EPR study of the oxidation reaction of nickel(0) phosphine complexes with Lewis and Brønsted acids |
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| Authors: | VV Saraev PB Kraikivskii DA Matveev K Lammertsma |
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| Institution: | a Department of Chemistry, Irkutsk State University, Str. K. Marksa, 1, Irkutsk 664033, Russian Federation
b Faculty of Sciences, Department of Chemistry, Vrije University, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands |
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| Abstract: | The oxidation of Ni(PPh3)4 with BF3 · OEt2, H3CCOOH, and F3CCOOH, and that of (PPh3)2Ni(C2H4) with BF3 · OEt2 is studied by EPR spectroscopy. The reaction of the Ni(0) complexes with BF3 · OEt2 gives Ni(II) complexes with which they react to form Ni(I) compounds with covalent Ni-F and Ni-B bonds that transform with excess BF3 · OEt2 into cationic paramagnetic Ni(I) complexes. Acetic acid also adds oxidatively to Ni(PPh3)4 to form a Ni(II) complex that reacts further to give Ni(I) hydride and carboxylate complexes. The Ni(I) hydride is transformed by the acid into the Ni(I) carboxylate with release of hydrogen, the amount of which depends on the rate of acid addition. The following Ni(I) complexes are identified in the reaction medium: Ni(PPh3)3]BF4, (PPh3)2Ni(OEt2)]BF4, (PPh3)Ni(OEt2)n]BF4, (PPh3)2NiBF2, (PPh3)3NiOOCCH3, and (PPh3)2Ni(OEt2)P(OEt)3]BF4. Oxidation schemes of Ni(0) complexes by Lewis and Brønsted acids are given. |
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| Keywords: | Oxidation Ni(0) complexes Lewis and Brø nsted acids Ni(I) complexes EPR |
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