Mario Glanz

Metallocenes of the alkaline earth metals and their carbene complexes

Abstract Novel alkaline earth metallocenes with various cyclopentadienyl ligands and their carbene adducts with 1,3-di-iso-propyl-4,5-dimethylimidazol-2-ylidene (iPr-carbene) are described. The syntheses of the magnesocenes (C5Me4H)2Mg (1), (C5Me4tBu)2Mg (2), and (C5H3-1-(SiMe3)-3-tBu)2Mg (3) were carried out by reaction of the corresponding cyclopentadiene with dibutylmagnesium. The calcocenes (C5Me4H)2(NH3)2Ca (6), (C5Me4H)2(NH3)(THF)Ca (7) and the barocene (C5Me4tBu)2(THF)2Ba (13) were prepaired by reaction of calcium and barium, respectively, with the corresponding cyclopentadienes. Refluxing 7 in THF–toluene yielded the ammonia-free complex (C5Me4H)2(THF)Ca (8). Metathesis reaction of (C5Me4iPr)Na with CaI2 gave the calcocene (C5Me4iPr)2(THF)Ca (9). (C5Me4tBu)2(py)2Ba (14) results from dissolving 13 in pyridine. 1,3-Di-iso-propyl-4,5-dimethylimidazol-2-ylidene reacted with 1, 3, 7, 8, 13, and (C5Me5)2(THF)2Sr in toluene or THF to give the air- and moisture-sensitive adducts (C5Me4H)2(iPr-carbene)Mg (4), (C5H3-1-(SiMe3)-3-tBu)2(iPr-carbene)Mg (5), (C5Me4H)2(iPr-carbene)Ca (10), (C5Me4iPr)2(iPr-carbene)Ca (11), (C5Me5)2(iPr-carbene)Sr (12), and (C5Me4tBu)2(iPr-carbene)Ba (15). The novel compounds have been characterized by elemental analysis, mass spectrometry and NMR spectroscopy as well as the X-ray structures of the metallocenes (1, 2, 6, 9, 13) and the carbene adducts (4, 10, 11, 12, 15).

Metallorganische Verbindungen der Lanthanoide. LXXVIII: Bis(pentamethylcyclopentadienyl)[4-(1,2,3,4,5-pentamethylcyclopentadien-1-yl)butoxy](tetrahydrofuran)lanthanoide

Abstract LnCl 3 (LnLa, Nd, Tm, Lu) reacts with NaCp* (Cp*C 5 (CH 3 ) 5 ) in THF to yield the complexes Cp* 2 Ln[O(CH 2 ) 4 Cp*(THF) ( 1 = La, 2 = Nd, 3 = Tm, 4 = Lu). Crystals of 2 are monoclinic, space group C 2/ c with a 2999.8(6), b 1396.1(3), c 1740.0(3) pm, s 90.54(1)°, V 7287(3) × 10 −3 m 3 and Z = 8. Least-squares refinement on the basis of 4680 reflections ( F o >4σ( F o )) led to a final R value of 0.0268. 4 crystallizes monoclinic, space group C 2/ c with a 2965.4(5), b 1384.6(3), c 1740.6(4) pm, s 90.81(1)°, V 7146(3) × 10 −30 m 3 and Z = 8. Least- squares refinement on the basis of 4097 reflections ( F o >4σ( F o )) led to a final R value of 0.028.

Metallorganische verbindungen der lanthanoide XCVI. Ylidartige olefinkoordination in komplexen dreiwertiger 4f-elemente☆

Abstract [(Me 3 Si) 2 N] 3 Ln (Ln  La ( 1 ) or Nd ( 2 )) and (C 8 H 8 Y(C 5 Me 5 ) ( 3 ) react with 1,3,4,5-tetramethyl-2-methylenimidazolin ( 4 ) to yield the ylidic olefin complexes [( Me 3 Si) 2 N]Ln[CH 2  CN(Me)C(me)C(Me)N (Me) ] (Ln  La ( 5 ) or Nd ( 6 )) and (C 8 H 8 )Y(C 5 Me 5 )[CH 2  CN(Me)C(me)N (Me)] ( 7 ). The molecular structures of 6 and 7 have been determined by X-ray diffraction.

Metallorganische verbindungen der lanthanoide: LXXVI. cyclooctatetraenyl(tetramethylcyclopentadienyl)-komplexe der lanthanoide☆

Abstract The complexes [(C8H8)Ln(μ-Cl)(THF)n]2 (Ln = Y, La, Pr, Sm, Gd, Dy, Er, Lu) react with Na(C5Me4H) in THF to yield complexes (C8H8)Ln(C5Me4H)(THF)x (Ln = Y, La, Pr, Sm, Gd, Dy, Er, Lu). Crystals of (C8H8)La(C5Me4H)(THF) 2 (2) are monoclinic, space group P21/n with a = 850.80(15), b = 1183.5(2), c = 2290.1(5) pm, β = 96.707(16)°, V = 2273.8(8) × 10−30 m3 and Z = 4. Least-squares refinement on the basis of 3070 reflections (Fo > 6σ(Fo)) led to a final R of 0.0305. Compound (C8H8)Lu(C5Me4H) (8) crystallizes monoclinic, space group P21/m with a = 927.6 (2), b = 1431.3(4), c = 1114.4(2) pm, β = 90.41(1)°, V = 1479.5(5) × 10−30 m3 and Z = 4. Least-squares refinement on the basis of 2329 reflections (Fo> 4σ(Fo)) led to a final R of 0.0276.

Lewis-acidic organometallic compounds of the lanthanides and the alkaline earth metals as catalysts for the activation of carbonyl groups

1,3-dialkyl-4,5-dimethylimidazol-2-ylidenes form adducts with various bis (alkylcyclopentadienyl) complexes of magnesium, calcium, strontium, barium, samarium, and ytterbium. The X-ray structures of selected metallocenes and carbene adducts are discussed. Liquid-crystalline homo- and block copolymers with a narrow molecular mass distribution index were obtained in high yields by living polymerization of mesogenic methacrylates with organosamarium complexes. Depending on the structure of the catalyst and the polarity of the solvent used, different, partially competitive reaction mechanisms are observed.

Metallorganische Verbindungen der Lanthanoide. LXXIV: Tris(tetramethylcyclopentadienyl)komplexe der Lanthanoide

Abstract LnCl3 (Ln = La, Sm, Th) reacts with Na(C5Me4H) in THF to yield the homoleptic complexes Ln(C5Me4H)3 (1: Ln = La; 2: Ln = Sm; 3: Ln = Tb). The crystals of 3 are rhomboedric, space group R 3 with a = 1053.5(5) pm, α = 95.04(3)°, V = 1153.2(7)· 10−30 m3 and Z = 2. Least-squares refinement on the basis of 392 reflections (Fo > 4σ(Fo)) led to a final R value of 0.0266.

Der Einfluß der Koordinationssphäre von Samarocenen auf die Synthese von flüssigkristallinen Polymethacrylaten

(C5Me5)2Sm(THF)2 (1) reagiert mit 1,3-Diisopropyl-4,5-dimethylimidazol-2-yliden C3N2Me2iPr2 (iPrcarben) unter Bildung von (C5Me5)2Sm(iPr-carben) (3) und aus (C5Me4Et)2Sm(THF)2 (2) und Al2Me6 entsteht in Toluol [(C5Me4Et)2Sm(CH3)Al(CH3)3]2 (6). 3 und 6 werden durch Einkristall-Rontgenstrukturanalysen charakterisiert. Die lebende Polymerisation von mesogenen Methacrylaten mit den Organosamariumkomplexen 1, 2, 3, (C5Me5)2Sm(C3H5) (4), (C5Me5)2Sm(CH3)(THF) (5), 6 und (C5Me4Et)2SmCH(SiMe3)2 (7) fuhrt in hohen Ausbeuten zu flussigkristallinen Homo- und Blockcopolymeren mit enger Molmassenverteilung. In Abhangigkeit von der Struktur des Katalysators und der Polaritat des Losemittels werden verschiedene, teilweise konkurrierende Mechanismen beobachtet. The Influence of the Coordination Sphere of Samarocenes on the Synthesis of Liquid Crystalline Polymethacrylates (C5Me5)2Sm(THF)2 (1) reacts with 1,3-Diisopropyl-4,5-dimethylimidazoline-2-ylidene C3N2Me2iPr2 (iPr-carben) with formation of (C5Me5)2Sm(iPr-carben) (3). The reaction of (C5Me4Et)2Sm(THF)2 (2) with Al2Me6 in toluene yields [(C5Me4Et)2Sm(CH3)Al(CH3)3]2 (6). 3 and 6 were characterized by single crystal X-ray structure analysis. Via living polymerization of mesogenic methacrylates with the organosamarium complexes 1, 2, 3, (C5Me5)2Sm(C3H5) (4), (C5Me5)2Sm(CH3)(THF) (5), 6, and (C5Me4Et)2SmCH(SiMe3)2 (7), liquid crystalline homo- and blockcopolymers were obtained with narrow molecular mass distribution indexes in high yield. Partial competitive mechanisms are observed dependend of the structure of the catalyst and the polarity of the solvents.

Metallorganische verbindungen der lanthanoide: LXXXV. Synthese und strukturaufklärung neuer cyclooctatetraenyl-cyclopentadienyl-sandwich-komplexe der seltenen erden

Abstract The mixed sandwich complexes [(C 8 H 8 )Ln(C 5 Me 4 Et)(THF) x ] (Ln = Y 1 , La 2 , Nd 3 , Sm 4 , Gd 5 , Tm 6 , Lu 7 ), [(C 8 H 8 )Ln{C 5 H 2 (SiMe 3 ) 3 }(THF) x (Ln = Pr 8 , Dy 9 ) and [(C 8 H 8 )Pr(C 5 Ph 5 )] ( 10 ), have been prepared by the metathetic reaction of [(C 8 H 8 )Ln(μ-Cl)-(THF) n ] 2 with NaC 5 Me 4 Et, LiC 5 H 2 (SiMe 3 ) 3 and NaC 5 Ph 5 in THF. The 1:2 reaction of 7 with acetylacetone results in displacement of the (C 8 H 8 )-ligand to generate the new complex [(C 5 Me 4 Et)Ln(acac) 2 ] (acac = [CH 3 C(O)CHC(O)CH 3 ] − ) ( 11 ). The molecular structures of 7 (monoclinic space group P 2 1 / c with a = 990.4(5) pm, b = 1228.2(5) pm, c = 2757.5(16) pm, β = 93.92(4)°, V = 3346(3)·10 −30 m 3 and Z = 8) and 11 (triclinic space group P 1 with a = 957.3(3) pm, b = 1064.5(2) pm, c = 1068.3(2) pm, α = 94.19(12)°, β = 96.37(17)°, γ = 96.71(16)°, V = 1070.3(4)·10 −30 m 3 and Z = 2) have been determined by X-ray diffraction.