- Tuning the dissociation of the Fe-PPh2(OR) bond in chiral-at-metal complexes [CpFe(Prophos)PPh2(OR)]PF6 (R = Me, Et, i Pr, t Bu). the preparative trick of N2 Bubbling
-
The compounds (RFe,RC)-/(SFe,R C)-[CpFe(Prophos)PPh(OMe)2]PF6 and (R Fe,RC)-/(SFe,RC)-[CpFe(Prophos) PPh2(OR)]PF6 (R = Me, Et, iPr, tBu) were synthesized, starting from (RFe,RC)-/(SFe,R C)-[CpFe(Prophos)NCMe]PF6, and characterized, including X-ray analyses. Bubbling a stream of N2 through the solution speeded up the slow substitution reactions by removing the acetonitrile formed in the rate-determining cleavage of the Fe-NCMe bond. Due to their acceptor ligands P(OMe)3 and PPh(OMe)2 the complexes [CpFe(Prophos)P(OMe) 3]PF6 and [CpFe(Prophos)PPh(OMe)2]PF 6 are configurationally stable at the metal atom. In contrast, [CpFe(Prophos)PPh3]PF6 does not form, due to the large cone angle of the ligand PPh3. Ideally, the electronic and steric effects of the ligands PPh2(OR) (R = Me, Et, iPr, tBu) are such that they tend to dissociate from the congested complexes (RFe,R C)- and (SFe,RC)-[CpFe(Prophos)PPh 2(OR)]PF6. In the series (RFe,RC)- and (SFe,RC)-[CpFe(Prophos)PPh2(OR)]PF 6, (R = Me, Et, iPr, tBu) electron donation and the cone angle of the ligands increase. Thus, the rates of the ligand exchange with P(OMe) 3 increased, initiated by the slow dissociation of the Fe-PPh 2(OR) bond. For the RFe,RC/S Fe,RC diastereomers of [CpFe(Prophos)PPh 2(OR)]PF6 the half-lives of the first-order reactions were 125/350 h (R = Me), 75/275 h (R = Et), and 12/34 h (R = iPr) in CDCl 3 at 60 C.
- Brunner, Henri,Kurosawa, Takaki,Muschiol, Manfred,Tsuno, Takashi,Balazs, Gabor,Bodensteiner, Michael
-
-
Read Online
- AgPO2F2 and Ag9(PO2F2)14: the first Ag(i) and Ag(i)/Ag(ii) difluorophosphates with complex crystal structures
-
The reaction of AgF2 with P2O3F4 yields a mixed valence AgI/AgII difluorophosphate salt with AgI4AgII5(PO2F2)14 stoichiometry - the first Ag(ii)-PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(ii)-PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric AgII5(PO2F2)144- anions and two types of AgI cations. One particular AgII site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(ii) in an oxo-ligand environment. Ag(i)PO2F2 - the product of the thermal decomposition of Ag9(PO2F2)14 - has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [AgIO4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2- anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations.
- Malinowski, Przemys?aw J.,Kurzyd?owski, Dominik,Grochala, Wojciech
-
-
Read Online
- Thermal decomposition of LiPF6-based electrolytes for lithium-ion batteries
-
The thermal decomposition of lithium-ion battery electrolytes 1.0 M LiPF6 in one or more carbonate solvents has been investigated. Electrolytes containing diethyl carbonate (DEC), ethylene carbonate (EC), a 1:1 mixture of EC/dimethyl carbonate (DMC), and a 1:1:1 mixture EC/DMC/DEC have been investigated by multinuclear nuclear magnetic spectroscopy, gas chromatography with mass selective detection, and size exclusion chromatography. Thermal decomposition affords products including: carbon dioxide (CO 2), ethylene (CH2CH2), dialkylethers (R 2O), alkyl fluorides (RF), phosphorus oxyfiuoride (OPF3), fluorophosphates [OPF2OR, OPF(OR)2], fluorophosporic acids [OPF2OH, OPF(OH)2], and oligoethylene oxides. The mechanism of decomposition is similar in all LiPF6/carbonate electrolytes. Trace protic impurities lead to generation of OPF2OR, which autocatalytically decomposes LiPF6 and carbonates. The presence of DEC leads to the generation of ethylene, while the presnce of EC leads to the generation of capped oligothylene oxides [OPF2(OCH 2CH2)nF].
- Campion, Christopher L.,Li, Wentao,Lucht, Brett L.
-
p. A2327-A2334
(2008/10/09)
-
- Fluoridolysis of Diphosphoryl Compounds
-
The behaviour of diphosphoryl compounds [X2(O)P]2Y in fluoridolysis reactions is decisively determinated by the nature of the bridging group Y. In the cases of Y=NH and CH2 and X=Cl [F2P(O)]2N(1-) and [F2P(O)]2CH2 are obtained quantitatively. For Y=NPh, O, and CH3 the formation of phosphrylated pentafluorophosphates [F5P-Y-POX2](1-) is observed. Amido and ester derivatives containing fluorine (see table 2) are obtained from the corresponding chloro compounds by Cl/F exchange. Fluoridolysis of the azadiphosphetidine 19 results in the formation of acyclic 19a.
- Loewe, C.,Pauli, J.,Riesel, L.
-
-