Lanthanide Complexes Coordinated by a Dianionic Bis(amidinate) Ligand with a Rigid Naphthalene Linker

Abstract

The synthetic pathway to a new bis(amidine) ligand with a conformationally rigid naphthalene linker, 1,8‐C10H6[NHC(tBu)=N(2,6‐Me2–C6H3)][N=C(tBu)NH(2,6‐Me2–C6H3)] (3) was elaborated. Deprotonation of this bis(amidine) ligand with two equivalents of nBuLi and subsequent reaction with anhydrous LnCl3 (Ln = Y, Nd, Sm) allowed the synthesisof the chlorido complexes [1,8‐C10H6{NC(tBu)N‐2,6‐Me2–C6H3}2]YCl(dme) (4), [1,8‐C10H6{NC(tBu)N‐2,6‐Me2–C6H3}2]Nd(dme)(μ‐Cl)2Li(dme) (5), and [1,8‐C10H6{NC(tBu)N‐2,6‐Me2–C6H3}2]Sm(thf)(μ‐Cl)2Li(thf)2 (6), which are coordinated by the linked dianionic bis(amidinate) ligand. The structures of complexes 4–6 were established by X‐ray diffraction studies, which reveal that the new ligand framework can coordinate to the lanthanide atoms in different fashions depending on the central atom ion size. Alkylation of complex 6 with equimolar amounts of LiCH2SiMe3 afforded the unexpected amido–amidinate complex [{1,8‐C10H6(NC(tBu)N‐2,6‐Me2–C6H3)2}{1,8‐C10H6(NC(tBu)N‐2,6‐Me2–C6H3)(NH)}Sm][Li(dme)3] (7), which obviously results from the cleavage of one amidinate group during decomposition of the transient alkyl species and ligand redistribution.

Synthesis, Structure, and Catalytic Behavior of Ytterbium Complexes Derived from a Linked Bis(β‐ketoiminato) Ligand

“…Another popular method for the synthesis of organolanthanide complexes is the metathetical reaction. For example, several amidinate lanthanide chlorides [Me 3 SiNC(Ph)N(CH 2 ) 3 NC(Ph)NSiMe 3 ] Ln Cl(THF) 2 ( Ln = Y, Yb),8a,8b [(Me 2 Si{NC(Ph)N(2, 6‐ i Pr 2 –C 6 H 3 )} 2 ) 2 (YCl) 2 (μ‐Cl)] – [Li(THF) 4 ] + ,8c [1, 8‐C 10 H 6 {NC( t Bu)N‐2, 6‐Me 2 –C 6 H 3 } 2 ]YCl(DME),8d and [C 6 H 4 ‐1, 2‐{NC( t Bu)N(2, 6‐ R 2 C 6 H 3 )} 2 ]Y(THF)(μ‐Cl) 2 Li(THF) 2 ( R = Me, i Pr)8e were reported to be synthesized by the reaction of lanthanide chloride with lithium salts of corresponding linked bis(amidinate) dianionic ligands. Therefore, the new linked bis(β‐ketoiminato) ytterbium chloride and its derivatives were conveniently synthesized by this method in the presented work.…”

Rare‐Earth Amido and Borohydrido Complexes Supported by Tetradentate Amidinate Ligands: Synthesis, Structure, and Catalytic Activity in Polymerization of Cyclic Esters

“…The lengths of the covalent Ln(1)–N(5) bond ( 3 : 2.295(3) Å; 4 : 2.389(3)–2.408(4) Å) are comparable with those in the formerly described amido yttrium [{Me 3 SiNC(Ph)N} 2 (CH 2 ) 3 ]Y(2,6‐Pr i 2 C 6 H 3 NH)DME (2.237(4) Å), {(3,5‐Me 2 C 3 HN 2 ) 3 B}Y[κ 3 ‐(4‐NH=(C 8 N 2 H 4 )(2‐NHC 6 H 4 ))]{(Me 2 N) 3 P=O} (2.309(5) Å) and neodymium complexes [3,5‐Bu t 2 ‐2‐O‐C 6 H 2 CH=N‐C 5 H 4 N] 2 NdN(SiMe 3 ) 2 (2.385(3) Å), [{Me 3 SiNC(Ph)N} 2 (CH 2 ) 3 ]Nd(2,6‐Pr i 2 C 6 H 3 NH)DME (2.342(7) Å), [{(NC 5 H 4 )NHCH 2 (3,5‐Bu t 2 ‐C 6 H 2 ‐2‐OH)}NdN(SiMe 3 ) 2 (THF)] 2 (2.372(3) Å) . The Ln–N amidinate distances in 3 and 4 are somewhat different (κ 4 ‐NNOO‐ligand 2.378(3)–2.379(3) Å ( 3 ), 2.473(2)–2.483(2) Å ( 4 ); κ 2 ‐NN‐ligand 2.21(2)–2.45(2) Å, average 2.34(6) Å ( 3 ), 2.415(5)–2.487(4) Å, average 2.46(2) Å ( 4 )), but are comparable with the corresponding values measured in the related seven‐coordinate yttrium amidinate complexes [{1,3‐C 6 H 4 (NC(Ph)NSiMe 3 ) 2 } 3 Y(THF)Y(µ‐Cl)Li(THF) 3 ] (2.341(6), 2.455(6) Å), [Y{ o ‐CH 3 O‐C 6 H 4 NC(Ph)N(SiMe 3 )}Cl 2 (THF) 2 ] 2 (2.384(2), 2.375(2) Å), [(2,6‐Et 2 C 6 H 3 N) 2 C(4‐Me‐C 6 H 4 )] 2 Y(THF)(Cl)(µ‐Cl)Li(THF) 3 (2.402(6)–2.464(5) Å), [1,8‐C 10 H 6 {NC(Bu t )N‐2,6‐Me 2 ‐C 6 H 3 } 2 ]YCl(DME) (2.331(1)–2.369(1) Å) [{Me 3 SiNC(Ph)N} 2 (CH 2 ) 3 ]YCl(DME) (2.360(3)–2.379(3) Å) and seven‐coordinate neodymium complexes (2.385(2)–2.604(7) Å) , . The C–N bond lengths within the amidinate fragments in 3 and 4 fall into a narrow interval ( 3 : 1.321(8)–1.333(9) Å, 4 : 1.313(4)–1.333(9) Å) thus being indicative of delocalization of the negative charge over the NCN fragments.…”

Yttrium and ytterbium(III) complexes with ansa-linked bis(amidinate) ligand containing conformationally rigid o-phenylene bridge

“…5) but is somewhat longer than the corresponding bond lengths in other known heptacoordinated bis(amidinate) yttrium complexes (([C 3 H 6 {NC(Ph)NSiMe 3 } 2 ]YCl(DME) (2.369(3) Å) 8 and C 10 H 6 {NC(Bu t )N 2,6 Me 2 C 6 H 3 } 2 YCl(DME) (2.350(1) Å). 9 It should be mentioned that the distances to the "internal" nitrogen atoms of the amidinate frag ments Y(1)-N(1) and Y(1)-N(2) (2.315(2), 2.336(1) Å) are noticeably shorter compared to the distances to the "external" Y(1)-N(3) and Y(1)-N(4) moieties (2.478(2), 2.435(1) Å). A similar tendency was observed previously for related compounds.…”