A variety of differently substituted 1,3,2-diazaphospholenium salts and P-halogeno-1,3,2-diazaphospholenes (X F, Cl, Br) were synthesized, and their molecular structures, bonding situation, and Lewis acid properties were characterized by experimental (single-crystal X-ray diffraction, NMR and IR/Raman spectroscopy, MS, conductometry, titrations with Lewis bases) and computational methods. Both experimental and computational investigations confirmed that the structure and bonding in the diazaphospholenium cations of OTf and BF 4 salts resembles that of neutral Arduengo carbenes and that the cations should not be described as genuinely aromatic. P-Halogenodiazaphospholenes are, in contrast to earlier assumptions, molecular species with covalent P À X bonds whose bonding situa-tion can be expressed in terms of hyperconjugation between the six p electrons in the C 2 N 2 unit and the s*(PÀX) orbital. This interaction induces a weakening of the P À X bonds, whose extent depends subtly on substituent influences and contributes fundamentally to the amazing structural similarity of ionic and covalent diazaphospholene compounds. A further consequence of this effect is the unique polarizability of the PÀCl bonds in P-chlorodiazaphospholenes, which is documented in a considerable spread of P À X distances and bond orders. Measurement of the stabil-ity constants for complexes of diazaphospholene compounds with Lewis bases confirmed the lower Lewis acidities and higher stabilities of diazaphospholenium ions as compared with nonconjugated phosphenium ions; this had been inferred from computed energies of isodesmotic halide-transfer reactions, and permitted also to determine equilibrium constants for PÀCl bond dissociation reactions. The results suggest, in accord with conductance measurements, that P-chlorodiazaphospholenes dissociate in solution only to a small extent. On the basis of these findings, the unique solvatochromatic behavior of NMR chemical shifts of these compounds was attributed to solvent-dependent PÀCl bond polarization rather than to shifts in dissociation equilibria.

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The taxonomic status of two bacterial strains isolated from human blood was characterized using a polyphasic approach. Chemotaxonomic investigations revealed the presence of cell-wall chemotype IV, short-chain mycolic acids that co-migrated with those extracted from members of the genus Williamsia and that produce C 16 : 0 and C 18 : 0 fatty acids on pyrolysis GC, and dihydrogenated menaquinone with nine isoprene units as the predominant isoprenologue. The generic assignment was confirmed by 16S rRNA gene sequencing. Comparative analysis of the 16S rRNA gene sequence showed that these isolates constitute a distinct phyletic line within the genus Williamsia, displaying 96?2 and 97?2 % sequence similarities to Williamsia muralis and Williamsia maris, respectively. The two isolates could be distinguished from the type strains of the latter species on the basis of several phenotypic traits. The genotypic and phenotypic data show that the strains merit classification as a novel species of Williamsia, for which the name Williamsia deligens sp. nov. is proposed, with type strain IMMIB RIV-956The genus Williamsia was proposed by Kämpfer et al. (1999) to accommodate actinomycetes with atypical cell morphology as revealed under electron microscopy that are unable to grow at 5 or at 45 uC and possess mycolic acids with carbon chain lengths of 50 to 56. Based on its mycolic acids, it seems that Williamsia takes an intermediate position between Rhodococcus (mycolic acid chain lengths of 34-45) and Gordonia (mycolic acid chain lengths of 54-66) (Kämpfer et al., 1999). The genus Williamsia currently comprises two recognized species, Williamsia muralis isolated from indoor building material of a children's day-care centre in Finland (Kämpfer et al., 1999) and Williamsia maris isolated from deep sediments of the Sea of Japan (Stach et al., 2004). In this paper we describe two bacterial strains which were isolated from human blood. Based on phylogenetic and phenotypic data it is proposed that these strains (designated IMMIB RIV-956 T and IMMIB RIV956Fl) are similar and should be classified as representing a novel species of the genus Williamsia. Isolates IMMIB RIV-956T and IMMIB RIV-956Fl were isolated from human blood. The type strains of W. maris (DSM 44693 T ) and W. muralis (DSM 44343 T ) were received from the DSMZ. All strains were cultured on Columbia agar supplemented with 5 % sheep blood agar and brain heart infusion (BHI) agar to determine their morphological characteristics. Production of pigments was determined by growing the strains at 27 u C for 7 days, and observations were made at 24 h intervals. Air-dried smears at 24, 48 and 72 h intervals were stained by using the Gram's method in order to determine the Gram reaction and cell morphology.

A bacterial isolate obtained from soil from a municipal landfill site in India was characterized using a polyphasic taxonomic approach. The colonies of the isolate were found to be yellow and highly mucoid. Comparative analysis of the 16S rRNA gene sequence showed that this isolate constitutes a distinct phyletic line within the genus Lysobacter, displaying >3 % sequence divergence with respect to recognized Lysobacter species. The generic assignment was confirmed by chemotaxonomic data, which revealed the presence of a fatty acid profile characteristic of members of the genus Lysobacter and consisting of saturated, unsaturated, straight-chain and branched-chain fatty acids as well as iso-C 11 : 0 3-OH as hydroxylated fatty acid, and the presence of an ubiquinone with eight isoprene units (Q-8) as the predominant respiratory quinone. The genotypic and phenotypic data show that strain IMMIB APB-9T merits classification as representing a novel species of the genus Lysobacter, for which the name Lysobacter defluvii sp. nov. is proposed. The type strain is IMMIB APB-9 T (=CCUG 53152 T =DSM 18482 T ).

The taxonomic status of a bacterium isolated from a perianal swab of a patient with a bone marrow transplant was characterized using a polyphasic taxonomic approach. Chemotaxonomic investigations revealed the presence of cell wall chemotype IV, short chain mycolic acids that co-migrated with those extracted from members of the genus Dietzia, and a dihydrogenated menaquinone with eight isoprene units as the predominant menaquinone. Generic assignment was confirmed by 16S rRNA gene sequencing. Comparative analysis of the 16S rRNA gene sequence showed that this isolate constitutes a distinct phyletic line within the genus Dietzia, displaying 97·5–98·7 % sequence similarity with Dietzia species with validly published names. The isolate could be distinguished from the type strain of Dietzia maris (1·6 % sequence divergence) and other species of the genus Dietzia by DNA–DNA hybridization, as well as by using a set of biochemical tests. Genotypic and phenotypic data show that the strain merits classification as a novel species of the genus Dietzia for which the name Dietzia cinnamea sp. nov. is proposed; the type strain is IMMIB RIV-399T (=DSM 44904T=CCUG 50875T).