Transmetallation vs adduct Diverse reactivity of N,O-ketiminato germylene with [Cp*MCl2]2 (M = Rh or Ir; Cp* = η5-C5Me5) and MCl5 (M = Nb and Ta)

International audienceThe reactions of the germylenes, [(Dipp)NCMeCHCORGeCl] (1a R = Me, 1b R = Ph) with [Ir2Cl2(μ-Cl)2(η5-Cp*)2] led to the formation of the adducts [(Dipp)NCMeCHCORGeClIrCl2Cp*] (3a R = Me and 3b R = Ph). On the other hand, [Rh2Cl2(μ-Cl)2(η5-Cp*)2] does not react with the germylenes (1a and 1b). When the reactions of 1a and 1b are carried out with [Cp*TaCl4], the reaction led to decomposition. The reaction of 1a or 1b with TaCl5 yielded the transmetallated products [(Dipp)NCMeCHCORTaCl4] (4a R = Me, 4b R = Ph) with the extrusion of GeCl2. Our theoretical studies show that for, the insertion of TaCl5 to 1a and the formation of 4a with concomitant elimination of GeCl2 is energetically favourable. Extrusion of SnCl2 is also observed when the corresponding stannylene, [(Dipp)NCMeCHCOMeSnCl] was reacted with TaCl5. All these compounds have been characterized by 1H and 13C NMR spectroscopy, elemental analysis and the constitution of compounds 1b, 3b, and 4a were confirmed by single-crystal X-ray crystallography

Chemistry of group 5 metallaboranes with heterocyclic thiol ligands: a combined experimental and theoretical study

International audienceThermolysis of [(Cp*Nb)(BH)], 1b (Cp* = η-CMe), with 2-mercaptobenzothiazole, CHNSCSH (MBT), and 2-mercaptobenzoxazole, CHNOCSH (MBO), yielded hydrogen substituted compounds 2 and 3 with a general formula [(Cp*Nb)(BH)(BHL)] (2: L = CHNSCS and 3: L = CHNOCS). A similar reaction of 1b with PhSe yielded the monosubstituted derivative [(Cp*Nb)(BH){BH(PhSe)}], 4. All further efforts towards persubstitution of 1b under various drastic conditions were unfruitful. In parallel, in an effort to find a better synthetic route to the known Ta-aziridine complex [Cp*TaBH(CHNS)CHSNCH], Cp*TaCl was treated with a 2-mercaptobenzothiazolyl-based borate ligand Na[HB(CHNSCS)]. Surprisingly, the reaction led to the formation of the half-sandwich trichloroaryltantalum(v) complex [Cp*TaCl{κ-N,S-CHNSCS}], 5, containing a heterocyclic thiol ligand. Using an alternative method complex 5 was isolated in good yield when Cp*TaCl was treated with the potassium salt of 2-mercaptobenzothiazole K[CHNSCS]. All the compounds were characterized by H, B{H}, and C{H} NMR spectroscopy, and their structures were unequivocally established by crystallographic analysis

Reactivity of CS2 – Syntheses and Structures of Transition-Metal Species with Dithioformate and Methanedithiolate Ligands

International audienceThe syntheses and structural characterization of the CS2–metal complexes [(η5-C5Me5M)(η2-S2CH2)(η3-S2CH)] (1: M = Mo; 2: M = W), which feature partially and fully reduced CS2, are reported. In addition, the cis and trans isomers of the dimetallic (sulfido)molybdenum complexes [(η5-C5Me5Mo)2(µ-S2CH2S)2] (3-cis and 4-trans) are described. The [Mo2S4] cores of 3-cis and 4-trans represent paddlewheel-like arrays. All the new compounds were characterized in solution by mass spectrometry, IR spectroscopy, and 1H and 13C NMR spectroscopy. Their structural architectures were established by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods on the model compounds 1′–4′-trans showed good agreement with the experimentally observed structural parameters. The large HOMO–LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps are consistent with the high thermodynamic stabilities of these complexes. Further, the presence of short metal–metal cross-cluster bonds in the X-ray structures of 3-cis and 4-trans is supported by natural bond order (NBO) calculations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei