The lithium silylamides [Li(μ 3 -NHSiMe 2 Bu t )] 6 (1) and [Li(μ-NHSiPr i 3 )(THF)] 2 (2) were reacted with ClSiMe 3 , ClSiMe 2 Bu t , or ClSiPr i 3 to prepare a series of secondary silylamines by salt metathesis reactions. These were deprotonated with KH to afford the group 1 transfer agents [K{μ-N(SiMe 2 Bu t )(SiMe 3 )}(C 7 H 8 )] 2 (3), [{K[μ-N(SiPr i 3 )(SiMe 3 )]} 2 ] ∞ (4), [{K[μ-N(SiMe 2 Bu t ) 2 ]} 2 (C 7 H 8 )] ∞ (5), [K{N(SiPr i 3 )(SiMe 2 Bu t )}] ∞ (6), [K{N(SiPr i 3 ) 2 }] ∞ (7), and [K{N(SiPr i 3 ) 2 }(THF) 3 ] (8). The synthetic utility of these group 1 transfer agents has been demonstrated by their reactions with [Ln(I) 3 (THF) 4 ] (Ln = La, Ce) in various stoichiometries to yield heteroleptic [La{N(SiMe 2 Bu t )(SiMe 3 )} 2 (μ-I)] 2 (9) and homoleptic [Ln{N(SiMe 2 Bu t )(SiMe 3 )} 3 ] (Ln = La 10, Ce 11) and [La{N(SiMe 2 Bu t ) 2 } 3 ] (12). The very bulky silylamide ligands described herein can impart unusual geometries to their lanthanide complexes. Complexes 10−12 remarkably exhibit approximate planarity in the solid state rather than the more common trigonal pyramidal shapes observed in previously reported neutral homoleptic lanthanide silylamide complexes. Complexes 1−12 have been variously characterized by X-ray crystallography, NMR spectroscopy, FTIR spectroscopy, and CHN microanalysis. ■ INTRODUCTIONBulky monodentate alkali metal secondary amides have been employed ubiquitously in diverse research fields. 1 This can in part be attributed to their utility as strong bases, with favorable properties including relatively low nucleophilicity and ease of handling, commercial availability of precursors, and high solubility in hydrocarbon solvents. 2 Of these reagents, the silylamide {N(SiMe 3 ) 2 } − (N″) has received considerable attention as both a base and a ligand since the disclosure of synthetic routes to HN″, 3 LiN″, 4 NaN″, 5 and KN″. 5 The group 1 transfer agents have been widely used to prepare homoleptic three-coordinate p-, d-, and f-block complexes of the general formula [M III (N″) 3 ], as the bulky silyl groups engender low coordination numbers, even for relatively large M III cations. These coordinatively unsaturated complexes can exhibit interesting reactivity profiles. 6 In the solid state, these complexes are trigonal planar D 3h for group 13 (M = Al, Ga, In, Tl) 7 and the first-row transition metals (Ti−Co) 8 and trigonal pyramidal C 3v for group 15 (M = P, As, Sb, Bi), 9 lanthanides (M = Sc, Y, La, Ce−Lu; the group 3 metals are included as lanthanide mimics), 10 and actinides (M = U, Pu). 11 [Ln(N″) 3 ] (Ln = lanthanide) complexes exhibit a zero dipole moment in solution, indicating that they are trigonal planar in this phase, 10g and the scandium homologue, [Sc(N″) 3 ], is trigonal planar in the gas phase and pyramidal in the solid state, which is attributed to crystal packing effects. 12 Germane to this discussion, the related Ln(II) "ate" complexes [MLn(μ-N″) 2 (N″)] (M = Li, Na, K; Ln = Sm, Eu, Yb) 13 exhibit approximately trigonal planar geometries about the lanthani...
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