Synthese von cyclischen, chiralen Verbindungen mit Ge–El‐Doppelbindungen (El = N, S, (O)) und deren dynamisches Verhalten in Lösung

Veith, Michael; Rammo, Andreas

doi:10.1002/zaac.199762301136

Cited by 48 publications

(26 citation statements)

References 17 publications

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“…2.05Å 96 and Ge Se ∼2.17Å 96,97 ). These distances are comparable to those observed for tetra-and penta-coordinated base-stabilized germanium(II) compounds.…”

Section: Their High Melting Points (172-199mentioning

confidence: 97%

“…But, up until recently,92,93 only four germanethiones, 94 -98 seven germaneselones 95,98 -101 and four germanetellones 37,91,95,102 had been isolated at room temperature and characterized structurally. These compounds are either thermodynamically stabilized 37,94,95,97,99,100 by coordination of Lewis base to the germanium, or kinetically stabilized by bulky protecting groups on the germanium. 91,96,101,102 Moreover, to our knowledge, no halogenated and also no nitrogen-substituted germanechalcogenones had been characterized until the recent work by our group.…”

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confidence: 99%

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Three‐coordinate divalent Group 14 element derivatives and related compounds

Saur

Alonso

Barrau

2005

Applied Organom Chemis

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INTRODUCTIONThis paper is an overview of a particular part of our systematic investigation of the divalent germanium and tin species focusing on the use in this chemistry of a β-diketiminato ligand with no encumbering aryl groups on the nitrogen. The bidentate three-atom bridging ligand L 2 (L 2 = PhNC(Me)CHC(Me)NPh), by its remarkable stabilizing properties, allows for easy isolation of subvalent germanium and tin compounds and, as such, permits a general insight on the chemistry of such species. The emphasis here will be on the divalent species L 2 (X)M (M = Ge, Sn), the germanechalcogenones L 2 (Cl)Ge Y, the transition- L (n−x) and the cationic ger- IntroductionThe divalent species of Group 14 elements are the heavier carbene analogues; for recent reviews, see Refs 6-10. They are generally transient species. As a general rule, when these species contain unfunctionalized organic ligands, they undergo rapid oligomerization and polymerization. In the last two decades, two principal methods of stabilization have been particularly investigated. Thus, various kinetically and/or thermodynamically stabilized divalent germanium and tin compounds have been isolated in a monomeric state. 1 -5,11 -81 The use of bulky groups bound to the Group 14 element to prevent aggregation permitted the first syntheses of stable monomer divalent species; the most noticeable are the dialkyl-germylene and -stannylene reported by Lappert and co-workers, 12 the first stable monomeric arylgermylene ((Mes * ) 2 Ge (Mes * = 2,4,6-t Bu 3 -phenyl)) described by Du Mont and co-workers, 14 and the well-known aryl-germylene and -stannylene Tbt(Tip)M 14 (M 14 = Ge, Sn; Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Tip = 2,4,6-i Pr 3 -phenyl) of Okazaki and co-workers. 25,29The ligand backbone may also play an important role in improving stability. Thus, the presence of ligands with donor side arms on the germanium or the tin element can (by transfer of electron density) reduce the deficit on 37 is, to our knowledge, the first example of an intramolecular base stabilized homoleptic dialkylgermylene. Various amino-, phosphino-, thioalkoxy-, alkoxy-and aryloxy-divalent species have also been isolated in monomeric form owing to this method of stabilization; one should mention in particular the studies of Jutzi and co-workers, 28,32,54,71 Veith and coworkers, 15,18,40,66 Parkin and co-workers, 67 Jurkschat and co-workers, 77,78 Dias and co-workers 31,35,42,69,80,81 and Roesky and co-workers. Main Group Metal Compounds -5Although a large number of homoleptic divalent germanium and tin species have been isolated using these concepts of stabilization, there are fewer examples of heteroleptic compounds having been reported, though the first functional heteroleptic germylenes R(Cl)Ge (R = Et, Ph) were obtained as viscous oils in the 1970 by our group.6 Few solidstate structures of such heteroleptic compounds have been described. Noteworthy examples are in the area of thermodynamic stabilization, the acetylacetonatogermylene R(I)Ge (R = OC (Me) 46...

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“…2.05Å 96 and Ge Se ∼2.17Å 96,97 ). These distances are comparable to those observed for tetra-and penta-coordinated base-stabilized germanium(II) compounds.…”

Section: Their High Melting Points (172-199mentioning

confidence: 97%

mentioning

confidence: 99%

Three‐coordinate divalent Group 14 element derivatives and related compounds

Saur

Alonso

Barrau

2005

Applied Organom Chemis

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“…Our idea was to generate such thermodynamically unstable compounds by using a further intramolecular nucleophilic ligand to raise the coordination number at the germanium or tin atom. For this purpose we have synthesized a variety of silazanes (13, 14, 15, Scheme 10) which consist, apart from the N-H groups used for bonding to germanium or tin atoms, of basic atoms (nitrogen or oxygen) [27][28][29].…”

Section: Base Stabilized Bis(amino)germaimines and -Thiones And The Cmentioning

confidence: 99%

Metal centered molecules and their application in chemistry and physics

Veith¹,

Rammo²,

Faber³

et al. 1999

Pure and Applied Chemistry

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Monocyclic as well as polycyclic silylamides of a series of main group metals such as Li, Ge, Sn and Pb (the last three elements mostly in the oxidation state þII) have been synthesized, analyzed by spectroscopic means and structurally characterized over the last 20 years. All these molecular compounds have in common a Lewis acidic (electrophilic) metal center with at least one bond to nitrogen. In the case of the bis(amino)germylenes, -stannylenes and -plumbylenes, the metal centers are poorly coordinated (only two bonds to nitrogen) and may directly react with organic -systems. This nonclassical behaviour will be discussed shortly. If the metal atoms are more highly coordinated by intramolecular nitrogen or oxygen bases, the oxidation to stable germaimines or germathiones is possible, whereas the corresponding tin compounds are only transient in nature. Finally, the use of special metal alkoxides [for example Ge(OtBu)

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“…[8,9] In the NtBubridged amide [{tBuN(CH 2 ) 2 NtBu}(Me)Si]N(tBu)[Ge{N(H)-SiMe 3 }(OSiMe 3 ){OCH 2 N(CH 3 ) 2 }], which contains sterically more demanding substituents on the nitrogen atom, the GeÀN bond is 184.2 pm long, and thus lies in the same range as the GeÀNAr(SiMe 3 ) bond lengths in 2 (Ge1ÀN4, Ge2ÀN7). [10] The dimers exist in the solid as isolated molecules, however, and there are no bridging intermolecular hydrogen bonds.…”

Section: In Memory Of Jean Rouxelmentioning

confidence: 99%