Synthesis,Crystal Structure and Spectroscopic Characterisation of Mono‐ and Dinuclear 5,5‐Diethylbarbiturato Complexes of Chromium(0) and Rhenium(I)

Addition of 5,5‐diethylbarbituric acid (H₂debarb, 1 ) to [CpCr(NO)₂Cl], [Re(CO)₅Br] or [(PPh₃)Re(CO)₄Br] in the presence of triethylamine and AgO₃SCF₃ (= AgOTf) resulted in the mono‐barbiturato complexes [CpCr(NO)₂(Hdebarb)] ( 2 ), [PPh₃Re(CO)₄(Hdebarb)] ( 3 ) and [Re(CO)₅(Hdebarb)] ( 4 ), respectively. Bis‐barbiturato complex [{(CO)₅Re}₂(debarb)] ( 5 ) with a doubly deprotonated barbiturate dianion formed when a molar ratio of metal complex to ligand of 2:1 was used. In the case of the rhenium complexes, AgO₃SCF₃ must be used additionally to cleave off bromide. All of the complexes were fully characterised by means of IR, mass and ¹H, ¹³C and ³¹P NMR spectra and elemental analysis. In addition, their solid‐state structures were determined by single‐crystal X‐ray diffraction studies. The complexes exhibit distorted pseudo‐tetrahedral ( 2 ) or pseudo‐octahedral ( 3 – 5 ) configuration around the metal atom. In all complexes the ring system of the Hdebarb ligand is essentially planar.     

The tris(triphenylphosphine)osmium zerovalent complexes Os(CO)2(PPh3)3, .Os(CO)(CNR)(PPh3)3, Os(CO)(CS)(PPh3)3, Os(CS)(cNR)(PPh3)3 and derived compounds

Detailed procedures for the syntheses of Os(CO)₂(PPh₃)₃, Os(CO)(CNR)-(PPh₃)₃ (R = p-tolyl), Os(CO)(CS)(PPh₃)₃ and Os(CS)(CNR)(PPh₃)₃, together with the derived complexes Os(CO)₂(CS)(PPh₃)₂, Os(CO)(CS)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CS)(PPh₃)₂, Os(η²CS₂)(CO)₂-(PPh₃)₂, Os(η²CS₂)(CO)(CS)(PPh₃)₂, Os(η²-CS₂)(CO)(CNR)(PPh₃)₂, Os(η²PhC₂Ph)(CO)₂(PPh₃)₂ and OsH(C2Ph)(CO)₂(PPh₃)₂ are described.     

Basicity of transiton metal carbonyl complexes : XIII. Reactions of the π-cyclopentadienyl complexes of molybdenum and tungsten with aprotic acids

The aprotic acids HgCl₂ and SnX₄ (X  Cl, Br) react with the π-complexes C₅H₅M(CO)(NO)(L) (II, M  Mo W; L  PPh₃) by attack at the metal center. With HgCl₂ complexes II yield stable neutral 1:1 adducts CpM(CO)(NO)(L)HgCl₂(III). In the case of SnCl₄, complexes II initially produce the ionic 1:2 adducts [CpM(CO)(NO)(L)(SnCl₃)]⁺SnCl₅^-(IV) which, as a result of oxidative elimination of CO, turn into the neutral complexes CpM(NO)(L)(SnCl₃)(Cl)(V). In reactions of II with SnBr₄ the corresponding CpM(NO)(L)(SnB₃)(Br) complexes are formed directly. The formation of III–V is accompanied by a considerable increase of the frequencies ν(CO) and ν(NO). The structures of the complexes IV (M  Mo) and V (M  Mo) have been established by an X-ray structure analysis.     

Sulfur-containing carbene-metal compounds: General route from carbon disulfide manganese complexes; X-ray structure of 1,3-dithiol-2-ylidenemanganese(I) derivative

Chiral carbene-manganese(I) complexes have been synthesized by the cyclo-addition of dimethyl acetylenedicarboxylate to the coordinated CS₂ ligand in Mn(η²-CS₂)(CO)(L)C₅H₄R (L = P(OMe)₃; PMe₂Ph; PMe₃). Irrespective of the nature of the ligand L, these 1,3-dithiol-2-ylidenemanganese(I) complexes are stable towards isomerisation into heterometallocycles and exhibit low frequency carbonyl absorption bands in the infrared consistent with a strong electron releasing effect of the carbene ligand. The structure of Mn(CS₂C₂(CO₂Me)₂)(CO)(P(OMe)₃)(C₅H₅) has been determined by X-ray analysis of a suitable crystal. The molecule shows a carbene carbonmanganese bond C(7)Mn of length 1.876 Å and a planar carbene which does not adopt the 1,3-dithiolium aromatic-ring geometry but contains a carboncarbon double bond, C(8)C(9), of length of 1.341 Å. The CO₂Me groups are out of the plane of the carbene ligand and two positions with equal occupancy are found for each oxygen atom O(3) and O(5) belonging to the CO groups.     

[M(CO)2(NO)], a new core in bioorganometallic chemistry: model complexes of [Re(CO)2(NO)] and [Tc(CO)2(NO)]

In this study selected bidentate (L²) and tridentate (L³) ligands were coordinated to the Re(I) or Tc(I) core [M(CO)₂(NO)]²⁺ resulting in complexes of the general formula fac-[MX(L²)(CO)₂(NO)] and fac-[M(L³)(CO)₂(NO)] (M = Re or Tc; X = Br or Cl). The complexes were obtained directly from the reaction of [M(CO)₂(NO)]²⁺ with the ligand or indirectly by first reacting the ligand with [M(CO)₃]⁺ and subsequent nitrosylation with [NO][BF₄] or [NO][HSO₄]. Most of the reactions were performed with cold rhenium on a macroscopic level before the conditions were adapted to the n.c.a. level with technetium (^99mTc). Chloride, bromide and nitrate were used as monodentate ligands, picolinic acid (PIC) as a bidentate ligand and histidine (HIS), iminodiacetic acid (IDA) and nitrilotriacetic acid (NTA) as tridentate ligands. We synthesised and describe the dinuclear complex [ReCl(μ-Cl)(CO)₂(NO)]₂ and the mononuclear complexes [NEt₄][ReCl₃(CO)₂(NO)], [NEt₄][ReBr₃(CO)₂(NO)], [ReBr(PIC)(CO)₂(NO)], [NMe₄][Re(NO₃)₃(CO)₂(NO)], [Re(HIS)(CO)₂(NO)][BF₄], [⁹⁹Tc(HIS)(CO)₂(NO)][BF₄], [^99mTc(IDA)(CO)₂ (NO)] and [^99mTc(NTA)(CO)₂(NO)]. The chemical and physical characteristics of the Re and Tc-dicarbonyl-nitrosyl complexes differ significantly from those of the corresponding tricarbonyl compounds.     

The chemistry of hetero-allene and -allylic derivatives with rhodium : I. The reactions of rhodium(I)-hetero-allylic compounds with hetero-allenes; B. Carbon Disulfide

The rhodium(I) complexes Rh[X-C(Z)-Y] (PPh₃)₂, in which [X-C(Z)-Y] represents an uninegative unsaturated heteroallylic bidentate ligand, coordinating via two of the three hetero atoms (X, Y, Z  P, S or N), react at elevated temperature with an excess of the hetero-allene SCS to give the rhodium(I)-thiocarbonyl complexes Rh[X-C(Z)-Z](CS)(PPh₃). In the initial step a first CS₂ molecule is coordinated side-on by one of the CS double bands. Subsequent reactions can be blocked at this stage by addition of pyridine, resulting in RhCl(η²-CS₂)(PPh₃)(py)₂. The formation of the CS complexes occurs in two ways. Either by direct sulfur abstraction from the Rh^I(η²-CS₂) complex by PPh₃ or by a dimerisation of two CS₂ molecules and elimination of a CS moiety, resulting in a Rh^III-thiocarbonyl-trithiocarbonato complex, immediately followed by demolition of the trithiocarbonato-CS^?2₃ fragment, by PPh₃ to SPPh₃ and CS₂.Complexes containing a CS^?2₃ fragment, but no CS moiety, can also be identified by IR measurements. These products may be formed in a sidereaction upon elimination of CS.     

Basicity of transition metal carbonyl complexes : IX. An infrared study of lewis acid reactions with cyclopentadienyl and arene derivatives of groups VI and VII transition metal carbonyls and nitrosyls

The different courses of the interactions of cyclopentadienyl and arene derivatives of Group VI and VII transition metal carbonyl and transition complexes with Lewis acids, in solutions, have been studied by IR spectroscopy.The information of adducts involving the metal atom was observed for CpRe(CO)₂L (L = CO, PR₃) with SnCl₄, SnBr₄, TiCl₄; AreneM(CO)₃ (M = Cr, Mo, W) with SnCl₄, TiCl₄; and Ph₃PC₅H₄M(CO)₃ (M = Cr, Mo, W) with TiCl₄ and AlCl₃. Complexes CpM(CO)₂NO and CpM(CO(NO)PPh₃, depending on thier donor and acceptor nature, form adducts involving the oxygen atoms of CO or NO groups or the metal atom. CpCr(NO)₂Cl reacts with Lewis acids via the chlorine atom. The relative basicity of the different sites in the complexes investigated is discussed.     

Chromium and molybdenum pentacarbonyl complexes of phosphinocarbodithioates: synthesis, molecular structure and behaviour in RAFT polymerisation

Molybdenum and chromium pentacarbonyldiphenylphosphinocarbodithioate complexes have been prepared in a one‐pot reaction from the corresponding metallocarbonyldiphenylphosphine. The complexes have been characterised by IR, ¹H, ³¹P and ¹³C NMR spectroscopies and by mass spectrometry. The solid‐state structures of [Cr(CO)₅{PPh₂CS₂CH(Ph)CH₃}] ( 1 ) and [Mo(CO)₅{PPh₂CS₂CH(Ph)CH₃}] ( 2 ) are reported. Compounds 1 and 2 are isostructural and crystallise in the triclinic P$\bar 1Molybdenum and chromium pentacarbonyldiphenylphosphinocarbodithioate complexes have been prepared in a one-pot reaction from the corresponding metallocarbonyldiphenylphosphine. The complexes have been characterised by IR, (1)H, (31)P and (13)C?NMR spectroscopies and by mass spectrometry. The solid-state structures of [Cr(CO)(5){PPh(2)CS(2)CH(Ph)CH(3)}] (1) and [Mo(CO)(5){PPh(2)CS(2)CH(Ph)CH(3)}] (2) are reported. Compounds 1 and 2 are isostructural and crystallise in the triclinic P1 space group. These new organometallic compounds are highly efficient reversible chain-transfer agents for reversible addition-fragmentation chain-transfer (RAFT) polymerisation of styrene (St) and n-butyl acrylate (nBA), with controlled number-average molar mass values and narrow dispersities (<1.2). The controlled character of the polymerisation was further exemplified by the synthesis of St and nBA diblock copolymers.     

Stepwise reduction of the thiocarbonyl ligand: hydride transfer to CS: thioformyl,thioformaldehyde, methylthiolato,secondary carbene,formyl and iminoformyl complexes of osmium

The complexes OsHX(CS)L(PPh₃)₂ (X  Cl, Br; L  CO and X  Cl; L  CN-p-tolyl), which contain mutually cis hydrido and thiocarbonyl ligands, undergo transfer of the hydrido ligand to CS when treated with CO to give blue complexes containing the thioformyl ligand [OsCHS]. OsCl(CHS)(CO)₂(PPh₃)₂ reacts with borohydride to give the first metal complex of the thioformaldehyde monomer, viz. Os(η²-CH₂S)(CO)₂(PPh₃)₂, which reacts rapidly with HCl to give OsCl(SCH₃)(CO)₂(PPh₃)₂ and then, by a slower reaction, OsCl₂(CO)₂(PPh₃)₂ and CH₃SH. The ligands produced in this stepwise reduction have possible relevance as models for postulated intermediates in the Fischer—Tropsch synthesis. Synthetic routes to formyl [OsCHO], iminoformyl [OsCHNMe] and secondary carbene complexes [OsCHSMe, OsCHNMe₂, OsCHOMe] are also demonstrated.     

[Fe2(μsb‐CO)(CO)3(NO)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)]: Synthese,Kristallstruktur und Koordinationsisomerie

[Fe₂(μ_sb‐CO)(CO)₃(NO)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)]: Synthesis, X‐ray Crystal Structure and Isomerization Na[Fe₂(μ‐CO)(CO)₆(μ‐P^tBu₂)] ( 1 ) reacts with [NO][BF₄] at —60 °C in THF to the nitrosyl complex [Fe₂(CO)₆(NO)(μ‐P^tBu₂)] ( 2 ). The subsequent reaction of 2 with phosphanes (L) under mild conditions affords the complexes [Fe₂(CO)₅(NO)L(μ‐P^tBu₂)], L = PPh₃, ( 3a ); η‐dppm (dppm = Ph₂PCH₂PPh₂), ( 3b ). In this case the phosphane substitutes one carbonyl ligand at the iron tetracarbonyl fragment in 2 , which was confirmed by the X‐ray crystal structure analysis of 3a . In solution 3b loses one CO ligand very easily to give dppm as bridging ligand on the Fe‐Fe bond. The thus formed compound [Fe₂(CO)₄(NO)(μ‐P^tBu₂)(μ‐dppm)] ( 4 ) occurs in solution in different solvents and over a wide temperature range as a mixture of the two isomers [Fe₂(μ_sb‐CO)(CO)₃(NO)(μ‐P^tBu₂)(μ‐dppm)] ( 4a ) and [Fe₂(CO)₄(μ‐NO)(μ‐P^tBu₂)(μ‐dppm)] ( 4b ). 4a was unambiguously characterized by single‐crystal X‐ray structure analysis while 4b was confirmed both by NMR investigations in solution as well as by means of DFT calculations. Furthermore, the spontaneous reaction of [Fe₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 5 ) with NO at —60 °C in toluene yields a complicated mixture of products containing [Fe₂(μ‐CO)(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 6 ) as main product beside the isomers 4a and 4b occuring in very low yields.     

Synthesis of low-valent thiocarbonyl complexes via 1,2-elimination of methylthiol from cis-metal-hydrido-dithiomethylester complexes. Os(cs)(CO)2(PPh3)2 and IrCl(CS)(PPh3)2.

[OS(η²-CS₂Me)(CO)₂(PPH₃)₂]⁺ and [Ir(η²-CS₂Me)Cl(CO)(PPh₃)₂)⁺ react with NaBH₄ giving OsH(CS₂Me)(CO)₂(PPh₃)₂ and IrH(CS₂Me)Cl(CO)(PPh₃)₂ respectively; These compounds contain mutually $\text{cis}$ hydride and η¹-dithiomethylester ligands and upon heating undergo 1,2-elimination of MeSH producing Os(CS)(CO)₂(PPh₃)₂ and IrCl(CS)(PPh₃)₂.     

Synthesis and characterization of rhenium(I) complexes with the polypyridinic quinone functionalized electron acceptor ligand [3,2-a:2′,3′-c]-benzo[3,4]-phenazine-11,16-quinone, Nqphen

In this work, the synthesis and characterization of fac-[Re(CO)₃(Nqphen)(L)]PF₆ complexes is reported. Nqphen is the quinone substituted acceptor ligand [3,2-a:2′,3′-c]-benzo[3,4]-phenazine-11,16-quinone, and L represents the donor monodentate pyridine substituted ligands 4-tert-butylpyridine (t-Bupy), 4-methoxypyridine (MeO-py) or 10-(4-picolyl)phenothiazine (py-PTZ). The complexes were synthesized by refluxing in methanol the metal precursor fac-Re(CO)₃(Nqphen)TfO (TfO = trifluoromethanesulphonate anion) with the corresponding L ligand. The UV-Vis spectra of the complexes are dominated by intense intraligand (IL) bands, and less intense metal ligand charge transfer (MLCT) bands with maxima in the 380-400 nm region. The IR shows the typical pattern for tricarbonyl Re complexes with facial (fac) geometry. An additional v(CO) stretching band, attributed to the quinone fragment of Nqphen, is observed.Electrochemical data indicate that the acceptor capacity of Nqphen is increased in the complexes with regard to the free ligand. This effect is sensitive to the nature of the L ligand, following the order: MeO-py < t-Bupy < py-PTZ, indicating therefore that the donor capacity of L affects the rest of the molecule. The results obtained for the fac-[Re (CO)₃(Nqphen)(pyPTZ)]PF₆ complex here reported were compared with those observed for the homologous complex fac-[Re(CO)₃(Aqphen)(L)]^0/+, with Aqphen = 12,17-dihydronaphtho[2,3-h]dipyrido[3,2-a:2′,3′-c]-phenazine-12,17-dione, and L = Cl⁻, TfO⁻, py-PTZ.     

Zur Kenntnis der Chemie der Metallcarbonyle und der Cyano-Komplexe in flüssigem ammoniak : XL. Über die Reaktion kationischer Cyclopentadienyl-carbonyl-nitrosyl-Komplexe des Mangans und Rheniums mit flüssigem Ammoniak

The reactions of the cationic complexes [CpMn(CO)₂NO]⁺, [MeCpMn(CO)₂NO]⁺ (Cp = η⁵-C₅H₅, MeCp = η⁵-C₅H₄CH₃), [CpRe(CO)₂NO]⁺, [CpMn(CO)(L)NO]⁺ (L = PPh₃, PEt₂Ph, AsPh₃, CNMe, CNEt), {[CpMn(CO)NO]₂Me₂PC₂H₄PMe₂}²⁺ and {CpMn(CO)NO]₂Ph₂PC₂H₄PPh₂}²⁺ with liquid NH₃ yield the neutral carbamoyl complexes CpMn(CO)(NO)CONH₂, MeCpMn(CO)(NO)CONH₂, CpRe(CO)(NO)CONH₂, CpMn(L)(NO)CONH₂ (L = PPh₃, PEt₂Ph, AsPh₃, CNMe, CNEt), [CpMn(NO)CONH₂]₂Me₂PC₂H₄PMe₂ and [CpMn(NO)CONH₂]₂Ph₂PC₂H₄PPh₂. Properties and reactions of these new compounds are described.     

Geometrical and Ground State Electronic Structures of Nitrosylcobalt Complexes [(RNCHCHNR)Co(NO)(CO)] (R = Isopropyl, 2,6‐Diisopropylphenyl or p‐Tolyl) from Experiment and DFT‐Calculations

The new complexes (RN=CH‐CH=NR)Co(NO)(CO), R = isopropyl ( 1 ), 2,6‐diisopropylphenyl ( 2 ) and p‐tolyl ( 3 ), were synthesized and spectroscopically characterized. Compounds 1 and 2 could be crystallized for X‐ray structure analysis, CO/NO disorder was observed for 1 . The results indicate a negligible amount of charge transfer from the Co(NO)(CO) moiety to the 1, 4‐diazabutadiene acceptor ligands in the ground state, in agreement with DFT calculations on 1 and as similarly reported for related 1, 4‐diaza‐1, 3‐butadiene complexes of Ni(CO)₂ and Fe(NO)₂.     

Permetalloplumbanes: Preparation of [Pb{Co(CO)3(L)}4] and [Pb{Fe(CO)2(NO)(L)}4].: Complexes containing four transition metal to lead bonds (L = tertiary arsine,phosphine or phosphite).

The sole and unexpected products from the reactions of a variety of lead (II) and lead (IV) compounds with [Co₂(CO)₆(L)₂] complexes (L = tertiary arsine, phosphine, or phosphite) in refluxing benzene solution are the blue, air-stable percobaltoplumbanes [Pb{Co(CO)₃(L)}₄]. These have also been obtained from the reaction of Na[Co(CO)₃(L)] (L  PBu₃ⁿ) with lead (II) acetate which with Na[Fe(CO)₂(NO)(L)] forms the isoelectronic [Pb{Fe(CO)₂(NO)(L)}₄] [L  P(OPh)₃]. The IR spectra of the complexes in the v(CO) and v(NO) regions are consistent with tetrahedral PbCo₄ or PbFe₄ fragments, trigonal bipyramidal coordination about the cobalt or iron atoms and linear PbCoAs, PbCoP, or PbFeP systems. Unlike [Pb{Co(CO)₄}₄], our complexes do not dissociate to [Co(CO)₃(L)]^? or [Fe(CO)₂(NO)(L)]^? ions when dissolved in donor solvents.     

Rhenium‐Dicarbonyl‐Nitrosyl‐Komplexe mit Imidazol

Rhenium Dicarbonyl‐Nitrosyl Complexes with Imidazole Different rhenium‐dicarbonyl‐nitrosyl complexes with imidazole (Im) as monodentate ligand have been synthesized and characterized, starting from [NEt₄][ReCl₃(CO)₂(NO)] and [ReCl(μ?Cl)(CO)₂(NO)]₂. Whereas the complexes [ReCl₂(Im)(CO)₂(NO)] and [ReCl(Im)₂(CO)₂(NO)]⁺ were achieved in high yields, the complex [Re(Im)₃(CO)₂(NO)]²⁺ with three imidazole ligands could only be isolated after complete removal of all halide ions (with AgBF₄) in low yield. The synthesis of a corresponding ^99mTc‐dicarbonyl‐nitrosyl complex with imidazole opens a new perspective for such compounds as potential radiopharmaceuticals and alternatives to the already established ^99mTc‐tricarbonyl complexes.     

Unusual reactivity of tantalum pentakis(dimethylpyrazolate) with CS2: scission of the C=S bond and formation of dmpz3CS– ligand

The reaction beetwen tantalum pentakis(3,5-dimethyl-pyrazolate) and CS₂ afforded novel complex [Ta(=S)(dmpz)₂{(dmpz)₃CS}]. In this reaction the molecule of CS₂ undergoes scission with the migration of one sulfide to the tantalum atom while three pyrazolate residues migrate to carbon with the formation of unusual (dmpz)₃CS^– ligand. The structure of the product was established by X-ray diffraction.     

Reaction Behavior of Decacarbonyldimetalates(2‐) (M = Cr and Mo) towards the Nitrosyl Carbonyls of Iron and Cobalt

The reaction of the nitrosyl carbonyl complexes [Fe(NO)₂(CO)₂] and [Co(NO)(CO)₃] with the decacarbonyldimetalates [M₂(CO)₁₀]^2– (M = Cr and Mo) in THF as the solvent at room temperature was investigated. Thereby a substitution of one nitrosyl ligand towards carbon monoxide was observed in each case. Both reactions afforded the known metalate complexes [Fe(NO)(CO)₃]^– and [Co(CO)₄]^–, respectively. These species were isolated as their corresponding PPN salts [PPN⁺ = bis(triphenylphosphane)iminium cation] in nearly quantitative yields. The products were unambiguously identified by their IR spectroscopic and elemental analytic data as well as by their characteristic colors and melting points.     

Gehinderte Ligandenbewegungen in Übergangsmetallkomplexen : VII. Rotation der olefinliganden L = malein- und furmarsäuredimethylester in komplexen des typs C5H5Mn(CO)2L und C5H5Cr(CO)(NO)L

The restricted rotation of the olefin ligands L = dimethyl maleate and dimethyl fumarate in complexes of the type C₅H₅Mn(CO)₂L and C₅H₅Cr(CO)-(NO)L, respectively, has been investigated on the basis of their temperature-dependent ¹H NMR spectra. The olefinic ligand is arranged preferably in a position where the CC double bond is parallel to the plane of the cyclopentadienyl ring. The possible stereoisomers are discussed using this model. The ¹H NMR spectra of C₅H₅Cr(CO)(NO)(trans-CH₃OOCCHCHCOOCH₃) provide direct evidence that the configuration (R or S) at the metal is stable up to 120°C, and that the restricted motion of the olefin is exclusively rotation around the metal—olefin bond. The activation barriers of the olefin rotation are found to be appreciably lower in the C₅H₅Mn(CO)₂L complexes (ΔG^≠(T_C) 11–12 kcal mol^?1) than in the isoelectric C₅H₅Cr(CO)(NO)L compounds (ΔG^≠(T_C) 15–20 kcal mol^?1).     

Erratum

The hydrido-thiocarbonyl osmium(II) complexes OsH₂(CS)(PPh₃)₃, OsHCl(CS)(PPh₃)₃, OsH(OClO₃)(CS)(PPh₃)₃, OsHCl(CS)(CNR)(PPh₃)₂ and [OsH(CS)(CO)(PPh₃)₃]⁺, (R = p-tolyl), have been derived from OsCl₂(CS)(PPh₃)₃ and [OsH(CS)(CO)(PPh₃)₃]⁺, the latter can be deprotonated to give the zerolavent complex, Os(CS)(CO)(PPh₃)₃.