of the known clusters [{(OC)(5)Cr}(6)Ge-6](2-)(1) and [{(OC)(5)Cr}(6)Sn-6](2-) (4) are reported. The new synthetic procedures also allow for the preparation of the molybdenum and tungsten derivatives [{(OC)(5)M}(6)Ge-6](2-) (M = Mo: 2; M = W: 3) and [{(OC)(5)M}(6)Sn-6](2-) (M = Mo: 5; M = W: 6). Compounds 1-6 were obtained as crystalline [Ph4P] salts, whose structures were determined for the whole series 1-6 by single-crystal X-ray analyses. All six [Ph4P] salts crystallise in tetragonal space groups, with the site group symmetries of the cluster core ranging from C-4h to D-4h The average octahedral symmetry of the cluster core in solution is evident from Sn-119 NMR spectroscopic data. Reversible one-electron oxidation of the dianions is suggested by cyclovoltammograms, while reduction is irreversible throughout. Electronic transitions which could be due to the cluster core were not found in the experimentally accessible energy range above 300 nm (below 4 eV). These findings indicate a high intrinsic stability of the precise electron clusters [Ge-6](2-) and [Sn-6](2-).

Dicyanomethanides, [RC(CN)(2)](-) (1(-)), are bridging ligands with an angular clamp-type shape. In the tripod/iron(II) system, [tripod = CH3C(CH2PPh2)(3)], they form binuclear species with three of the clamp-type ligands bridging two iron centers. An appropriate stoichiometric mixture of the tripod ligand, iron(II) salts and the dicyanomethanide ligand leads to the exclusive formation of [tripodFe{mu -NC-C(R)-CN)(3)-Fetripod](+) (3(+)), Altogether, seven constituent groups arrange themselves in this type of aggregate. The process of self-aggregation is distinctly modified by the presence of cyanide ions that may act as linear rod-type bridging ligands. Equimolar mixtures of tripod, iron(II) salts, dicyanomethanide ligands and cyanide form tetranuclear aggregates [(tripodFe)(3){mu -NC-C(R)-CN}(3){mu -CN}(3)FeX](+) (5(+)). In these species, the iron centers form a trigonal-pyramidal arrangement with three octahedrally coordinated low-spin tripodiron(II) entities in the basal plane and a tetrahedrally coordinated high-spin iron(II) at the apex. The iron centers in the basal plane are connected by mu (2)-bridging dicyanomethanide ligands. The apical iron center is coordinated by the N-termini of three cyano ligands, which complete the octahedral coordination of the basal low-spin iron(II) centers. The fourth, external ligand X at the tetrahedrally coordinated high-spin iron(H) apex can be varied, but in most cases it is found to be a terminally coordinated dicyanomethanide entity, Without counting this variable ligand X, thirteen constituent groups of four different types selectively aggregate to form the cage compounds 5(+.) While the dinuclear compounds 3 are diamagnetic, the tetranuclear species 5(+) have magnetic moments close to the spin-only value of mu (S.O.) = 4.9 mu (B), for tetrahedral high-spin iron(II). The Mossbauer spectra are in agreement with the description of 5(+) above, which contain three low-spin tripodiron(II) entities and one high-spin iron(II) center. The synthesis, spectroscopic data, cyclic voltammetric data, Mossbauer data and X-ray analytical data for a series of compounds of types 3(+) and 5(+) are presented in this paper.

Organometallic monocyanometalates [M-CN](-) (1(-)) [M = Cr(CO)(5) 1a(-), Cr(eta (6)-CF3C6H5)(CO)(2) 1b(-), Mn(eta (5)-CH3C5H4)(CO)(2) 1c(-)] produce tetrametallic (2(-)) and trimetallic (3) aggregates upon reaction with tripod and iron(II) salts [tripod = CH3C(CH2PPh2)(3)]. The tetranuclear compound [tripodFe{NC-M}(3)](-) (2(-)) [M = Cr(CO)(5)] or the trinuclear species [tripodFe(CO)[NC-M](2)] (3) [M = Cr(CO)(5) 3a, Cr(eta (6)-CF3C6H5)(CO)(2) 3b, Mn(Tl1-CH3C5H4)(CO)2 3c] can be selectively formed by following the appropriate reaction protocols. Organometallic dicyanometalates [NC-M'-CN](-) (4-) [M' = Mn(CO)(4) 4a(-), CpFe(CO) 4b(-), CpCo(CN) 4c(-)] react in a similar manner to give pentanuclear species [tripodFe[NC-M'-CN](3)Fetripod](+) (5(+)), - In compounds 2-and 3, two easily oxidizable organometallic groups are linked through a tripodFe(NC)(2) unit, while in 5(+) two tripodiron(II) entities are linked through a less readily oxidizable M'(CN)2 unit. For both types of compound, at least two distinct reversible oxidations are observed by cyclic voltammetry. The potentials at which these oxidations occur are characteristic of the terminal groups in each case. The potentials of the two consecutive oxidation steps are separated by between 150 and 350 mV The oxidation products of compounds 2-, 3, and 5(+) can hence be classified as class III mixed-valence species with comproportionation constants K-C of between 10(2) and 10(6). The extent of electronic coupling mediated by the M'(CN)(2) or M'(NC)(2) bridging entities is thus similar to that mediated by [RC(CN)(2)](-) bridging ligands in otherwise analogous compounds, for which Kc values of around 10(4) are observed. All the aforementioned compounds have been characterized by analytical and spectroscopic techniques, including cyclic voltammetry and UV/Vis spectroscopy. In addition, X-ray crystallographic data are reported for 2(-), 3a, 3b, 3c, and 5a(+).

Improved syntheses of the known clusters [{(OC)5Cr}6Ge6]2− (1) and [{(OC)5Cr}6Sn6]2− (4) are reported. The new synthetic procedures also allow for the preparation of the molybdenum and tungsten derivatives [{(OC)5M}6Ge6]2− (M = Mo: 2; M = W: 3) and [{(OC)5M}6Sn6]2− (M = Mo: 5; M = W: 6). Compounds 1−6 were obtained as crystalline [Ph4P] salts, whose structures were determined for the whole series 1−6 by single-crystal X-ray analyses. All six [Ph4P] salts crystallise in tetragonal space groups, with the site group symmetries of the cluster core ranging from C4h to D4h. The average octahedral symmetry of the cluster core in solution is evident from 119Sn NMR spectroscopic data. Reversible one-electron oxidation of the dianions is suggested by cyclovoltammograms, while reduction is irreversible throughout. Electronic transitions which could be due to the cluster core were not found in the experimentally accessible energy range above 300 nm (below 4 eV). These findings indicate a high intrinsic stability of the precise electron clusters [Ge6]2− and [Sn6]2−.

Na-2[M-2(CO)(10)] and GeCl4 react to give the compounds [(CO)(5)MGeCl3](-), 1a - 1c (M = Cr, Mo, W). From M(CO)(5) . THF and GeI2 in the presence of I- compounds [(CO)(5)MGeI3](-), 2a - 2c (M = Cr, Mo, W) are obtained. Compounds 2a and 2c react with alkoholates or thiolates to produce the cage compounds [{(CO)(5)Cr}(6)Ge-6(mu(2)-OH)(2)(mu(3)-O)(6)](2-), 3, [{(CO)(5)Cr}(6)Ge-6-(mu(2)-OEt)(2)(mu(2)-O)(4)(mu(3)-O)(2)](2-), 4, and [{(CO)(5)W}(6)Ge-6(OR)(2)(mu(2)-O)(2)(mu(3)-O)(4)](2-), 5. A structural pattern common to all these compounds is an idealised octahedral arrangement of six germanium atoms. Each of these six germanium atoms binds to an M(CO)(5) protective group. The germanium atoms are integrated in the core of the cage compounds by mu(3)-O, mu(2)-O and mu(2)-OH bridges. The co-ordination number of germanium is generally four, with one bond radiating to the external M(CO)(5) building block. In compounds 3 and 4 the remaining three germanium bonds radiate to the bridging groups within the cage. Compounds 5 contain two germanium centres which are linked to the cage by only two bonds and with the two remaining bonds to the external M(CO)(5) entity and to a terminal OR or SR group. Syntheses and structures of compounds 1 - 5 are described.

The starlike anion [{(CO)5Cr}3Pb]2− (1) with its trigonal-planar coordination at the central metal Pb and its short Pb−Cr bonds (273 pm; left-hand structure) is an organometallic equivalent of CO32−. The conjugated Pb-pπ–Cr-dπ bonding system in 1 corresponds to the conjungated pπ–pπ bonding system of the carbonate ion. The unsaturated character of 1 is revealed in the formation of the PMe3 adduct [{(CO)5Cr}3PbP(CH3)3]2− (2) (d(Cr−Pb)=282 pm; right-hand structure).

GeI2 reacts with [M-2(CO)(10)](2)- (M = Cr, W) leading to reductive coupling of two GeI2 units to produce the [Ge2I4](2-) ligands of [{(OC)(5)M}I2Ge-GeI2{M(CO)(5)}](2-) (1a and 2a). The [Ph4P] salts of these anions have been characterised by X-ray structure analyses as have the [Ph4P] salts of [{(OC)(5)M}C2Ge-GeCl2{M(CO)(5)}](2-) (1b and 2b) obtained from the iodo derivatives la and 2a by halide metathesis with [Ph4P]Cl. Treatment of GeI2 with [W-2(CO)(10)](2-) in the presence of 2,2'-bipyridine leads to [{(OC)(5)W}I2Ge-Ge(bipy){W(CO)(5)}] (3). The digermanium ligands in 1-3 contain germanium in the unconventional formal oxidation state +I. Reductive condensation of [{(OC)(5)Cr}I2Ge-GeI2{Cr(CO)(5)}](2-) (1a) by addition of [Cr-2(CO)(10)](2-) leads to the octahedral cluster [{(OC)(5)Cr}(6)Ge-6](2-) (4) in a yield of 40%. The sequence of reactions as reported describes the first systematic approach to the synthesis of [E-6](2-) clusters.

Pb22− forms the axle of the cartwheel-shaped compound [{(CO)5W}4Pb2]2− (see picture for structure). The Pb−Pb distance of 281 pm is the shortest of this kind observed so far, and is in agreement with the idea of a coordinatively stabilized diplumbaacetylide ion.

CH3C(CH2PPh2)(3)CoCl (1) is easily accessible from CH3C(CH2PPh2)(3)CoCl2 by reduction with activated zinc powder. Upon dehalogenation with TlPF6, 1 reacts with dienes to give [tripodCo(I)-(eta(4)-diene)](+) (2) The heterodienes acrolein and methyl vinyl ketone produce the analogous eta(4)-heterodiene compounds 3. When crotonaldehyde is used as the potential eta(4)-diene ligand, decarbonylation is observed leading to [tripodCo(I)-(CO)(2)](+) (4). Reaction of [tripodCo(ag)](BF4)(2) with allyl mercaptan produces [tripodCo(I)-(eta(4)-thioacrolein)](+) (3a) through dehydrogenation of the Ligand precursor. 1,2-Diketones such as benzil and phenanthrenequinone do not coordinate in a eta(4) fashion but rather generate eta(2)-coordinate enediolato ligands by an electron-transfer process, resulting in compounds of the type {tripodCo(III)-[eta(2)-RC(O)=C(O)R]}(+) (5). All the compounds have been characterized by standard analytical and spectroscopic techniques, including X-ray analysis in some cases. Compounds 4 and 5 show trigonal-bipyramidal coordination in the solid state, whereas the coordination polyhedra in compounds 2 and 3 are better described as square-pyramidal. While a minimum of two phosphorus resonances might be expected for each of these coordination geometries, only one time-averaged signal is normally observed. Only with the eta(4)-coordinated heterodienes acrolein, methyl vinyl ketone, and thioacrolein present in 3 is there a resolution of the signals of the three chemically distinct phosphorus nuclei at low temperatures. By P-31-NMR Line-shape analysis, the activation barriers for the rotational reorientation of the heterodienes are found to be around Delta H-not equal = 47 kJmol(-1) for all three compounds 3.