摘要:

AbstractWater at low temperatures (T<300 K) reveals a multitude of unusual physico‐chemical properties, which originate from the strong directivity of the hydrogen bonds. This directivity forces the molecules into a tetrahedral arrangement of first neighbors and thus leads to a poor packing efficiency. All anomalies of the liquid become more pronounced in the metastable range below the melting pressure curve. In the following article, methods for the investigation of the supercooled range are presented. A few anomalous static and dynamic properties are described and compared with the properties of normal liquids. The experimental results are discussed in the context of computer simulations and the more recent theories on cold water. It can be concluded that the anomalies of water, for instance the density maximum of the liquid phase and the initial decrease in viscosity with pressure, are confined to thepT‐range:T<300 K,p≲ 200 MPa. At these pressures, lowering the temperature leads to an unexpected behavior of almost all physical properties. They seem to approach a phase transition atT≃ (TM− 50 K), the nature of which has not yet been fully characterized. This phenomenon has hitherto been observed only in supercooled water.—In the future it will be possible to use supercooled aqueous solutions for kinetic studies, thus expanding the available dynamic range for the investigation of aqueous solutions c

ISSN:0570-0833    

DOI:10.1002/anie.198203153

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractSalts of 3d, 4d, and 5d metals in the presence of the ligands 1,1,1,‐tris(diphenylphosphinomethyl)ethane (triphos) or tris (2‐diphenylphosphinoethyl) amine (np3) react with white phosphorus P4(or yellow As4) to produce several mononuclear sandwich and dinuclear triple‐decker sandwich complexes, which contain the unprecedentedcyclo‐triphosphorus (orcyclo‐triarsenic) unit acting as atrihapto‐ligand. In these complexes the metal atoms are bonded to the there phosphorus atoms of the phosphane ligand and to the three atoms of thecyclo‐P3orcyclo‐As3unit. The complexes are diamagnetic or have μeff‐values corresponding to one or two unpaired electrons. Thecyclo‐P3ligand is coordinatively unsaturated as proved by the fact that the mononuclear sandwich compounds may form Lewis‐base adducts with electron‐acceptor fragments. Reaction of the complexes (np)3M (M = Ni, Pd) with white P4leads to formation of diamagnetic compounds [(np3)M(η1‐P4)], in which the metal atom is bonded to the three phosphorus atoms of the np3‐ligand and in addition to one P atom of the intact P4molecule, which behaves as amonohapto‐ligand. This article contains a review of the syntheses and structures of these complexes as well as a unified, albeit qualitative, approach

ISSN:0570-0833    

DOI:10.1002/anie.198203301

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractUroporphyrinogen III plays a key role in the biosynthesis of heme, the red pigment of blood.In vivostudies with specifically14C‐ and3H‐labeled precursors have revealed that the formation uroporphyrinogen III in the organism follows several primary and subsidiary pathways. Model experiments on the pattern of biosynthesis have led to simple and effective methods of synthesizing uroporphyrin analogs and have shown that their production is strongly favored thermodynamically. The biologically porphyrins important thus available permit a mechanistic explanation of the light‐induced dermatoses in porphyria diseases and suggest promising medical applications in diagnosis and th

ISSN:0570-0833    

DOI:10.1002/anie.198203431

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1982, 827. DOI:10.1002/anie.198208270

ISSN:0570-0833    

DOI:10.1002/anie.198203541

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1982, 913. DOI:10.1002/anie.198209130

ISSN:0570-0833    

DOI:10.1002/anie.198203552

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1982, 862. DOI:10.1002/anie.198208620

ISSN:0570-0833    

DOI:10.1002/anie.198203562

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1982, 929. DOI:10.1002/anie.198209290

ISSN:0570-0833    

DOI:10.1002/anie.198203631

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198203641

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.198203651

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY

摘要:

AbstractThe complete manuscript of this communication appears in:Angew. Chem. Suppl. 1982, 922. DOI:10.1002/anie.198209220

ISSN:0570-0833    

DOI:10.1002/anie.198203661

出版商:Hüthig&Wepf Verlag    

年代:1982

数据来源: WILEY