EPR光谱法评估稀土金属（II）配合物的电子转移反应性,Organometallics

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EPR光谱法评估稀土金属（II）配合物的电子转移反应性
Organometallics ( IF 2.5 ) Pub Date : 2020-03-23 , DOI: 10.1021/acs.organomet.9b00837
Samuel A. Moehring ₁ , William J. Evans ₁

Affiliation

为了评估Sc（II），Y（II）的稀土金属络合物和镧系金属的+2氧化态的相对还原能力，三价Ln ^III A ₃化合物与二价[ LN“ ^II A' ₃ ] ^1-复合物已被检查，其中Ln =钪，Y，或一种镧系元素和A为C ₅ ħ ₄森达₃（CP'），C ₅ H ^ ₃（森达₃）₂（CP” ），C ₅ Me ₄ H（Cp ^tet），N（SiMe ₃）₂（NR ₂），2,6- ^t Bu ₂ -C ₆ H ₃ O（OAr）或2,6- ^t Bu ₂ -4-Me-C ₆ H ₂ O（OAr'）。选择特定的组合以允许通过EPR光谱法评估Ln（II）配合物。的[LN ^II CP' ₃ ] ^1-的Y复合物（II），LA（II）和Lu（II）具有在它们都减少LN类似的还原能力^III CP' _3种该组中的其它金属的复合物。然而，这些Y（II），LA（II）和Lu（II）配合物的所有被还原剂比[钆更强^II CP' ₃ ] ^1-，不能减少LN ^III CP' _3种Y，La和Lu的复合物。这些结果不适用于所有配体，因为[Gd ^II（NR ₂）₃ ] ^1–可以将Y ^III（NR ₂）₃还原为[Y ^II（NR ₂）₃ ] ^1–。Y和Sc的酰胺和芳基氧化物络合物的相似之处在于[Y ^II（NR ₂）₃ ] ^1–还原Sc ^III（NR ₂）₃和[Y ^II（OAr'）₃] ^{1 –}还原Sc ^III（OAr'）₃。既[Y ^II（NR ₂）₃ ] ^1-和[Y ^II（桨'）₃ ] ^1-降低ý ^III CP' ₃。[拉^II的Cp ^TET₃ ] ^1-具有类似于[La中的还原能力^II CP' ₃ ] ^1-，和两者都比[拉还原剂更强^II CP“ ₃ ] ^1-。Ln ^II I _2都没有Sm，Tm，Dy和Nd的络合物可以将Y和La的Ln ^III A ₃络合物还原为[Ln ^II A ₃ ] ^1–。在“相同金属不同的配体”反应中，发现了多个EPR信号，这表明配体交换与电子转移反应性一起发生。

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Evaluating Electron Transfer Reactivity of Rare-Earth Metal(II) Complexes Using EPR Spectroscopy

To evaluate the relative reducing capacities of rare-earth metal complexes of Sc(II), Y(II), and complexes of the lanthanide metals in their +2 oxidation state, a series of reactions of trivalent Ln^IIIA₃ compounds with divalent [Ln′^IIA′₃]^1– complexes has been examined, where Ln = Sc, Y, or a lanthanide and A is C₅H₄SiMe₃ (Cp′), C₅H₃(SiMe₃)₂ (Cp″), C₅Me₄H (Cp^tet), N(SiMe₃)₂ (NR₂), 2,6-^tBu₂-C₆H₃O (OAr), or 2,6-^tBu₂-4-Me-C₆H₂O (OAr′). The specific combinations were chosen to allow evaluation by EPR spectroscopy of the Ln(II) complex. The [Ln^IICp′₃]^1– complexes of Y(II), La(II), and Lu(II) have similar reducing abilities in that they all reduce Ln^IIICp′₃ complexes of the other metals in this group. However, these Y(II), La(II), and Lu(II) complexes all are stronger reductants than [Gd^IICp′₃]^1–, which cannot reduce Ln^IIICp′₃ complexes of Y, La, and Lu. These results do not apply to all ligand sets, since [Gd^II(NR₂)₃]^1– can reduce Y^III(NR₂)₃ to [Y^II(NR₂)₃]^1–. The amide and aryloxide complexes of Y and Sc are similar in that [Y^II(NR₂)₃]^1– reduces Sc^III(NR₂)₃ and [Y^II(OAr′)₃]^1– reduces Sc^III(OAr′)₃. Both [Y^II(NR₂)₃]^1– and [Y^II(OAr′)₃]^1– reduce Y^IIICp′₃. [La^IICp^tet₃]^1– has reductive capacity similar to that of [La^IICp′₃]^1–, and both are stronger reductants than [La^IICp″₃]^1–. None of the Ln^III₂ complexes of Sm, Tm, Dy, and Nd can reduce Ln^IIIA₃ complexes of Y and La to [Ln^IIA₃]^1–. In the “same-metal-different-ligands” reactions, multiple EPR signals are found, suggesting that ligand exchange occurs alongside the electron transfer reactivity.

更新日期：2020-03-23

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