Electron-rich Metal Centers Research Articles

Synthesis, Structure, and Electrochemistry of an Electron-Rich Chiral Diaminoferrocene, (S,S)-Bis(2,5-dimethylpyrrolidinyl)ferrocene

The chiral diamine (S,S)-bis(2,5-dimethylpyrrolidinyl)ferrocene (6) was prepared from diaminoferrocene and (2R,5R)-2,5-hexanediol cyclic sulfate in the presence of a base. The short C-N bond, long Fe-C(N) bond, and planarnitrogen observed in the crystal structure of 6 are consistent with efficient N-to-Cp electron donation. The resulting electron-rich metal center (with the most negative shift in redox potential yet observed for aminoferrocenes) was characterized electrochemically.

Synthesis, characterization, and DNA binding properties of a series of Ru, Pt mixed-metal complexes.

A series of mixed-metal complexes coupling ruthenium light absorbers to platinum reactive metal sites through polyazine bridging ligands have been prepared of the form [(tpy)RuCl(BL)PtCl(2)](PF(6)) (BL = 2,3-bis(2-pyridyl)pyrazine (dpp), 2,3-bis(2-pyridyl)quinoxaline (dpq), 2,3-bis(2-pyridyl)benzoquinoxaline (dpb); tpy = 2,2':6',2' '-terpyridine). These systems possess electron-rich Ru metal centers bound to five polyazine nitrogens and one chloride ligand. This leads to complexes with low-energy Ru --> BL charge-transfer bands that are tunable with BL variation occurring at 544, 632, and 682 nm for dpp, dpq, and dpb, respectively. This tuning of the charge-transfer energy results from a stabilization of the BL(pi) orbitals in this series as evidenced by the cathodic shift in the first reduction of these complexes occurring at -0.50, -0.32, and -0.20 V vs Ag/AgCl, for dpp, dpq, and dpb, respectively. The chlorides bound to the Pt(II) center are substitutionally labile giving these complexes the ability to covalently bind to DNA. All three title bimetallics, [(tpy)RuCl(BL)PtCl(2)](PF(6)), avidly bind double-stranded DNA with t(1/2) = 1-2 min, substantially reducing the migration of DNA through an agarose gel. Details of the synthetic methods, FAB MS data, spectroscopic and electrochemical properties, and DNA binding studies are presented.

Organometallic complexes for nonlinear optics.: Part 27. Syntheses and optical properties of some iron, ruthenium and osmium alkynyl complexes

The syntheses of the alkynyl complexes M(4-CCC 6H 4NO 2)(dppe)(η-C 5H 5) [M=Fe ( 1), Ru ( 2), Os ( 3)], Os(4-CCC 6H 4NO 2)(PPh 3) 2(η-C 5H 5) ( 4) and Ru(4-CCC 6H 4NO 2)(CO) 2(η-C 5H 5) ( 5) are reported. Structural studies reveal a decrease in RuC(1) distance on proceeding from 5 to 2, consistent with greater back-donation of electron density to the alkynyl ligand from the more electron-rich metal center in 2. Electrochemical data show that the M II/III couple for the dicarbonyl complex 5 is at a significantly more positive potential than that of the related diphosphine complex 2, consistent with ligand variation modifying the electron richness and hence donor strength of the metal center. Time-dependent density functional calculations on model complexes M(4-CCC 6H 4NO 2)(PH 3) 2(η-C 5H 5) (M=Fe, Ru, Os) have been employed to assign the intense low-energy optical transition in these complexes as MLCT in character, the higher energy band being phenyl–phenyl* in nature. Molecular quadratic optical nonlinearities have been measured using the hyper-Rayleigh scattering procedure at 1064 nm. β values vary as Fe≤Ru≤Os for metal variation and CO<phosphines for co-ligand variation, the latter consistent with the variation in donor strength of the metal center inferred from electrochemical and crystallographic data. The observed trend in β on metal variation follows the trend in backbonding energies calculated by DFT.

Double C(sp3) dehydrogenation as a route to coordinated Arduengo carbenes: experiment and computation on comparative π-acidity

Reaction of [RuHClL2]2 (L=PiPr3) with the C/C unsaturated cyclic carbene:C(NMeCH)2 produces the 16-electron square-pyramidal RuHCl[CNMeCHCHNMe]L2 by a chloride bridge-splitting reaction. Double H2C(sp3) dehydrogenation of cyclic H2C(NMeCH2)2 is successful for producing the C/C saturated carbene (bound to Ru); the two hydrogens removed are found as RuHCl(H2)L2. In this case, the free carbene is unstable with respect to dimerization to the olefin. The 13C chemical shifts of the carbene carbons of these two complexes, the Ru/C distance, the N–C(carbene) distance, and a variety of reaction energies (from DFT calculations) and calculated atomic charges are generally consistent with these two carbenes, aromatic and non-aromatic, both binding similarly, and with little back donation from this electron-rich center. The 13C chemical shifts are perhaps the most sensitive parameter. Collectively, these results suggest that, if the C/C unsaturated and the C/C saturated Arduengo carbenes differ in their binding to this electron-rich metal center, the difference is at or below detection limits.

Reactions of quadruply chelated silyl- and germyl-molybdenum hydrido complexes with isocyanides: observation of the trans-influence on the silyl ligand

The reactions of a series of silyl- and germyl-molybdenum hydrido complexes, [MoH3{E(Ar)[Ph2PCH2CH2P(Ph)C6H4–o]2}] (E = Si, Ge; Ar = Ph, C6F5, 4-Me2NC6H4), with various isocyanides result in the liberation of hydrogen and formation of the molybdenum isocyanide complexes, [MoH(CNR){E(Ar)[Ph2PCH2CH2P(Ph)C6H4–o]2}] (R = t-Bu, cyclo-C6H11, PhCH2, Ph, 2,6-Me2C6H3), in which the isocyanide ligand ligates at the site opposite to the E atom. The new complexes show in their solid-state IR spectra an intense band assignable to CN stretching, which is found to be considerably lower than that of the corresponding free isocyanide (more than 100 cm−1), demonstrating the existence of π-back-bonding from the electron-rich metal centre to the isocyanide ligand. Both X-ray crystallographic analyses and spectroscopic evidence confirm the strong trans-influence of the Si group.

Comparative behaviours of phospha-alkynes and alkynes at electron-rich phosphinic metal centres

The coordination chemistry of phospha-alkynes (PCR) at electron-rich and sterically hindered {M(diphosphine) 2} [M=Mo(0), W(0), Re(I), Fe(II)] centres, in which the PCR ligand adopts the very rare and electronically unfavoured end-on (η 1) coordination mode, as well as at the less sterically demanding {Rh(triphos)} + site, are described and compared with those exhibited by alkynes at the same metal centres. At the former sites, the η 1-PCR ligand behaves as a weak π-acceptor and is typically activated to α-nucleophilic addition to give phospha-alkene, phosphine and phosphinidene oxide products, although activation towards electrophilic (protic) addition has also been recognized upon hydrometalation (insertion into a metal–H bond to give a phospha-alkenyl species). At the same metal sites, the η 2-coordination of alkynes is unfavoured (on both electronic and steric grounds) and these substrates undergo rearrangements (H-shifts) towards η 1-bonded alkynyl and vinylidene derivatives, or towards a less sterically demanding η 2-allene species, and these products are activated towards β-electrophilic addition (protonation) on account of their π-electron withdrawal ability which contrasts with the behaviour of the η 1-P-ligated phospha-alkyne and derivatives. The alkyne and phospha-alkyne insertions into an Fe–H bond are also compared, as well as their cycloaddition reactions (cyclotri- and cyclodimerisations, respectively) at the {Rh(triphos)} + centre which exhibits open coordination sites for η 2-ligation. The above reactions are discussed in terms of both stereochemical and electronic effects.

A bimetallic building block with terminal free ligands designed for molecular wire synthesis

The reaction between (dppe) 2W(N 2) 2 and CNC 6H 4NC produces (dppe) 2CNC 6H 4NCWCNC 6H 4NCWCNC 6H 4NC(dppe) 2, a dimer containing electron-rich metal centers, a protective sheath of organic ligands, and terminal free isocyanide groups.

Phosphiranes as Ligands for Platinum Catalysed Hydrosilylations

The stability of phosphiranes can be enhanced by inclusion of the PC2 ring into a polycyclic framework. BABAR-Phos type phosphiranes are easily prepared in high yield, they are thermally stable and allow the synthesis of various platinum(0) complexes. In contrast to other platinum(0) phosphine complexes, these are active hydrosilylation catalyst precursors. The reversible insertion of an electron rich metal centre into one P–C bond of the phosphirane ring was demonstrated for the first time.

Transition Metal Complexes with Sulfur Ligands. 136.1 Enforced Trans Coordination of Thiolate Donors in Electron Rich Iron, Ruthenium, and Nickel [M(L)(pyN2H2S2)] and [M(L)(pyS4)] Complexes (L = CO, PPh3, DMSO) (pyN2H2S22- = 2,6-Bis(2-mercaptophenylamino)dimethylpyridine(2−); pyS42- = 2,6-Bis(2-mercaptophenylthio)dimethylpyridine(2−))

In the course of a systematic study of transition metal complexes exhibiting three properties, electron rich metal centers, core structures with trans thiolate donors, and the capability to bind nitrogenase related small molecules, the pentadentate ligands pyN2H2S2-H2 (=2,6-bis(2-mercaptophenylamino)dimethylpyridine) and pyS4-H2 (=2,6-bis(2-mercaptophenylthio)dimethylpyridine) have been synthesized. Alkylation of 2(3H)-benzothiazolone by 2,6-bis[(tosyloxy)methyl]pyridine and subsequent alkaline hydrolysis yielded pyN2H2S2-H2 (3). Template alkylation of [Ni(S2C6H4)2]2- (6) by 2,6-bis[(tosyloxy)methyl]pyridine gave [Ni(pyS4)]2 (7) whose acidic hydrolysis yielded pyS4-H2·HCl (9). The reaction of Fe(II) salts with pyN2H2S22- gave [Fe(pyN2H2S2)] (10). Five-coordinate 10 is paramagnetic (μeff (293 K) = 5.34 μB), has a trigonal bipyramidal structure, and coordinates CO to give diamagnetic [Fe(CO)(pyN2H2S2)] (11). Although the ν(CO) of 11 (1928 cm-1 (KBr)) indicates electron rich Fe centers and strong Fe−CO bonds...

Spectroelectrochemical studies and molecular orbital calculations on mononuclear complexes [Mo(TpMe,Me)(NO)Cl(py)] (where py is a substituted pyridine derivative): electrochromism in the near-infrared region of the electronic spectrum

Reaction of [Mo(TpMe,Me)(NO)Cl2] [where TpMe,Me is hydrotris(3,5-dimethylpyrazolyl)borate] with substituted pyridine derivatives (py-R) affords the complexes [Mo(TpMe,Me)(NO)Cl(py-R)] [1, R=4-(1-butylpentyl); 2, R=4-Ph; 3, R=3-Ph; 4, R=4-benzoyl; 5, R=3-benzoyl; 6, R=4-acetyl; 7, R=3-acetyl; 8, R=4-cyano; 9, R=3-cyano; 10, R=4-Cl; 11, R=3-Cl; 12, py-R=isoquinoline]. Two of the complexes, 5 and 8, have been crystallographically characterised. These neutral, 17-electron complexes [formally Mo(I)] were examined by UV/VIS/NIR spectroelectrochemistry. All of them undergo a chemically reversible one-electron reduction to the 18-electron monoanion at potentials which are sensitive to the nature of the pyridyl substituent R. Whereas the neutral (17-electron) forms of the complexes only show transitions in the UV and visible regions of the spectrum of the type we have described before, the reduced forms of the complexes show intense, low-energy transitions ascribable to MLCT transition from the electron-rich metal centre [formally Mo(0)] to the π* orbitals of the pyridyl ligands. The 4-substituted pyridines show only one such low-energy transition (e.g. for [1]-, λmax=830 nm; Iµ=12000 d mol-1 cm-1), but those complexes in which the pyridyl ligand has a strongly electron-withdrawing substituent at the C3 position of the pyridyl ligand develop two new MLCT transitions on reduction of which one is well into the near-IR region: e.g. for complex [5]-, λmax=717 nm; Iµ=5300 d mol-1 cm-1 and λmax=1514 nm; Iµ=2500 d mol-1 cm-1. These spectroscopic results have been rationalised by ZINDO calculations which were used both to calculate the frontier molecular orbitals of the complexes, and to calculate the electronic spectra of the reduced complexes. The strong near-IR transitions in the reduced complexes with 3-substituted pyridines, especially [5]- and [7]-, are of particular significance for the development of electrochromic dyes for use in electro-optic switching in this region of the spectrum.

Hydrogen bonds involving transition metal centres – a brief review

Hydrogen bonding is a topic which has received much attention over the years and continues to do so as the importance of such interactions is established in all areas of chemistry. The class of hydrogen bonds that directly involves electron-rich transition metal centres in the three-centre interaction has received little attention until quite recently. Such interactions are of importance in understanding intermolecular interactions between organometallic molecules and are particularly relevant to understanding proton transfer reactions that directly involve transition metal centres. Hydrogen bonds in which transition metal centres serve as the hydrogen-bond acceptor, i.e. X―H...M (X = C, N, O, S), can be identified on the basis of geometric and spectroscopic criteria which confirm: (i) that such interactions should be classified alongside conventional hydrogen bonds (X―H...X'), and (ii) that these three-centre four-electron interactions can be distinguished from the better known three-centre two-electron X―H...M (X = B, C, Si, P, S) interactions. In salts of the type R 3 NH + Co(CO) 3 L - , where L = CO, P(OR) 3 or PR 3 , it is shown that increasing the basicity of the hydrogen-bond acceptor [Co(CO) 3 L - ] by changing L leads to strengthening of the N―H...Co hydrogen bond. Furthermore, in reactions where the products were dictated by a competition between N―H...N and N―H...Co hydrogen-bond formation, results suggested that N―H...N were formed preferentially, inferring that those hydrogen bonds involving metal centres are the weaker hydrogen bonds. Some initial results that point towards the construction of larger hydrogen-bonded assemblies involving X―H...M hydrogen bonds are also discussed.

Synthesis and Single Crystal X-ray Diffraction Study on the First Isolable Carbonyl Complex of an Actinide, (C5Me4H)3U(CO)

We wish to report that the duodecamethyl metallocene (C[sub 5]Me[sub 4]H)[sub 3]U (2) provides an electronic and steric environment that enables the synthesis and structural characterization by X-ray methods of the first isolable carbonyl complex of an actinide element, (C[sub 5]Me[sub 4]H)U(CO). Results of our study has demonstrated that, under appropriate conditions and with a suitable choice of coligands, uranium carbonyl complexes can be isolated. Our results question the current view of actinide carbonyls as unstable or unisolable entities. Preliminary results indicate that the electron-rich metal center in 2 may give rise to a correspondingly rich and diverse chemistry, an area which we are now exploring. 15 refs., 1 fig.

Electronic structure of exohedral interactions between C 60 and transition metals

The electron distribution and orbital interactions of C 60 with metals coordinated at different sites on the outside of the fullerene are evaluated. These sites include the position of a metal atom directly above a carbon atom (η 1 site), the metal atom centered above two carbons of a pentagon or above two carbons between two pentagons (both η 2 sites), the metal atom centered above a pentagon (η 5 site), and the metal atom centered above a hexagon (η 6 site). The frontier orbitals of C 60 are illustrated first with three-dimensional orbital contour plots. A palladium atom is then used to probe the bonding at the different sites on the C 60 surface. The results with Pd 0 are compared to our earlier study with the harder Ag + ion in order to examine the effects of metal electron richness and size. In addition, these results are compared with the bonding to more traditional ligands that represent the hapticity of these sites, such as methyl (η 1), ethylene (η 2), cyclopentadienyl (η 5), and benzene (η 6). The strength of the metal-C 60 interaction and the amount of charge delocalized from the metal to C 60 is sensitive to the site of coordination, the electron richness of the metal, and distortions in the geometry of C 60. As discussed in our previous work, the frontier orbitals of C 60 are well-suited for synergistic bonding of a metal atom to a carbon-carbon pair in an alkene-like fashion, in which the HOMO of C 60 donates carbon-carbon π bonding electron density to the metal, and the LUMO of C 60 accepts electron density from the metal into a carbon-carbon π* antibonding orbital. Although the HOMO and LUMO of C 60 describe the basic interaction, many frontier orbitals are involved. The site above the CC bond between two pentagons is favored over the site above the CC bond within a pentagon, and the interaction above the other sites is indicated to be net repulsive by these calculations. The differentiation between these sites increases with the electron richness of the metal center. The bonding of the metal to C 60 is generally weaker than to the small ligands, except for very electron rich metal centers where the bonding to the η 2 site between pentagons apparently becomes stronger than the bonding to ethylene.

Coordination chemistry of nitriles and cyanamide at electron-rich metal centres

The reactions of various nitriles with dinitrogen or isocyanide complexes presenting an electron-rich d 6 transition metal site are described and shown to give the following compounds: the nitrile complexes [ReCl(NCR)(dppe) 2] (R=alkyl or aryl; dppe=Ph 2PCH 2CH 2PPh 2), [Re(NCR) 2(dppe) 2][BF 4] or [Re(N 2)(NCR)(dppe) 2][BF 4], derived from the reactions of NCR with trans-[ReCl(N 2)(dppe) 2]; the cyanamide compounds trans- [Re(CNR)(NCNH 2)(dppe) 2][BF 4] (which can undergo deprotonation to the corresponding hydrogen cyanamide, NCNH, complexes), from the reaction of NCNH 2 with trans-[ReCl(CNR)(dppe) 2]; the cyanoimido complexes trans-[M(NCN) 2(dppe) 2] (MMo or W), from the dehydrogenation reaction of NCNH 2 with trans-[M(N 2) 2(dppe) 2]; and the trimethylsilyl isocyanide species trans-[ReCl(CNSiMe 3)(dppe) 2], from the reaction of trimethylsilyl cyanide (NCSiMe 3) with trans-[ReCl(N 2)(dppe) 2]. The neutral organonitrile complexes undergo protonation either at the nitrile ligand or at the metal, to give the methyleneamido or the hydrido complexes (ReCl(NCHR)(dppe) 2] + or [ReHCl(NCR)(dppe) 2] +, respectively; further protonation of nitri]es to amines and hydrocarbons or coupling with alkynes, although in very low yields, have been detected at some Mo(0) phosphinic centres. Moreover, reaction of the trimethylsilyl isocyanide complex with MeOH or with HBF 4 affords trans-[ReCl(CNH)(dppe) 2] or trans-[ReCl(CNH 2)(dppe) 2][BF 4], with the simplest isocyanide or aminocarbyne ligands, respectively. The electrochemical behaviour of those complexes is also outlined and shown to involve electroinduced dehydrogenation or deprotonation reactions for the cyanamido methyleneamido or hydrido complexes.

ChemInform Abstract: Carbene Complexes Derived from the Activation of Isocyanides and Alkynes by Electron‐Rich Metal Centers

ChemInformVolume 21, Issue 22 Reviews ChemInform Abstract: Carbene Complexes Derived from the Activation of Isocyanides and Alkynes by Electron-Rich Metal Centers A. J. L. POMBEIRO, A. J. L. POMBEIRO Cent. Quim. Estrutural, Inst. Super. Tec., 1096 Lisbon, Port.Search for more papers by this author A. J. L. POMBEIRO, A. J. L. POMBEIRO Cent. Quim. Estrutural, Inst. Super. Tec., 1096 Lisbon, Port.Search for more papers by this author First published: May 29, 1990 https://doi.org/10.1002/chin.199022316Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume21, Issue22May 29, 1990 RelatedInformation

Übergangsmetall-carbin-komplexe XCVIII. N-Alkylierung eines ethylisocyanid-liganden am molybdän(0); Synthese und oxidationsreaktionen erster cyclopentadienyl-substituierter molybdän-diethylaminocarbin-komplexe

A large scale, high yield synthesis of the first cyclopentadienyl-substituted diethylaminocarbyne complexes of molybdenum has been developed starting from (η 5-C 5H 5)Mo(CO) 3I ( 1). In the first step of the synthetic procedure 1 is quantitatively transformed with EtNC in CH 2Cl 2 into an isomeric mixture of cis- and trans-(η 5-C 5H 5)Mo(CO) 2(EtNC)I ( 2a, 2b). The isomers 2a and 2b are then quantitatively reduced with sodium powder to the zerovalent molybdenum complex Na[(η 5-C 5H 5)Mo(CO) 2(EtNC)] ( 3). The ethylisocyanide ligand in 3 is susceptible to electrophilic attack at nitrogen. Thus reaction of 3 with Et 3OBF 4 gives as the major product, the low valent diethylaminocarbyne complex (η 5-C 5H 5)(CO) 2MoCNEt 2 ( 4). A minor product, the η 2-iminoacyl complex (η 5-C 5H 5)(CO) 2Mo[η 2-C(NEt)Et] ( 5), is also formed in this reaction via electrophilic attack on the electron rich metal center of 3. Compounds 4 and 5 are separated by column chromatography and isolated as yellow and red, microcrystalline solids in 60 and 8% yield respectively. Oxidative decarbonylation of 4 with I 2 and Br 2 leads to the high valent diethylaminocarbyne complexes (η 5-C 5H 5)(I) 2(CO)MoCNEt 2 ( 6) and (η 5-C 5H 5)(Br) 2-(CO)MoCNEt 2 ( 7), isolated as thermally stable, black and purple solids in quantitative yield. Composition and structure of the complexes 2a–7 were determined by total elemental analyses, IR, 1H NMR and 13C NMR spectra and the spectral data compared with the analogous tungsten compounds.

Electron-rich metal centres (Au, Pt) as sources of organometallic complexes with unusual features

The central gold(I) atoms in binuclear complexes of the type[AuR 2] + (R = C 6F 5, C 6Cl 5 CH 2PR 3) are able to donate electron density to silver(I) cations to form polymeric or oligomeric compounds containing the cyclic Au 2Ag 2 moiety, with direct AuAg bonds unsupported by any other bridging ligand. One of the gold atoms in binuclear (μ,μ′-bis(diphenylphosphinium)bis(methylido)digold(I) also donates electron density to the gold(III) atom in Au(C 6F 5) 3 to form the first unbridged direct Au IAu III bond. Anionic Pt II complexes [PtR 4] 2−, [PT 2(μ-X) 2R 4 2−, [Pt 2(μ-R 2) 2R 4] 2−, etc. (R = C 6F 5) react with silver salts or complexes to form a variety of unusual heteronuclear derivatives, most of which display o-X…Ag short contacts, which seem tobe responsible for the stability of the clusters. The homoleptic anion [Pt 2(μ-C 6F 5) 2(C 6F 5) 4] − containing Pt in the average oxidation state of +2.5 can also be prepared by oxidation of the electron-rich binuclear Pt II precursor.

ChemInform Abstract: Reaction of Alkynes at Mononuclear Electron‐Rich Transition Metal Centres

ChemInformVolume 20, Issue 21 Reviews ChemInform Abstract: Reaction of Alkynes at Mononuclear Electron-Rich Transition Metal Centres A. J. L. POMBEIRO, A. J. L. POMBEIRO Centro Quim. Estrut., Compl. I, Inst. Superior Tecn., 1096 Lisabon, PortugalSearch for more papers by this author A. J. L. POMBEIRO, A. J. L. POMBEIRO Centro Quim. Estrut., Compl. I, Inst. Superior Tecn., 1096 Lisabon, PortugalSearch for more papers by this author First published: May 23, 1989 https://doi.org/10.1002/chin.198921337Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue21May 23, 1989 RelatedInformation

Preparation and X-ray crystal structure of (Ph 3P) 2PtS 2N 2·C 7H 8: a reinvestigation of the reaction of S 4N 4H 4 with (Ph 3P) 4Pt

The reaction of S 4N 4H 4 with (Ph 3P) 4Pt in toluene produces the yellow complex (Ph 3P) 2PtS 2N 2·C 7H 8 shown by X-ray crystallography to contain a five- membered metallathiazene ring with PtN = 2.093(9) Å, PtS = 2.294(6) Å and two short [1.499(16) and 1.548(12) Å and one long [1.702(15) Å] SN bonds. The crystals are triclinic with space group P 1 ; a = 11.328(2); b = 12.366(2); c = 16.822(3) Å; α = 94.12(1); β = 108.57(1); γ = 112.93(1)°; V = 2004.8(2) Å 3; Z = 2. The final R and R w values were 0.047 and 0.058, respectively. The same complex is obtained from the reactions of (Ph 3P) 4Pt with S 4N 4 or (Ph 3P) 2PtC 2H 4 with S(NSO) 2. The reaction of NiCl 2 with a mixture of S 4N 4H 4 and the Wittig reagent, Ph 3PCH 2, produces Ni(S 2N 2H) 2. The mechanisms of the reactions of S 4N 4H 4 and S 4N 4 with electron-rich metal centres are discussed briefly.

Facts and Fantasy on Tetrathio Oxalate—Activation and Condensation of Carbon Disulfide

Abstract In its reactions with electron-rich metal centers, including the mercury cathode, CS2 undergoes a wide variety of reactions to produce CnSm groups in varying charges and coordination modes. The coupling of two CS2 molecules to formally give C2S4 group has been shown to produce three different moieties: (a) Coupling via C-S bond formation to produce an MC(:S)SC(:S)S ring. (b) Coupling via C-C bond formation to formally produce ethenetetrathiol. (c) Coupling via electroreductive dimerization to produce stable tetrathio oxalate salts.