The First Example of a μ₂-Imido Functionality Bound to a Lanthanide Metal Center:  X-ray Crystal Structure and DFT Study of [(μ-ArN)Sm(μ-NHAr)(μ-Me)AlMe₂]₂ (Ar = 2,6-ⁱPr₂C₆H₃)¹

Abstract

Reaction of 3 equiv of 2,6-diisopropylaniline with Sm[N(SiMe 3 ) 2 ] 3 affords the dimeric species [Sm(NHAr) 3 ] 2 (1). X-ray crystallography illustrates that each metal center in 1 engages in an η 6 -arene interaction with the aryl ring of an amide ligand attached to an adjacent samarium. IR spectroscopy indicates that the π-arene interactions are maintained in solution. Reaction of 1 with 4 equiv of trimethylaluminum leads to formation of the bis(µ 2 -imido) complex [(µ-ArN)Sm(µ-NHAr)(µ-Me)AlMe 2 ] 2 (2). The molecular structure of 2 contains a unique central Sm 2 N 2 core which displays extremely short bridging Sm-N distances of 2.152-(8) and 2.271(7) Å, characteristic of an imido complex. Density functional theory (DFT) calculations have been carried out in order to gain a better understanding of the nature of the bonding interactions within complex 2 and indicate that the 5d metal acceptor orbitals play a significant role in stabilizing π-donation from the imido groups to the samarium centers within the Sm 2 N 2 core.

Titanium Imido Complexes of Cyclooctatetraenyl Ligands

“…Unsymmetrically bridging imides have previously been observed for several different transition-metal complexes and this effect increases p donation to the metal centre. [27,35,38] The ligands of the complex are slightly distorted from their regular geometries. The dimethylphenyl group of the imide is bent slightly towards the Ti atom in the same asymmetric unit, so the Ti···Ti vector makes an angle of 84.78 with the best plane of the phenyl ring.…”

“…The dimethylphenyl group of the imide is bent slightly towards the Ti atom in the same asymmetric unit, so the Ti···Ti vector makes an angle of 84.78 with the best plane of the phenyl ring. Neither of the ipsocarbon atoms of the bridging m-N-2,6-Me 2 C 6 H 3 ligands displays any interaction with the Ti centre in contrast to the significant interactions seen in similar zirconium, [27] samarium [38] and uranium [39][40][41][42] complexes. This lack of interaction could be for steric reasons or because titanium is smaller than these other metals.…”

Effect of the f-Orbital Delocalization on the Ligand-Field Splitting Energies in Lanthanide-Containing Elpasolites

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Theoretical modeling of such complexes involves high-cost methods because of the role of electron correlation and the necessity of taking into account the effects of the environment of the f-elements. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Density-functional-theory methods based on the Kohn-Sham equations (KS-DFT) became standard tools in modeling large polyatomic systems. [30][31][32] In practice, KS-DFT calculations apply approximations to the exchangecorrelation functional and the associated potential which are usually rather adequate.…”

Dinitrogen and Related Chemistry of the Lanthanides: A Review of the Reductive Capture of Dinitrogen, As Well As Mono- and Di-aza Containing Ligand Chemistry of Relevance to Known and Postulated Metal Mediated Dinitrogen Derivatives

“…However, imide species, which are amide precursors in the Schrock and Chatt cycles, have been reported sparingly in the literature [58,59,60,61,62,63,64,65,66,67]. Attempts to isolate a terminal lanthanide imide complex have as yet been unsuccessful.…”