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'Lewis Acid Base Adducts' in keywords
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2001 (2)
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1Author    Gerhard Müller, Hans-Joachim Matheus3, Martin WinklerbRequires cookie*
 Title    Donor-Acceptor Complexes between Simple Phosphines. First Structural Data for an Almost Forgotten Class of Compounds  
 Abstract    Lewis acid-base adducts between simple phosphines have been structurally characterized for the first time in the form of (Me3 P)PBr3 (1) and (MeiPjPB^Bz' (2; Bz' = 3,5-dimethyl-benzyl). On the basis of its solid-state structure the bonding situation in 1 may be described as intermediate between a neutral donor-acceptor complex containing hypervalent phosphorus(III) and an ion pair, according to the resonance formulae Me3 P —► PBn — [Me3 P-PBr2 ]+Br_ . The weak (incomplete) bond formation to the third bromine atom clearly reflects the reluctance of trivalent phosphorus to accommodate more than four electron pairs in its valence shell. (Crystal data for 1: monoclinic P2\ln, a = 7.142(3), b = 16.844(2), c = 8.139(4) A, ß = 106.24(2)°, Z = 4). As a result of the inferior acceptor properties of PB^Bz' as compared to PBr3 , 2 has more ion pair character [MeiP-PBrBz] Br"othan 1. (Crystal data for 2: orthorhombic P 2j 2i2 i, a = 7.063(2), b = 8.578(2)rf c = 25.158(4) A, Z = 4). Both compounds have short P-P bonds (1: 2.264(2); 2: 2.236(2) A). The results are compared with previous IR/Raman and NMR investigations on 1 : 1 and 2 : 1 adducts between organophosphines (as donors) and phosphorus trihalides (as acceptors). 
  Reference    Z. Naturforsch. 56b, 1155—1162 (2001); received July 17 2001 
  Published    2001 
  Keywords    Hypervalence, Phosphines, Lewis Acid-Base Adducts 
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 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-1155.pdf 
 Identifier    ZNB-2001-56b-1155 
 Volume    56 
2Author    Gerhard Müller, Jörg Brand, SimoneElisabeth JetterRequires cookie*
 Title    Donor-Acceptor Complexes between Organoamines and Phosphorus Tribromide  
 Abstract    Lewis acid-base adducts between NMe3, tmeda (A^A^Af'-tetramethylethylenediamine), and 1.4-dimethylpiperazine as donors and PBr3 as acceptor have been prepared and structurally characterized. NMe3 and tmeda form 1:1 adducts (Me3 N)PBr3 (1) and (tmeda)PBr3 (2), re­ spectively, while 1,4-dimethylpiperazine adds 2 molecules of PBr3 leading to [(1,4-dimethyl-piperazine)(PBr3):] (3). Adduct 2 is found in two modifications 2a and 2b with different crystal and molecular structures. (Crystal data of 1: monoclinic P2\/n, a = 5.983(3), b = 10.821(2), c = 13.877(5) Ä, ß = 99.70(2)°, Z = 4. 2a: monoclinic P2i/c, a = 7.891(1), b = 12.826(1), c = 12.218(2) A ,ß = 102.162(6)°, Z = 4. 2b: monoclinic P2]/n, a = 11.687(2), b = 8.375(1), c = 12.668(1) A, ß = 102.74(1)°, Z = 4. 3: monoclinic P2Jc, a = 6.383(3), b = 16.36(3), c = 8.407(3) A,ß= 101.49(2)°, Z= 2). The molecular structures of 1 and 2 indicate a partially ionic character with a strongly bonded amine and one (1) or two (2) weakly bonded bromine atoms. In 2 the donor tmeda is bonded through both nitrogen atoms to one phosphorus atom. In 3 the 1.4-dimethylpiperazine ring is in chair conformation, the methyl and PBr3 substituents being in equatorial and axial positions, respectively. Due to axial-axial repulsion the N-P donor-acceptor bonds are long while the P-Br bonds are rather uniform in length. 
  Reference    Z. Naturforsch. 56b, 1163—1171 (2001); received July 17 2001 
  Published    2001 
  Keywords    Hypervalence, Phosphines, Lewis Acid-Base Adducts 
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 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-1163.pdf 
 Identifier    ZNB-2001-56b-1163 
 Volume    56 
3Author    Karl Hensena, Markus Kettner3, Thorsten Stumpfb, Michael BoltecRequires cookie*
 Title    Synthese und Kristallstrukturbestimmung von Silicium-Komplexen der Koordinationszahl sechs mit Dimethylpyridinen Syntheses and Crystal Structure Determination of Hexacoordinated Silicon-Complexes with Dimethylpyridines  
 Abstract    Trichlorosilane, HSiCl3, forms with 3,4-dimethylpyridine in aprotic solvents a crystalline l:2-compound which is stable at room temperature and readily soluble in CHC13. Colourless crystals of the dicationic complex, [H2Si(3,4-dimethylpyridine)4]2+ 2Cl~ • 6 CHC13 (verified by X-ray structure analysis) are obtained by dismutation of HSiCl3(3,4-dimethylpyridine)2 in CHC13 within one week at room temperature.29Si NM R indicates that SiCl4 is generated as a second product. H2SiCl2 with 2,4-dimethylpyridine as well as MeHSiBr2 with 3,5-dimethylpyridine in aprotic solvents form 1:2-compounds stable at room temperature. X-ray structure analyses in both cases establish neutral-complexes with a hexa-coordinated silicon atom. E in le itu n g 
  Reference    Z. Naturforsch. 55b, 901—906 (2000); eingegangen am 1. Juni 2000 
  Published    2000 
  Keywords    Silicon Complex, Dimethylpyridines, Lewis Acid Base Adducts 
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 TEI-XML for    default:Reihe_B/55/ZNB-2000-55b-0901.pdf 
 Identifier    ZNB-2000-55b-0901 
 Volume    55 
4Author    Karl Hensena>, Markus Kettner3, T., Peter Pickel3, Michael BoltebRequires cookie*
 Title    Neue dikationische Silicium-Komplexe mit N-Methylimidazol New Dicationic Silicon Complexes with N-M ethylimidazole  
 Abstract    The reactions of the dibromosilanes Et2SiBr2, Ph2SiBr2, EtHSiBr2, PhHSiBr2 and MeHSiBr2 with N-methylimidazole (NMI) led to white powders stable at room temperature (with Et2SiBr2 an 1:2 adduct, with EtHSiBr2 and Ph2SiBr2 1:3 adducts, and with PhHSiBr2 and MeHSiBr2 1:4 adducts). The compounds crystallize from solutions in chloroforme and acetonitrile. The X-ray single crystal investigations show in all five cases dicationic complexes. 
  Reference    Z. Naturforsch. 54b, 200—208 (1999); eingegangen am 8. Oktober 1998 
  Published    1999 
  Keywords    Dialkyldibromosilanes, Alkyldibromosilanes, N-Methylimidazol, Lewis-Acid-Base-Adducts, Crystal Structure 
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 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-0200.pdf 
 Identifier    ZNB-1999-54b-0200 
 Volume    54 
5Author    Karl Hensen3, Frank Gebhardta, Michael BoltebRequires cookie*
 Title    Synthese und Kristallstrukturbestimmung von Additionsverbindungen aus Alkyldimethylbromsilanen und N-Trimethylsilylimidazol Syntheses and Crystal Structure Determination of Addition Compounds of Alkyldimethylbromosilanes and N-Trimethylsilylimidazole  
 Abstract    The bromosilanes RMe2SiBr (R = Me, Et, n-Pr and /-Pr) form ionic l:l-compounds with N-trimethylsilylimidazole (NTMSI), stable at room temperature. Crystals of the compounds with R = Et, n-Pr and i-Pr are obtained by sublimation. From the product of the reaction of 1,1-dibromosilacyclopentane with NTMSI single crystals of N,N'-bis(trimethylsilyl)imidazolium-bromide (R = Me) were obtained. In the new adducts both silicon atoms are tetracoordinated. 
  Reference    Z. Naturforsch. 52b, 1491—1496 (1997); eingegangen am 31. Juli 1997 
  Published    1997 
  Keywords    Alkyldimethylbromosilanes (alkyl = Me, Et, «-Pr and /-Pr), N-Trimethylsilylimidazole, Lewis-Acid-Base Adducts, Crystal Structure 
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 TEI-XML for    default:Reihe_B/52/ZNB-1997-52b-1491.pdf 
 Identifier    ZNB-1997-52b-1491 
 Volume    52