The Variable Di(mesityl)boroxide Coordination Chemistry of the Lanthanide Metals
Kito Gilbert-Bass1, Domonic Caruth1, Tyler Kerr1
1Department of Chemistry, University of California, Irvine, California 92697-2025, United States.
Abstract:
The coordination chemistry of the di(mesityl)boroxide ligand, (OBMes2)1- (Mes = C6H2Me3-2,4,6), with lanthanide elements has been explored to examine its utility in providing complexes stabilized by the electron-deficient alkoxide-like nature of this ligand. Protonolysis reactions between LnIII(NR2)3 (R = SiMe3) and HOBMes2 generated the crystalline bimetallic complexes, [(Mes2BO)2LnIII(μ-OBMes2)]2, which were characterized by X-ray crystallography for Ln = La, Ce, Nd, and Gd. The metal atoms of the dimers are linked through the oxygen atoms of bridging boroxide ligands and through metal-arene interactions. The monometallic LaIII(OBMes2)3(THF)3 was crystallographically characterized from the metathesis reaction between LaI3 and KOBMes2. The analogous Nd complex, NdIII(OBMes2)3(THF)3, was obtained by adding THF to [(Mes2BO)2NdIII(μ-OBMes2)]2. A heteroleptic complex, NdIII(NR2)2(OBMes2)(THF), was obtained by the reaction between NdIII(NR2)3 and HOBMes2. Initial studies of the reduction of these Ln(III) boroxides did not generate crystallographically characterizable Ln(II) complexes, and treatment of the heteroleptic NdIII(NR2)2(OBMes2)(THF) with KC8 led to the Nd(III) ligand redistribution product K(μ-OBMes2)2NdIII(NR2)2. A crystallographic study of the products obtained from the reaction between SmI2(THF)2 and KOBMes2 revealed the Sm(II) oxo cluster, SmII4(μ-OBMes2)6(μ4-O), as well as a Sm(III) potassium-incorporating complex [K(μ-OBMes2)3SmIII(OBMes2)(THF)]. The Sm(II) cluster reacts with the xylyl isocyanide, CNXyl (Xyl = 2,6-Me2C6H4), to form two cocrystallized Sm(III) complexes, SmIII(OBMes2)3(CNXyl)3 and SmIII(OBMes2)3(CNXyl)(Et2O).
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