pyS Ligand Research Articles

Compounds of the types Pn(pyS)3 (Pn = P, As, Bi; pyS: pyridine-2-thiolate) and Sb(pyS) x Ph3–x (x = 3–1); molecular structures and electronic situations of the Pn atoms

Abstract The compounds Pn(pyS)3 (Pn = P, As, Sb, Bi) were synthesized from the respective chloride (Pn = P, As, Sb) or nitrate (Bi), pyridine-2-thiol (pySH) and triethylamine (NEt3) as a supporting base in THF (P, Sb), CHCl3 (As) or methanol (Bi). Sb(pyS)3 was also obtained from the reaction of SbCl3 with LipyS (prepared in situ) in methanol. The compounds Sb(pyS)2Ph and Sb(pyS)Ph2 were prepared in a one-pot reaction starting from SbCl3 and SbPh3 (1:1 ratio). Upon Cl/pyS substitution, the resulting reaction mixture allows for a facile separation of the products in hot hexane. P(pyS)3 and As(pyS)3 crystallize isostructurally to the reported structure of Sb(pyS)3 with κ-S-bound pyS ligands. These crystal structures feature close Pn···Pn contacts which are most pronounced for the arsenic derivative. Bi(pyS)3 adopts a different molecular structure in the solid state, which features two chelating (κ 2-S,N-pyS) ligands and a κ-S-bound ligand. The presence of N→Bi interactions between the nitrogen atom of the κ-S-pyS ligand and the Bi atom of another molecule renders this structure a polymer chain along the crystallographic b axis with Bi⋅⋅⋅Bi van-der-Waals contacts. The structures of this set of Pn(pyS)3 compounds were also studied in solution using 1H NMR spectroscopy, revealing equivalent pyS ligands in discrete Pn(pyS)3 molecules. The molecular structure of Sb(pyS)Ph2 was optimized by quantum chemical methods, and a comparison with the structures reported for the other Sb/pyS/Ph combinations reveals Sb(pyS)2Ph to feature the strongest Sb···N interactions with the κ-S-pyS ligand. The results of 1H NMR spectroscopic investigations of the compounds Sb(pyS) x Ph3–x (x = 3–0) suggest the Ph protons in ortho position to be incorporated into intramolecular C–H···S contacts for x = 2 and 1. Natural localized molecular orbital (NLMO) calculations were employed in order to gain insights into the electronic situations of the Pn atoms and Pn–R bonds (R = S, C), especially for the effects caused by formal substitution of Pn in the compounds Pn(pyS)3 and the ligand patterns in the compounds Sb(pyS) x Ph3–x (x = 3–0). For the latter series of compounds, the electronic situation of the Sb atom was further studied by 121Sb Mössbauer spectroscopy, providing a correlation between the calculated electron density at Sb [ρ(0)] and the experimentally observed isomer shift δ. The missing link between group 15 and group 13 metal compounds of the type M(pyS)3, compound Al(pyS)3, was synthesized in this work. In the solid state (confirmed crystallographically), the mer isomer of this tris-chelate complex with distorted octahedral Al coordination sphere was found. This coordination mode was confirmed for the solution state (CDCl3) by 1H and 13C NMR spectroscopy at T = −40 °C.

Synthesis and Oxidation of a Paddlewheel-Shaped Rhodium/Antimony Complex Featuring Pyridine-2-Thiolate Ligands.

The paddlewheel-shaped complex [Sb(μ-pyS)4 Rh]2 (1) (pyS- = 2-S-C5 H4 N- ) was synthesized from [Rh(pyS)(cod)]2 (cod=1,5-cyclooctadiene) and Sb(pyS)3 . Upon oxidation with ONMe3 , the complex [(μ-O)Sb(μ-pyS)3 Rh(κ2 -pyS)]2 (2) is formed. Both 1 and 2 form dimers and feature short Rh-Sb bonds and bridging pyS ligands. 121 Sb Mössbauer spectro- scopy and computational studies were employed to elucidate the Rh-Sb bonding in 1 and 2. Both covalent (Rh-Sb, X-type Sb ligand) and dative (Rh→Sb, Z-type; Rh←Sb L-type Sb ligand) interactions have to be considered for the description of their bonding situations.

Mixed-valence state of symmetric diruthenium complexes: synthesis, characterization, and electron transfer investigation

Complexes of the type {[(pyS)Ru(NH(3))(4)](2)-μ-L}(n), where pyS = 4-mercaptopyridine, L = 4,4'-dithiodipyridine (pySSpy), pyrazine (pz) and 1,4-dicyanobenzene (DCB), and n = +4 and +5 for fully reduced and mixed-valence complexes, respectively, were synthesized and characterized. Electrochemical data showed that there is electron communication between the metal centers with comproportionation constants of 33.2, 1.30 × 10(8) and 5.56 × 10(5) for L = pySSpy, pz and DCB, respectively. It was also observed that the electronic coupling between the metal centers is affected by the π-back-bonding interaction toward the pyS ligand. Raman spectroscopy showed a dependence of the intensity of the vibrational modes on the exciting radiations giving support to the assignments of the electronic transitions. The degree of electron communication between the metal centers through the bridging ligands suggests that these systems can be molecular wire materials.

Reaction of molybdenum hexa‐carbonyl with mercapto‐pyridine (PySH) or mercapto‐pyridine oxide (PyS→O) and crystal structure of [Et4N][Mo2(PyS)3(CO)5

AbstractMixed‐valence dinuclear molybdenum complex [Et4N][ Mo2(PyS)3(CO)5] (1) (PyS=C5H4NS) has been synthesized and characterized by crystallography. 1 crystallizes in monoclinic system with space group P21/c with a= 1.5769(11) nm, b= 1.3144(5) nm, c= 1.6935(10) nm; β= 111.20(4)o; V=3.2724 nm3; Z=4, Dc=l.61 g/cm3, μ= 9.7 cm−' and F(000)=1600. The final R=0.054 and wR=0.073, for 1811 observed reflection with I >3@I). In compound 1, one chelating PyS ligand and two bridging PyS ligands are 3‐electron and 5‐electron donors, respectively, and two molybdenum atoms are located in different coordination environments resulting in mixed‐valence state. The reaction mechanism of Mo(CO)6 with PySH and PyS→O (C5H5SN→O) was investigated and two reaction pathways were proposed.

Syntheses, reactivity, and crystal structures of molybdenum complexes with pyridine-2-thionate (pyS)-containing ligands: crystal structures of [Mo(eta(3)-C(3)H(5))(CO)(2)](2)(mu-eta(1),eta(2)-pyS)(2), exo-[Mo(eta(3)-C(3)H(5))(CO)(eta(2)-pyS)(eta(2)-dppe)], [Mo(CO)(3)(eta(1)-SC(5)H(4)NH)(eta(2)-dppm)], and [Mo(CO)(eta(2)-pyS)(2)(eta(2)-dppm)

The doubly bridged pyridine-2-thionate (pyS) dimolybdenum complex [Mo(eta(3)-C(3)H(5))(CO)(2)](2)(mu-eta(1),eta(2)-pyS)(2) (1) is accessible by the reaction of [Mo(eta(3)-C(3)H(5))(CO)(2)(CH(3)CN)(2)Br] with pySK in methanol at room temperature. Complex 1 reacts with piperidine in acetonitrile to give the complex [Mo(eta(3)-C(3)H(5))(CO)(2)(eta(2)-pyS)(C(5)H(10)NH)] (2). Treatment of 1 with 1,10-phenanthroline (phen) results in the formation of complex [Mo(eta(3)-C(3)H(5))(CO)(2)(eta(1)-pyS)(phen)] (3), in which the pyS ligand is coordinated to Mo through the sulfur atom. Four conformational isomers, endo,exo-complexes [Mo(eta(3)-C(3)H(5))(CO)(eta(2)-pyS)(eta(2)-diphos)] (diphos = dppm, 4a-4d; dppe, 5a-5d), are accessible by the reactions of 1 with dppm and dppe in refluxing acetonitrile. Homonuclear shift-correlated 2-D (31)P((1)H)-(31)P((1)H) NMR experiments of the mixtures 4a-4d have been employed to elucidate the four stereoisomers. The reaction of 4 and pySK or [Mo(CO)(3)(eta(1)-SC(5)H(4)NH)(eta(2)-dppm)] (6) and O(2) affords allyl-displaced seven-coordinate bis(pyridine-2-thionate) complex [Mo(CO)(eta(2)-pyS)(2)(eta(2)-dppm)] (7). All of the complexes are identified by spectroscopic methods, and complexes 1, 5d, 6, and 7 are determined by single-crystal X-ray diffraction. Complexes 1 and 5d crystallize in the orthorhombic space groups Pbcn and Pbca with Z = 4 and 8, respectively, whereas 6 belongs to the monoclinic space group C2/c with Z = 8 and 7 belongs to the triclinic space group Ponemacr; with Z = 2. The cell dimensions are as follows: for 1, a = 8.3128(1) A, b = 16.1704(2) A, c = 16.6140(2) A; for 5d, a = 17.8309(10) A, b = 17.3324(10) A, c = 20.3716(11) A; for 6, a = 18.618(4) A, b = 16.062(2) A, c = 27.456(6) A, beta = 96.31(3) degrees; for 7, a = 9.1660(2) A, b = 12.0854(3) A, c = 15.9478(4) A, alpha = 78.4811(10) degrees, beta = 80.3894(10) degrees, gamma = 68.7089(11) degrees.

Reactions of [Mn2(μ-pyS)2(CO)6] with bidentate N-donor ligands: Crystal structure of [Mn(η1-pyS)(bipy)(CO)3] (bipy = 2,2'-bipyridyl, pySH = pyridine-2-thiol)

The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 equivalents of 2,2′-bipyridyl (bipy), 1,10-phenanthroline (phen), and ethylenediamine (en) to give the corresponding monomeric complexes [Mn(η1-pyS)(bipy)(CO)3] (2), [Mn(η1-pyS)(phen)(CO)3] (3), and [Mn(η 1-pyS)(en)(CO)3] (4). The pyS ligand in these complexes acts as a monodentate, two-electron donor ligand, which coordinates to manganese through the sulfur atom. This is confirmed by an X-ray structure determination of 2, which contains two structural isomers in the asymmetric unit. Crystals of this compound are the monoclinic, space group P2 1/c, a = 21.593(4), b = 10.463(2), c = 16.385(3) A, β = 102.468(13)°, V = 3614.5(12) A3, and Z = 8. The three CO groups are facially distributed in both isomers, but the relative positions of the pyS and bipy ligands are different.

Self-assembled monolayers formed by [M(CN)5(pyS)]4−(M = Fe, Ru) on gold: a comparative study on stability and efficiency to assess the cyt c heterogeneous electron transfer reaction

A comparative study involving SAMs formed by [(CN)5M(pyS)]4− inorganic complexes (M = Fe, Ru; pyS = 4-mercaptopyridine) on gold (MpySAu) has been performed. The characterization data for these complexes suggests that the ruthenium complex exhibit a greater π-back-bonding effect that more strongly stabilizes the MpyC–S bond, thus anticipating its application as a SAM that would better enhance the gold adlayer stability than the iron complex. The MpySAu electrodes were characterized by SERS and electrochemical (LSV) techniques. The ex situ SERS spectra data for both SAMs suggest a σ interaction between the gold and sulfur atom of the complexes, inducing a perpendicular arrangement in relation to the surface. The spectra performed for freshly prepared MpySAu adlayers did not show any significant changes that would reflect the degradation of the adlayer. The LSV desorption curves of the SAMs indicate a better enhancement in the C–S bond strength of the pyS ligand when coordinated to the [Ru(CN)5]3− moiety. Comparatively to the data obtained for the desorption process of the pyS monolayer, the reductive desorption potentials, Erd, present shifts of −170 and −110 mV for the Ru and Fe complexes, respectively. The voltammetric curves of cytochrome c (cyt c) performed with the MpySAu electrodes showed electrochemical parameters consistent with that reported for the native protein. These results taken together reinforce that the π back-bonding effect from the [M(CN)5]3− metal center [Ru (4d) > Fe (3d)] strongly affects the MpySAu adlayer stability, reflecting the adlayer performance on the assessment of the cyt c hET reaction.

The [Ru(CN)5(pyS)]4- Complex, an Efficient Self-Assembled Monolayer for the Cytochrome c Heterogeneous Electron Transfer Studies

The organothiol 4-mercaptopyridine (pyS) has been used extensively as facilitator for the assessment of heterogeneous electron transfer reaction of cytochrome c (cyt c). Its efficiency, however, is strongly affected by the instability of the adlayer due to the C-S bond cleavage. The K(4)[Ru(CN)(5)(pyS)].3H(2)O complex was synthesized and characterized aiming its utilization as an inorganic self-assembled monolayer (SAM) that would enhance the gold adlayer stability. The SAM formed by this complex onto gold (RupySAu) was characterized by spectroscopic (FTIRRAS and SERS) and electrochemical (LSV) techniques. The ex situ vibrational SERS and FTIRRAS spectra data of this SAM formed onto gold suggest a sigma interaction between the gold and sulfur atoms of the complex, inducing a perpendicular arrangement in relation to the surface normal. Additionally, SERS and FTIRRAS spectra performed for freshly prepared RupySAu adlayer and for large immersion times in the precursor solution have not shown any significant change that would reflect the degradation of the adlayer. The LSV desorption curves of this SAM indicate an enhancement in the C-S bond strength of the pyS ligand when coordinated to the [Ru(CN)(5)](3-) moiety. Comparatively to the data obtained for the desorption process of the pyS monolayer, the reductive desorption potential, E(rd), of the RupySAu presents a shift of -17 mV. This bond strength intensification leads to an increase in the stability of the monolayer. The voltammetric curves of cyt c carried out with the RupySAu electrode showed electrochemical parameters consistent with those reported for the native protein, as well as the maintenance of the electrochemical kinetic data after repetitive cycles. The results all together suggest that the pi back-bonding effect from the [Ru(CN)(5)](3-) metal center plays an important role in the stability of the RupySAu adlayer, improving the assessment of the cyt c heterogeneous electron transfer reaction.

Reactivity of [(μ-H)Os 3(CO) 8{Ph 2PCH 2P(Ph)C 6H 4}] with organic heterothiols; X-ray structures of [H(μ-H)Os 3(CO) 8(η 2-pyS){Ph 2PCH 2P(Ph)C 6H 4}] and [Os 3(CO) 8(μ-η 2-pyS){Ph 2PCH 2P(Ph)C 6H 4}

The reaction of [(μ-H)Os 3(CO) 8{Ph 2PCH 2P(Ph)C 6H 4}] ( 3) with pyridine-2-thiol (pySH, C 5H 4NSH) at room temperature gave two novel clusters [(μ-H)Os 3(CO) 8(μ-pyS)(μ-dppm)] ( 4) and [H(μ-H)Os 3(CO) 8(η 2-pyS){Ph 2PCH 2P(Ph)C 6H 4}] ( 5) in 55 and 15% yields, respectively. Compound 4 is formed by simple oxidative addition of pySH and demetallation of the phenyl ring of dppm ligand whereas the 50-electron cluster 5 results from oxidative addition of pySH and coordination of the thiolate moiety as a chelating ligand and cleavage of one of the metalmetal bonds. The analogous reaction of 3 with pySH at 80°C gave the new compound [Os 3(CO) 8(μ-η 2-pyS){Ph 2PCH 2P(Ph)C 6H 4}] ( 6) in 20% yield together with 4 and 5 in 40 and 7% yields, respectively. Compound 6 contains a chelating/bridging pyS ligand and an orthometallated dppm ligand. In contrast, the reaction of 3 with pyrimidine-2-thiol (pymSH, C 4H 3N 2SH) at room temperature and at 80°C affords only the simple oxidative addition product [(μ-H)Os 3(CO) 8(μ-pymS)(μ-dppm)] ( 7). Compound 6 reacts with molecular hydrogen to give 5 and 4 in 20 and 10% yields, respectively. Compound 5 was converted to 6 (30%) with the formation of 3 (10%) by refluxing in heptane at 98°C. The new complexes 4, 5, 6 and 7 have been characterized by spectroscopic data together with X-ray structure determinations for 5 and 6.

An organometallic mercaptopyridine complex with unusual bond shift fluxionality: metal-mediated tautomerism of (pentamethylcyclopentadienyl)bis(pyridine-2-thiolato)rhodium(III)

Studies have been carried out on unique molecular non-rigidity of Cp *Rh III(PyS) 2 (PyS=pyridine-2-thiolato). One PyS ligand bonds to the rhodium ion in an S-monodentate mode (RhS(2)=2.3799(9) Å) while the other ligand chelates to the metal in an N,S-bidentate mode (RhS(1)=2.4380(9); RhN(1)=2.089(2) Å). Both PyS ligands possess a significant contribution from the thiol tautomer in the solid state. Even though the conformation and configuration of the molecule are still retained in solution, an unusual metal-mediated tautomeric non-rigidity for the PyS region is observed in the solution around room temperature.

Reactions of [Mn2(μ-pyS)2(CO)6] with bidentate phosphines: X-ray structure of [Mn(η2-pyS) (η2-dppp)(CO)2] [dppp = Ph2P(CH2)3PPh2, pySH = pyridine-2-thiol

The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 molar equivalents of Ph2P(CH2)3PPh2 (dppp) and Ph2P(CH2)2PPh2 (dppe) to give the respective monomeric chelate complexes [Mn(η2-pyS)(η2-dppp)(CO)2] (2) and [Mn(η2-pyS)(η2-dppe)(CO)2] (3). In contrast, with 2 molar equivalents of Ph2P(CH2)5PPh2 (dpppe), 1 gave the highly insoluble polymeric complex [Mn(η2-pyS)(μ-dpppe)(CO)2]n (4). An X-ray structure determination shows that 2 crystallizes in the monoclinic space group P21/n with a = 10.721(2) A, b = 19.712(5) A, c = 14.846(4) A, β = 109.06(2)°, V = 2965.5(14) A3, and Z = 4. The complex has a distorted octahedral geometry with the dppp ligand, one CO group and the N atom of the chelating pyS ligand occupying equatorial sites, and one CO group and the S atom of the pyS ligand lying in the axial positions.

Reactions of [Mn2(μ-pyS)2(CO)6] (pySH=pyridine-2-thiol) with triphenylphosphine (PPh3), diphenylphosphine (PHPh2) and bis(diphenylphosphino)methane (dppm): X-ray crystal structure of [Mn(pyS)(η1-dppm)2(CO)2

The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 M equivalents of both PPh3 and PHPh2 to give the respective monomeric phosphine complexes [Mn(pyS)(L)(CO)3][L = PPh3 (2) and PHPh2 (3)]; with 4 M equivalents of dppm, it yielded the complex [Mn(pyS)(η1-dppm)2(CO)2](4). An X-ray structure determination of 4 shows that it crystallizes in the monoclinic space group P21/n with a = 11.027(3), b = 24.984(7), c = 18.379(5) A, β = 99.870(8)°, V = 4988(2) A3, and Z = 4. The complex has an octahedral geometry with the chelating pyS ligand and two CO groups occupying the equatorial sites and the two monodentate dppm ligands lying in the trans positions.

Synthesis and molecular structures of di- and trinuclear molybdenum complexes containing pyridine-2-thiolato (pyS) ligand

Dinuclear complexes [Mo 2(μ-pyS) 2(CO) 4(PPh 3) 2], [Mo 2(μ-pyS) 2(CO) 5(PPh 3)] ( 2) and a trace quality of trinuclear complex [Mo 3( μ-pyS) 3( μ 3-pyS) 2(CO) 6] ( 3) were obtained from the reaction of [Mo(CO) 3(MeCN) 3] with pyridine-2-thione (pySH) and PPh 3 in THF. The crystal structures of 1 · 2C 7H 8 and 3 · C 7H 8 have been determined by X-ray diffraction studies. Crystals of 1 · 2C 7H 8 are monoclinic, space group C2 c and Z = 4, with a = 18.797(3), b = 11.143(4), c = 28.157(7) A ̊ , β = 101.23(2)° . The structure was refined to R = 0.050 and Rw = 0.057 for 3146 observed reflections. Crystals of 3 · C 7H 8 are monoclinic, space group P2 a and Z = 4, with a = 13.912(2), b = 17.161(2), c = 15.577(3) A ̊ , β = 101.17(1)° . The structure was refined to R = 0.046 and Rw = 0.051 for 4357 observed reflections. The molecule of 1 consists of two Mo(CO) 2(PPh 3) fragments linked by an MoMo (2.974(2) Å0 and by two doubly-bridging pyS ligands. The compound 3 contains a bent open geometry of three molybdenum atoms (Mo(1)Mo(2)Mo(3) angle 122.99(3)°) linked by two MoMo bonds (2.943(1) and 2.950(1) Å) and by two doubly- and two triply-bridging pyS ligands.

Tetraethylammonium Tris(pyridine-2-thiolato-S,N)cobalt(II), (Et4N)[Co(2-S-C5H4N)3

Na[Co(CO)4] was reacted with pyridine-2-thiol (PyS) in tetrahydrofuran to give the title complex, (C8H20N)[Co(C5H4NS)3], in which the three S atoms and the three N atoms of the PyS ligands coordinate to the central CoII atom, forming three four-membered chelate rings with S—Co—N angles of 66°. The geometry around the CoII atom is distorted octahedral. The average Co—S and Co—N bond distances are 2.568 and 2.108 A, respectively.

Abstraction of the pyS ligand from [Re 2Ru 2(μ 4-S) (μ-C 5H 4N)(μ-pyS)(CO) 13] by [Ru 3(CO) 12]. Crystal structure of [Re 2Ru 2(μ-H)(μ 4-S)(μ-C 5H 4N)(CO) 14

The cluster [Re 2Ru 2(μ 4-S)(μ-C 5H 4N)(μ-pyS)(CO) 13] (pyS = pyridine-2-thionato) reacts with [Ru 3(CO) 12] at 150°C to give the product [Re 2Ru 2(μ-H)(μ 4-S)(μ-C 5H 4N)(CO) 14], which contains the same arrangement of metal atoms around the tetrahedral sulphur ligand as the parent. The loss of the pyS ligand is compensated for by the addition of a hydride and a carbonyl ligand and by the formation of an ReRe bond.

The Synthesis and Crystal Structure of the First Trinuclear Molybdenum Complex Containing PyS Ligands [Mo_3(CO)_6(μ-PyS)_2(μ_3-PyS)_2

The deprotonated derivative pyridine-2-thiolato (PyS~-) of pyridine-2-thione (PySH)is a potentially amibidentate or multi-functional donor which coordinates toward transitionmetals with either the exocyclic S or heterocyclic N atom or both atoms to form differentcoordination modes. We have recently reported the synthesis and crystal structure ofthe first dinuclear molybdenum complex with doubly-bridging PyS ligands [Mo_2(CO)_4(μ-PyS)_2(PPh_3)_2]which was obtained from the reaction of [Mo(CO)_3(CH_3CN)_3] with

Synthesis and solution behavior of mononuclear palladium(II) and platinum(II) complexes containing pyridine-2-thiolate as a ligand. Crystal structure of chloro(pyridine-2-thiolato)- (triphenylphosphine)palladium(II)

Various types of mononuclear pyridine-2-thiolato (pyS) complexes [M(pyS) 2(PPh 3) 2], [MCl(pyS)(PPh 3)], [M(pyS) 2(PPh 3)] (M=Pd(II), Pt(II)) and [PdCl(pyS)(PPh 3) 2]·CH 2Cl 2, and the complex of pyridine-2-thiol [PdCl 2(pySH)(PPh 3)] have been prepared. The solution behavior of these complexes has been examined by 1H and 31P{ 1H} NMR measurements as well as the determination of the molecular weights. The coordination modes of the pyS ligand in the complexes, including chelation, S-unidentate, and the fast exchange between them, have been elucidated. The crystal structure of [PdCl(pyS)(PPh 3)] has been determined. The complex crystallizes in the triclinic space group P1, Z=2, a=12.969(6), b=10.246(5), c=9.493(3) Å, α=114.53(3), β=72.57(3), γ=105.71(3)°. The structure has been determined using conventional heavy atom methods, final R w=0.067 based on 2546 significant ( I>;3σ( I)) reflections. The Pd atom is four-coordinated by the Cl, P, S and N donor atoms, constituting a square-planar, trans-(P,N) structure; the pyS ligand is chelated with a small bite angle. In the crystals, there are two independent molecules, the structures of which differ from one another in the disposition of the pyridine ring folded in opposite directions on the plane defined by the Pd, Cl, P and S atoms.

Mixed tetranuclear rhenium–ruthenium compounds formed by carbon–sulphur bond cleavage in reactions of [Re2(pyS)2(CO)6](pyS = pyridine-2-thionate) with [Ru3(CO)12]. Crystal structures of [ReRu3(µ4-S)(µ-C5H4N)(CO)14] and [Re2Ru2(µ-S)(µ-C5H4N)(µ-pyS)(CO)13

The dinuclear compound [Re2(pyS)2(CO)6](pyS = pyridine-2-thionate) reacts with [Ru3(CO)12] to give a series of compounds containing ReRu3, Re2Ru2, and Re3Ru groups and which are formally built up by the combination of Re(pyS)(CO)3 and Ru(CO)x(x= 2, 3 or 4) units. The compound [ReRu3(µ4-S)(µ-C5H4N)(CO)14] is formed by C–S bond cleavage and exists as two non-interconverting but inseparable isomers in solution. A single crystal selected from the crystallised mixture was found by X-ray structure determination to contain just one pure diastereomer as a mixture of enantiomers. The four metal atoms are linked by a µ4-S ligand and a disordered 2-pyridyl ligand bridges two Ru(CO)3 groups. The isomers in solution result from the interchange of Re(CO)4 and Ru(CO)4 units. Two non-interconvertible isomers of the compound [Re2Ru2(µ4-S)(µ-C5H4N)(µ-pyS)(CO)13] were separated and each structurally characterised. Their structures are extremely similar (except that one has CH2Cl2 molecules in the crystal) differing only in the orientation of the 2-pyridyl bridges. Full crystallographic characterisation depended upon the correct positioning of C and N atoms. The compound [Re3Ru(µ4-S)(µ-C5H4N)(pyS)2(CO)11] also forms separable non-interconverting isomers. One contains two doubly bridging pyS ligands and the other one doubly and one triply bridging pyS ligand. Therefore isomerism in these compounds has three separate origins.

New fluxional seven-co-ordinate molybdenum(II) and tungsten(II) complexes: X-ray structure of the pyridine-2-thionato complex [W(C5H4NS)2(CO)2(PMe2Ph)

The reaction of [W(CO)3(MeCN)3] with pyridine-2-thione (pySH) at room temperature gives the tungsten(II) compound [W(pyS)2(CO)3](1) and the tungsten(0) compound [W(CO)5(pySH)](2). To slow the rate of intramolecular exchange of the pyS ligands in (1), PMe2Ph was introduced to give [W(pyS)2(CO)2(PMe2Ph)](4). Crystals of (4) are monoclinic space group C2/c, a= 30.738(9), b= 9.867(2), c= 16.048(9)A, β= 121.04(3)°, and Z= 8 and the X-ray structure was refined to R= 0.0330 and R′= 0.0335. Molecules of (4) contain two chelating pyS ligands and the tungsten is seven-co-ordinated. Approximately determined exchange rates for the diastereotopic Me groups of PMe2Ph and of the non-equivalent pyS ligands are the same indicating that both exchanges result from the same process. The corresponding molybdenum compound is isostructural and shows similar fluxionality.

Synthesis and reactivity of mono-, tri-, and poly-nuclear ruthenium carbonyl complexes containing the pyridine-2-thiolate ligand (pyS). Stepwise preparation of [Ru(pyS)2(CO)2] by reaction of [Ru3(CO)12] with pyridine-2-thiol

The thermal reaction of [Ru3(CO)12] with pyridine-2-thiol (pySH) gives the trinuclear complex [Ru3(µ-H)(µ3-pyS)(CO)9](1), which is subsequently converted into the polymer [{Ru(µ3-pyS)(CO)2}n](2). Further reaction of polymer (2) with pyridine-2-thiol gives the monomeric compound [Ru(pyS)2(CO)2](3). Complexes (1) and (2) contain triply bridging pyS ligands while in complex (3) both pyS ligands are chelating. These results indicate that the reactivity of [Ru3(CO)12] with pyridine-2-thiol is different to that found for [Os3(CO)12] and for [Ru3(CO)12] with 2-aminopyridine and 2-hydroxypyridine. The reactions of complexes (1)–(3) with several P-donor ligands are also described. Infrared and 1H and 31P-{1H} n.m.r. spectral data for all the compounds are presented and discussed in relation to their structures.