27Al-NMR-Spektroskopie zur Charakterisierung von Organoaluminium-Verbindungen

Benn, Reinhard; Janssen, Edo; Lehmkuhl, Herbert; Rufińska, Anna

doi:10.1016/0022-328x(87)85147-1

Cited by 107 publications

(52 citation statements)

References 48 publications

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“…The average AlÀN bond length is 1.813(3) with NÀAlÀN angles of 120 (1) Tables S5 and S6). The bond lengths and angles associated with the first coordination sphere of the aluminum atom in these compounds are analogous to similar compounds, such as [R 2 Al(m-OCH 2 CH 2 OMe)] 2, [69,70] [Me 2 Al(m-OCH 2 C 6 H 4 -2-OMe)] 2 , [71] and [Me 2 Al(m-OC 6 H 4 -2-OMe)] 2 . [71] The bridging oxygen atoms form a central (AlO) 2 ring, with average Theoretical Calculations of 27 …”

Section: Structural Featuresmentioning

confidence: 92%

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

et al. 2006

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Ultra-wideline 27Al NMR experiments are conducted on coordination compounds with 27Al nuclei possessing immense quadrupolar interactions that result from exceptionally nonspherical coordination environments. NMR spectra are acquired using a methodology involving frequency-stepped, piecewise acquisition of NMR spectra with Hahn-echo or quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) pulse sequences, which is applicable to any half-integer quadrupolar nucleus with extremely broad NMR powder patterns. Despite the large breadth of these central transition powder patterns, ranging from 250 to 700 kHz, the total experimental times are an order of magnitude less than previously reported experiments on analogous complexes with smaller quadrupolar interactions. The complexes examined feature three- or five-coordinate aluminum sites: trismesitylaluminum (AlMes3), tris(bis(trimethylsilyl)amino)aluminum (Al(NTMS2)3), bis[dimethyl tetrahydrofurfuryloxide aluminum] ([Me2-Al(mu-OTHF)]2), and bis[diethyl tetrahydrofurfuryloxide aluminum] ([Et2-Al(mu-OTHF)]2). We report some of the largest 27Al quadrupolar coupling constants measured to date, with values of C(Q)(27Al) of 48.2(1), 36.3(1), 19.9(1), and 19.6(2) MHz for AlMes3, Al(NTMS2)3, [Me2-Al(mu-OTHF)]2, and [Et2-Al(mu-OTHF)]2, respectively. X-ray crystallographic data and theoretical (Hartree-Fock and DFT) calculations of 27Al electric field gradient (EFG) tensors are utilized to examine the relationships between the quadrupolar interactions and molecular structure; in particular, the origin of the immense quadrupolar interaction in the three-coordinate species is studied via analyses of molecular orbitals.

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Section: Structural Featuresmentioning

confidence: 92%

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

et al. 2006

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“…According to these data it may be confirmed that methylaluminum complexes based on pyridine 75 containing dialcohols are dimeric or at least take part in the equilibrium process monomer-dimer in solution (for fourcoordinate Al alkoxides δ= ~70 ppm; for five-coordinate Al alkoxides δ= ~40 ppm; for six-coordinate Al alkoxides δ= ~0 ppm). [45][46][47][48][49][50][51][52][53] It should be noted, that crystal structure (X-ray data; 80 see below) of 3a was studied; this derivative formed dimer with five-coordinate Al atoms due to bridging CH 2 CZ 2 O-groups, what is in correlation with NMR data. It should be noted that methylaluminum complexes of this type may be obtained in high yields by transmetallation reaction [54][55][56] from corresponding germylenes.…”

Section: Methylmentioning

confidence: 97%

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

et al. 2015

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A series of substituted pyridine dialcohols (2,6-bis(hydroxyalkyl)pyridines), 1-4, was used for the synthesis of various types of aluminum complexes. Aluminum methyl derivatives, 2-4a, were obtained by the reaction of AlMe3 with the corresponding ligand or transmetallation reactions of germylenes. Aluminum chloride complexes, 3-4b, were obtained by substitution of the Me group under the action of chlorinating agents. Methoxy-, 2-4c, or benzyloxy-, 2d, aluminum complexes were synthesized in transalkoxylation reaction of Me2Al(OX) (X = Me, Bn) by the corresponding ligand. All complexes obtained were thoroughly investigated by multinuclear NMR and X-ray analysis. It has been established that the structure of the ligand (number of carbon atoms) determines the nature of the complexes formed. Compounds were used as initiators of ring-opening polymerization of l-lactide and ε-caprolactone and showed moderate activity with controlled or immortal character.

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“…26 ppm fu È r jeden Ersatz der Methylgruppen durch einen Chlor-Substituenten. Unter Beru È cksichtigung dieses Substituenteneinflusses [43] indizieren die 27 Al-Resonanzlagen der genannten Verbindungen bei 165 ppm bzw. ca.…”

Section: Multikern-nmr-spektroskopische Untersuchungenunclassified

Synthese, Röntgenstrukturanalyse und Multikern-NMR-spektroskopische Untersuchung einiger intramolekular stickstoffstabilisierter Bor-, Aluminium- und Galliumorganyle

Schumann

Wassermann

Schutte

et al. 2000

Z. anorg. allg. Chem.

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Die intramolekular stickstoffstabilisierten Organoaluminium‐ und Organoborverbindungen Me2Al‐ (CH2)3NMe2 (1), Me2AlC10H6‐8‐NMe2 (2), iPr2Al(CH2)3NEt2 (3), (CH2)5Al(CH2)3NMe2 (4) und (CH2)5B(CH2)3NMe2 (5) werden aus Me2AlCl und den entsprechenden Lithiumorganylen bzw. aus AlCl3 oder BCl3, dem Lithiumalkyl und iPrMgCl oder BrMg(CH2)5MgBr erhalten. AlCl3 und GaCl3 reagieren mit LiCH2CHMeCH2NMe2 bzw. Li(CH2)3NMe2 unter Bildung von Cl2AlCH2CHMeCH2NMe2 (6) bzw. Cl2Al(CH2)3NMe2 (8) und Cl2Ga(CH2)3NMe2 (9). Bei der Umsetzung von 6 bzw. 8 oder 9 mit BrMg(CH2)5MgBr bzw. BrMg(CH2)6MgBr entstehen (CH2)5AlCH2CHMeCH2NMe2 (7) bzw. (CH2)6Al(CH2)3NMe2 (10) und (CH2)6Ga(CH2)3NMe2 (11). Das durch Komproportionierung aus AlCl3 und Me2AlCl erhaltene MeAlCl2 reagiert mit 2 Äquivalenten Li(CH2)3NMe2 zu MeAl[(CH2)3NMe2]2 (12) und mit MeN[(CH2)3MgCl]2 unter Bildung von MeAl[(CH2)3]2NMe (13). Entsprechend reagieren MeAlCl2 oder MeGaCl2 bzw. GaCl3 mit einem Äquivalent Lithiumorganyl zu den intramolekular stickstoffstabilisierten Organoaluminium‐ und Organogalliumchloriden MeClAl(CH2)3NMe2 (14), MeClGa(CH2)3NMe2 (15), MeClGaC6H4‐2‐CH2NMe2 (16) und Cl2GaC6H4‐2‐CHMeNMe2 (17). Die Verbindungen wurden durch Elementaranalysen, 1H‐, 11B‐, 13C‐ und 27Al‐NMR‐Untersuchungen sowie massenspektrometrisch charakterisiert. Die Einkristall‐Röntgenstrukturanalysen von 1, 2, 4, 5 und 17 zeigen die monomeren Molekülstrukturen mit intramolekularer Stickstoff‐Koordination.

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27Al-NMR-Spektroskopie zur Charakterisierung von Organoaluminium-Verbindungen

Cited by 107 publications

References 48 publications

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

Synthese, Röntgenstrukturanalyse und Multikern-NMR-spektroskopische Untersuchung einiger intramolekular stickstoffstabilisierter Bor-, Aluminium- und Galliumorganyle

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27Al-NMR-Spektroskopie zur Charakterisierung von Organoaluminium-Verbindungen

Cited by 107 publications

References 48 publications

Ultra‐wideline 27Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Ultra‐wideline 27Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

Synthese, Röntgenstrukturanalyse und Multikern-NMR-spektroskopische Untersuchung einiger intramolekular stickstoffstabilisierter Bor-, Aluminium- und Galliumorganyle

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Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments

Ultra‐wideline ²⁷Al NMR Investigation of Three‐ and Five‐Coordinate Aluminum Environments