Insertion of a Carbodiimide into the Ln−N σ-Bond of Organolanthanide Complexes. Isomerization and Rearrangement of Organolanthanides Containing Guanidinate Ligands

The reaction of (C 5 H 5 )YCl 2 (THF) 3 with LiN i Pr 2 and subsequently with 2 equiv of N, N ‘-diisopropylcarbodiimide ( i PrN C N i Pr) in THF gave the organoyttrium guanidinates Y[ i PrNC(N i Pr 2 )N i Pr] 3 ( 1 ) and (C 5 H 5 ) 2 Y[ i PrNC(N i Pr 2 )N i Pr] ( 2 ), which may be rationalized by the rearrangement reaction of the diinsertion product (C 5 H 5 )Y[ i PrNC(N i Pr 2 )N i Pr] 2 . Treatment of i PrN C N i Pr with lanthanocene primary amides [(C 5 H 5 ) 2 LnNHR] 2 (R = t Bu, Ln = Yb, Er, Dy, Y; R = Ph, Ln = Yb) gave the unexpected products (C 5 H 5 ) 2 Yb[RNC(NH i Pr)N i Pr] (R = t Bu, Ln = Yb ( 3 ), Er ( 4 ), Dy ( 5 ), Y( 6 ); R = Ph, Ln = Yb ( 7 )), indicating that a novel isomerization reaction involving a 1,3-hydrogen shift takes place along with the insertion of carbodiimide into the Ln−N σ-bond, which provides an efficient synthesis of organolanthanide complexes with asymmetrical guanidinate ligands. All these complexes were characterized by elemental analysis and spectroscopic properties. The structures of complexes 1 − 5 and 7 were also determined by X-ray diffraction analysis.