Terminal Carbonyl Ligands Research Articles

Chemistry of polynuclear metal complexes with bridging carbene or carbyne ligands. Part 73. Reactions of [WCo(CR)(CO)8](R = C6H4Me-4 or Me) with alkynes. Crystal structures of [WCo{µ-C(C6H4Me-4)C(Me)C(Me)C(O)}(CO)6(PPh3)] and [WCo{µ-C(Ph)C(Me)C(Me)C(OH)}(CO)6(PPh3)][BF4

In light petroleum at room temperature the compound [WCo(CR)(CO)8](R = C6H4Me-4) reacts with MeCCMe or EtCCEt to give the complexes [WCo{µ-C(R)C(R1)C(R1)C(O)}(CO)7](R1= Me or Et), whereas MeCCEt affords an inseparable mixture of the species [WCo{µ-C(R)C(R1)C(R2)C(O)}(CO)7](R1= Me, R2= Et; R1= Et, R2= Me). Reactions between [WCo(CMe)(CO)8] and MeCCMe or MeCCPh yield the compounds [WCo{µ-C(Me)C(Me)C(Me)C(O)}(CO)7] and [WCo{µ-C(Ph)C(Me)C(Me)C(O)}(CO)7], respectively. Treatment of these various products with PPh3 leads to substitution of a CO ligand on the cobalt atom by the phosphine, and the structure of one of these derivatives [WCo{µ-C(C6H4Me-4)C(Me)C(Me)C(O)}(CO)6(PPh3)] has been established by X-ray diffraction. The W–Co bond [2.737(1)A] is spanned by the C(C6H4Me-4)C(Me)C(Me)C(O) fragment, with the terminal carbon atoms of the chain σ bonded to the cobalt, and with the carbon atoms of the C(C6H4Me-4)C(Me)C(Me) moiety η3 co-ordinated to the tungsten. The latter carries four terminal CO groups, and the cobalt two such ligands and the PPh3 group [Co–P 2.237(2)A, P–Co–W 146.4(1)°]. Protonation of the complex [WCo{µ-C(Me)C(Me)C(Me)C(O)}(CO)7] with HBF4·Et2O affords the salt [WCo{µ-C(Me)C(Me)C(Me)C(OH)}(CO)7][BF4]. Three PPh3 derivatives of the alkyne-adducts of [WCo(CR)(CO)8](R = C6H4Me-4 or Me) have also been protonated, and the structure of the salt [WCo{µ-C(Ph)C(Me)C(Me)C(OH)}(CO)6(PPh3)][BF4] has been established by X-ray diffraction. The results confirm that in the latter the phenyl group is attached to the carbon atom at the end of the µ-C4 chain, and that this carbon atom and that of the C(OH) group are σ bonded to the cobalt. The tungsten atom is ligated by all four carbon atoms of the bridging ligand, by the cobalt atom [W–Co 2.660(1)A], and by four terminal carbonyl groups. The cobalt atom carries two terminal carbonyl ligands and the PPh3 group [Co–P 2.261(1)A] with the latter sited transoid to the W–Co bond [P–Co–W 144.8(1)°]. The n.m.r. data (1H, 13C-{1H}, 31P-{1H}) for the new compounds are reported and discussed in relation to their structures.

X-Ray crystal structures of two isomers of the hydrido–carbonyl anion [Re7(µ-H)C(CO)21]2–. The problematic existence of triply bridging hydrides in clusters containing interstitial main-group elements

The X-ray crystal analyses of two different salts of the hydrido–carbido carbonylrhenate anion [Re7HC(CO)21]2–, obtained by protonation of [Re7C(CO)21]3–, have shown the presence of two structural isomers, differing in the location of the hydride ligand. The [NEt4]+ salt (isomer a) crystallizes in the monoclinic system, space group P21/c(no. 14), with a= 10.168(3), b= 43.282(8), c= 11.505(3)Å, β= 91.72(2), and Z= 4. The [NEt4]+[C7H7]+ mixed salt (isomer b) crystallizes in the monoclinic system, space group P21(no. 4), with a= 12.007(4), b= 16.725(5), c= 12.004(4)Å, β= 105.79(2)°, and Z= 2. The gross features of the two structures are those of the parent anion [Re7C(CO)21]3–, where a carbon-centred monocapped octahedron of metal atoms is surrounded by 21 terminal carbonyl ligands, three for each metal. In both isomers, the hydride ligand has been indirectly located, on the basis of potential energy computations, as doubly bridging, on an edge of the basal triangle in isomer (2a), in accord with the idealized Cs symmetry of the anion, and on an inter-layer edge of the octahedron in the less symmetric (C1) isomer (2b). Carbon-13 and 1H n.m.r. analyses at low temperatures have also shown the presence in solution of two isomers, rapidly exchanging at room temperature. The ratio between the two isomers is temperature dependent and for this equilibrium ΔH⊖=–982 cal mol–1 and ΔS⊖=–1.7 cal–1 K–1 mol–1 have been estimated. A possible correspondence between the two solid-state and the two solution isomers is discussed. Simple geometric considerations, showin the ‘non-innocent’ nature of triply bridging hydrides in clusters containing interstitial main-group elements, X, are also presented. Depending on the metal size and on the geometry of the cage, anomalous H ⋯ X contacts can arise; in particular, for the wide family of octahedral carbido clusters, the lack of genuine examples of µ3-H co-ordination suggests a repulsive character of this H ⋯ C interaction.

Mixed-metal cluster derivatives of Co 3(μ 3-CPh)(CO) 9: Crystal structures of Co 3(μ 3-CPh)(CO) 9, HFeCo 2(μ 3-CPh)(CO) 9, and FeCo 2(μ-AuPPh 3)(μ 3-CPh)(CO) 9

The compound Co 3(μ 2-CPh)(CO) 9 ( 1) reacts with Na 2[Fe(CO) 4] in tetrahydrofuran to afford the mixed-metal hydride cluster HFeCo 2(μ 3-CPh)(CO) 9 ( 2) after acid treatment. The structures of 1 and 2 have been determined by X-ray diffraction. The cluster 1 crystallizes in space group P 1 ( Z = 4) with a 8.034(3), b 15.760(7), c 15.900(7) Å, α 101.11(3), β 100.99(3), γ 100.13(3)°, and the cluster 2 in the space group C2/ c ( Z = 8) with a 14.114(4), b 7.804(3), c 33.844(12) Å, β 96.13(3)°. The two structures are similar, with a M 3 triangle triply bridged by the alkylidyne carbon atom and with three terminal carbonyl ligands bonded to each metal atom. The hydride ligand in 2 could not be located from the difference Fourier maps, but the structure of its gold triphenylphosphine derivative FeCo 2(μ-AuPPh 3)(μ 3-CPh)(CO) 9 ( 3), which was synthesized in toluene by a direct reaction of 2 with Au(PPh 3)Cl in the presence of TlPF 6, indicates that the hydride ligand is in an edge bridging position. The cluster 3 crystallizes in space group Pna2 1 ( Z = 4) with a 34.617(6), b 8.793(2), c 11.226(2) Å.

Iridium-carbonyl clusters: VI. Mixed-metal clusters via metal-hydride coupling. Synthesis of CpMM′ 3(CO) 11 (M = Mo, W; M′ = Co, Ir) and the crystal structure of CpMoIr 3(CO) 11

The reaction of CpM(CO) 3H (M = Mo, W), with IrCl(CO) 2( p-toluidine) leads to the species CpMIr 3(CO) 11; reaction of CpM(CO) 3H with Co 4(CO) 12 produces the known species CpMCo(CO) 11 in high yield. The newly-reported species CpMoIr 3(CO) 11 has been subjected to an X-ray structural analysis. It crystallizes in the centrosymmetric orthorhombic space group Pbca (No. 61) with a 12.2830(15), b 13.5113(18), c 24.9418(30) Å, V 4139.3(9) Å 3 and Z = 8.Diffraction data were collected with a Syntex P2 1 automated diffractometer (Mo- K α radiation, 2θ 4.0–45.0°) and the structure was refined to R 5.4% for all 2421 data ( R 4.5% for those 2141 data above 3σ(¦ F 0¦)). CpMoIr 3(CO) 11 is neither isomorphous nor isostructural with the known species CpWIr 3(CO) 11 or CpMoCo 3(CO) 11. It differs by possessing three bridging carbonyl ligands which encircle one MoIr 2 face of the tetrahedral MoIr 3 cluster. The structure is completed by a Cp ligand on Mo and eight terminal carbonyl ligands (one on the molybdenum atom, three on the unique iridium atom and two each on the iridium atoms associated with the MoIr 2(μ-CO) 3 moiety). The molecule has approximate C s symmetry.

Molecular structure and fluxional behaviour of the iron-rhodium methoxymethylidyne cluster complex Fe 2 Rh(μ-H)(μ 3-COCH 3)(CO) 7(η-C 5H 5)

The complex Fe 2Rh(μ-H)(μ 3-COCH 3)(CO) 7(η-C 5H 5) prepared by treatment of Fe 3(μ-H)(μ-COCH 3)(CO) 10 with Rh(CO) 2 (η-C 5H 5), has been examined by single crystal X-ray diffraction. The compound crystallises in the monoclinic space group C2/ c (No. 15) with a 25.409(2), b 8.129(1), c 17.044(1) Å, β 103.744(6)°, V 3419.6(6) Å 3 and D c 2.02 g cm −3 for Z = 8 and M = 519.8. Data were collected for 2° ⩽ θ ⩽ 30° with graphite monochromated X-radiation (Mo- K α) using an Enraf-Nonius CAD4-F diffractometer. The structure was refined to R = 0.025 ( R itw = 0.037) for 3557 observed [ I ⩾ 3(σ I)], absorption corrected data. The complex contains an asymmetrically bonded methoxymethylidyne ligand capping an Fe 2Rh triangular face (Fe(1)-C(8) 1.863(3), Fe(2)-C(8) 1.881(3), Rh-C(8), 2.211(3) Å). The terminal carbonyl ligand on the rhodium atom shows slight semi-bridging interactions with the two iron atoms (Fe(1) … C(7) 2.888(4), Fe(2) … C(7), 2.769(4) Å, Rh-C(7)-O(7) 169.1(4)°. The iron—iron vector is spanned by a (directly located) μ-hydride ligand. Variable temperature 13C NMR studies reveal fluxional behaviour, including a temperature dependence both of the alkylidyne carbon chemical shift (δ 323.5 at +80°C, δ 319.2 at −90°C) and its 103Rh coupling constant ( 1 J(Rh-C) 23 Hz at −90°C, 26 Hz at +80°C). These data suggest an increased interaction of the ‘semi-μ 3’ alkylidyne ligand with the rhodium centre at higher temperatures, primarily associated with the highest energy fluxional process. Extended Hückel MO calculations on this complex allow a rationalisation of the ‘semi-μ 3’ nature of the COCH 3 group.

Structural studies on ruthenium carbonyl hydrides: X. Crystal structure of (μ-H)Ru 3(CO) 10(μ-SEt)

The complex (μ-H)Ru 3(CO) 10(μ-SEt) crystallizes in the centrosymmetric orthorhombic space group Pbca (No. 61) with a 17.361(2), b 12.804(4), c 17.484(3) Å, V 3886.5(14) Å 3 and Z = 8. Diffraction data (Mo- K α, 2θ = 4.0-45.0°) were collected with a Syntex P2 1 automated diffractometer and the structure was solved and refined to R 5.9% for 1800 reflections with |F o| > 3σ(| F o|) ( R4.1% for those 1413 reflections with |F 0| > 6σ(|F 0|)). The complex contains a triangular cluster of ruthenium atoms in which Ru(2) and Ru(3) are each linked to three terminal carbonyl ligands while Ru(1) is linked to four. Additionally Ru(2) and Ru(3) are bridged by a SEt ligand [Ru(2)S 2.389(4), Ru(3)S 2.391(4) Å and Ru(2)SRu(3) 73.0(1)°] and a hydride ligand. The di-bridged RuRu linkage (Ru(2)Ru(3) 2.843(1) Å is slightly longer than the non-bridged bonds (Ru(1)-Ru(2) 2.831(2) and Ru(1)Ru(3) 2.825(1) Å).

Structural studies on osmium carbonyl hydrides: XXXI. Crystal and molecular structure of CpWOs 3(CO) 9(μ-H)(μ-O)(μ-CHCH 2C 6H 4Me), a hydrido-alkylidene produced by hydrogenation of a μ 3-alkylidyne

The complex CpWOs 3(CO) 9(μ-H)(μ-O)(μ-CHCH 2C 6H 4Me), previously prepared by hydrogenation of CpWOs 3(CO) 9(μ-O)(μ 3-CCH 2C 6H 4Me), has been subjected to a single-crystal X-ray diffraction study. The complex crystallizes in the non-centrosymmetric monoclinic space group Cc( C s 4; No. 9) with a 14.1510(27), b 13.9257(22), c 13.3179(19) Å, β 92.023(13)°, V 2622.8(7) Å 3 and D(calcd) 3.06 g cm −3 for Z = 4 and mol. wt. 1206.8. Single-crystal X-ray diffraction data were collected with a Syntex P2 1 automated four-circle diffractometer and the structure was refined to R 3.5% for all 2476 independent observations (Mo- K α radiation, 2θ = 4.5–40.0°) and R 3.4% for those 2430 data with | F 0| > 3.0σ(| F 0|). The molecule contains a tetrahedral WOs 3 core associated with 60 valence electrons. Each osmium atom is associated with three terminal carbonyl ligands and the tungsten atom is linked to an η 5-C 5H 5 ligand. In addition, the μ-oxo ligand is involved in a WO: → Os bridge (in which WO(B) 1.737(17), Os(3)← :O(B) 2.167(16) Å and WO(B)Os(3) 96.0(7)°), the μ-hydride ligand spans the Os(1)Os(3) linkage and the μ-CHCH 2C 6H 4Me ligand bridges the WOs(2) linkage (WC(1) 2.068(26) and Os(2)C(1) 2.281(26) Å).

Synthesis and x-ray crystallographic characterization of (μ 3-Bi) 2Fe 3(CO) 9: A reformulation of Hieber's Bi 2Fe 5(CO) 20

When [HFe(CO) 4] − is treated first with NaBiO 3 and then dilute H 2SO 4, a complex mixture of neutral metal carbonyl clusters results, some of which can be extracted into petroleum ether. Upon prolonged standing the extract yields a precipitate which has been characterized by X-ray crystallography as Bi 2Fe 3(CO) 9. The complex Bi 2Fe 3(CO) 9 crystallizes in the centrosymmetric orthorhombic space group Cmcm ( D 2 h 17; No. 63) with a 10.616(2) Å, b 13.458(3) Å, c 11.347(3) Å, V 1621.1(7) Å 3 and Z = 4. Single-crystal X-ray diffraction data (Mo- K α, 2θ = 4.5–55.0°) were collected on a Syntex P2 1 four-circle diffractometer and the structure was refined to R F 5.4% and R W F 4.5% for all 1039 independent data ( R F 4.5% and R W F 4.5% for those 851 reflections with | F 0| > 3.0σ(| F 0|)). The molecule lies on a site of crystallographic C 2 v symmetry and is disordered. The individual molecules have a trigonal bipyramidal Bi 2Fe 3 core with the bismuth atoms occupying the apical sites (BiFe 2.617(2)–2.643(2) Å, FeFe 2.735(5)–2.757(5) Å). Each iron atom is linked to three terminal carbonyl ligands and the molecule has approximate C 3 h symmetry. The nine peripheral oxygen atoms are ordered and define a tricapped trigonal prism. The equatorial iron atoms are disordered with the two Fe 3 triangles mutually displaced by approximately 30°; the disordered ensemble has approximate D 3 h symmetry.

Synthesis of tetra-and penta-nuclear platinum–osmium carbido-cluster complexes from non-carbido-precursors: X-ray structural studies on [Os3Pt (µ-H)2(µ4-C)(CO)10{P(cyclo-C6H11)3}],[Os3Pt2(µ-H)2(µ5-C)(µ-CO)(CO)9{P(cyclo-C6H11)3}2], and [Os3Pt2(µ-H)(µ5-C)(µ-OMe)(µ-CO)(CO)9{P(cyclo-C6H11)3}2

The reaction between the compounds [Os3(µ-H)(µ3-CH)(CO)10] and [Pt(C2H4)2{P(cyclo-C6H11)3}] in toluene at 80 °C affords two cluster complexes, one containing a single platinum atom [Os3Pt(µ-H)2(µ4-C)(CO)10{P(C6H11)3}](1), and the other two platinum atoms, [Os3Pt2(µ-H)2(µ4-C)(µCO)(CO)9{P(C6H11)3}2](2). Both have been characterised by single-crystal X-ray diffraction studies. Compound (1) contains a triangle of osmium atoms [Os–Os 2.828(1)–2.906(1)Å], with the Pt atom bonded to one osmium [Os(2)–Pt 2.764(1)Å]. The carbido-carbon atom is irregularly bonded [1.90(2)–2.21(2)Å] to all four metal atoms. Each osmium atom is ligated by three terminal carbonyl ligands, whilst the platinum atom is bonded to a terminal carbonyl group and a P(cyclo-C6H11)3 moiety. Two hydrido-ligands bridge the Os(1)–Os(3) and Os(1)-Os(2) vectors. Compound (2) contains a square-planar arrangement comprising two osmium and two platinum atoms with the third osmium atom [Os(3)] bridging the Os(1)–Os(2) edge. The angle between the planes Os(1)Os(2)Pt(1)Pt(2) and Os(1)Os(2)Os(3) is 76.4°. The carbido-carbon atom is approximately equidistant [2.065(11)T–2.120(10)Å] from all five metal atoms, and the metal–metal separations are Os–Os 2.855(1)–2.917(1), Os–Pt 2.929(1)–2.935(1), and Pt(1)–Pt(2) 2.716(1)Å. Each osmium atom carries three terminal carbonyl ligands, whilst the platinum atoms are symmetrically bridged by a carbonyl ligand, and each is ligated by a P(cyclo-C6H11)3 group. The two hydrido-ligands bridge equivalent edges [Os(1)–Os(3) and Os(2)–Os(3)]. The n.m.r. data (1H, 13C-{1H}, and 31P-{1H}) are all consistent with the structures established in the solid state. Treatment of [Pt(C2H4)2{P(cyclo-C6H11)3}] with [Os3(µ-H)(µ-COMe)(CO)10] in toluene at ambient temperatures affords a pentanuclear metal complex [Os3Pt2(µ-H)(µ5-C)(µ-OMe)(µ-CO)(CO)9{P(C6H11)3}2](3), the structure of which was again determined by single-crystal X-ray diffraction. Two platinum and two osmium atoms are arranged in a ‘buckled’ square with the third osmium atom [Os(3)] metal–metal bonded only to Os(1). As in (2), the carbido–metal distances are approximately equal [2.075(22)–2.144(20)Å]. Moreover, the metal–metal distances Os–Os [2.813(1)–2.853(1)Å] and Os–Pt [2.891(1)–2.941(1)Å] are rather similar to those in (2) but the Pt–Pt distance [2.668(1)Å] is noticeably shorter. In (3) each osmium atom carries three terminal carbonyl ligands, while a single carbonyl group asymmetrically bridges the two platinum atoms [Pt–µ-CO 2.032(23) and 1.968(20)Å]. Each platinum bears a P(cyclo-C6H11)3 group, with the hydrido-ligand bridging the shorter of the two Pt–Os edges [Pt(1)–Os(1)]. The n.m.r. spectra are consistent with the structure established in the solid state though some dynamic behaviour is evident.

The preparation and X-ray crystal structure of W 3(μCN) 3(NO) 3(CO) 9

The nitrosation of Na[W(CO) 5CN] using amyl nitrite and sulphuric acid in a two phase water— diethyl ether system gives the trinuclear compound W 3(μCN) 3(NO) 3(CO) 9. A single crystal X-ray diffraction study showed that the compound contains a nine-membered ring of three tungsten atoms and three bridging cyanide groups. The terminal carbonyl and nitrosyl ligands were not distinguishable.

Übergangsmetall—methylen-komplexe: LIII. Synthese und struktur eines dreifach verbrückten cobalt-komplexes der μ-alkyliden-reihe

The μ-ethylidene complex (μ-CHCH 3)[(η 5-C 5Me 5)Co(μ-CO)] 2 (Me  CH 3) accessible along the diazoalkane route from [(η 5-C 5Me 5)Co(μ-CO)] 2 and diazoethane exhibits both in solution (IR spectroscopy) and in the crystalline state (X-Ray diffraction) a nearly C s -symmetrical structure with a triply bridged metal—metal bond. This compound thus differs from the parent μ-methylene complex of analogous composition, which latter compound exists as a mixture of the isomers A and B with terminal and edge-bridging carbonyl ligands, respectively (IR spectra, X-Ray diffraction). A structural comparison with closely related alkylidene- and carbonyl-bridged derivatives reveals a striking lack of correlation between metal—metal bond lengths and formal bond orders as they result from the EAN rule.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 28. Synthesis and X-ray crystal structures of the compounds [MoW2(µ-CR)2(µ-CO)2(CO)4(η-C5H5)2] and [AuW2(µ-CR)2(CO)4(η-C5H5)2][PF6](R = C6H4Me-4)

The compound [W(CR)(CO)2(η-C5H5)](R = C6H4Me-4) reacts readily with the complexes [M(CO)3(NCMe)3](M = Mo or W) in hexane at reflux to afford the trimetal compounds [MW2(µ-CR)2(µ-σ:η2-CO)2(CO)4(η-C5H5)2], n.m.r. and i.r. data for which are reported. The molybdenum–ditungsten compound was fully characterised structurally by a single-crystal X-ray diffraction study. It comprises a bent W–Mo–W spine [148.2(2)°] with the Mo–W bonds [2.938(1)A] bridged by CC6H4Me-4 groups. The Mo atom carries two terminal carbonyl ligands; the bisector of the angle between these is an approximate axis of two-fold symmetry for the molecule as a whole. The two molybdenum–tungsten–carbene ring systems are not coplanar, but are twisted relative to one another so that the two planes are nearly orthogonal. The Mo–W and Mo–C(carbene) bonds do not form a pseudo-tetrahedral group, however, because of the presence of two cis carbonyl ligands on the central Mo atom. An especially interesting feature is that, of the two terminal carbonyl ligands on each tungsten atom, one is η2-bonded to the central molybdenum atom. The significance of this is discussed. Crystals are triclinic, space group P(no. 2), and the structure has been refined to R= 0.038 for 3 711 intensities measured to 2θ= 55° at 210 K. Treatment of chloro(tetrahydrothiophene)gold(I) with [W(CR)(CO)2(η-C5H5)] in tetrahydrofuran in the presence of TIPF6 affords the salt [AuW2(µ-CR)2(CO)4(η-C5H5)2][PF6], while [Ag(NCMe)4][BF4] and [W(CR)(CO)2(η-C5H5)] give [AgW2(µ-CR)2(CO)4(η-C5H5)2][BF4]. The spectroscopic data (i.r. and n.m.r.) for these gold and silver compounds are discussed, and the structure of the former has been established by X-ray diffraction. The cation has a bent W–Au–W spine [162.8(1)°] with the Au–W bonds [2.752(1)A] bridged by the CC6H4Me-4 groups. The dihedral angle between the two dimetallacyclopropene rings is 62°. The tungsten atoms carry η-C5H5 groups and two terminally bound CO ligands. Crystals are orthorhombic, space group Pnna(no. 52), and the structure has been refined to R= 0.050 for 1 654 reflections measured to 2θ= 50° at 200 K.

The synthesis of some bi- and tri-metallic clusters containing rhodium; X-ray crystal structures of [MoRh3(µ3-CO)3(CO)3(PPh3)3(η-C5H5)]·CH2Cl2and [MoRhPt(µ-CO)2(µ-PPh2)(µ-1-σ:1–2-η-C6H5)-(PPh3)2(η-C5H5)

Treatment of the complexes [MRh(µ-CO)2(CO)(PPh3)2(η-C5H5)](M = Mo or W) with [Fe2(CO)9] in tetrahydrofuran at room temperature affords the tetranuclear 56 valence-electron cluster compounds [MRh3(µ3-CO)3(CO)3(PPh3)3(η-C5H5)]. The structure of the molybdenumtrirhodium species, which crystallises with a molecule of CH2Cl2, has been established by a single-crystal X-ray diffraction study. The metal-atom core approximates to a regular tetrahedron, with Rh–Rh separations 2.710(1)–2.729(1)A, and Mo–Rh distances 2.764(1)–2.778(1)A. The molybdenum atom carries the η-C5H5 ligand, and a CO and a PPh3 group are attached to each rhodium atom. These terminal carbonyl ligands are directed below the Rh3 triangle, and the three ligated phosphorus atoms lie above. In addition, a CO group triply bridges each of the MoRh2 faces of the cluster. The reaction between [MoRh(µ-CO)2(CO)(PPh3)2(η-C5H5)] and [Pt(C2H4)(PPh3)2] in tetrahydrofuran at 50 °C yields the complexes [MoPt(µ-PPh2)(CO)2(PPh3)2(η-C5H5)] and [MoRhPt(µ-CO)2(µ-PPh2)(µ-1-σ:1–2-η-C6H5)(PPh3)2(η-C5H5)]. The structure of the 44 valence-electron trimetal compound has been determined by X-ray diffraction. The three metal atoms form a triangle [Mo–Pt 2.958(1), Mo–Rh 2.619(1), and Pt–Rh 2.662(1)A], the molybdenum atom carries the η-C5H5 ligand, and the platinum and rhodium atoms are co-ordinated by PPh3 groups. The three edges of the metal triangle are bridged; the Mo–Rh edge by two CO ligands, the Mo–Pt by PPh2, and the Rh–Pt by a C6H5 group. One carbon of the phenyl group is σ bonded to platinum and together with an adjacent carbon is η2-co-ordinated to the rhodium. The n.m.r. data (1H, 13C-{1H}, and 31P-{1H}) for the new compounds are reported and discussed.

Synthesis of mixed-metal clusters by the reaction of the unsaturated cluster [Os3(µ-H)2(CO)10] with transition-metal hydrides: the X-ray crystal structures of [Os3H3(CO)10{Cu(PPh3)}] and [Os3H3(CO)11{Ir(PPh3)}

The co-ordinatively unsaturated dihydride cluster [Os3(µ-H)2(CO)10] reacts with the transition-metal hydrides [{CuH(PPh3)}6], [IrH(CO)2(PPh3)2], [RhH(CO)(PPh3)2], and [NiH(Cl)({P(C6H11)3}2] to give the mixed-metal clusters [Os3H3(CO)10{Cu(PPh3)}](1), [Os3H3(CO)11{Ir(PPh3)}](2), [Os3H3(CO)11{Rh(PPh3)}](3), and [Os3H2(CO)10{Ni[P(C6H11)3]}](4). These complexes have been characterized by i.r. and n.m.r. spectroscopy, and the structures of (1) and (2) have been established by single-crystal X-ray analysis. In complex (1) the three Os atoms lie at the vertices of an isosceles triangle the long edge [3.026(3)A] of which is bridged by the Cu atom of the Cu(PPh3) ligand. The hydrides were not located directly but evidence suggests that they bridge the long Os–Os bond and the two Os–Cu bonds. The carbonyl arrangement is similar to that observed in [Os3H2(CO)10]. In complex (2) the Ir atom caps the Os3 triangle to form a distorted tetrahedral metal framework. The three Ir–Os bond lengths [2.759(3), 2.789(2), and 2.917(3)A] show considerable variation. The distribution of the eleven terminal carbonyl ligands and the phosphine group, which is co-ordinated to the Ir atom, indicates that the three hydrides bridge the two longer Os–Os bonds, and the longest Os–Ir bond. From the spectroscopic data the overall geometry of complex (3) is closely related to that of (2), while (4) has a tetrahedral metal arrangement with hydrides and carbonyl groups bridging Os–Os and Os–Ni edges.

Photoinduced formation of phosphido-bridged clusters derived from Ru 3(CO) 9(PPh 2H) 3. Crystal and molecular structure of Ru 3(μ-H)(μ-PPh 2) 3(CO) 7

The new complex Ru 3(CO) 9(PPh 2H) 3 (I) was prepared by the direct thermal reaction of Ru 3(CO) 12 with PPh 2 H and was spectroscopically characterized. Irradiation of I with λ ≥ 300 nm leads to the formation of Ru 2(μ-PPh 2) 2(CO) 6 (II) and three new phosphido-bridged complexes, Ru 3(μ-H) 2(μ-PPh 2) 2(CO) 8 (III), Ru 3(μ-H) 2(μ-PPh 2) 2(CO) 7(PPh 2H) (IV) and Ru 3(μ-H)(μ-PPh 2) 3(CO) 7 (V). These complexes have been characterized spectroscopically and Ru 3 (μ-H)(μ-PPh 2) 3(CO) 7 by a complete single crystal X-ray structure determination. It crystallizes in the space group P2 1/ n with a 20.256(3), b 22.418(6), c 20.433(5) Å, β 112.64(2)°, V 8564(4) Å 3, and Z = 8. Diffraction data were collected on a Syntex P2 1 automated diffractometer using graphite-monochromatized Mo-K α radiation, and the structure was refined to R F 4.76% and R w F 5.25% for the 8,847 independent reflections with F 0 > 6σ(F 0). The structure consists of a triangular array of Ru atoms with seven terminal carbonyl ligands, three bridging diphenylphosphido ligands which bridge each of the RuRu bonds, and the hydride ligand which bridges one RuRu bond. Complex IV was also shown to give V upon photolysis and is thus an intermediate in the photoinduced formation of V from I.

Crystal structure of a complex with a substituted methylene ligand bound to a triosmium cluster: Os 3(CO) 10(μ-CO)(μ-CHSiMe 3)

The complex Os 3(CO) 10(μ-CO)(μ-CHSiMe 3) crystallizes in the centrosymmetric monoclinic space group P2 1/ n with a 15.463(9), b 9.352(3), c 16.757(7) Å, β 107.38(4)°, V 2312.6(17) Å 3 and Z = 4. Diffraction data (Mo- K α, 2θ(max) = 40°) were collected on a Syntex P2 1 diffractometer and the structure was refined to R F 4.2% and R wF 4.8% for all 2170 data ( R F 3.3%, R wF 4.5% for those 1914 data with | F 0|=>3σ(| F 0|)). The molecule contains a triangular array of osmium atoms in which Os(2) and Os(3) are each associated with three terminal carbonyl ligands, while Os(1) is associated with four terminal carbonyls. Atoms Os(2) and Os(3) are mutually bridged by a nearly symmetrical bridging carbonyl ligand (Os(2)-C(1) 2.186(17) Å; Os(3)-C(1) 2.101(17) Å) and a bridging CHSiMe 3 ligand with Os(2)-C(2) 2.159(15) and Os(3)-C(2) 2.188(16) Å. The structure is an ordered analogue of the species Os 3(CO) 10(μ-CO)(μ-CH 2) which suffers from a four-fold disorder.

Structural chemistry of binuclear metal centres. Crystal and molecular structures of the µ-vinyl and µ-methylcarbene complexes [Fe2(CO)2(µ-CO)(µ-CHCH2)(η-C5H5)2][BF4] and [Fe2(CO)2(µ-CO)(µ-CHMe)(η-C5H5)2

Protonation of [Fe2(CO)(µ-CO){µ-C(O)C2H2}(η-C5H5)2] with HBF4·OEt2 affords the µ-vinyl cation of [Fe2(CO)2(µ-CO)(µ-CHCH2)(η-C5H5)2][BF4](1 ). Reaction of (1) with NaBH4 yields the µ-carbene complex [Fe(CO)2(µ-CO)(µ-CHMe)(η-C5H5)2](2). Both (1) and (2) have been studied using X-ray diffraction methods. Complex (1) crystallizes in the orthorhombic space group Pnma(no. 62) with unit-cell dimensions a= 12.149(4), b= 10.745(3), c= 12.470(3)A, and Z= 4. The structure has been refined to R 0.083 for 1 281 intensity data, and consists of isolated [Fe2(CO)2(µ-CO)(µ-CHCH2)(µ-C5H5)]+ cations and [BF4]– anions, each lying on sites of crystallographic mirror symmetry. The cations show orientational disorder, with the methylene function of the µ-vinyl group occupying two sites of occupancy 0.5 related by the mirror plane. The iron atoms are singly bonded to one another and are separated by 2.595(2)A, being bridged both by vinyl and carbonyl ligands. In addition each iron atom carries one terminal carbonyl ligand and an η5-cyclopentadienyl moiety. The molecular cation adopts a conformation which places the cyclopentadienyl ligands mutually cis with the vinylic methylene anti to these groups. Complex (2) crystallizes in the orthorhombic space group Pnma(no. 62) with unit-cell dimensions a= 15.096(9), b= 14.414(8), c= 6.336(4)A, and Z= 4. The structure has been refined to R 0.046 for 1 631 intensity data, and consists of isolated molecules of [Fe2(CO)2(µ-CO)(µ-CHCH3)(η-C5H5)2] each lying on sites of crystallographic mirror symmetry. The Fe–Fe distance is 2.520(2)A and is indicative of a bond order of unity, the bond being bridged both by methylcarbene and carbonyl ligands. In addition each iron atom carries one terminal carbonyl ligand and an η5-bound cyclopentadienyl moiety. The conformation of the molecule of (2) is similar to that of (1) having mutually cis cyclopentadienyl groups and the methyl group oriented anti to these.

Chemistry of the metal carbonyls. Part 82. Synthesis of complexes with bonds between rhodium and the sub-group 6 metals; X-ray crystal structure of [CrRh(µ-CO)2(CO)2(η-C5Me5)(η-C6H6)

Irradiation with u.v. light of mixtures of [Cr(CO)3(η-arene)](arene = C6H6, C6H3Me3-1,3,5, or C6Me6) and [Rh(CO)2(η-C5Me5)] in tetrahydrofuran (thf) affords the dimetal compounds [CrRh(µ-CO)2(CO)2(η-C5Me5)(η-arene)]; the complex [CrRh(µ-CO)2(CO)2(η-C9H7)(η-C6H3Me3-1,3,5)](C9H7= indenyl) has been similarly prepared from [Rh(CO)2(η-C9H7)] and [Cr(CO)2(thf)(η-C6H3Me3-1,3,5)]. The i.r. and n.m.r. data for these species are reported and discussed in relation to the molecular structure of [CrRh(µ-CO)2(CO)2(η-C5Me5)(η-C6H6)] which has been established by an X-ray diffraction study : crystals are orthorhombic, space group Pnma(no. 62), in a unit cell with a= 10.635(4), b= 11.690(3), c= 15.275(5)A, and Z= 4. The structure has been refined to R 0.051 from 1 584 independent intensities [I 2.5σ(I)]. The molecule is constrained crystallographically to Cs, symmetry, the mirror plane being defined by the terminal carbonyl ligand on each metal atom, the Rh–Cr bond [2.757(2)A], and the centroids of the two cyclic ligands. The pentamethylcyclopentadienyl ligand on the Rh atom is in a trans relationship to the η6-benzene ligand on the Cr atom, and both lie astride (perpendicular to) the mirror plane. The two other carbonyl ligands are terminal to the Cr atom, but are strongly semi-bridging to the Rh atom [Cr–C 1.902(7), Rh–C 2.200(7)A], and define planes which are nearly perpendicular to the mirror plane. Some distortion of the Rh–C5 geometry towards a ‘diolefin’ type attachment is noted and discussed. Reaction of the compounds [M(CO)5(thf)](M = Cr or W) and [Mo(NCMe)(CO)5] with [Rh2(µ-CO)2(η-C5Me5)2] affords the heteronuclear trimetal cluster complexes [MRh2(µ-CO)2(CO)5(η-C5Me5)2] in high yield. These species may be regarded as molecules in which an M(CO)5 fragment, isolobal with CH2, is ‘complexed’ by an ethylene-like [Rh2(µ-CO)2(η-C5Me5)2] fragment.

Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 21. Reactivity of µ-(methoxy-p-tolylmethylene) and µ-(p-tolylmethylidyne) groups at a platinum–tungsten centre. X-Ray crystal structure of [PtW{µ-C(OMe)C6H4Me-4}(µ-Ph2PCH2PPh2)(CO)5

Treatment of [PtW{µ-C(OMe)R}(CO)5(cod)](R = C6H4Me-4, cod = cyclo-octa-1,5-diene) with dppm (Ph2PCH2PPh2) affords [PtW{µ-C(OMe)R}(µ-dppm)(CO)5](1), the structure of which has been established by X-Ray crystallography. As expected, the platinum–tungsten bond [2.818(3)A] is spanned by the dppm and C(OMe)R ligands. The five-membered ring involving the chelating phosphine and the two metal atoms adopts an envelope conformation with one of the P atoms lying out of the plane. The [graphic omitted] ring is asymmetric [Pt–C 1.97(3), W–C 2.49(3)A]. The platinum atom carries one terminal carbonyl ligand and the tungsten atom four, making the co-ordination at these two metal centres essentially square planar and octahedral, respectively. Compound (1) reacts with HBF4·OEt2 to yield the salt [PtW(µ-CR)(µ-dppm)(CO)5][BF4], and with BBr3 to give [PtWBr(µ-CR)(µ-dppm)(CO)4], but the latter is better prepared by treating the salt with NEt4Br. Reactions of the complex [PtW(µ-CR)(µ-dppm)(CO)5][BF4] with several nucleophilic reagents have been investigated leading to the synthesis of the compounds [PtW(µ-CRR′)(µ-dppm)(CO)5](R′= Me, H, CCBu1, or SC6H4Me-4) and [PtW{µ-C(η2-C5H5)R}(µ-dppm)(CO)4]. The n.m.r. data (1H, 31P-{1H}, 13C-{1H}, and 195Pt-{1H}) for the new compounds are reported and discussed.

X-Ray and neutron diffraction studies on [Ru4(CO)8(µ-H)4{P(OCH3)3}4] at 293 and 20 K : characterisation of the vibrational behaviour of two-co-ordinate hydrogen atoms

X-Ray and neutron diffraction studies on the complex [Ru4(CO)8H4{P(OCH3)3}4] have been carried out at 293 and 20 K respectively. At room temperature the structure is monoclinic, space group P21/c with cell parameters a= 15.700(4), b= 11.775(3), c= 21.331(5)Å, β= 100.49(4)°, and Z= 4. At 20 K the structure is triclinic, space group P with a= 15.371(3), b= 11.508(2), c= 21.079(3)Å, α= 90.07(1), β= 100.09(1), γ= 92.09(2)°, and Z= 4. The X-ray determination shows the molecular structure to consist of distorted tetrahedral Ru4 units substituted so that each ruthenium atom is bound to two terminal carbonyl ligands, one trimethyl phosphite ligand, and two hydride ligands. Despite positional disorder affecting four methoxy groups, the µ-hydride ligands spanning four edges of the Ru4 tetrahedron were located and refined. At low temperature the structure is ordered with two molecules per asymmetric unit, and the neutron analysis provides precise characterization of the molecular structure. All the Ru–H–Ru bridges are symmetrical with mean Ru–H = 1.773(2)Å and show closed three-centre two-electron bonding. Final agreement indices are R(F)= 0.043, R′(F)= 0.038 for 6 647 unique X-ray data, and R(F)= 0.048, R′(F)= 0.038 for 8 601 unique neutron data. Analysis of the vibrational behaviour of the hydride hydrogen atoms as determined in the neutron analysis indicates that this motion is consistent with these hydrogens residing in a single-minimum potential well provided by symmetric three-centre, two-electron Ru–H–Ru interactions.