Synthesis and Characterization of Three Homoleptic Bismuth Silanolates: [Bi(OSiR3)3] (R = Me,Et, iPr)

The bismuth tris(triorganosilanolates) [Bi(OSiR₃)₃] ( 1 , R = Me; 2 , R = Et; 3 , R = iPr) were prepared by reaction of R₃SiOH with [Bi(OtBu)₃]. Compound 1 crystallizes in the triclinic space group with Z = 2 and the lattice constants a = 10.323(1) Å, b = 13.805(1) Å, c = 21.096(1) Å and α = 91.871(4)°, β = 94.639(3)°, γ = 110.802(3)°. In the solid state compound 1 is a trimer as result of weak intermolecular bismuth‐oxygen interactions with Bi–O distances in the range 2.686(6)–3.227(3) Å. The coordination at the bismuth atoms Bi(1) and Bi(3) is best described as 3 + 2 coordination whereas Bi(2) shows a 3 + 3 coordination. The intramolecular Bi–O distances fall in the range 2.041(3)–2.119(3) Å. Compound 3 crystallizes in the orthorhombic space group Pbcm with Z = 4 and the lattice constants a = 7.201(1) Å, b = 23.367(5) Å and c = 20.893(1) Å, whereas the triethylsilyl‐derivative 2 is liquid. In contrast to [Bi(OSiMe₃)₃] ( 1 ) compound 3 is monomeric in the solid state, but shows similar intramolecular Bi–O distances in the range 1.998(2)–2.065(5) Å. The bismuth silanolates are highly soluble in common organic solvents and strongly moisture sensitive. Compound 1 shows the lowest thermal stability.     

Synthesis, characterization, and structural studies of mixed-ligand diorganotin esters, [R2Sn(OP(O)(OH)Ph)(OS(O)2R1)]n [R = n-Bu, R1 = Me (1), n-Pr(2); R = Et, R1 = Me (3)] with 1D and 3D coordination polymeric motifs

Mixed-ligand diorganotin esters, [R 2Sn(OP(O)(OH)Ph)(OS(O) 2R (1))] n [R = n-Bu, R (1) = Me ( 1), n-Pr ( 2); R = Et, R (1) = Me ( 3)], have been synthesized by reacting the tin precursors, R 2Sn(OR (1))OS(O) 2R with an equimolar amount of phenylphosphonic acid under mild conditions (room temperature, 6-8 h, CH 2Cl 2). These have been characterized by IR, multinuclear ( (1)H, (13)C{ (1)H}, (31)P, and (119)Sn) NMR, and single crystal X-ray diffraction studies. The asymmetric unit of 1 is comprised of a tetramer with four crystallographically unique tin atoms. The structure reveals a central eight-membered (Sn-O-S-O) 2 cyclic ring with two exocyclic tin atoms, which results from micro 3-binding of the two methanesulfonate groups. The remaining two sulfonates are monodentate and contribute in O...HO(P) hydrogen bonding. The molecular structure is extended into a 3D coordination polymer with the aid of hydrogenphenylphosphonate group on each tin atom, acting in a micro 2-O 2P mode and forms a series of eight-membered (Sn-O-P-O) 2 rings in the structural framework. 2 and 3 are isostructural and represent linear 1D coordination polymers via micro 2-binding mode of both alkanesulfonate and hydrogenphenylphosphonate groups.     

Gemischtligandkomplexe des Rheniums. IX. Reaktionen am Nitridoliganden von [ReN(Me2PhP)(Et2dtc)2]. Synthese,Charakterisierung und Kristallstrukturen von [Re(NBCl3)(Me2PhP)(Et2dtc)2], [Re(NGaCl3)(Me2PhP)(Et2dtc)2] und [Re(NS)Cl(Me2PhP)2(Et2dtc)]

Mixed-ligand Complexes of Rhenium. IX. Reactions on the Nitrido Ligand of [ReN(Me₂PhP)(Et₂dtc)₂]. Synthesis, Characterization, and Structures of [Re(NBCl₃)(Me₂PhP)(Et₂dtc)₂], [Re(NGaCl₃)(Me₂PhP)(Et₂dtc)₂], and [Re(NS)Cl(Me₂PhP)₂(Et₂dtc)] BCl₃, GaCl₃ and S₂Cl₂ react with the well-known [ReN(Me₂PhP)(Et₂dtc)₂] by attack of the nucleophilic nitrido ligand. Final products of these reactions are [Re(NBCl₃)-(Me₂PhP)(Et₂dtc)₂], [Re(NGaCl₃)(Me₂PhP)(Et₂dtc)₂], and [Re(NS)Cl(Me₂PhP)₂Et₂dtc)] which have been studied by mass spectrometry, IR spectroscopy and X-ray diffraction. [Re(NBCl₃)(Me₂PhP)(Et₂dtc)₂] crystallizes in the triclinic space group P1 , Z = 2, a = 8.151(6), b = 9.935(8), c = 18.67(1) Å; α = 94.42(4), β = 97.09(1), γ = 101.35(4)°. The coordination geometry is a distorted octahedron. The equatorial coordination sphere is occupied by one phosphorus and three sulphur atoms. The fourth sulphur atom is in trans position to the Re?N? B moiety. The almost linear Re?N? B unit has an Re?N? B angle of 170.5(3)° with a Re? N bond length of 1.704(3) Å. The analogous [Re(NGaCl₃)(Me₂PhP)(Et₂dtc)₂] crystallizes in P2₁/c with a = 8.138(3), b = 18.279(2), c = 19.880(6) Å; β = 99.81(2)°; Z = 4. Rhenium has a distorted octahedral environment. The Re? N? Ga bond is slightly bent with an angle of 154.5(4)° and a Re? N bond length of 1.695(6) Å. [Re(NS)Cl(Me₂PhP)₂(Et₂dtc)] crystallizes in the triclinic space group P1 , Z = 4, a = 9.514(2); b = 16.266(5); c = 18.388(3) Å; α = 88.75(2), β = 76.59(2), γ = 85.50(2)° with two crystallographically independent molecules in the asymmetric unit. Rhenium has a distorted octahedral environment with the chloro ligand in trans position to the almost linear thionitrosyl group. The Re?N bond lengths are 1.795(6) and 1.72(1) Å, respectively, and the N?S distances are 1.55(1) and 1.59(1) Å, respectively.     

Synthesis and spectral characterization of stannocanes of the type [O(CH2CH2S)2SnR2](R=Me1,Bun2,Ph3)

The stannocanes of the type [O(CH₂CH₂S)₂SnR₂](R=Me1,Buⁿ 2,Ph3) have been synthesized in an improved method by the reaction of R₂SnCl₂ with 2, 2′-oxydiethanethiol O(CH₂CH₂SH)₂ in molar ratio of 1:1 at the presence of sodium ethoxide in anhydrous ethanol. The reactions are carried out under inert atmosphere. These compounds have been extensively characterized by FT-IR, UV-Vis spectrophotometry, multi-nuclear (¹H, ¹³C, ¹¹⁹Sn) NMR, elemental analysis and mass spectrometry. The obtained data clearly indicates that, there is a strong interaction between oxygen atom of the ligand as a donor and Sn atom of the organotin species as a Lewis acid acceptor. Therefore, the resulted dithiostannocanes possess a transannular secondary bonding and hypervalency at the central Sn atom which leads to an increase in the coordination number of tin from four to five-coordinated tin.      

[Fe(C12H8N3O2)Cl2(ROH)], with R = Me and Et

The title octahedral complexes, [bis(pyridine‐2‐carbonyl)­amin­ate]­di­chloro­(methanol)­iron(III), [Fe(C₁₂H₈N₃O₂)­Cl₂‐(CH₄O)], and [bis­(pyri­dine‐2‐carbonyl)­amin­ate]­di­chloro‐(ethanol)­iron(III), [Fe­(C₁₂H₈N₃O₂)Cl₂(C₂H₆O)], both crystallize in space group and have similar structures. Mono­anionic bpca^? [bis(pyridine‐2‐carbonyl)­amin­ate] acts as a planar tridentate ligand in both cases. Coordination bond distances are in the range typical of high‐spin Fe^III complexes. Carbon–oxygen distances are typical of a C=O double bond suggesting the negative charge of the bpca^? ligand is localized on the central N atom.     

Synthesis and Structures of Homoleptic Methyl‐ and Phenylthiomethylaluminium Complexes [Al(CH2SR)3](R = Me,Ph)

Sulfur‐substituted methylmercury compounds [Hg(CH₂SR)₂]( 1a, R = Me; 1b, R = Ph ) react with aluminium amalgam in refluxing toluene with transmetallation to give homoleptic tris(thiomethyl)aluminium complexes [Al(CH₂SR)₃]( 2a, R = Me; 2b, R = Ph ) (degree of conversion: >80%, isolated yields: 2a 63%, 2b 41%). Their identities were confirmed by NMR spectros‐copy (¹H, ¹³C) and X‐ray crystal structure analyses. In crystals of compound 2a the aluminium atoms possess a trigonal‐bipyramidal arrangement with the coordination polyhedron defined by three carbon and two sulfur atoms. Two of the three CH₂SMe ligands are bridging ligands (μ‐η²; 1kC:2kS), the third one is terminal bound (η¹; kC). The structure is polymeric. Crystals are threaded by helical chains built up of six‐membered Al₂C₂S₂ rings. Crystals of 2b are built up of centrosymmetrical dimers with six‐membered Al₂C₂S₂ rings having bridging CH₂SPh ligands (μ‐η²; 1kC:2kS). On each Al atom two terminal (η¹; kC)CH₂SPh ligands are bound. They exhibit quite different Al‐C‐S angles (116.7(4) and 106.5(3)?). Similar values (114.32115.7? and 109.52109.9?) were found in ab initio calculations of model compounds [{Al(CH₂SR)₃}₂]( 3a, R=H; 3b, R=Me; 3c, R=CH=CH₂ ). A conformational energy diagram for rotation of one of the terminal CH₂SH ligand in the parent compound 3a around the Al‐C bond is discussed in terms of repulsive interactions of lone electron pairs of sulfur atoms.     

Synthesis and Structural Characterization of the Complex 〔Et_4N〕_2〔Ni_2(C_2S_4)(C_3S_5)_2〕

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A 2D honeycomb-shaped network based on a starburst cluster: [Ag4(micro3-Cl)(PPh2(CH2)2PPh2)1.5{S2P(OR)2}3](R = Et, Pri)

The first 2D metal-organic framework utilizing PPh2(CH2)2PPh2 (dppe) units as the linkers and tetranuclear silver clusters, [Ag4(micro3)-Cl){S2P(OR)2}3], as the network nodes in the formation of the honeycomb-shaped layer structure is reported.     

Regioselective and reversible carbon-nitrogen bond formation: synthesis, structure and reactivity of ureato-bridged complexes [Mo2(NAr)2(mu-X){mu-ArNC(O)NAr}(S2CNR2)2](Ar = Ph, p-tol; X = S, NAr; R = Me, Et, Pr)

Reaction of ArNCO with syn-[MoO(mu-O)(S2CNR2)]2 or syn-[MoO(mu-NAr)(S2CNR2)]2 at 110 degrees C leads to the facile formation of bridging ureato complexes [Mo2(NAr)2(mu-NAr){mu-ArNC(O)NAr}(S2CNR2)2](Ar = Ph, p-tol; R = Me, Et, Pr), formed upon substitution of all oxo ligands and addition of a further equivalent of isocyanate across one of the bridging imido ligands. Related sulfido-bridged complexes [Mo2(NAr)2(mu-S){mu-ArNC(O)NAr}(S2CNR2)2] have been prepared from syn-[Mo2O2(mu-O)(mu-S)(S2CNR2)2]. When reactions with syn-[MoO(mu-NAr)(S2CNEt2)]2 were followed by NMR, intermediates were observed, being formulated as [Mo2O(NAr)(mu-NAr){mu-ArNC(O)NAr}(S2CNEt2)2], which at higher temperatures convert to the fully substituted products. A crystallographic study of [Mo2(N-p-tol)2(mu-S){mu-p-tolNC(O)N-p-tol}(S2CNPr2)2] reveals that the bridging ureato ligand is bound asymmetrically to the dimolybdenum centre-molybdenum-nitrogen bonds trans to the terminal imido ligands being significantly elongated with respect to those cis-a result of the trans-influence of the terminal imido ligands. This trans-influence also leads to a trans-effect, whereby the exchange of aryl isocyanates can occur in a regioselective manner. This is followed by NMR studies and confirmed by a crystallographic study of [Mo2(N-p-tol)2(mu-N-p-tol){mu-p-tolNC(O)NPh}(S2CNEt2)2]--the PhNCO occupying the site trans to the terminal imido ligands. Ureato complexes also react with PhNCS, initially forming [Mo2(NAr)2(mu-S){mu-ArNC(O)NAr}(S2CNR2)2], resulting from exchange of the bridging imido ligand for sulfur, together with small amounts of [Mo2(NAr)2(mu-S)(mu-S2)(S2CNEt2)2], containing bridging sulfide and disulfide ligands. The ureato complexes [Mo2(NAr)2(mu-S){mu-ArNC(O)NAr}(S2CNR2)2] react further with PhNCS to give [Mo2(NAr)2(mu-S)2(S2CNR2)2]n (n = 1, 2), which exist in a dimer-tetramer equilibrium. In order to confirm these results crystallographic studies have been carried out on [Mo2(N-p-tol)2(mu-S)(mu-S2)(S2CNEt2)2] and [Mo2(N-p-tol)2(mu-S)2(S2CNPr2)2]2.     

Synthesis and characterisation of cyclo-boratetrasiloxane, (RBO)(Me2SiO)3 (R=nBu,Ar), derivatives

Low temperature reactions of dilute solutions of 1,5-dichloro-1,1,3,3,5,5-hexamethyltrisiloxane with boronic acids {RB(OH)₂; R=ⁿBu, C₆H₄Me-2, C₆H₄Me-3, C₆H₄Me-4, C₆H₄OMe-3, C₆H₄OMe-4, C₆H₄Br-2, C₆H₄Br-3, C₆H₄Br-4} in the presence of a twofold excess of Et₃N afforded the 8-membered ring products, cyclo-boratetrasiloxanes, (RBO)(Me₂SiO)₃, in moderate yields. New compounds were colourless oils and were characterised by elemental analysis, NMR (¹H, ¹¹B, ¹³C, ²⁹Si), IR and MS. The cyclo-boratetrasiloxanes are weakly Lewis acidic, with acceptor number (AN) values of ∼30, but do not form adducts with amines.     

Reactions of [ReN(Cl)(Me2PhP)2(HEt2tcb)] with Lewis Acids. Synthesis,Characterization and Structures of [Re(NBBr3)Br2(Me2PhP)3], [Re(NGaCl3)Cl(Me2PhP)2(H2Et2tcb)][GaCl4] and [Re{NB(C6F5)3}Cl(Me2PhP)2(HEt2tcb)] (H2Et2tcb=N,N-diethylthiocarbamoylbenzamidine)

Reactions of [ReN(Cl)(Me₂PhP)₂(HEt₂tcb)] (HEt₂tcb⁻=N,N-diethylthiocarbamoylbenzamidinate, Me₂PhP=dimethylphenylphosphine) with Lewis acidic compounds such as BBr₃, (C₆F₅)₃B or gallium(III) chloride yield nitrogen-bridged binuclear complexes with covalent bonds between the nitrido ligand and boron or gallium. The reactions go along with activation of the transition metal centre which can lead to ligand re-arrangements and reactions with solvent molecules.The reaction with BBr₃ results in cleavage of the bonds to the chelating ligand. [Re(NBBr₃)Br₂(Me₂PhP)₃] was isolated as the only product with a nitrido bridge. The bis-chelate [ReN(HEt₂tcb)₂] was formed as a side-product.Upon formation of a nitrido bridge to GaCl₃ the first co-ordination sphere of rhenium is retained. The co-ordinated thiocarbamoylbenzamidinate, however, undergoes protonation and is bonded as a neutral, bidentate ligand in the product [Re(NGaCl₃)Cl(Me₂PhP)₂(H₂Et₂tcb)][GaCl₄].In [Re{NB(C₆F₅)₃}Cl(Me₂PhP)₂(HEt₂tcb)], which can be obtained in good yield from the reaction of [ReN(Cl)(Me₂PhP)₂(HEt₂tcb)] with (C₆F₅)₃B, the co-ordination environment of the metal remains essentially unchanged.X-ray structural studies on the products suggest that the strong structural trans influence of the terminal nitrido ligand in the starting complex decreases significantly as a consequence of the formation of the N–B/Ga bonds. The rhenium–nitrogen multiple bond distances, however, remain almost unchanged.     

Synthesis,characterization and in vitro antitumour activity of diorganotin bisxanthates [R2Sn(S2COR′)2] (R=Me,Et, nBu,Ph; R′=Et,iPr, Hex) and crystal structure of bis(O-ethyldithiocarbonato)diphenyltin(IV)

A series of diorganotin bisxanthate compounds, [R₂Sn(S₂COR′)₂] (R=Me, Et, nBu, tBu, and Ph; R′?Et, iPr and cHex) have been prepared and characterized by spectroscopic methods (IR, NMR and FAB MS). The xanthate ligands chelate the R₂Sn moieties forming disparate Sn–S bonds leading to skew-trapezoidal biypramidal tin atom geometries. The crystal structure of a representative compound, [Ph₂Sn(S₂COEt)₂], confirms the spectroscopic results and shows the tin atom to be coordinated by two asymmetrically chelating xanthate ligands [Sn–S(1) 2.486(1), Sn–S(2) 3.052(1) Å and Sn–S(3) 2.484(1), Sn–S(4) 3.220(1) Å] with the two phenyl substituents lying over the weaker Sn–S interactions so that C–Sn–C is 126.5(1)°. Crystal data for [Ph₂Sn(S₂COEt)₂]: monoclinic space group P2₁/n: a=9.645(1), b=23.723(3), c=9.798(2) Å, ß=100.23(1)°, V=2206.2 ų, Z=4; 2708 data refined to final R 0.023. A selection of these compounds has been evaluated for activity against the L1210 mouse leukaemia cell line.     

Synthesis and X-ray and Spectral Study of the Compounds [Q4N]2[Fe2(S2O3)2(NO)4] (Q = Me,Et, n-Pr,n-Bu)

Iron nitrosyl complexes with general formula [Q₄N]₂[Fe₂(S₂O₃)₂(NO)₄] (Q = Me, Et, n-Pr, n-Bu) were synthesized by the exchange reaction of K₂[Fe₂(S₂O₃)₂(NO)₄] with tetraalkylammonium bromides. The molecular and crystal structure of [(CH₃)₄N]₂[Fe₂(S₂O₃)₂(NO)₄] were studied by X-ray diffraction analysis. The iron atom in the four-membered cycle of the [2Fe–2S] anion is bound to another Fe atom and to two sulfur atoms and is coordinated by two nonequivalent NO groups, each bridging sulfur atom being bound to the SO₃group. The structurally equivalent iron atoms are in the state Fe^1–(S= 1/2). The Mössbauer spectroscopy method shows that the complexes are diamagnetic due to the strong Fe–Fe bond. It is found that the SO₃group provides higher stability of the thiosulfate anion than the anion in Roussin's red salt [Fe₂S₂(NO)₄]^2–.     

Synthesis, Characterization, and Comparative Properties of [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] and [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)

The reaction of [PPN](2)[Re(6)C(CO)(19)] with Mo(CO)(6) and Ru(3)(CO)(12) under sunlamp irradiation provided the new mixed-metal clusters [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] and [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)], which were isolated in yields of 85% and 61%, respectively. The compound [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] crystallizes in the monoclinic space group P2(1)/c with a = 20.190 (7) ?, b = 16.489 (7) ?, c = 27.778 (7) ?, beta = 101.48 (2) degrees, and Z = 4 (at T = -75 degrees C). The cluster anion is composed of a Re(6)C octahedral core with a face capped by a Mo(CO)(4) fragment. There are three terminal carbonyl ligands coordinated to each rhenium atom. The four carbonyl ligands on the molybdenum center are essentially terminal, with one pair of carbonyl ligands (C72-O72 and C74-O74) subtending a relatively large angle at molybdenum (C72-Mo-C74 = 147.2(9) degrees ), whereas the remaining pair of carbonyl ligands (C71-O71 and C73-O73) subtend a much smaller angle (C71-Mo-C73 = 100.5(9) degrees ). The (13)C NMR spectrum of (13)CO-enriched [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] shows signals for four sets of carbonyl ligands at -40 degrees C, consistent with the solid state structure, but the carbonyl ligands undergo complete scrambling at ambient temperature. The (13)C NMR spectrum of (13)CO-enriched [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)] at 20 degrees C is consistent with the expected structure of an octahedral Re(6)C(CO)(18) core capped by a Ru(CO)(3) fragment. The visible spectrum of [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] shows a broad, strong band at 670 nm (epsilon = 8100), whereas all of the absorptions of [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)] are at higher energy. An irreversible oxidation wave with E(p) at 0.34 V is observed for [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)], whereas two quasi-reversible oxidation waves with E(1/2) values of 0.21 and 0.61 V (vs Ag/AgCl) are observed for [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)]. The molybdenum cap in [Re(6)C(CO)(18)Mo(CO(4))](2-) is cleaved by heating in donor solvents, and by treatment with H(2), to give largely [H(2)Re(6)C(CO)(18)](2-). In contrast, [Re(6)C(CO)(18)Ru(CO)(3)](2-) shows no tendency to react under similar conditions.     

Highly efficient [Ni{iPrHNC(S)NP(S)(OiPr)2-1,3-N,S'}2]/PR3 (R3 = Me3, Me2Ph) complexes for the generation of Ni(0) for catalysis

We have developed new complexes of the type [Ni{iPrHNC(S)NP(S)(OiPr)(2)-1,3-N,S'}(2)]/PR(3) (R(3) = Me(3), Me(2)Ph) for the generation of Ni(0) catalysts which can be used for the catalytic addition of Ph(2)S(2) to 1-, 2- and 3-hexynes. A detailed study of the catalytic reaction mechanism suggests two possible pathways for the in situ formation of Ni(0) species, depending on the presence or absence of water.