Reductive C-O Cleavage of Ethereal Solvents and 18-Crown-6 in Ln(NR 2 ) 3 /KC 8 Reactions (R = SiMe 3 ).

The high reactivity accessible from the reduction of the tris(amide) complexes Ln(NR 2 ) 3 (R = SiMe 3 ) with potassium graphite in the presence of a variety of ethers is demonstrated by crystal structures of six different types of products of C-O bond cleavage reactions with Ln = Y, Ho, Er, and Lu. Specifically, 1,2-dimethoxyethane (DME) can be cleaved in Ln(NR 2 ) 3 /KC 8 reactions as shown by three different types of crystals: [K (crypt)][(R 2 N) 3 Y(OCH 2 CH 2 OCH 3 )], 1-Y , [(R 2 N) 2 Y(μ-OCH 2 CH 2 OCH 3 -κO,κO')] 2 , 2-Y , and [K 2 (18-c-6) 3 ]{[(R 2 N) 3 Lu] 2 [(μ-OCH 2 CH 2 O)]}, 3-Lu (18-c-6 = 18-crown-6; crypt = 2.2.2-cryptand). THF can be ring opened by the Y(NR 2 ) 3 /KC 8 reaction system, as shown by crystals of the butoxide, [K(crypt)][(R 2 N) 3 Y(OCH 2 CH 2 CH 2 CH 3 )], 4-Y . The cyclic ether, oxetane, OC 3 H 6 , ring opens in Ln(NR 2 ) 3 /KC 8 reactions to form crystals of the propoxide, [K(18-c-6)(OC 3 H 6 )][(R 2 N) 3 Ln(OCH 2 CH 2 CH 3 )], 5-Ln , for Ln = Ho and Er. In Et 2 O, the Y(NR 2 ) 3 /KC 8 reactions do not attack the solvent, but C-O cleavage of 18-c-6 is observed to form {[(R 2 N) 2 ]Y[μ-η 1 : η 1 -O 2 (C 10 H 20 O 4 )K]} 2 , 6-Y . These Ln(NR 2 ) 3 /KC 8 C-O cleavage reactions are typically accompanied by C-H bond activation reactions, which form cyclometalates such as [K(crypt)]{(R 2 N) 2 Ln[N(SiMe 3 )(SiMe 2 CH 2 )-κC,κN]}, 7-Ln (Ln = Y, Ho, Er), and [K(18-c-6)]{(R 2 N) 2 Y[N(SiMe 3 )(SiMe 2 CH 2 )-κC,κN]}, 8-Y , which are common decomposition products of Ln(NR 2 ) 3 reactions. In addition, in this study, the hydride complex, [K(18-c-6)][(R 2 N) 3 YH], 9-Y , was isolated. NMR analysis indicates that the yttrium reactions form mixtures that consistently contain the yttrium cyclometalates 7-Y and 8-Y as major components. These results show the diversity of available reaction pathways for the Ln(NR 2 ) 3 /KC 8 system and highlight the inherent difficulties in isolating Ln(II) complexes containing the [Ln(NR 2 ) 3 ] 1- anion.