Erbium Mixed‐Ligand β‐Diketiminato‐Diamido Complex: Unusual Structure of Diamide Ligand

Abstract

A novel mixed-ligand erbium complex [(NacNac)ErL(THF)] (1) containing two types of sterically hindered ligands -monoanionic N-mesityl substituted b-diketiminate (NacNac = (MesNÀC(Me)CHC(Me)-NMes) À , Mes = 2,4,6-Me 3 C 6 H 2 ) and dianionic modified diamide ligand with mesityls as the N-aryl substituents (L = (MesNÀC(H)(Me)-C(= CH 2 )-NMes) 2À ) -was isolated from the salt metathesis reaction of [(NacNac)Er(THF) 2 ] with potassium salt of doubly reduced diazabutadiene K 2 (DAD-Mes 2À ) (DAD-Mes = MesN=C(Me)-C(Me) = NMes) prepared in si-tu. A solid-state structure of 1 was determined by single-crystal X-ray diffraction and revealed unusual asymmetrical diamide ligand with sp 3 -and sp 2 -hybridized carbon backbone atoms and exometallacyclic double carbon-carbon bond. In spite of the energy preference of symmetrical form of diamide ligand Lsym (Lsym = (MesNÀC(Me) = C(Me)-NMes) 2À ) calculated by DFT asymmetrical form L was found as minor product in the mixture of dipotassium salts obtained by reduction of DAD-Mes.

The Manifold Structural Chemistry of Alkali Metal Enediamide Complexes

“…Well‐investigated enediamide‐type DAD complexes have been reported mainly for the rare earth and early transition metals, particularly comprising Group IV and Group V metals, although a few late transition metal enediamide complexes have been reported , . An ytterbium(III) enediamide compound has recently been shown to behave as single‐ion magnet, while several Group IV enediamide complexes have been shown to be promising homogeneous catalysts e.g.…”

Low-Coordinate Mixed Ligand NacNac Complexes of Rare Earth Metals

“…The deviation of rare earth metals from the corresponding plane N1C1C2N2 of BIAN dipp is equal to 1.26(1), 1.32(1), and 1.21(1) Å, while the deviation from the N3C3C5N4 plane of β-diketiminato ligand amounts to 1.51(1), 1.62(1), and 1.45(1) Å for complexes 1 – 3 , respectively. The observed deviation is even more pronounced than in the mixed-ligand erbium complex with NacNac Mes and DAD ligands [ 50 ]. Due to such deviation, short contacts between the central metal and carbons C1 and C2 of BIAN ligand are observed in all complexes ( 1 – 3 ): the distances Ln1–C1 and Ln1–C2 are 2.640(2) and 2.636(2) Å for complex 1 , 2.708(3) and 2.741(3) Å for complex 2 , and 2.672(2) and 2.696(2) Å for complex 3 .…”

“…For example, [(NacNac Mes )YCl 2 (THF) 2 ] supported by N-mesityl substituted β-diketiminato ligand (NacNac Mes = 2,4,6-Me 3 C 6 H 2 -NC(Me)CHC(Me)N-2,4,6-Me 3 C 6 H 2 ) was used for the synthesis of mixed-ligand complexes β-diketiminato catecholate derivatives [ 49 ]. The salt metathesis reactions of [(NacNac Mes )ErCl 2 (THF) 2 ] with potassium salt of doubly reduced diazabutadiene (DAD Mes )K 2 (DAD Mes = 2,4,6-Me 3 C 6 H 2 -NC(Me)-C(Me)N-2,4,6-Me 3 C 6 H 2 ) prepared in situ, afforded a new mixed-ligand erbium complex [LEr(CH 2 -DAD Mes )(THF)] containing dianionic DAD ligand with an unusual double bond and hydrogen redistribution (CH 2 -DAD Mes = 2,4,6-Me 3 C 6 H 2 -NC(H)(Me)-C(=CH 2 )N-2,4,6-Me 3 C 6 H 2 ) [ 50 ]. Recently, a series of 2,6-diisopropylphenyl-substituted β-diketiminato-diiodides [(NacNac dipp )LnI 2 (THF) n ] (NacNac dipp = 2,6- i Pr 2 C 6 H 3 -NC(Me)CHC(Me)N-2,6- i Pr 2 C 6 H 3 ); Ln = Dy, Gd, Tb [ 51 ], Nd, Sm [ 52 ]) was involved in the salt metathesis reactions with potassium phenyl- and 2-pyridylthiolates resulting in β-diketiminato-thiolato complexes.…”

Rubidium and Cesium Enediamide Complexes Derived from Bulky 1,4-Diazadienes

“…Metal DAD complexes comprising the ligand in its enediamide form are known for the lanthanide elements, 6 − 15 early transition-metals 16 − 25 and some late transition-metals. 26 , 27 Enediamide complexes have also found some practical applications.…”

“…Metal DAD complexes comprising the ligand in its enediamide form are known for the lanthanide elements, − early transition-metals − and some late transition-metals. , Enediamide complexes have also found some practical applications. Recently, it was demonstrated that an Yb­(III) enediamide complex behaves as a single-ion magnet, whereas several group 4 metal enediamide complexes turned out to be useful homogeneous catalysts for the ring-opening polymerization of cyclic esters and for olefin polymerization …”