Latest documents http://publikationen.ub.uni-frankfurt.de/index/index/ Mon, 09 Nov 2009 09:02:47 +0200 Mon, 09 Nov 2009 09:02:47 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6963 The absolute configuration of the title compound, [Fe(C5H5)(C36H29OP2)], is Sp at the ferrocene group and S at the asymmetric C atom. Both P atoms have a trigonal-pyramidal conformation. There is a short intramolecular C-H...P contact with an H...P distance of 2.56 Å. The hydroxy group is involved in an intramolecular O-H...[pi]phenyl interaction. The crystal packing shows five very weak intermolecular C-H...[pi] contacts, with H...Cg distances between 3.26 and 3.39 Å (Cg is the centroid of a phenyl or cyclopentadienyl ring). Key indicators: single-crystal X-ray study; T = 162 K; mean σ(C–C) = 0.004 Å; R factor = 0.038; wR factor = 0.083; data-to-parameter ratio = 22.3. Jan W. Bats; Angelino Doppiu; Andreas Rivas Nass; A. Stephen K. Hashmi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6963 Fri, 11 Sep 2009 09:02:47 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6962 The absolute configuration of the title molecule, [Fe(C5H5)(C38H34NP2)]·CHCl3, is R,Rp. The molecular structure is similar to the structure of the solvent-free compound [Fukuzawa, Yamamoto & Kikuchi (2007). J. Org. Chem. 72, 1514-1517], but some torsion angles about the P-Cphenyl bonds differ by up to 25°. The P atoms and the N atom have a distorted trigonal-pyramidal geometry. The chloroform solvate group donates a C-H...[pi] bond to the central benzene ring and is also involved in six intermolecular C-H...Cl contacts with H...Cl distances between 2.96 and 3.13 Å. Key indicators: single-crystal X-ray study; T = 163 K; mean σ(C–C) = 0.003 Å; R factor = 0.039; wR factor = 0.088; data-to-parameter ratio = 24.2. Jan W. Bats; Andreas Rivas Nass; Angelino Doppiu; Ralf Karch; A. Stephen K. Hashmi article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6962 Fri, 11 Sep 2009 08:55:20 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6894 The asymmetric unit of the title compound, C10H20I2Si2, contains two half-molecules. Both complete molecules are generated by crystallographic inversion centers located at the mid-points of the central C-C single bonds; the butadiene groups are planar, with a trans conformation about the central C-C bond. The molecules show short intramolecular H...I contacts of 2.89 and 2.92 Å. The crystal packing shows no short intermolecular contacts. Key indicators: single-crystal X-ray study; T = 155 K; mean σ(C–C) = 0.002 Å ; R factor = 0.021; wR factor = 0.059; data-to-parameter ratio = 43.6. Jan W. Bats; Birgit Urschel; Thomas Müller article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/6894 Fri, 04 Sep 2009 12:56:15 +0200 http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/5844 C2-symmetric bisamidines 8 have been tested as chiral Brønsted bases in the Diels- Alder reaction of anthrones and N-substituted maleimides. High yields of cycloadducts and significant asymmetric inductions up to 76% ee are accessible. The proposed mechanism involves proton transfer between anthrone and bisamidine, association of the resulting ions and finally a cycloaddition step stereoselectively controlled by the chiral ion pair. Deniz Akalay; Gerd Dürner; Jan W. Bats; Michael W. Göbel article http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/5844 Thu, 25 Sep 2008 16:05:19 +0200