Lorna Linford

Sulphur-containing metal complexes: X. Reactions of [Fe(CO)5] with ethylenetrithiocarbonate. Structure of [Fe3(Co)9{CS(CH2)2S}S] containing a μ-dithiocarbene ligand

Abstract Four different conversions were observed when a mixture of [Fe(CO)5] and ethylenetrithiocarbonate was irradiated with ultraviolet light in tetrahydrofuran: (i) the thione bond in the ligand was broken and the sulphur atom was incorporated into a cluster to produce [Fe3(CO)9(μ3-S)2], (I); (ii) cleavage of the two CS single bonds occurred and the S(CH2)2S moiety was used to stabilize the complex [Fe2(CO)6{μ-S(CH2)2S}], (II); (iii) the ligand exhibited significant charge redistribution during coordination, in the compound [Fe2(CO)6-{S CS(CH 2 ) 2 S }], (III) and finally, (iv) the thione bond was cleaved and both fragments were used by the metalcarbonyl to yield the major product, [Fe3(CO)9{μ3- CS(CH 2 ) 2 S }(μ3-S)], (IV). A single crystal X-ray study of IV revealed that a dithiocarbene ligand caps an open iron triangle by forming a methylene bridge between two iron atoms and links up with the third iron atom via a sulphur atom.

Formation and Reactions of Organosulfur and Organoselenium Organometallic Compounds

Publisher Summary This chapter discusses the reactions of organosulfur and organoselenium compounds mediated by transition metals. In organic synthetic reactions, the scope and applications of organosulfur and organoselenium chemistry have increased tremendously. Organosulfur complexes of low oxidation state metals are generally less stable than their phosphorus counterparts, but this relative instability lends the complexes their reactivity. Organosulfur ligands are the reactive centers of the complexes. Low-valent nickel species catalyze the reaction between Grignard reagents and aryl or alkenyl sulfide in the preparation of alkylarenes, biaryls, and alkenes. In contrast, ultra violet (UV) irradiation of dithiane or trithiane in the presence of [Fe(CO)5] leads to the scission of only one C–S bond and the formation of an asymmetric complex. The molybdenum dimer can be converted, by alkylation, to a cation, which can be transformed into an anion by two-electron chemical reduction. Although the thiolysis of alkoxycarbenes to form thiocarbenes is not a new reaction, the new method, in which a catalyst is used, minimizes the formation of unwanted side products and dramatically increases the yield.

Sulphur-containing metal complexes: XXIII. Synthesis of new complexes containing the Fe2(CO)6S2 butterfly unit. Crystal and molecular structure of [Fe2(CO)6{μ-S2P(C6H4OMe-p)Fe(CO)4}], determined from two different crystal modifications☆

Abstract Diiron nonacarbonyl, [Fe 2 (CO) 9 ], reacts with Lawessons reagent, ( p MeOC 6 H 4 ){ovtsqb|P(=S)SP(=S)(C 6 H 4 OMe- p )S}, in tetrahydrofuran to give a number of products including [Fe 2 (CO) 6 {μ-S 2 P(C 6 H 4 OMe- p )Fe(CO) 4 }] (III). Single crystal X-ray analyses of this compound, show a dithionophosphine unit, S-P(R)-S (R = C 6 H 4 OMe- p ), to bridge the iron-iron bond of Fe 2 (CO) 6 via the two sulphur atoms and to link a Fe(CO) 4 moiety through coordination of the phosphorus atom. Reaction of Me 2 P(=S)P(=S)Me 2 with [Fe(CO) 5 ] under irradiation with ultraviolet light, affords the anti form of [Fe 2 (CO) 6 {μ-SPMe 2 } 2 ] (V) as major product. Two separate crystal structure determinations on compound III were carried out as it crystallizes under similar condition in two different crystal modifications. Two packing modes are possible because the near-mirror symmetry of the molecule allows two equivalent orientations in the crystal.

Synthesis and characterization of gold(I) and gold(III) thione complexes

Abstract [AuCl], H[AuCl4] or [AuCl3] react with various thiones to form stable complexes of the type [AuCl(thione)] or [AuCl3(thione)] in high yields. The products were characterized by 1H NMR, IR and UV spectroscopy and by determining the crystal and molecular structures of [AuCl(S CSCH 2 CH 2 S )] and [AuCl3(SCHNMe2)]. Due to large standard deviations it is not possible to differentiate between the two AuS distances [2.258(4) and 2.296(12) A].

Distinctive chemo- and stereo-selective reactions of [Fe(CO)2Cp]+ and [AuPPh3+ with the anionic thioketene complex, [W(CO)5&[;C(OEt)(Ph)C(Ph)=C=S&];]−. Crystal structures of Z-[W(CO)5&[;C(SFe[CO]2Cp)C(Ph)=C(OEt)Ph&];] and E-[W(CO)5&[;S=C(AuPPh3)C(Ph)=C(OEt)Ph&];]

Abstract Reaction of the unusual thioketone adduct [W(CO) 5 &[;C(OEt)(Ph)C(Ph)=C=S&];]Li with [Fe(CO) 2 CpI] gives two binuclear tungsten iron complex isomers of composition [W(CO) 5 &[;C(SFe[CO] 2 Cp)C(Ph)=C(OEt)Ph&];] that differ only in the position of the iron substituent at the extremely short C(carbene)S bond. Crystallization affords only the isomer in which the metal atoms are oriented trans , as is shown by the X-ray crystal structure. Both isomers have a Z configuration about the C=C double bond. Treatment of the same adduct with [AuC/PPh 3 ] affords a binuclear compound in which the tungsten and gold atoms are linked by a thione group. This conversion is also stereo-selective with regard to the alkene bond and only the E isomer is formed. The structure of the product [W(CO) 5 &[;S=C(AuPPh 3 )C(Ph)=C(OEt)(Ph)&];] was determined by X-ray diffraction. Comparison of structural features with the related thioaldehyde complex, E -[W(CO) 5 &[;S=CHC(Ph)=C(Ph)(OEt)&];] reveals the significant electron-withdrawing effect of the gold fragment.

Formation and characterization of neutral and cationic amino(thio)carbene complexes of gold(I) from thiazolyl precursors

Benzothiazole-2-yl-, 4-methylthiazolyl- and thiazolyl-lithium reacted with [AuCl(tht)](tht = tetrahydrothiophene) to form bis(thiazolyl)aurate compounds which can be protonated or alkylated to give mono- and bis-(carbene) complexes of the type [Au([graphic omitted])([graphic omitted])] and [Au(CNRCX1= CX2S)2]+(X1X2= C4H4; X1= Me, X2= H; X1= X2= H; R = H or Me). The strongly ligated gold phosphine and perfluorophenyl complexes [AuCl(PPh3)] and [Au(C6F5)(tht)] as well as AuCN also reacted with the thiazolyllithiums to afford, upon protonation or alkylation, cationic and neutral carbene compounds. Complicating side-reactions, such as homoleptic rearrangement, protonation or alkylation on carbon rather than nitrogen and dissociative polymerization were observed. The crystal structure of the neutral mono(carbene) complex [Au([graphic omitted])([graphic omitted])] shows a gold–gold interaction with a distance of 3.075(1)A.

Synthesis and characterization of [Cr(CO)5{SCHCHC(SEt)2}] and [Cr(CO)5{SC(SCHCH2)SEt}] by ring-opening of 1,3-dithiolane-2-thione: crystal and molecular structure of [Cr(CO)5{SCHCHC(SEt)2}]

The compound [Cr(CO)5{S[graphic omitted]}] reacted with Li(NPri2), CS2, and [Et3O][BF4] to afford either [Cr(CO)5{SCHCHC(SEt)2}](1) or [Cr(CO)5{SC(SCHCH2)SEt}](2) depending upon the reaction conditions employed. The crystal structure of the co-ordinated thioaldehyde (1) was determined [orthorhombic, space group Pbcm, a= 11.530(5), b= 18.745(9), c= 7.889(4)A, and Z= 4] and refined to R= 0.040 and R′= 0.038. All the atoms except those of four axial CO ligands and some hydrogens lie in one plane.

Sulphur-containing metal complexes. Part 9. Synthesis of trisubstituted aminocarbene–thioether chelates of chromium(0) and tungsten(0)

Several isocyanide–thioether complexes, cis-[M(CNR)(CO)4{S(R1)CH2R2}][M = Cr: R = But, R1R2=(CH2)3S; R = R1= Ph, R2= SPh; R = cyclo -C6H11 or CH2Ph, R1R2=(CH2)3S. M = W : R = But, R1R2=(CH2)3S] were prepared by u.v. irradiation of the corresponding pentacarbonyl(isocyanide) complexes in the presence of the thioether compounds. Deprotonation of two of these, cis-[M(CNBut)(CO)4{[graphic omitted]H2}](M = Cr or W), with LiBu and addition of PEt3, resulted (via consecutive carbonylation and isocyanide insertion into a metal–carbene bond) in the formation of the evasive trisubstituted aminocarbene–thioether chelates, fac-[[graphic omitted]}(PEt3)], upon alkylation with [Et3O][BF4]. Replacement of the phosphine by 1,3-dithiolane-2-thione under similar reaction conditions yielded, unexpectedly, the substitution products cis-[Cr(CNR)(CO)4{S[graphic omitted]}](R = But or Ph). When in addition, the isocyanide had been substituted for CO, the first saturated cyclic dithiocarbene complex of chromium, [Cr(CO)5{[graphic omitted]}], was formed.

Insertion of iron carbonyl into a CS bond of tetrathiofulvalene

Abstract Irradiation of a mixture of tetrathiofulvalene (TTF) and iron pentacarbonyl in THF gives a dinuclear hexacarbonyl iron chelate, Fe2(CO)6[μ-SC( CSCHCHS )SCHCH] (1), by ring-opening of TTF adjacent to an internal double bond. The donated ligand electrons originate from an sp2 carbon atom, a sulphur atom, and a carbon—carbon double bond.

Preparation and characterization of two isocyanide derivatives of monosubstituted [Fe3(CO)9S2]; crystal structure of [Fe3(CO)8(CNPh)(µ2-S)2]

Irradiation of [Fe(CO)5] in the presence of PhNCS produced [Fe3(CO)9(µ3-S)2] and two isomeric phenyl isocyanide derivatives, [Fe3(CO)8(CNPh)(µ3-S)2], substituted on either a central or a terminal iron atom. The crystal structure of the centrally substituted isomer was determined by X-ray diffraction.