Crystal Packing Forces Dictate η¹- versus η²-Coordination of Benzyl Groups in [Guanidinate]Zr(CH₂Ph)₃

Abstract

An X-ray structure determination of {CyNC-[N(SiMe 3 ) 2 ]NCy}Zr(CH 2 Ph) 3 , crystallized from pentane, differs from the solid-state structure previously reported for the same compound crystallized from toluene. In contrast to the earlier report, we find no evidence for the presence of an η 2 interaction in the solid state by X-ray crystallography or in solution by means of 1 H or 13 C NMR spectroscopy.

Zinc Guanidinate Complexes and Their Application in Ring‐Opening Polymerisation Catalysis

“…of the (neutral) guanidine, predicted to proceed by protonolysis of the zinc−carbon linkage. The ligand precursors, [R 2 NC{NR′}{NHR′}], were prepared from the reaction between the lithium diamide LiNR 2 (R = SiMe 3 , Me) and i PrN=C=N i Pr, followed by quenching of the intermediate lithium salt with a stoichiometric amount of water, to afford [Me 2 NC(N i Pr)(NH i Pr)] ( 1 ) and [(Me 3 Si) 2 NC(N i Pr)(NH i Pr)] ( 2 ) 26. The compounds were isolated as colourless and yellow liquids, respectively, and were used without further purification.…”

Homoleptic U(iii) and U(iv) amidate complexes

“…Several factors could be considered as influencing this behavior: i) the higher covalent character of U(IV) 53 could favor stronger U-N interations in 4; ii) the effect of electrostatic repulsion in U-L interactions in anionic 5 relative to neutral 4 may result in a lower coordination number; iii) in situations where the energy differences are small, crystal packing effects cannot be ruled out. 54 Notably, 5 was the main product of the reaction between 3 and UI3(1,4-dioxane)1.5 regardless of the stoichiometry used; no U(III) products with increased coordination numbers were isolated.…”

Evaluating f‐Element Bonding from Structure and Thermodynamics

“…[56] Unrestricted DFT calculations on the thorium aminodiboranate complex [Th(H 3 BNMe 2 BH 3 ) 4 ] provide a 16-coodinate structure; however single-crystal X-ray and neutron diffraction studies indicate that the ligands distort and the Th center becomes 15-coordinate when placed within a nonsymmetric crystal environment. [57] If periodic boundary conditions are imposed based on the experimental cell dimensions, DFT calculations reproduce the 15-coordinate structure.…”