The reaction of a reactive nickel dimethyl 1 bearing a redox-active,dissymmetric ligand,which is obtained by deprotonation of 2-pyrimidin-2-yl-1H-benzimidazole(Hbimpm)with a divalent lanthanide complex,Cp*_(2)Yb(OEt_(...The reaction of a reactive nickel dimethyl 1 bearing a redox-active,dissymmetric ligand,which is obtained by deprotonation of 2-pyrimidin-2-yl-1H-benzimidazole(Hbimpm)with a divalent lanthanide complex,Cp*_(2)Yb(OEt_(2)),affords an unprecedented,trimeric 2 with C(sp^(3))-C(sp^(3))bond formation between two ligands in an exo position.Meanwhile,the transient,dimeric species 3 can be isolated with the same ligand coupling fashion,however,with a drastic distorsion angle of the bimpm ligand and reactive NiMe2 fragment,revealing the possible mechanism of this rearrangement.A much more stable dimeric conge ner,5,with an exo ligand coupling,is synthesized in the presence of 18-crown-6,which captures the pot assium counter ion.The C-C coupling formation between two bimpm ligands results from the effective electron transfer from divalent lanthanide fragments.Without the divalent lanthanide,the reductive coup ling occurs on a different carbon of the ligand,nicely showing the modulation of the spin density induced by the presence of the lanthanide ion.The electronic structures of these complexes are investigated by magnetic study(SQUID),indicating a 2 F7/2 ground state for each ytterbium in all the heterometallics.This workfirstly reports ligand coupling reactivity in a redox-active,yet dissymmetric system with divalent organolanthanides,and the reactive nickel moiety can impact the intriguing transition towards a stable homoleptic,trinulear lanthanide species.展开更多
基金the H2020 European Research Council(ERC)under the European Union’Horizon H2020 research program(grant agreement No.716314)CNRS and Ecole Polytechnique are thanked for funding.
文摘The reaction of a reactive nickel dimethyl 1 bearing a redox-active,dissymmetric ligand,which is obtained by deprotonation of 2-pyrimidin-2-yl-1H-benzimidazole(Hbimpm)with a divalent lanthanide complex,Cp*_(2)Yb(OEt_(2)),affords an unprecedented,trimeric 2 with C(sp^(3))-C(sp^(3))bond formation between two ligands in an exo position.Meanwhile,the transient,dimeric species 3 can be isolated with the same ligand coupling fashion,however,with a drastic distorsion angle of the bimpm ligand and reactive NiMe2 fragment,revealing the possible mechanism of this rearrangement.A much more stable dimeric conge ner,5,with an exo ligand coupling,is synthesized in the presence of 18-crown-6,which captures the pot assium counter ion.The C-C coupling formation between two bimpm ligands results from the effective electron transfer from divalent lanthanide fragments.Without the divalent lanthanide,the reductive coup ling occurs on a different carbon of the ligand,nicely showing the modulation of the spin density induced by the presence of the lanthanide ion.The electronic structures of these complexes are investigated by magnetic study(SQUID),indicating a 2 F7/2 ground state for each ytterbium in all the heterometallics.This workfirstly reports ligand coupling reactivity in a redox-active,yet dissymmetric system with divalent organolanthanides,and the reactive nickel moiety can impact the intriguing transition towards a stable homoleptic,trinulear lanthanide species.
