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Thiolate protected metal clusters are valuable precursors for the design of tailored nanosized catalysts. Their performance can be tuned precisely at atomic level, e.g. by the configuration/ type of ligands or by partial/complete removal of the ligand shell through controlled pre-treatment steps. However, the interaction between the ligand shell and the oxide support, as well as ligand removal by oxidative pre-treatment, are still poorly understood. Typically, it was assumed that the thiolate ligands are simply converted into SO 2 , CO 2 and H 2 O. Herein, we report the first detailed observation of sulfur ligand migration from Au to the oxide support upon deposition and oxidative pre-treatment, employing mainly S K-edge XANES. Conse- quently, thiolate ligand migration not only produces clean Au cluster surfaces but also the surrounding oxide support is modified by sulfur-containing species, with pronounced effects on catalytic properties

This review is focused on the chemistry of titanocene sulfide compounds. The linking element for all compounds discussed in this review is the presence of a bent titanocene fragment consisting of two aromatic cyclopentadienyl rings and one electron deficient central titanium atom coordinated between them. Several types of sulfur ligands bonding to titanocene fragment, such as hydrosulfide, sulfide or thiolate are described, as well as the various types of sulfur ligand functions in titanocene complexes have been observed. The titanocene sulfide chemistry is more than fifty years old, but since it is still evolving, it offers a plethora of surprises and challenges.

The protonation of trans-[Os(OMe)2{N(Pri2PS)2}2] (1) with HBF4, followed by treatment with NH3(g) afforded the oxo-bridged dimer [Os2(μ-O){N(Pri2PS)2}4F2] (2). Reaction of 2 with Ag(OTf) (OTf− = triflate) gave the heterometallic Os(IV)/Ag(I) complex [Os2(μ-O){N(Pri2PS)2}4F2(AgOTf)2] (3), in which each Ag(OTf) moiety binds to three sulfur atoms of two [N(Pri2PS)2]− ligands. The solid-state structures of complexes 2 and 3 have been established by X-ray crystallography.

The molecular structure of [Cp*2Mo2P2S3] (1; Cp* = η5-C5Me5) has been reinvestigated. In DFT studies a series of various positional isomers A−E have been calculated for the model complex [(C5H5)2Mo2P2S3]. The energetically favored isomer [Cp*2Mo2(μ,η2:2-PS)2(μ-S)] (1B) reacts with W(CO)5THF to give [Cp*2Mo2P2S3·W(CO)5] (2). X-ray diffraction analysis of 2 confirms the presence of two η2:2-PS dumbbells and one singly bridging sulfur ligand, the W(CO)5 fragment being coordinated at one of the P atoms. Arrangement B is also found in the structure of the diadduct [Cp°2Mo2P2S3{W(CO)5}2] (3; Cp° = t-BuMe2C5H2), which is more stable than its Cp* analogue. 31P solid-state MAS NMR spectroscopic studies of 1 and 2 confirm the existence of only one isomer, but reveal disorder phenomena in the solid state within the cyclo-P2S3 middle deck. Addition of excess W(CO)5THF to 1 proceeds via elusive [Cp*2Mo2P2S3{W(CO)5}2] to give the cluster [{Cp*2Mo2W(CO)3(μ2,η2:2-PS)(μ3,η1:1:2-PS)(μ3-S)}{W(CO)5}2] (5). The molecular stru...

6-Ethynylferrocene-2,11-dithia[3.3]orthocyclophane has been prepared by cross-coupling 6-bromo-2,11-dithia[3.3]orthocyclophane to ethynylferrocene under Sonogashira conditions. The dynamic structure in solution of this potential ligand has been examined by variable temperature NMR whereas its solid state structure has been determined by X-ray diffraction studies. The electrochemical parameters of this cyclophane have also been examined.

The sulfur-rich iron carbonyl dimer complexes [Fe(CO) 2 (S′ Si S 2 )] 2 ( 2 ), and [Fe(CO)(S′ Si S 2 )] 2 ( 3 ) have been prepared. The [2Fe–2S] cores of the new complexes are planar. The binding mode of the tridentate sulfur ligand in complex 2 is facial with a S(thiolate)–Fe–S(thiolate) angle of 92°, while in complex 3 , the S′ Si S 2 ligand binds the metal with a S(thiolate)–M–S(thiolate) angle of 120°. The Fe–Fe distance is reduced from 3.45 A in complex 2 to 2.78 A in the 32 electron dimer complex 3 . Complexes 2 and 3 are at equilibrium in solution and can be readily interconverted by addition or removal of CO.

Potassium 1,3-dipyrrolidinopropan-2-O-xanthate (LK), and its complexes with Co(II), Ni(II) and Cu(I) have been prepared and characterized as [CoL2(H2O)2] · 2H2O, [NiL2(H2O)2] and CuL · 2H2O by FT-IR, 1H and 13C NMR spectroscopies, elemental analyses, magnetic susceptibility and TGA techniques.

Treatment of [Cp*RuCl2]x (Cp* = η5-C5Me5) with K[N(Ph2PS)2] afforded [Cp*Ru{N(Ph2PS)2}Cl] (1). Reduction of 1 with Li[BEt3H] gave the 16-electron half-sandwich Ru(II) complex [Cp*Ru{N(Ph2PS)2}] (2). Complexes 1 and 2 have been characterized by X-ray crystallography. The Ru–Cp*(centroid) and average Ru–S distances in 1 are 1.827 and 2.3833(5) A, respectively. The corresponding bond distances in 2 are 1.739 and 2.379(1) A. Treatment of 2 with 2-electron ligands L afforded the adducts [Cp*Ru{N(Ph2PS)2}L] (L = CO (3), 2,6-Me2C6H4NC (4), MeCO2C CCO2Me (5)). Oxidation of 2 with tetramethylthiuram disulfide gave the Ru(IV) complex [Cp*Ru{S2CNMe2}2][N(Ph2PS)2] (6). The Ru–Cp*(centroid) and average Ru–S distances in 6 are 1.897 and 2.387(1) A, respectively.

The silver(I) complexes of 2,2′,3,3′-tetrahydro-4,4′-dithia-1,1′-binaphthylidene (ttp) having a nine-member SAgS chelating ring, [Ag(ttp)(ClO4)]n (1) and [Ag2(ttp)2(CF3SO3)2]n (2), have been synthesized and characterized by single-crystal X-ray diffraction. The ttp is found to offer a potential coordination site for complexation, which can be utilized to generate an interesting array of silver(I) complexes with a one-dimensional chain and a chiral chain.

Complexes of Au(I) and Cu(I) with 1-(thiomethyl)-2-(diphenylphosphino)ethane (PSMe) have been prepared; the two products have the same general formula MCl(PSMe). The structure of the gold complex has been determined by X-ray crystallography. AuCl(PSMe) crystallizes in the monoclinic system, space group P2 1 /c, a= 11.618(9), b = 11.664(7), c = 13.013(8) A , V = 1615 A , β = 113.6(1) °, Z = 4 . The complex is linear with PAuCl = 177.9(1)°. The copper complex has been studied by mass, IR and NMR spectroscopies, in view of the results so obtained we have postulated a dinuclear structure with a chloride bridge for this compound.

Substitution reactions at the nickel site of the cubane-type cluster [(Ph3P)NiFe3S4(LS3)]2- (2) have been investigated in the course of a synthetic approach to the C-clusters of CODH. Reaction of 2 with RS- or toluene-3,4-dithiolate affords [(RS)NiFe3S4(LS3)]3- (R = Et (5), H (6)) or [(tdt)NiFe3S4(LS3)]3- (7), demonstrating that anionic sulfur ligands can be bound at the NiII site. Clusters 5 and 6 contain tetrahedral Ni(micro3-S)3(SR) sites. Cluster 7 is of particular interest because it includes a cubanoid NiFe3(micro2-S)(micro3-S)3 core and an approximately planar Ni(tdt)(micro3-S)2 unit. The cubanoid structure is found in all C-clusters, and an NiS4-type unit has been reported in C. hydrogenoformans CODH. Clusters 5/6 are formulated to contain the core [NiFe3S4]1+ identical with Ni2+ (S = 1) + [Fe3S4]1- (S = 5/2) and 7 the core [NiFe3S4]2+ identical with Ni2+ (S = 0) + [Fe3S4]0 (S = 2) on the basis of structure, 57Fe isomer shifts, and 1H NMR isotropic shifts. Also reported are [(EtS)CuFe3S4(LS3)]3- (9) and [Fe4S4(LS3)(tdt)]3- (11). The structures of 5-7, 9, and 11 are presented. Cluster 11, with a five-coordinate Fe(tdt)(micro3-S)3 site, provides a clear structural contrast with 7, which is currently the closest approach to a C-cluster but lacks the exo iron atom found in the NiFe4S4,5 cores of the native clusters. (CODH = carbon monoxide dehydrogenase, LS3 = 1,3,5-tris((4,6-dimethyl-3-mercaptophenyl)thio)-2,4,6-tris(p-tolylthio)benzene(3-), tdt = toluene-3,4-dithiolate).

A new, simpler, more general and dependable method of synthesizing dithiocarboxalato complexes of molybdenum(IV) is reported. It involves reaction of MoCl4·(CH3CH2CH2CN)4 with the acid form of the sulfur ligand. Thirteen Mo(IV) complexes are reported, 11 of which are new compounds and 5 of which contain newly synthesized dithiocarboxylato ligands. All ligands were prepared as the acids and converted to tetraalkylammonium salts for characterization. Infrared and visible-ultraviolet spectral data for the complexes are detailed.

π INDO CI calculations for the carbon monoxide complex of cytochrome P-450 show that the “hyper” spectrum is produced by strong interaction between the UV and the Soret bands. This interaction depends on the sulfur ligand charge and on the iron-sulfur distance. The “hyper” spectrum can only be explained assuming a partial negative sulfur charge less than “−0.6”.

The polydentate cyclic sulfur compounds β-2,4,6-trimethyl-s-trithiane and 1,3,5,7-tetrathiacyclooctane form the chelate complexes (CH3CHS)3M(CO)3 (M = Cr, Mo) and (CH2S)4Mo(CO)4. The mixed, substituted compounds (RCHS)3(bipyMo(CO)3)2 (R = H, CH3) and (CH2S)4(bipyMo(CO)3)n (n = 1, 2) contain the sulfur ligand cis to the coordinated 2,2′-bipyridine. The chemical and spectroscopic properties of the new compounds are described.

Phosphinous imides form ionic complexes of the type [C5H5Ni-(R2PNR′PR2)]X (R = C6H5; R′ = CH3, C6H5; X = BF4, Cl). NaCN reacts with [C5H5Ni(R2PNCH3PR2)]BF4 to give the neutral complex C5H5Ni-(R2PNCH3PR2)CN (R = C6H5) in which the phosphinous imide acts as a monodentate ligand.

[C5H5Fe(CO)2thf]+ reacts with the ligands LL and LLL to give the cations [C5H5Fe(CO)2LL]+ (LL = RS(CH2)nSR, 1,4-dithiane) and [C5H5Fe(CO)2LLL]+ (LLL = 1,3,5-trithiane, tris(methylmercapto)methane) containing monodentate coordinated sulfur ligands. In a similar way, sulfur ligand bridged dinuclear dications [(C5H5Fe(CO)2)2(μ-LL)]2+ and [(C5H5Fe(CO)2(μ-LLL)]2+ and tri-nuclear trications [(C5H5Fe(CO)2)3(μ-LLL)]3+ are formed. Irradiation of the mononuclear cations gives the chelate complexes [C5H5Fe(CO)(η2-LL)]+.