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The synthesis of a variety of tungsten alkyl complexes of the type [N3N]WR ([N3N]3- = [(Me3SiNCH2CH2)3N]3-; R = Me, Et, Bu, CH2Ph, CH2SiMe3, CH2CMe3, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopentenyl) was attempted by alkylation of [N3N]WCl complexes. Only the methyl, phenyl, and cyclopentenyl complexes could be isolated. The susceptibility of the [N3N]WR complexes is similar to that of [N3N]WCl; the effective moment is depressed as a consequence of a combination of spin−orbit effects and low-symmetry ligand-field components that result in zero-field splitting of the d2 ground-state spin triplet. No linear alkyl complexes could be observed as a consequence of α,α-dehydrogenation to give molecular hydrogen and alkylidyne complexes, [N3N]W⋮CR‘. [N3N]W(cyclopropyl) evolves ethylene in a first-order process to give [N3N]W⋮CH, while [N3N]W(cyclobutyl) is converted into the 1-tungstacyclopentene complex, [N3N]W(CHCH2CH2CH2), as confirmed in an X-ray study. [N3N]W(CHCH2CH2CH2) decomposes readily in a first-order manner to give [N3N]W⋮CCH2CH2CH3. An attempt to prepare [N3N]W(cyclopentyl) led to formation of [N3N]W(cyclopentylidene)(H), as confirmed in an X-ray study. NMR studies suggest that [N3N]W(cyclopentylidene)(H) is in equilibrium with [N3N]W(cyclopentyl) where ΔH° = 11.8(6) kcal mol-1 and ΔS° = 33(2) eu or K eq ≈ 0.1 at 46 °C. From these and other data it is concluded that the rate constant for α elimination in [N3N]M(cyclopentyl) is approximately the same for Mo and W. The [N3N]W(cyclopentenyl) complex is unstable, decomposing to give a complex containing a “bent imido” ligand, [(Me3SiNCH2CH2)2(NCH2CH2)N]W(1-(trimethylsilyl)cyclopentene), as confirmed in an X-ray study.

Prototypes of new families of precatalysts and catalysts, [Ru((−)‐Me‐DuPHOS)(H)(η6‐1,3,5‐cyclooctatriene)](BF4) and the derived “[Ru((−)‐Me‐DuPHOS)(H)(sol)](BF4)”, are presented. They are used in an industrial, catalytic, enantioselective hydrogenation that leads to (+)‐cis‐methyl dihydrojasmonate [Eq. (1)]. This stereoisomer is the odorant component of an important, large volume perfumery chemical. P−P=Diphosphane ligand (for example, Me‐DuPHOS=1,2‐bis((2R,5R)‐2,5‐dimethylphospholanyl)benzene); sol=solvent.

have been prepared. Heating these compounds leads to the metallasulfur cubane complexes (Cp*MS)2(Cp*IrS)2 (10, M = Ir; 13, M = Rh). The observation that diiridium/dirhodium complex 13 is the only product obtained quantitatively from the thermolysis of 12 provides evidence that the dimeric units remain intact on the pathway to cubane formation rather than dissociating to monomeric units followed by reassembly into the tetramer. A mechanistic study of the cubane-assembly reaction was undertaken using complex 15. The reaction is first-order in [15] and zero-order in [PR3] when the concentration of phosphine is low. At high (flooding) [PR3], the rate is second-order in [15] and inverse second-order in phosphine concentration. These data are consistent with a mechanism in which a doubly unsaturated intermediate, Cp*MS2-IrCp*, is generated by reversible loss of phosphine and then in a second bimolecular step dimerizes to form the cubane. The reactions of 3 with methyl bromide, carbon monoxide, and tert-butyl isocyanide are also described. The single crystal X-ray structures of Cp*Ir(PMe3)S2lrCp* (3), Cp*Ir(CN-f-Bu)(«-S)2lr(CN-f-Bu)Cp* (9), and (Cp*IrS)4 (10) have been determined. Complex 3 crystallized in the monoclinic system, space group P2i with a = 8.556(1) A, b = 14.093(2) A, c = 10.977(2) A, /3 = 103.28(1)°, and Z = 2. Refinement by standard least-squares techniques gave final residuals R = 0.039 and 7?w = 0.046. Complex 9 crystallized in the monoclinic system, space group C2lc with a = 18.798(5) A, b = 9.554(2) A, c = 18.219(3) A, /? = 90.34°, and Z = 8. Refinement by standard least-squares techniques gave final residuals R = 0.034 and 7?w = 0.040. Complex 10 crystallized in the orthorhombic system, space group 74 with a = 12.026(3) k,b = 12.026(3) A, c = 14.844(3) A, and Z = 2. Refinement by standard least squares techniques gave final residuals R = 0.031 and Rv = 0.039.Metal-sulfur clusters are central components of the active sites of enzymes such as ferredoxin and nitrogenase.1-4 Such complexes also have been studied extensively because of their relevance to metal-catalyzed hydrodesulfurization.5'6 An important aspect in modeling and understanding the key processes involved in these systems has been the rational synthesis of heterometallic cluster complexes, especially sulfur cubane complexes.7-18 Despite many studies in this area, little

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