Heteroleptic and heterometallic divalent lanthanide bis(trimethylsilyl)amide complexes: mixed ligand, inverse sandwich, and alkali metal derivatives

The utility of the [(Me3Si)(2)N](-) ligand in providing access to new membe rs of three classes of divalent lanthanide organometallic complexes is demo nstrated by the synthesis of inverse sandwich bimetallic, heteroleptic mono metallic, and heterometallic bridged derivatives. {[(Me3Si)(2)N]Sm(THF)(2)} (2)(mu -C8H8) (1) can be obtained from [(Me3Si)(2)N](2)Sm(THF)(2), Sml(2)(T HF)(2), and K2C8H8 in THF and crystallizes from THF with a planar (C8H8)(2- ) ring sandwiched between two {[(Me3Si)(2)N]Sm(THF)(2)}(+) cations. The ana logous {[(Me3Si)(2)N]Yb(THF)(2)}(2)(mu -C8H8) (2) can be generated from K[N (SiMe3)(2)], YbI2(THF)(2), and K2C8H8, in THF. Heteroleptic (C5Me5)Yb[N(SiM e3)(2)](THF)(2) (3) is generated from K[N(SiMe3)(2)] and {(C5Me5)Yb(THF)(2) (mu -I)](2) in THF and crystallizes from toluene with a distorted piano sto ol geometry. The bridged alkali metal derivatives {K-2[Zr-2(O ' Pr)(9)]} {Y b[N(SiMe3)(2)](3)}(THF)(3) (4), KSm[N(SiMe3)(2)](3) (5). and NaSm[N(SiMe3)( 2)](3) (6) show the diversity of bridging modes available with [(Me3Si)(2)N ](-) ligands in complexes with similar Ln/N(SiMe3)(2) sub-structures, in th is case the trigonal planar {[(Me3Si)(2)N](3)Ln}(-) anions. (C) 2001 Elsevi er Science Ltd. All rights reserved.