Thioxoethenylidene (CCS) as a Bridging Ligand

Tethered Alkylidenes for REMP from Carbon Disulfide Cleavage

Reactions between tungsten alkylidyne [tBuOCO]W≡CtBu(THF)2 1 and sulfur containing small molecules are reported. Complex 1 reacts with CS2 to produce intermediate η2 bound CS2 complex [O2C(tBuC═)W(η2-(S,C)-CS2)(THF)] 8. Heating complex 8 provides a mixture of a monomeric tungsten sulfido complex 9 and a dimeric complex 10 in a 4:1 ratio, respectively. Heating the mixture does not perturb the ratio. Addition of excess THF in a solution of 9 and 10 (4:1) converts 10 to 9 (>96%) with concomitant loss of (CS)x. Both 9 and 10 can be selectively crystallized from the mixture. An alternative synthesis of exclusively monomeric 9 involves the reaction between 1 and PhNCS. Demonstrating ring expansion metathesis polymerization (REMP), tethered tungsten alkylidene 8 polymerizes norbornene to produce cis-selective syndiotactic cyclic polynorbornene (c-poly(NBE)).

Thiocarbonylphosphorane and arsorane ligands

Independently unstable thiocarbonylphosphorane or arsorane ligands SCAR₃ (A = P, As) are observed in the salts [W(η²-C,S-SCAR₃)(CO)₂(Tp*)]PF₆ [AR₃ = PCy₃, PMe_nPh_3-n: n = 0, 1, 2, AsMePh₂; Tp* = tris(dimethylpyrazolyl)borate] which arise from the reactions of phosphonio- or arsoniocarbynes [W(≡CAR₃)(CO)₂(Tp*)]⁺ with sulfur.

Heterobimetallic μ2-Halocarbyne complexes

The halocarbyne complexes [M(≡CX)(CO)2(Tp*)] (M = Mo, W; X = Cl, Br; Tp* = hydrotris(dimethylpyrazolyl)borate) react with [AuCl(SMe2)], [Pt(-H2C=CH2)(PPh3)2] or [Pt(nbe)3] (nbe = norbornene) to furnish rare examples of μ2-halocarbyne...

Construction of an iminoketenylidene

The new isonitrile-μ-carbido complexes [WPt(μ-C)Br(CNR)(PPh₃)(CO)₂(Tp*)] (R = C₆H₂Me₃-2,4,6, C₆H₃Me₂-2,6; Tp* = hydrotris(dimethylpyrazolyl)borate) rearrange irreversibly in polar solvents to provide the first examples of iminoketenylidene (CCNR) complexes.

Diferrocenyl Thioketone: Reactions with (Bisphosphane)Pt(0) Complexes-Electrochemical and Computational Studies

Diferrocenyl thioketone reacts smoothly with (bisphosphane)Pt(0) complexes in toluene solution at room temperature yielding 1:1 adducts identified as ferrocenyl (Fc) functionalized platinathiiranes. Their structures were unambiguously confirmed by means of spectroscopic methods as well as by X-ray diffraction analysis. A unique, ferrocene-rich platinathiirane, bearing three Fc-units, was prepared starting with [bis(diphenylphosphino)ferrocene] Pt(0(η²-norbornene). For comparison, a similar platinathiirane with one Fc-unit was obtained from the reaction of the latter complex with thiobenzophenone. Quantum-chemical calculations were carried out to describe the bonding pattern and frontier molecular orbitals of the ferrocene-rich platinathiirane complexes. These calculations confirmed that the C=S bond loses its formally double-bond character upon complexation (bisphosphane)Pt(0). Cyclic voltammetry measurements were performed to characterize the obtained platinathiiranes in CH₂Cl₂ solutions. For comparison, the cyclic voltammogram for diferrocenyl thioketoneas a mixed-valent (Fe^II-Fe^III) compound was also recorded and analyzed. The results point out to a diffusion controlled electrode process in case of differocenyl thioketone and mixed diffusion and adsorption controlled electrode process in the case of the studied platinathiiranes.

Phosphaisonitrile umpolung – synthesis and reactivity of chloro aminophosphino carbynes

The synthesis of the first P-halo-aminophosphinocarbyne complex is described in addition to exploration of its ligand-based reactivity towards nucleophilic substitution and P-halide abstraction processes as a possible route to cationic aminophosphaisonitrile derivatives.

Bis(alkylidynyl)tellurides and ditellurides

The tellurocarbonylates [M(CTe)(CO)₂(Tp*)]⁻ (M = Mo, W; obtained from [M(CBr)(CO)₂(Tp*)] and Li₂Te or [M(CLi)(CO)₂(Tp*)] and Te) react with an additional equivalent of [M(CBr)(CO)₂(Tp*)] to give bis(alkylidynyl)tellurides, [M₂(μ-CTeC)(CO)₄(Tp*)₂], whilst oxidation with [Fe(η-C₅H₅)₂]PF₆ affords the corresponding ditellurides [M₂(μ-CTe₂C)(CO)₄(Tp*)₂].

Rearrangement of bis(alkylidynyl)phosphines to phospha-acyls

A range of bis(alkylidynyl)phosphines RP{CM(CO)₂(Tp*)}₂ (M = Mo, W; R = Cl, Ph, Cy; Tp* = hydrotris(dimethylpyrazolyl)borate) are obtained from the reactions of [M(CLi)(CO)₂(Tp*)] with Cl₂PR or alternatively via the palladium(0)-mediated reactions of [W(CBr)(CO)₂(Tp*)] with RPH₂ (R = Py, Cy).

High oxidation state bromocarbyne complexes

Bromination of the carbyne complexes [W(CR)Br(CO)₂(dcpe)] (R = Ph, SiPh₃; dcpe = 1,2-bis(dicyclohexylphosphino)ethane) provides high oxidation state derivatives [W(CPh)Br₃(dcpe)] and [W(CBr)Br₃(dcpe)], the latter via an unprecedented bromodesilylation process.

Coordination chemistry of phosphinocarbynes: phosphorus vs. carbyne site selectivity

The phosphinocarbyne complex [W(CPPh₂)(CO)₂(Tp*)] (1: Tp* = hydrotris(dimethylpyrazolyl)borate) coordinates transition metal fragments via the phosphine to form bimetallic species [W{CPPh₂RhCl₂(Cp*)}(CO)₂(Tp*)] (2) and [W(CPPh₂AuCl)(CO)₂(Tp*)] (3).