Jörg Demtschuk

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).

Hydrotris(1,2,4-triazolyl)borato Complexes with the Main Group Elements Ca, Sr, and Pb – Unexpectedly Bent ML2 Structures and a Stereochemically Inactive Lone Pair at Lead(II)

The coordination of the modified poly(azolyl)borato ligand hydrotris(1,2,4-triazolyl)borato (L) with main group metals leads to complexes with coordination numbers of eight and the formula [CaL2(H2O)2], [SrL2(H2O)2], and [PbL2(H2O)2]. The two L ligands coordinate in a “bent” arrangement to allow for the coordination of the two aqua ligands. This is in sharp contrast to six-coordinated, pseudo-octahedral CaTp2 and PbTp2 complexes [Tp = hydrotris(pyrazolyl)borato]. The calcium, strontium, and lead complexes are isostructural. No stereochemical lone pair activity is evident in [PbL2(H2O)2]. Two additional water molecules of crystallization complete the crystal structure of [CaL2(H2O)2] · 2 H2O and [PbL2(H2O)2] · 2 H2O. In the synthesis of [PbL2(H2O)2] an intermediate of the form [Pb(μ3-L)(NO3)H2O] could isolated and structurally characterized. There, the lead(II) center is seven coordinated with a presumably stereochemically active lone pair. Long M–L bonds argue for a more ionic bonding to the modified tris(triazolyl)borato ligand when compared to analogous M–Tp complexes. Hydrotris(1,2,4-triazolyl)borato Komplexe mit den Hauptgruppenelementen Ca, Sr und Pb – unerwartet gewinkelte ML2 Strukturen und ein stereochemisch inaktives freies Elektronenpaar an Blei(II) Die Koordination des modifizierten Poly(azolyl)borato-Liganden Hydrotris(1,2,4-triazolyl)borato (L) mit Hauptgruppenmetallen ergibt Komplexe mit der Koordinationszahl acht und der Formel [CaL2(H2O)2], [SrL2(H2O)2], and [PbL2(H2O)2]. Die beiden L-Liganden koordinieren in einer „gewinkelten” Anordnung, um die Koordination der beiden Aqualiganden zu ermoglichen. Dies steht im Gegensatz zu den sechsfach-koordinierten, pseudo-oktaedrischen CaTp2- und PbTp2-Komplexen [Tp = hydrotris(pyrazolyl)borato]. Die Calcium-, Strontium- und Bleikomplexe sind isostrukturell. Es ist keine stereochemische Aktivitat des freien Elektronenpaares in [PbL2(H2O)2] zu erkennen. Zwei zusatzliche Kristallwasser-Molekule vervollstandigen die Kristallstruktur von [CaL2(H2O)2] · 2 H2O und [PbL2(H2O)2] · 2 H2O. Bei der Synthese von [PbL2(H2O)2] wurde eine Zwischenstufe mit der Formel [Pb(μ3-L)(NO3)H2O] isoliert und strukturell charakterisiert. In dieser Zwischenstufe ist das Blei(II)-Atom siebenfach koordiniert mit einem vermutlich stereochemisch aktiven freien Elektronenpaar. Lange M–L Bindungen legen eine starker ionische Anbindung des modifizierten Tris(triazolyl)borato-Liganden an das Metall nahe, im Vergleich zu den analogen M–Tp Komplexen.

Organometallic Compounds of the Lanthanides. 127 [1] Synthesis of Monomeric Bis(cyclopentadienyl)lanthanide Tetrahydroborates with Bulky Cyclopentadienyl Ligands. Single Crystal X-ray Structures of [(η5-C5Me5)2SmBH4(THF)] and [(η5-C5Me4Et)2Y(μ-H)2BH2(THF)]

The trichlorides of yttrium, samarium, and lutetium react with 2 equivalents of Na[C5H4 tBu] and 1 equivalent of NaBH4 to give [(η5-C5H4 tBu)2LnBH4(THF)] (Ln = Y (1), Sm (2), Lu (3)) or with 2 equivalents of Na[C5Me4R] and 1 equivalent of NaBH4 to form [(η5-C5Me4R)2 · LnBH4(THF)] (R = H, Ln = Y (4), Sm (5), Lu (6); R = Me, Ln = Y (7), Sm (8), Lu (9); R = Et, Ln = Y (10), Sm (11), Lu (12); R = iPr, Ln = Y (13), Sm (14), Lu (15)). The new compounds have been characterized by elemental analysis, NMR spectroscopy and mass spectrometry. The crystal structures of 8 and 10 were determined by single crystal X-ray diffraction. Organometall-Verbindungen der Lanthanoide. 127 Synthese von monomeren Bis(cyclopentadienyl)lanthanoid-tetrahydroboraten mit sperrigen Cyclopentadienyl-Liganden. Einkristallstrukturen von [(η5-C5Me5)2SmBH4(THF)] and [(η5-C5Me4Et)2Y(μ-H)2BH2(THF)] Die Trichloride von Yttrium, Samarium und Lutetium reagieren mit 2 Aquivalenten Na[C5H4 tBu] und 1 Aquivalent NaBH4 zu [(η5-C5H4 tBu)2LnBH4(THF)] (Ln = Y (1), Sm (2), Lu (3)) oder mit 2 Aquivalenten Na[C5Me4R] und 1 Aquivalent NaBH4 zu [(η5-C5Me4R)2 · LnBH4(THF)] (R = H, Ln = Y(4), Sm (5), Lu (6); R = Me, Ln = Y (7), Sm (8), Lu (9); R = Et, Ln = Y (10), Sm (11), Lu (12); R = iPr, Ln = Y (13), Sm (14), Lu (15)). Die Verbindungen wurden elementaranalytisch, NMR-spektroskopisch und massenspektrometrisch charakterisiert. Die Kristallstrukturen von 8 und 10 wurden aus Einkristallstruktur-Daten bestimmt.

Metallorganische verbindungen der lanthanoide CIX organolanthanoidfluoride: Synthese und strukturaufklärung von trimerem Bis(tert.-butylcyclopentadienyl)samarium(III)-fluorid

Abstract The organolanthanide fluoride [( η 5 -C 5 H 4 1 Bu) 2 Sm( μ -F))] 3 ( 1 ) was generated by oxidation of [( η 5 -C 5 H 4 1 Bu) 2 Sm(THF) 2 ] with Me 3 SnF. The X-ray structural analysis of 1 showed the trimeric compound to be monoclinic space group C 2/ c , Z = 4, with a = 18444.6(6), b = 1537.5(3), c = 1871.2(9)pm, β = 104.55(4)° and D calc = 1.597 g cm 3 . The structure was solved from 3942 observed reflections with F o > 4 σ ( F o ) and refined to a final R = 0.0735.

Organometallic compounds of the lanthanides. CIII Mixed sandwich complexes of the 4f elements: synthesis and crystal structure of (ν8-cyclooctatetraenyl)(ν5-2,5-di-tert.-butylpyrrolyl) samarium, -thulium, and -lutetium☆

[(ν8-C8H8)Ln(μ-Cl)(THF)]2 (Ln = Sm, Tm, Lu) reacts with Na[pyr∗] (pyr∗ = NC4H2tBu2-2,5) to form [(ν8-C8H8)Ln(ν5-pyr∗)(THF)x] (Ln = Sm 1, x = 1; Ln = Tm 2, Lu 3, x = 0). The novel sandwich compounds have been characterized by C,H,N analysis, mass spectrometry and NMR spectroscopy. Additionally, an X-ray structural analysis of 1 was performed. The crystals of 1 are monoclinic, space group P21/c with a = 11.131(2) A, b = 20.023(3) A, c = 20.118(5) A, β = 91.16(2)°, V = 4482.8(14) A3and Z = 4. The final refinement resulted in R1 = 3.09% (I>2σ(I)).

Erste Komplexe von Yttrium und Lutetium mit schwefelfunktionalisierten Cyclopentadienylliganden

Yttriumtrichlorid reagiert mit 2 Aquivalenten Na[C5H4CH2CH2SEt] (1) zu (η5-C5H4CH2CH2SEt)2YCl (2). Die schrittweise Reaktion von Lutetiumtrichlorid mit jeweils einem Aquivalent von 1 und Na[C5Me5] verlauft unter Bildung von (η5-C5Me5)(η5-C5H4CH2CH2SEt)LuCl (4). Durch Alkylierung von 2 bzw. 4 mit LiMe werden die Komplexe (η5-C5H4CH2CH2SEt)2YMe (3) bzw. (η5-C5Me5)(η5-C5H4CH2CH2SEt)LuMe (5) erhalten. Die Verbindungen wurden elementaranalytisch, NMR-spektroskopisch und massenspektrometrisch charakterisiert. Die Molekulstrukturen von 2 und 4 wurden aus Einkristallstruktur-Daten bestimmt. Organometallic Compounds of the Lanthanides. 132 First Complexes of Yttrium and Lutetium with Sulfur functionalized Cyclopentadienyl Ligands Yttrium trichloride reacts with 2 equivalents of Na[C5H4CH2CH2SEt] (1) to form (η5-C5H4CH2CH2SEt)2YCl (2). The stepwise reaction of lutetium trichloride with one equivalent of 1 and one equivalent of Na[C5Me5] yields (η5-C5Me5)(η5-C5H4CH2CH2SEt)LuCl (4). Alkylation of 2 and 4 with LiMe gives (η5-C5H4CH2CH2SEt)2YMe (3) or (η5-C5Me5)(η5-C5H4CH2CH2SEt)LuMe (5), respectively. The new compounds have been characterized by elemental analysis, NMR spectroscopy and mass spectrometry. The molecular structures of 2 and 4 were determined by single crystal X-ray diffraction.

Organometallic compounds of the lanthanides CXV. Donor substituted chiral ansa-lanthanidocenes: Synthesis of dimehyl(dimethylaminoethylcyclopentadienyl) (tetramethylcyclopentadienl) silane dipotassium and of some chiral ansa-metallocene derivatives of Y, Sm, Ho, Er and Lu

Abstract Reaction of Me 2 SiCl 2 with [C 5 HMe 4 ]Na in tetrahydrofuran (THF) followed by treatment with [C 5 H 4 CH 2 CH 2 NMe 2 ]Na gives Me 2 Si(C 5 HMe 4 )(C 5 H 4 CH 2 CH 2 NMe 2 ), which reacts with KH to yield the dipotassium salt K 2 [Me 2 Si(C 5 Me 4 )(C 5 H 3 CH 2 CH 2 NMe 2 )] ( 1 ). The reaction of YCl 3 (THF) 3 and the lanthanide trichlorides LnCl 3 (THF) n (Ln = Sm, Ho, Er, Lu) with 1 in THF results in the yttrium complex and the lanthanide complexes [Me 2 Si(C 5 Me 4 )(C 5 H 3 CH 2 CH 2 NMe 2 )]LnCl [Ln = Y ( 2 ), Sm ( 3 ), Ho ( 4 ), Er ( 5 ), Lu ( 6 )]. The complexes 2 , 4 and 6 react with Li[CH 3 ] in ether to yield the chiral monomethyl compounds [Me 2 Si(C 5 Me 4 )(C 5 H 3 CH 2 CH 2 NMe 2 )]LnMe [Ln = Y ( 7 ), Ho ( 8 ), Lu ( 9 )]. The new complexes were characterized by elemental analysis, MS and NMR spectroscopy as well as 2 and 9 by single crystal X-ray structure analysis.

SYNTHESIS, CRYSTAL STRUCTURE AND CATALYTIC ACTIVITY OF SOME NEW CHIRAL ANSA-METALLOCENES OF YTTRIUM, LANTHANUM, SAMARIUM, LUTETIUM AND OF ZIRCONIUM

Chiral silicon bridged yttrio- and lanthanidocene chlorides [MeRSi(C 5 H 4 )(C 5 Me 4 )LnCl] 2 (R=Et ( a ), Ph ( b ); Ln=Y ( 4a , b ), La ( 5a , b ), Sm ( 6a , b ), Lu ( 7a , b )) and zirconocene dichlorides [MeRSi(C 5 H 4 )(C 5 Me 4 )ZrCl 2 ] (R=Et ( 8a ), Ph ( 8b )) were synthesized. Compounds 4 – 7 react with sodium acetate yielding the corresponding monomeric acetates [MeRSi(C 5 H 4 )(C 5 Me 4 )LnO 2 CMe] (R=Et ( a ), Ph ( b ); Ln=Y ( 9a , b ), La ( 10a , b ), Sm ( 11a , b ), Lu ( 12a , b )). All compounds were characterized by elemental analysis, 1 H and 13 C{ 1 H}-NMR spectroscopy, and by mass spectrometry. Single crystal X-ray structure determinations show a dimer for 6a and a monomer for 8a . The zirconocenes 8a , b are active catalysts for the polymerization of ethylene and propylene in the presence of methylalumoxane (MAO).

Organometallic compounds of the lanthanides. CXXI. Donor-substituted lanthanidocenes. Synthesis of mixed unbridged lanthanidocene chloride and alkyl derivatives

Abstract Stepwise reaction of ScCl3(THF)3 and the lanthanide trichlorides LnCl3(THF)n (Ln=Nd, Sm, Ho, Lu) first with (dimethylaminoethyl)cyclopentadienyl potassium (KCpDo) and then with tetramethylcyclopentadienyl sodium (NaCp*H) or with pentamethylcyclopentadienyl sodium (NaCp*), respectively, yields the mixed sandwich complexes CpDoCp*HScCl (1), CpDoCp*HLnCl {Ln=Nd (2), Sm (3), Ho (4), Lu (5)} and CpDoCp*LuCl (6), respectively. Treatment of 1–5 with methyl lithium in Et2O afforded the chiral alkyl derivatives CpDoCp*HScMe (7) and CpDoCp*HLnMe {Ln=Nd (8), Sm (9), Ho (10), Lu (11)}, respectively. Reaction of 6 with LiCH2SiMe3 yields the corresponding alkyl derivative CpDoCp*LuCH2SiMe3 (12). The new complexes were characterized by elemental analysis, MS and NMR spectroscopy, as well as by single crystal X-ray structure analysis (1 and 7).

Synthese und Charakterisierung donor-funktionalisierteransa-Metallocene von Yttrium, Neodym, Samarium, Erbium und Lutetium

Die schrittweise Reaktion von Me2SiCl2 mit K[C5H4tBu], Li[C5H4SiMe3] oder K[C5H3tBuMe-3], gefolgt von K[C5H4CH2CH2NMe2] fuhrt zu gemischt substituierten Dicyclopentadienyldimethylsilanen, deren doppelte Deprotonierung mit KH die Dikaliumsalze K2[Me2Si · (C5H3tBu-3)(C5H3CH2CH2NMe2-3)] (1), K2[Me2Si · (C5H3SiMe3-3)(C5H3CH2CH2NMe2-3)] (2) und K2[Me2Si · (C5H2tBu-3-Me-5)(C5H3CH2CH2NMe2-3)] (3) zuganglich macht. Durch Umsetzung von 1, 2 oder 3 mit LnCl3(THF)x (Ln = Y, La, Nd, Sm, Er, Lu) entstehen die Komplexe [Me2Si(C5H3tBu-3)(C5H3CH2CH2NMe2-3)]LnCl [Ln = Y (4 a), Sm (4 c), Lu (4 e)], [Me2Si(C5H3SiMe3-3) · (C5H3CH2CH2NMe2-3)]LnCl [Ln = Y (5 a), Sm (5 c), Lu (5 e)] und [Me2Si(C5H2tBu-3-Me-5)(C5H3CH2CH2NMe2-3)] · LnCl [Ln = Y (6 a), Nd (6 b), Sm (6 c), Er (6 d), Lu (6 e)]. Die Alkylierung von 4 a, 4 c, 5 a, und 6 b, 6 e mit LiCH3, LiCH2SiMe3 oder LiCH(SiMe3)2 erlaubt die Isolierung der Alkylmetallocene [Me2Si(C5H3tBu-3)(C5H3CH2CH2NMe2-3)] · LnR [R = CH3, Ln = Y (7 a), Sm (7 c); R = CH2SiMe3, Ln = Y (8 a)], [Me2Si(C5H3SiMe3-3)(C5H3CH2CH2NMe2-3)] · YCH3 (9 a) und [Me2Si(C5H2tBu-3-Me-5) · (C5H3CH2CH2NMe2-3)]LnR (R = CH3, Ln = Lu (10 e); R = CH2SiMe3, Ln = Lu (11 e); R = CH(SiMe3)2, Ln = Nd (12 b), Lu (12 e)]. Die neuen Verbindungen wurden elementaranalytisch, NMR-spektroskopisch und massenspektrometrisch charakterisiert. Die Molekulstrukturen von 6 c und 6 e wurden aus Einkristallstrukturdaten bestimmt.