Organometallic Compounds of the Lanthanides. 110.¹ Donor-Functionalized Chiral Cyclopentadienyl Complexes of Calcium, Samarium(II), and Ytterbium(II). A New Class of Chiral Metallocenes

Abstract

Twelve optically active metallocene complexes of Ca, Sm(II), and Yb(II) containing cyclopentadienyl systems with a chiral N-or O-substituted side chain as ligands are described. Specifically, the ligand systems (S)-( 2systems were employed. The starting materials for their synthesis are ethyl (S)-(-)-lactate, (R)-(-)-2-methoxy-2-phenylethanol, (S)-(+)-2-amino-1-propanol, and (R)-(-)-2-phenylglycinol, respectively. Each of the cyclopentadienyl systems was converted by a 2:1 reaction of the potassium salt with the metal diiodide into the corresponding metallocene, [M{(S)-η 5 :η Sm (2b), Yb (2c)), and [M{(S)-η 5 :η 1 -C 5 H 4 (CH(Ph)CH 2 NMe 2 )} 2 ] (M ) Ca (4a), Sm (4b), Yb (4c)). The novel compounds have been characterized by C, H, N analysis, mass spectrometry, NMR spectroscopy, and optical rotation. Additionally, an X-ray structural analysis of 2c, 3a, and 4a was performed.

Homolysis of the Ln–N bond: Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with 2-pyridylmethyl and 3-pyridylmethyl-functionalized indenyl ligands

“…The average distance of 2.723 (14) Å in 3 is longer than those of 2.683(5) Å , 2.68(1) Å , and 2.68(2) Å found in (Me 2 NCH(Me)CH 2 C 5 H 4 ) 2 Yb [13], Yb(Cp Py ) 2 [14], and Yb(Cp Py(s) ) 2 [14], respectively. The Yb-N distance of 2.561(7) Å in 3 is shorter than the corresponding values of 2.587(7) Å in [g 5 :g 1 -(2-C 5 H 4 NCH 2 )C 9 H 6 ] 2 Yb II (THF) [12], 2.673(11) Å in [Me 2 Si(Me 2 NCH 2 CH 2 C 9 H 5 )(t-Bu-NH)] 2 Yb II , 2.650(12) Å in (Me 2 NCH 2 CH 2 C 9 H 5 SiMe 3 ) 2 -Yb, 2.588(7) Å in (Me 2 NCH 2 CH 2 C 9 H 6 ) 2 Yb [7a], and 2.603(4) Å in (Me 2 NCH(Me)CH 2 C 5 H 4 ) 2 Yb [13]. But, the Yb-N distance of 2.561(7) Å in 3 is longer than those of 2.48(1) Å found in Yb(Cp Py ) 2 [14], and Yb(Cp Py(s) ) 2 [14], respectively.…”

“…This distance is shorter than the corresponding values of 2.806(12) Å in [Me 2 Si(Me 2 NCH 2 CH 2 C 9 H 5 )(t-BuNH)] 2 -Yb II [7a], 2.782(8) Å in [g 5 :g 1 -(2-C 5 H 4 NCH 2 )C 9 H 6 ] 2 Yb II (THF) [12], 2.778 (14) Å in (Me 2 NCH 2 CH 2 C 9 H 5 SiMe 3 ) 2 Yb [7a], is close to 2.722(10) Å in (Me 2 NCH 2 CH 2 C 9 H 6 ) 2 Yb [7a]. The average distance of 2.723 (14) Å in 3 is longer than those of 2.683(5) Å , 2.68(1) Å , and 2.68(2) Å found in (Me 2 NCH(Me)CH 2 C 5 H 4 ) 2 Yb [13], Yb(Cp Py ) 2 [14], and Yb(Cp Py(s) ) 2 [14], respectively. The Yb-N distance of 2.561(7) Å in 3 is shorter than the corresponding values of 2.587(7) Å in [g 5 :g 1 -(2-C 5 H 4 NCH 2 )C 9 H 6 ] 2 Yb II (THF) [12], 2.673(11) Å in [Me 2 Si(Me 2 NCH 2 CH 2 C 9 H 5 )(t-Bu-NH)] 2 Yb II , 2.650(12) Å in (Me 2 NCH 2 CH 2 C 9 H 5 SiMe 3 ) 2 -Yb, 2.588(7) Å in (Me 2 NCH 2 CH 2 C 9 H 6 ) 2 Yb [7a], and 2.603(4) Å in (Me 2 NCH(Me)CH 2 C 5 H 4 ) 2 Yb [13].…”

“…The N-Yb-N angle of 106.7(4)°found in 3 is smaller than the corresponding value of 159.8°in [g 5 :g 1 -(2-C 5 H 4 NCH 2 )C 9 H 6 ] 2 Yb II (THF) [12] for different coordination geometry, but the N-Yb-N angle of 106.7(4)°found in 3 is larger than those of 95.1(1)°in [Me 2 Si(Me 2 NCH 2 -CH 2 C 9 H 5 )(t-BuNH)] 2 Yb II , 92.8(5)°in (Me 2 NCH 2 CH 2 C 9 -H 5 SiMe 3 ) 2 Yb, 103.7(2)°in (Me 2 NCH 2 CH 2 C 9 H 6 ) 2 Yb [7a], 103.1(2)°in (Me 2 NCH(Me)CH 2 C 5 H 4 ) 2 Yb [13], 100.8(2)°i n Yb(Cp Py ) 2 , and 84.04(4)°in Yb(Cp Py(s) ) 2 [14] due to steric effects.…”

Synthesis and Characterization of the First Bisand Tris[1-(ω-alken-1-yl)indenyl]lanthanide Complexes

“…1 to 4) prove unambigeously that, in contrast to the indenyllanthanide complexes with N-or O-donor substituted indenyl sidearms [4,6,7], the alkenylindenyl side chains are not coordinated to the metal atom. They are turned away from the metal center showing an orientation similar to that of the allyl groups in decaallylferrocene [10].…”

“…Recent research was especially focused on the synthesis of complexes with substituted cyclopentadienyl [3] and indenyl [4] ligands containing strong donor atoms like nitrogen [5] or oxygen [3 e, 3 i, 4 d, 6] in their side chains in order to stabilize the otherwise very labile lanthanide complexes by additional coordination [7]. In fact, in this way it was possible to obtain moderately stable, solvent-free complexes and even bis(indenyl)lanthanide chloride complexes of the larger lanthanides [7]. In this connection, it was of special interest to investigate if the double bond in (alkenylindenyl)lanthanide complexes will coordinate the metal atoms yielding complexes stable enough to be more comfortably handled, but yet showing catalytic activity.…”