E International Edition in English A Journal of the Gesellschaft Deutscher Chemiker 1994 3317 Pages 699-792 COVER PICTURE The cover picture shows in the foreground the oxygen-bridged binuclear iron(rv) complex p-oxo-bis[ (octaethylcorrolato)iron(~v)]( N = green, 0 = blue, Fe = pink, ethyl substituents have been omitted), which may bring about a renaissance of the metallocorroles. The fact that corroles stabilize metals in unusual oxidation states BS trianionic ligands has now been proven by E. Vogel et al.-see pp. 731 -735-with some iron(iv) corrole complexes, formed from the stable, diiron complex shown, which crystallizes as black rhombuses. The question mark in the background emphasizcs the uncertainty associated with the unequivocal assignment of the oxidation state to the metal center in complexes with “non-innocent” ligands such as corroles. REVIEWS Wild mixtures of stereoisotners are usually formed in the synthesis of oligo(nucleoside phosphorothioate)s owing to the stereogenic phosphorus centers. Is the preparation of isomers with defined configuration at each phosphorus atom feasible, and if so. how far off is the stereoselective synthesis? In this review the problems of the stereoselective preparation of these compounds are outlined, and new synthetic methods are discussed. Oligo(nuc1eoside phosphorothioate)s have potential as “antisense therapeutics” for treatment of viral infections, cancer, and possibly even AIDS. But medical applications require stereochemically uniform compounds. Contents W. J. Stec,* A. Wilk ................... 709- 722 Stereocontrolled Synthesis of Oligo(nucleoside phosphorothioate)s HIGHLIGHTS Readout of an entire protein sequence from a mass spectrum, a high sample throughput, and the possibility of sequencing modified peptides or peptides containing unusual amino acids are the advantages of the combination of Edman degradation and mass spectrometry (MS). Fully automated sequencers based on this ladder sequencing technique would provide viable alternatives to the standard sequencers equippcd with on-line HPLC. This technique shows the potential of novel ionization and MS techniques for future protein analysis. J. W. Metzger* ........................... 723-725 Ladder Sequencing of Peptides and Proteins-A Combination of Edman Degradation and Mass Spectrometry Like a complicated puzzle containing pieces that do not belong, the determination of the structure of the active site of photosystem 11presents several intricacies. The picture on the right shows a new model for the 0x0- and carboxylato-bridged Mn, cluster. which also considers the coordinated cofactors Ca' + and C I ~The , concept is based on spectroscopic data (ESR, EXAFS) from years of research. K . Wieghardt* ........................... A Structural Model for the Water-Oxidizing Manganese Cluster in Photosystem I1 Will optical resolution by HPLC with chiral columns become obsolete? With a new technique, which should be amenable to upscaling, suspensions of crystalline host compounds such as 1 and 2 in hexane or water form 1 : I complexes with the one enantiomer of a racemic alcohol or ether such as 3 and 4 that fits best into its lattice. The two enantiomers can then be separated by vacuum distillation. 1 2 3 G. Kaupp* ................................ 728-729 Resolution of Racemates by Distillation with Inclusion Compounds 4 COMMUNICATIONS a The unusual oxidation state + I V for iron centers can be stabilized by porphyrin-like corrole ligands in such a way that the compounds 1 (R = CI, Ph, OFecorrole) can be isolated at room temperature. The oxygen-bridged binuclear iron(1v) corrole, which can be readily converted into the mononuclear ironfrv) corrole, forms as the only defined product from the reaction of the ligand with [Fe,(CO),J followed by workup in air. In contrast, only a few iron(rv) porphyrins are known so far, and these are too unstable to be isolated as solids. Far-reaching analogies between p-oxodiiron(iii) complexes of porphycenes and porphyrins with regard to physical. chemical. and structural properties are revealed by investigations of the new metalloporphycenes 1 (R = nPr, t B u ) . These are obtained by using standard methods for porphyrin chemistry. The Fe-0-Fe angle in 1 (R = nPr) differs widely (145 ) from those of the metalloporphyrins (1 61 180') and that of 1 (R = t B u ; 179") as a result of reduced steric interactions. 725-728 E. Vogel,* S. Will, A. Schulze Tilling, L. Neumann, J. Lex, E. Bill, A. X. Trautwein, K . Wieghardt ............................. 731 -735 - 0 Metallocorroles with Formally Tetravalent Iron 1 RyJR ,N'"I\N ' / R - M. Lausmann, I. Zimmer, J. Lex, H. Lueken, K. Wieghardt, E. Vogel* ........... 736-739 R p-Oxodiiron(rr1) Complexes of Porphycenes ~ Neither in the solid state, nor in solution-proof of the existence of indigoid compounds such as I with thioxo instead of 0x0 groups remains elusive. The oxidation of leucoindigoid precursors does not lead to 1 in any example examined, but rather to the valence isomeric 1.2-dithiines 2 o r to niacrocyclic bisdisulfides, depending on the heteroatom X (S. NCH,, NH. 0). * xg? W. Schroth,* E. Hintzsche, M. Felicetti, R. Spitzner, J. Sieler, R . Kempe .................... X X S 1 \s - \ / 2 739-741 Concerning the Questionable Existence of Thioxoindigoid Compounds Contents Coordination with participation of manganese distinguishes complexes 1 and 2. The P-Mn bond in 1 remains intact, whereas in 2 the bond is cleaved and the P atoms are subject to electrophilic attack. Me L. Brunet. F. Mercier, L. Ricard, F. Mathey* ............... 742-745 The Reactivity of Phosphacymantrenes towards Palladium(n) and Palladium(o) Compounds: Synthesis, Structure, and Chemistry of Pd,Mn, and Pd,Mn, Arrays Me Me Me 1 2 The synthesis of new, medium-sized copper clusters with unusual structures and a successful combination of experiment and theoretical calculation- this is offered by the present communication. The reaction of CuAc with PR,R' (R, R' = Et, Ph) and E(SiMe,), (E = S , Se) leads to the clusters 1-4. Several of these might be intermediates in the synthesis of larger cluster complexes. The structure of [Cu,,Se,(PH,),] calculated by ab initio methods agrees with the structure of 1 within the limits of the methods. Vertex-sharing BO, and PO, tetrahedra form the framework of the title compounds. Ca[BPO,] and Sr[BPO,] crystallize in the stillwellite structural type and contain tetrahedral chain anions k[BPO:-]. which can be described as loop-branched "dreier" single chains. In Ba,[BP,O,,] the :,tetrahedral anions form "zweifach" open "vierer" single chains. Given these results and the known linking modes of tetrahedral units, it is expected that borophosphates with layered and framework structures. as well as microporous structures, can be found. In a one-pot reaction, aldononitriles can be synthesized smoothly from glycosyl azides by successive treatment with N-bromosuccinimide (NBS) and activated metals M* [Eq. (a)]. By the correct choice of the reducing agent, the intermediate alcoholate can be trapped with electrophiles. Er The determination of the structures of molecules in solution is a challenge. Now the relative configuration, and to a certain extent, the preferred conformation of a flexible chiral compound can be determined by calculations employing data obtained from NMR cross-relaxation experiments. Force field parameters and conformational preferences need not be specified. A look behind hydrogenation catalysts: How is the hydrogen molecule bound to the metal atom of a carbonyl complex in the intermediate? Which positions of a substrate molecule are attacked as a result? The course of a photochemical hydrogenation [Eq. (a)] could now be followed for the first time by NMR spectroscopy through nuclear spin polarization effects. z hv, p-H, a,L,c" hv, P-H, I co (M = Cr) C 0 ~ - co (M = Mo) (a) S. Dehnen, A. SchCfer. D. Fenske,* R. Ahlrichs ................................ 746-748 New Sulfur- and Selenium-Bridged Copper Clusters; Ah Initio Calculations on [Cu,,Se,(PH,),] Clusters R. Kniep," G . Gozel, B. Eisenmann, C. Rohr, M. Asbrand, M. Kizilyalli .............................. 749-751 Borophosphates- .A Neglected Class of Compounds: Crystal Structures of Mn"[BPO,] (MI' = Ca, Sr) and Ba,[BP,O,,] A. Furstner,* J.-P. Praly * __.........___._________._...... 751 -753 Conversion of Glycosyl Azides via N-Bromoglycosylimines to Aldononitriles M. Reggelin,* M. Kock, K. Conde-Frieboes, D. Mierke ................................. 753-755 Determination of the Relative Configuration by Distance Geometry Calculations with Proton-Proton Distances from NOESY Spectra A. Thomas, M. Haake, E-W. Grevels, J. Bargon* .......... 755-757 In Situ NMR Investigations of Photocatalyzed Hydrogenations with Parahydrogen in the Presence of Metal Carbonvl Compounds of Group 6 Simply heating a suspension of [Ph,P][VO,CI,] and tBuPO,H, in acetonitrile in a sealed tube to 100°C gave the first of the three title compounds as dark green crystals. The structure of this compound (shown on the right) could not have a more pleasing simplicity. Relatively minor changes in the starting materials led to other, more complicated products. J. Salta. Q. Chen. Y.-D. Chang, J. Zubieta* ........... 757-760 I I P Neutral molecules are encapsulated in the cluster anions in the title, which were produced by solvothermal reactions of [nBu,N],[H,V,,O,,] and PhAsO,H, in CH,OHiH,O (99 : 1) with and without Et,NCI. The structures are shown schematically below. The Oxovanadium- Organophosphonate System: Complex Cluster Structures [(VO),(fBuPO,),CIl, [(VO),jPhP(O),OP(O),Ph~ 4C1]-, and ~~,,~zs(~2~~z(Ph~0,~,,Cl,l"~ with Encapsulated Chloride Anions Prepared from Simple Precursors M. I. Khan, J. Zubieta . . . _ _ _ . _ _760-762 ._____ The Oxovanadium-Organoarsonate System: [2CH,OH c VI20,,(0H),(phAsO,),,,l"- and [ 2 H z 0 = VlZ0,2(OH)2- (H,0)z(PhAs0,)l,(PhAs0,H),12-, Clusters with Nanometer Dimensions and Cavities for Neutral Molecules Carbon rods 1-5 up to five nanometers long are formed by oxidative polymerization of trans-bis(triisopropylsily1)-protected tetraethynylethene with phenylacetylene as end-capping reagent. The X-ray crystal structures of 1 and 2 show perfectly planar, conjugated carbon frames. Compounds 1 - 5 are readily reduced; the number of reversible one-electron reductions equals the number of tetraethynylethene moieties in each molecular rod. TIPS = triisopropylsilyl. J. Anthony, C. Boudon, F. Diederich," J.-P. Gisselbrecht. V. Gramlich, M. Gross, M . Hobi. P. Seiler _.._.__...._.__._..___ 763-766 Stable Soluble Conjugated Carbon Rods with a Persilylethynylated Polytriacetylene Backbone l,n=l 2,n=2 3,n=3 4,n=4 5,n=5 TIPS/ In solution, in an organic glass, and in an argon matrix-the irradiation of the bisdiazo compound 1 always leads to the silirene 2 as the main product. The latter was characterized both directly by IR spectroscopy and by its products of trapping experiments. Compound 2 is the first silirene without substituents at the double bond. N,=CH HC=N, \ / Si H,C' 'CH, T7 I Si H,C/ 'CH, 2 M. Trommer, W. Sander,* C. Marquard ............................. 1,l -Dimethyl-1H-silirene 766-769 Contents More than three PR,Au ligands were coordinated for the first time to an element of the sixth main group: the p4-S atom of the title compound occupies the apical position in the tetragonal pyramidal framework (shown on the right); its four Au atoms are arranged in a butterfly form with a hinge angle of 30 ’. F. Canales, M. C. Gimeno, P. G. Jones, A. Laguna* ........... 769-770 Discrete metal clusters in quasi-solid solution are present in amorphous sulfides of the transition metals in the intermediate oxidation states. A “chemical” possibility for their characterization is cyanolgsis. In this way the title compound I was “extruded” from amorphous Re$, , which is built up of tetranuclear clusters. The Re:” Re:” cluster arises through oxidation of the hypothetical “intermediate” [Re,(t‘z-S),(~u,-S),(CN) , O ] s -. A. Mullet-,* E. Krickemeyer, H. Bogge, H. Ratajczak, A. Armatage .............................. Aurophilicity at Sulfur Centers : Synthesis and Structure of the Tetragold(1) Species [(Ph3PA~),S](CF,S0,), . 2CH,CI2 770-773 A Building Principle of Amorphous Chalcogenides of Transition Metals: The “Extrusion” of the Electron-Rich Cluster [Re,S,(S0,),(CN),0]8~ from a-Re,& 1 Kinetically inert and yet catalytically active is the lanthanum complex 1, whereas the analogous Eu and Dy complexes catalyze neither cleavage of R N A oligomers nor transesterification of a phosphate diester. A possible explanation for the different behavior is the size of the La3+ ion. which enables an expansion of the coordination sphere from nine to ten. S. Amin, J. R. Morrow,* C. H. Lake, M. R. Churchill ......................... 1 H2N 773 -77s Lanthanide(II1) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of [La(tcmc)(CF,SO,)(EtOH)](CF,SO,), + 3 CF,SO; + EtOH S.-H. Jang, P. Gopalan, J. E. Jackson,* B. Kahr* ........... 775-777 The structure of the peroxides 1, which arise on oxidation of the corresponding triarylmethyl radicals in air, remained unrecognized for a long time. The false assumption that triarylmethyl radicals are linked methylto-methyl on peroxidation parallels the earlier misconception that triphenylmethyl dinier was hexaphenylethane. R = H, OCH,. Dithiiranes were hitherto considered unstable and were only discussed as elusive intermediates. The dithiirane 1, in contrast, can be readily isolated, purified. and characterized by spectroscopy and X-ray diffraction as well as by a series of chemical reactions. Jacobson and Heintschel Peroxides Ph 1 The First Isolable Dithiirane by Oxidation of a Dithietane Ph Exchange of a P-methine unit for an N atom of a pyrrole ring of a porphyrin leads to a new type of porphyriin isomer, which is formed by condensation of pyrrole grid p-tolylaldehyde. Ni” ions are surprisingly coordinated by 1 as tetradentate ligand, that is through the three N atoms and the C atom of the inner cycle. The framework of the green metalloporhyrin is planar. A. Ishii, T. Akazawa, T. Maruta, J. Nakayama,* M. Hoshino, M . Shiro ............... 777-779 Me P. J. Chmielewski, L. Latos-Graiynski.* K. Rachlewicz, T. Glowiak ................................. 779-781 Tetra-p-tolylporphyrin with an Inverted Pyrrole Ring: A Novel Isomer of Porphyrin 1 C n n ten t c Within reach appears to be the total synthesis of dynemicin A now that after the preparation of the endiyne moiety, the synthesis of the pentacyclic anthraquinone skeleton has been achieved. Starting from 1, the key steps of the reaction sequence are two ortho metalations at quinoline which furnish the ketone 2 after quenching with the appropriate electrophile, cyclization, and oxidation. The ketone is probably a suitable precursor for the totai synthesis of this cystostatic and antibiotic agent. m2 p1 Me0 0 N0 Me0 0 OMe K. C. Nicolaou,* J. L. Gross, M. A. Kerr. R. H. Lemus, K . Ikeda, K. Ohe ....................................... 781 -783 Synthesis of the Anthraquinone Framework of Dynemicin A OMe AgBF, assists chloride abstraction, and the HBF, formed as intermediate acts as catalyst for the ligand exchange in the simple synthesis of homo- and heteroleptic monomeric platinum complexes according to Equation (a). Z, Z' = H, Me. A. D. Ryabov,* R. van Eldik* ............................ 783-784 An Easy Route to Homo- and Heteroleptic Biscycloplatinated Complexes without Recourse to Organohthium Compounds Z (4 amtoluene Q Z Z' Z Highly reactive and sparingly soluble, the first tetraaminophosphoniurn salt P(NH,),I (crystal structure of the cation shown on the right) is accessible from phosphorothionic triamide. For the acid- base pair H,PN,f/PN:- the structures could be compared over eight dissociation steps for the first time. W. Schnick.* S. Horstniann, A. Schmidpeter .......................... Synthesis and Crystal Structure of the First Tetraaminophosphonium Salt P(NH,),I The same compound, 1,2,3,4-Cb0H, ( l ) , is both the major kinetic product of the reaction of C,, or C,,H, with BH, and the thermodynamically most stable isomer of C,,H,. This was predicted by ab initio calculations and confirmed by experiment. C. C. Henderson, C. M. Rohlfing, R. A. Assink, P. A. Cahill* .............................. 1 The ionizing power of liquid SO, is sufficient to induce reactions between acetals or SKI-active alkyl chlorides with allylsilanes without additional Lewis acids [Eq. (a), X = OCH,, R = PhCH(OCH,), n-C,H,,CH(OCH,), etc.; X = CI, R = Ph,C, PhMe,C, etc.]. Reactions in liquid SO, are economical and ecologically advantageous. An additional benefit: they are extremely simple to perform! RX + CH,=CH-CH,-SiMe, SO, a me ,SIX , R-CH2-CH=CH, 785-786 786-788 C,,H,: Kinetics and Thermodynamics of Multiple Addition to C,, H. Mayr,* G. Gorath, B. Bauer 788-789 Liquid Sulfur Dioxide as a Lewis-Acidic Solvent for the Alkylation and Alkoxyalkylation of Allylsilanes (a) * Author 10 whom correspondence should be addressed BOOKS Contents Coordination Chemistry of Aluminum Biosensors. Theory and Applications * G. H. Robinson . D. G. Buerk The Organic Chemistry of Drug Design and Drug Action * R. B. Silverman u! Uld ............................................... 791 U. Bilitewski ...................................... 791 J. D. Dohertx ..................................... 792 Author Index A-29 Preview A-30 The Best Cover Picture in 1993 Many thanks to all readers in Germany and overseas who took the trouble to tell us their favorite cover pictures from last year. We were glad that every cover appealed to someone; nevertheless, some were streaks ahead of others. The clear favorite as first choice was the April cover, showing the spectral “landscape” of the fluorescence excitation spectra of single perylene molecules in a polyethylene film. This was followed by the February cover (a copper- tellurium cluster), and the third most frequently quoted in first place were the January and March issues (an eleven-component supercomplex and a tetraethynyltetradehydro[l2]annulene,respectively). Most often mentioned (that is, as first, second, or third choice) was the October cover (atomic force microscopy image of DNA), followed by September (dendrimer-the largest characterized hydrocarbon) and April (see above) in that order. How are the cover pictures conceived? Most often they are thanks to the creativity of our authors who send a cover picture suggestion along with their manuscript. That is most welcome. Of course, in some cases the stimulus for the picture comes from the editors. The winners of a year’s subscription to Angewandte C/zer.uk or VCH books to the value of DM 300.- are S. Kazarian, Nottingham; J. Gross, Darinstadt ; D. Klostermeyer, Munich; E. Lattmann, Hannover; F. Starck, Erlangen; C. Steuckart, Gottingen.