| | 1 | Author
| Gerhard Müller, Hans-Joachim Matheus3, Martin Winklerb | Requires 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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| default:Reihe_B/56/ZNB-2001-56b-1155.pdf | | | | Identifier
| ZNB-2001-56b-1155 | | | | Volume
| 56 | |
| 2 | Author
| Gerhard Müller, Jörg Brand, SimoneElisabeth Jetter | Requires 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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| default:Reihe_B/56/ZNB-2001-56b-1163.pdf | | | | Identifier
| ZNB-2001-56b-1163 | | | | Volume
| 56 | |
| 3 | Author
| Karl Hensena, Markus Kettner3, Thorsten Stumpfb, Michael Boltec | Requires 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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| default:Reihe_B/55/ZNB-2000-55b-0901.pdf | | | | Identifier
| ZNB-2000-55b-0901 | | | | Volume
| 55 | |
| 4 | Author
| Karl Hensena>, Markus Kettner3, T., Peter Pickel3, Michael Bolteb | Requires 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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| default:Reihe_B/54/ZNB-1999-54b-0200.pdf | | | | Identifier
| ZNB-1999-54b-0200 | | | | Volume
| 54 | |
| 5 | Author
| Karl Hensen3, Frank Gebhardta, Michael Bolteb | Requires 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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| default:Reihe_B/52/ZNB-1997-52b-1491.pdf | | | | Identifier
| ZNB-1997-52b-1491 | | | | Volume
| 52 | |
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