15793-01-8Relevant articles and documents
Zerovalent Nickel Compounds Supported by 1,2-Bis(diphenylphosphino)benzene: Synthesis, Structures, and Catalytic Properties
Neary, Michelle C.,Quinlivan, Patrick J.,Parkin, Gerard
, p. 374 - 391 (2018/01/10)
Zerovalent nickel compounds which feature 1,2-bis(diphenylphosphino)benzene (dppbz) were obtained via the reactivity of dppbz towards Ni(PMe3)4, which affords sequentially (dppbz)Ni(PMe3)2 and Ni(dppbz)2. Furthermore, the carbonyl derivatives (dppbz)Ni(PMe3)(CO) and (dppbz)Ni(CO)2 may be obtained via the reaction of CO with (dppbz)Ni(PMe3)2. Other methods for the synthesis of these carbonyl compounds include (i) the formation of (dppbz)Ni(CO)2 by the reaction of Ni(PPh3)2(CO)2 with dppbz and (ii) the formation of (dppbz)Ni(PMe3)(CO) by the reaction of (dppbz)Ni(CO)2 with PMe3. Comparison of the ν(CO) IR spectroscopic data for (dppbz)Ni(CO)2 with other (diphosphine)Ni(CO)2 compounds provides a means to evaluate the electronic nature of dppbz. Specifically, comparison with (dppe)Ni(CO)2 indicates that the o-phenylene linker creates a slightly less electron donating ligand than does an ethylene linker. The steric impact of the dppbz ligand in relation to other diphosphine ligands has also been evaluated in terms of its buried volume (%Vbur) and steric maps. The nickel center of (dppbz)Ni(PMe3)2 may be protonated by formic acid at room temperature to afford [(dppbz)Ni(PMe3)2H]+, but at elevated temperatures, effects catalytic release of H2 from formic acid. Analogous studies with Ni(dppbz)2 and Ni(PMe3)4 indicate that the ability to protonate the nickel centers in these compounds increases in the sequence Ni(dppbz)2 3)2 3)4; correspondingly, the pKa values of the protonated derivatives increase in the sequence [Ni(dppbz)2H]+ 3)2H]+ 3)4H]+. (dppbz)Ni(PMe3)2 and Ni(PMe3)4 also serve as catalysts for the formation of alkoxysilanes by (i) hydrosilylation of PhCHO by PhSiH3 and Ph2SiH2 and (ii) dehydrocoupling of PhCH2OH with PhSiH3 and Ph2SiH2.
Studies of structural effects on the half-wave potentials of mononuclear and dinuclear nickel(II) diphosphine/dithiolate complexes
Redin, Kendra,Wilson, Aaron D.,Newell, Rachel,DuBois, M. Rakowski,DuBois, Daniel L.
, p. 1268 - 1276 (2008/10/09)
Two series of mononuclear Ni(II) complexes of the formula (PNP)Ni(dithiolate) where PNP = R2PCH2N(CH 3)CH2-PR2, R = Et and Ph, have been synthesized containing dithiolate ligands that vary from five- to seven-membered chelate rings. Two series of dinuclear Ni(II) complexes of the formula {[(diphosphine)Ni]2(dithiolate)}(X)2 (X = BF4 or PF6) have been synthesized in which the chelate ring size of the dithiolate and diphosphine ligands have been systematically varied. The structures of the alkylated mononuclear complex, [(PNPEt)Ni(SC 2H4SMe)]OTf, and the dinuclear complex, [(dppeNi) 2(SC3H6S)](BF4)2, have been determined by X-ray diffraction studies. The complexes have been studied by cyclic voltammetry to determine how the half-wave potentials of the Ni(II/I) couples vary with chelate ring size of the ligands. For the mononuclear complexes, this potential becomes more positive as the natural bite angle of the dithiolate ligand increases. However, the potentials of the Ni(II/I) couples of the dinuclear complexes do not show a dependence on the chelate ring size of the ligands. Other aspects of the reduction chemistry of these complexes have been explored.
Preparation and properties of new methyl(alkoxo)- and methyl(thiolato)nickel and methyl(alkoxo)- and methyl(thiolato)palladium complexes. CO and CS2 insertion into the alkoxo-palladium bond
Kim, Yong-Joo,Osakada, Kohtaro,Sugita, Kouji,Yamamoto, Takakazu,Yamamoto, Akio
, p. 2182 - 2188 (2008/10/08)
Reactions of fluorinated alcohols (HOCH(CF3)2, HOCH2CF3, and HOCH(CF3)C6H5) or aromatic thiols (HSC6H5 and HSC6H4-p-CH3) with dialkylnickel and -palladium complexes (NiMe2(bpy), NiEt2(bpy) (bpy = 2,2′-bipyridine), NiMe2(dpe), and PdMe2(dpe) (dpe = 1,2-bis(diphenylphosphino)ethane)) give the corresponding monoalkyl complexes with an alkoxo or a thiolato ligand (NiMe(OR)(bpy), NiEt(OR)(bpy), MMe(OR)(dpe), and MMe(SAr)(dpe) (M = Ni, Pd; R = CH(CF3)2, CH2CF3, CH(CF3)C6H5)). These complexes have been characterized by elemental analysis and NMR (1H, 31P{1H}, 19F, and 13C{1H}) spectroscopy. The methyl(alkoxo)nickel(II) and -palladium(II) complexes thus obtained react with carbon monoxide at normal pressure to give carboxylic esters in high yields. Reaction of carbon monoxide with NiMe(SAr)(dpe) (Ar = C6H5, C6H4-p-CH3) also gives the corresponding carbothioic esters in good yields, while PdMe(SPh)(dpe) is unreactive with carbon monoxide under similar conditions. The 31P{1H} and 13C{1H} NMR spectra of the reaction mixture of PdMe(OCH(CF3)2)(dpe) with an equimolar amount of 13CO at -60°C show the formation of PdMe (13COOCH(CF3)2)(dpe) produced through insertion of the carbon monoxide into the Pd-O bond. When the reaction temperature is raised to -20°C, this alkoxycarbonyl complex undergoes reductive elimination to give 1,1,1,3,3,3-hexafluoro-2-propyl acetate. The reaction is accompanied by simultaneous decarbonylation of the alkoxycarbonyl ligand to regenerate PdMe(OCH(CF3)2)(dpe). The reaction of PdMe(OCH(CF3)Ph)(dpe) with carbon disulfide gives an isolable palladium complex, PdMe(SCSOCH(CF3)Ph)(dpe), formed by insertion of CS2 into the Pd-O bond, while PdMe(SPh)(dpe) is unreactive with CS2.
