Comparison of the Molecular Structures of Monovalent Cation Salets of N,N-Dimethyldithiocarbamate. Novel Synthesis and Crystal Structure of (Phi4)(S2CN(CH3)2)2H2O

Crystals of the tetraphenylphosphonium N,N-dimethyldithiocarbamate dihydrate (C₂₇H₃₀NO₂PS₂; F.W. = 495.6) are monoclinic; P2₁/n; a = 13.349(6), b = 20,968(6), c = 9.800(4) Å, β = 109.01(3)°; Z = 4; V = 2593.4(16) Å^3; Dₓ = 1.269 gcm- 3 . Data were collected at ambient temperature using MoKα radiation (λ = 0.71069 Å).F(000) = 1048, linear absorption coefficient, n = 2.80 cm- 1. The structure was solved by direct methods and subsequently refined by full matrix least squares techniques. Final R value = 0.064 for 1 61 0 reflections and 298 varied parameters. Due to the nature of the cation, interactions between the tetraphenylphosphonium group and the sulfur atoms of the anion are absent, unlike previous dimethyldithiocarbamate structures (Na+, Cs+, TI+). Intermolecular interactions between the waters of hydration and the anion are present

Reaction of Titanocene Dichloride with Acetylenedicarboxylate

The reaction of Cp2TiCl2 with either the mono- or dipotassium salt of acetylenedicarboxylic acid (ADC) gives high yields of an insoluble orange product. The insoluble compound shows potential semiconductor behavior, as evidenced by an apparent bandgap in the orange region of the visible spectrum. Under N2 ,the compound decomposes at 238° C, eventually losing approximately 46% total mass up to 1350° C. The exothermic decomposition in air, beginning at 235° C, results in the formation of titanium oxides

Kinetic and DFT Studies on the Mechanism of C−S Bond Formation by Alkyne Addition to the [Mo3S4(H2O)9]4+ Cluster

Reaction of [Mo3(μ3-S)(μ-S)3] clusters with alkynes usually leads to formation of two C−S bonds between the alkyne and two of the bridging sulfides. The resulting compounds contain a bridging alkenedithiolate ligand, and the metal centers appear to play a passive role despite reactions at those sites being well illustrated for this kind of cluster. A detailed study including kinetic measurements and DFT calculations has been carried out to understand the mechanism of reaction of the [Mo3(μ3-S)(μ-S)3(H2O)9]4+ (1) cluster with two different alkynes, 2-butyne-1,4-diol and acetylenedicarboxylic acid. Stoppedflow experiments indicate that the reaction involves the appearance in a single kinetic step of a band at 855 or 875 nm, depending on the alkyne used, a position typical of clusters with two C−S bonds. The effects of the concentrations of the reagents, the acidity, and the reaction medium on the rate of reaction have been analyzed. DFT and TD-DFT calculations provide information on the nature of the product formed, its electronic spectrum and the energy profile for the reaction. The structure of the transition state indicates that the alkyne approaches the cluster in a lateral way and both C−S bonds are formed simultaneously

UNIQUE REACTIVITY CHARACTERISTICS OF MO-COORDINATED !&-AND S$-LIGANDS

Abstract-Th

Unique reactivity characteristics of Mo-coordinated S2-2 and S2-4 ligands

The synthesis of the new dithiolene complexes, [{(MeOOC)2C2S2}2Mo([mu]2-S)]-2 and [OMo(S2C2(COOMe)2)2]-, is reported. These complexes are obtained by the reaction of dicarbomethoxyacetylene (DMA) with either [(S4)Mo(S)([mu]2-S)2Mo(S)(S4)]2- or [(CS4)Mo(S)([mu]2-S)2Mo(S)(CS4)]2- and [OMo(S4)2]2-, respectively. The reaction of [(S4)Mo(O)([mu]2-S)2Mo(O)(S2)]2- with DMA results in the new dithiolene complex [{(MeOOC)2C2S2}Mo(O)([mu]2-S)]-2, which is the isomeric form of the vinyl disulfide complex obtained in the reaction of the [(S2)Mo(O)([mu]2-S)2Mo(O)(S2)]2- complex with DMA. The difference in reactivity between the two complexes that contain the same [Mo2O2S2]2+ core is attributed to the intrinsically different reactivity characteristics of the S2-4 and S2-2 ligands. As a result of Mo-S d[pi]-p[pi] bonding an alternation in the S---S bond lengths is observed in virtually all of the structurally characterized Mo-S4 units. The consequent weakening of the S---S bonds adjacent to the Mo---S bonds allows for the ready dissociation of S02 from the Mo-coordinated S2-4 ligands. This weakening also accounts for the facile formation of dithiolenes in cycloaddition reactions of alkynes with the Mo-S4 units. By comparison, the S---S bond in side-on Mo-coordinated S2-2 ligands is strengthened as a result of depopulation of the ligand [pi]*-orbitals. Reactions of the latter with alkynes do not proceed by cycloaddition. Instead, insertion into the Mo---O bond has been reported for at least one such reaction. The importance of activated polysulfide ligands in the hydrodesulfurization reaction is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26402/1/0000489.pd

(NPr4n)[SRev(S4)(S3CMe2)]: Ein [SRev(S4)2]−-Derivat

Müller A, Lemke M, Krickemeyer E, Bögge H, Penk M. (NPr4n)[SRev(S4)(S3CMe2)]: Ein [SRev(S4)2]−-Derivat. Monatshefte für Chemie Chemical Monthly. 1993;124(8-9):857-866