Tetrakis(dithiocarboxylato)molybdenum(IV) complexes of the type Mo(S2CR)4 (R = Me, Et, iPr, Ph) were synthesized, characterized, and prescreened as precursors for aerosol assisted chemical vapor deposition (AACVD) of MoS2 thin films. The thermal behavior of the complexes as determined by TGA and GC-MS was appropriate for AACVD, although the complexes were not sufficiently volatile for conventional CVD bubbler systems. Thin films of MoS2 were grown by AACVD at 500 °C from solutions of Mo(S2CMe)4 in toluene. The films were characterized by GIXRD diffraction patterns which correspond to a 2H-MoS2 structure in the deposited film. Mo-S bonding in 2H-MoS2 was further confirmed by XPS and EDS. The film morphology, vertically oriented structure, and thickness (2.54 μm) were evaluated by FE-SEM. The Raman E12g and A1g vibrational modes of crystalline 2H-MoS2 were observed. These results demonstrate the use of dithiocarboxylato ligands for the chemical vapor deposition of metal sulfides.

Six carbazole-derived mono-, di- and trinuclear ruthenium complexes featuring one to three square pyramidal, five-coordinated {Ru(CO)Cl(PiPr3)2(CHCH-)} entities were prepared by the regio- and stereospecific insertion of the hydride precursor HRu(CO)Cl(PiPr3)2 into the CC bond of the corresponding ethynylated N-substituted carbazoles. They were characterized by IR, UV/Vis, and NMR spectroscopy, electrochemistry, and, in up to four different oxidation states, by UV/Vis/NIR and IR spectroelectrochemistry. Their radical cations were additionally investigated by EPR spectroscopy. Experimental studies are complemented by (TD-)DFT calculations. Electrochemical studies on these complexes showed two to four reversible, consecutive one-electron oxidation processes. Half-wave potential separations ΔE½ between individual redox-waves and the derived comproportionation constants Kc indicate that intermediate oxidation states are sufficiently stable with respect to disproportionation to be generated and investigated in solution. Spectroscopic data indicate strong carbazole ligand contributions to every oxidation and notable involvement of the vinylruthenium moieties to the lower oxidation steps. UV/Vis/NIR spectroelectrochemistry reveals a polyelectrochomic behavior of all complexes with, however, less pronounced absorptivities when compared to the simple triarylamine counterparts. The pattern of two separate, moderately spaced Ru(CO) bands for the MV radical cations IIa+, IIb+ and III+ indicates that the unipositive charge is unevenly distributed over the two chemically equivalent vinylruthenium subunits.

Metalcarbon multiple bonds exhibit enhanced nucleophilicity at the alpha carbon within ONO trianionic pincer alkylidyne complexes. Defined as the inorganic enamine effect, this phenomenon is a result of the overlap of the N atom lone pair within the ONO3- ligand and a pi bond from the metalcarbon multiple bond. Treating the proligand [OCH2NCH2O]H-3 (2) with ((BuO)-Bu-t)(3)W=CR (where R = Et, Bu-t) results in the formation of the dianionic pincer complexes [OCH2NHCH2O]W equivalent to CR(OtBu) (where R = Et (3-Et), tBu (3-tBu(anti))). Deprotonation of 3-Bu-t(anti) by treatment with Ph3P-CH2 forms the anionic alkylidyne complex {[(ONO)-N-CH2-O-CH2]W equivalent to(CBu)-Bu-t((OBu)-Bu-t)}{CH3PPh3} (4-Bu-t). DFT calculations modeling 4-tBu reveal overlap of the N atom lone pair with a W=C p bond. However, 4-Bu-t reacts with electrophiles preferentially at the pincer N atom as opposed to the W equivalent to Ca group. Multinuclear NMR spectroscopy, combustion analysis, and single-crystal X-ray crystallography are employed to characterize complexes 3-Et, 3-Bu-t(anti), and 4-Bu-t.

This report describes two approaches to form complexes featuring Mo-C multiple bonds and a trianionic pincer ligand. Treating the trianionic pincer ligand precursor [(BuOCO)-Bu-t]H-3 (1) with MeLi provides the corresponding dilithio salt [(BuOCHO)-Bu-t]Li-2(THF)(3) (6) in situ, which further reacts with Mo(NAr) (CHCMe2Ph)(OTf)(2)(DME) to provide the terphenyl diphenolate complex [(BuOCHO)-Bu-t]Mo(NAr)CHCMe2Ph (5). Complex 5 is characterized by H-1, C-13{H-1} NMR spectroscopy, combustion analysis, and single crystal X-ray diffraction. The solid state structure of 5 reveals a distorted trigonal pyramidal geometry for the Mo(VI) ion. Treating 5 with one equiv. of phosphorane in toluene converts the diphenolate ligand into a trianionic pincer ligand by deprotonation of the pincer C-ipso-H proton to give the alkylidene salt {[(BuOCHO)-Bu-t]Mo(NAr)(CHCMe2Ph)}{Ph3PCH3} (7). Treating [(BuOCO)-Bu-t]MoNMe2(NHMe2)(2) (2), containing a d(2) Mo(IV) ion, with terminal alkynes (H-C CR, R = Ph, 3,5-F2C6H3, 3,5-(CF3)(2)C6H3 and SiMe3) produces in excellent yield the corresponding metallocyclopropylidene complexes 10-R (R = H, F, CF3) and 11 (R = SiMe3). X-ray diffraction studies on single crystals of 10-H and 11 reveal three important features: 1) a highly distorted hexacoordinate Mo(VI) center, 2) a metallocyclopropene(eta(2)-vinyl) fragment, and 3) a highly distorted CH group in the metallocyclopropene unit. A single point calculation and an NBO analysis performed on 10-H' confirms the multiple bond between Mo1 and C28. The highest occupied Kohn-Sham molecular orbital (HOMO) represents a pi-combination between d(yz) of Mo1 and the p(y) orbital of C28, and the corresponding pi*-combination of those orbitals constitutes the lowest unoccupied molecular orbital (LUMO). Published by Elsevier B.V.

A new C-2-symmetric chelating di-N-heterocyclic carbene (NHC) ligand is reported. The stable free di-carbene (+/-)[DEAM-BY] (3) forms upon treating the imidazolium salt(+/-)[DEAM-BI][OTf](2) (2) with potassium bis-trimethylsilylamide (where DEAM-BY=trans-9,10-dihydro-9,10-ethanoanthracene-11,12-bis(1-benzyl)imidaz-2-ylidene and DEAM-BI = trans-9,10-dihydro-9,10-ethanoanthracene-11,12-bis(1-benzyl)imidazolium). Metalation reactions of 2 with [Rh(COD)Cl](2) and [Ir(COD)Cl](2) are carried out under mild conditions to produce either mono- or bimetallic complexes. Each compound is characterized by NMR spectroscopy, combustion analysis, and single-crystal X-ray crystallography. Published by Elsevier Ltd.

New iridium and rhodium complexes prepared from C2-symmetric trans-9,10-dihydro-9,10-ethanoanthracene-11,12-bis(1-R)-benzimidazolidine-2-ylidene ligands (R = Me, iPr, and diPh) have been synthesized and characterized. Their catalytic activities have been tested in enantioselective hydrogenation and hydroformylation reactions. The ee's for the reactions are low. Evidence indicates that even chelating di-N-heterocyclic carbene ligands are susceptible to reductive elimination.