40391-85-3Relevant articles and documents
POP-pincer silyl complexes of group 9: Rhodium versus iridium
Esteruelas, Miguel A.,Oliván, Montserrat,Vélez, Andrea
, p. 12108 - 12119 (2013)
9,9-Dimethyl-4,5-bis(diisopropylphosphino)xanthene (xant(P iPr2)2) derivatives RhCl{xant(P iPr2)2} (1) and IrHCl{xant(PiPr 2)[iPrPCH(Me)CH2]} (2) react with diphenylsilane and triethylsilane to give the saturated d6-compounds RhHCl(SiR3){xant(PiPr2)2} (SiR 3 = SiHPh2 (3), SiEt3 (4)) and IrHCl(SiR 3){xant(PiPr2)2} (SiR3 = SiHPh2 (5), SiEt3 (6)). Complexes 3 and 5 undergo a Cl/H position exchange process via the MH{xant(PiPr2) 2} (M = Rh (8), Ir (E)) intermediates. The rhodium complex 3 affords the square planar d8-silyl derivative Rh(SiClPh2) {xant(PiPr2)2} (7), whereas the iridium derivative 5 gives IrH2(SiClPh2){xant(PiPr 2)2} (9), which is stable. In agreement with the formation of 7, the reactions of 8 with silanes are a general method to prepare square planar d8-rhodium-silyl derivatives. Thus, the addition of triethylsilane and triphenylsilane to 8 initially leads to the dihydrides RhH2(SiR3){xant(PiPr2)2} (SiR3 = SiEt3 (10), SiPh3 (11)), which lose molecular hydrogen to afford Rh(SiR3){xant(PiPr 2)2} (SiR3 = SiEt3 (12), SiPh 3 (13)). Treatment of 7 with NaBArF4· 2H2O leads to the cationic five-coordinate d6-species [RhH{Si(OH)Ph2}{xant(PiPr2)2}] BArF4 (14) through a silylene intermediate. According to the participation of the latter in the formation of 14, this cation is an efficient catalyst precursor for the monoalcoholysis of diphenylsilane with a wide range of alcohols, reaching turnover frequencies at 50% of conversion between 4000 and 76 500 h-1. The X-ray structures of 3, 6, 7, 9, 12, and 14 are also reported.
Carbon dioxide hydrosilylation to methane catalyzed by zinc and other first-row transition metal salts
Zhang, Qiao,Fukaya, Norihisa,Fujitani, Tadahiro,Choi, Jun-Chul
supporting information, p. 1945 - 1949 (2019/12/12)
We accomplished zinc catalyzed hydrosilylation of carbon dioxide (CO2) to silyl formate (C+II), bis(silyl)acetal (C0), methoxysilane (C1II), and finally methane (C1IV). Among several zinc salts, we found that Zn(OAc)2 with ligand 1,10-phenanthroline was the best. A turnover number of 815000 was achieved using the zinc catalyst to yield C+II. Unexpectedly, we observed the generation of CO from CO2 and hydrosilane for the first time. In addition to Zn, other first-row transition metals (Mn, Fe, Co, Ni, and Cu) also served as Lewis acid catalysts for CO2 hydrosilylation, regardless of the nature of the metal.
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.
