Oligonukleare Benzylthiolat‐Zinkkomplexe

Oligonuclear Benzylthiolate Zinc Complexes From solutions of zinc nitrate and sodium benzylthiolate crystallize, depending on the reaction conditions, tetraalkylammonium salts of the zinc complexes [Zn₂(SBz)₆]^2—, [Zn₄(SBz)₁₀]^2—, and [Zn₈(S)(SBz)₁₆]^2—. In each complex the zinc ions are tetrahedrally coordinated by sulfur atoms. [Zn₄(SBz)₁₀]^2— has an adamantane framework. The bridging thiolate sulfur atoms in [Zn₈(S)(SBz)₁₆]^2—, unlike those in icosahedral reference compounds, form a cuboctahedral framework.     

Zinkkomplexe des N,N,S‐Liganden 2‐Mercaptobenzyl‐bis‐(2‐pyridylmethyl)amin

Zinc Complexes of the N,N,S‐Ligand 2‐Mercaptobenzyl‐bis‐(2‐pyridylmethyl)amine An improved synthesis of the title ligand MBPA–H has made its complex chemistry accessible. With diethyl zinc it forms the reactive ethyl complex (MBPA)Zn–C₂H₅ ( 1 ) whose reaction with phenol leads to (MBPA)Zn–OC₆H₅ ( 2 ). With zinc nitrate the labile compound (MBPA)Zn–ONO₂ ( 3 ) is formed which in turn is converted with thiophenolate into (MBPA)Zn–SC₆H₅ ( 4 ). Structure determinations of 2 and 3 have confirmed severely deformed trigonal‐bipyramidal coordinations of the zinc atom whose ligation patterns correspond to those in some hydrolytic zinc enzymes.     

Ungewöhnliche Bildung und Struktur eines O‐Sulfinato‐Zinkkomplexes

Unusual Formation and Structure of a O‐Sulfinato Zinc Complex Whereas the reaction between hydrotris[(N‐xylyl)‐thioimidazolyl]borato‐zinc perchlorate ([ L· Zn‐OClO₃]) and ethanethiolate under an inert atmosphere leads to the thiolate complex [ L· Zn‐SC₂H₅], the same reaction in air produces the sulfinato complex [ L· Zn‐O‐S(O)‐C₂H₅] ( 1 ). 1 is the first fully characterized sulfinato‐zinc complex. Its structure determination has confirmed the unusual coordination of the sulfinato ligand via one of its oxygen atoms.     

Neue ONS‐Liganden und ihre Zinkkomplexe mit Bezug zum Zinkenzym Alkoholdehydrogenase

New ONS Ligands and their Zinc Complexes with Relation to the Zinc Enzyme Alcoholdehydrogenase By ring opening of dimethyl thiirane with ethanolamine or by Schiff base condensation between salicylic aldehydes and 2‐mercaptoisobutylamine the tridentate ONS ligands H₂MIEA, H₂MIIMP, and H₂MIIMTP were obtained. The former yielded the zinc complex (MIEA)Zn(ethanolamine) ( 1 ) with a trigonal bipyramidal ZnO₂N₂S coordination. The latter two and Zn[N(SiMe₃)₂]₂ yielded the presumably dimeric complexes Zn(MIIMP) and Zn(MIIMTP) ( 2 a , b ). Benzoyl pyridine and phenylhydroxymethylpyridine as bidentate coligands L could be combined with H₂MIIMP in the complexes L · Zn(MIIMP) ( 3 , 4 ) whose ZnO₂N₂S coordination corresponds to that of 1 . Partial hydrolytic degradation led to the unusual trinuclear complex 5 which contains, inter alia, the condensation product of the salicylic aldimine and benzoyl pyridine as a ligand. The complexes obtained and the coordination patterns observed represent new structural analogies with the environment of zinc in the enzyme horse liver alcoholdehydrogenase.     

Zinkkomplexe des chelatisierenden N,S,S-Liganden N-(2-Mercaptoethyl)-2-mercaptoanilin

Zinc Complexes of the Chelating N,S,S Ligand N-(2-Mercaptoethyl)-2-mercaptoaniline The organic compound N-(2-mercaptoethyl)-2-mercaptoaniline (LH₂) which as a ligand offers two SH functions, which can be deprotonated, and one NH donor function was prepared by a new method. Its reaction with zinc salts yielded the 1:1 complex ZnL. The structure analysis identified the complex as a molecular tetramer with bridging thiolate groups, a tetrahedral ZnNS₃ coordination, and a step-like Zn₄S₄ ring as the central structural unit. Attempts to break up the tetramer by addition of coligands were successful only for 2,2′-bipyridine which produced the complex LZn · bipy.     

Phenol Based‐Ligands with Two Adjacent N,N′,O‐Binding Pockets

The synthesis of three new ligands and their coordination behavior towards zinc ions with strongly coordinating anions and cobalt ions with weakly coordinating anions are reported. The ligands have two adjacent imidazolyl‐pyridinyl and pyrazolyl‐pyridinyl binding pockets, respectively, which are linked by a phenol unit. We also investigated the dynamic behavior of the ligand having the imidazolyl‐pyridiyl sidearm in solution. The reaction of the ligands and ZnCl₂ yielded complexes of the type [ L Zn₂Cl₃]. When we used Co^II salts with weakly coordinating anions, complexes of the general formula [ L ₂Co₂]²⁺ were formed.     

Ein dreikerniger Zinkkomplex mit ZnS4‐, ZnS3O‐ und ZnS2NO‐Koordinationen

A Trinuclear Zinc Complex with ZnS₄, ZnS₃O, and ZnS₂NO Coordinations The reaction between the tris(thioimidazolyl)borate complex [Tt^tBuZn‐OClO₃] and 2‐pyridylbenzylalcohol (PBAH) yields the compound[(Tt^tBu)₃Zn₃(PBA)] (ClO₄)₂. In its trinuclear complex cation tris(thioimidazolyl)borate ligands, which adopt the umbrella conformation, bridge the zinc ions, which have the three different coordinations ZnS₄, ZnS₃O and ZnS₂NO.     

Struktur eines Blei(II)‐Komplexes mit verknüpften Monothioquadratationen als Liganden

A Lead(II) Complex with Linked Monothiosquarate Ions as Ligands The thiosquarate ligand bis‐1,2‐(2‐hydroxy‐3,4dione‐cyclobut‐1‐enylsulfanyl)‐ethane and its lead(II) complex have been prepared. According to the crystal structure analysis the complex has a unique layer structure in the solid state. The layers consist of a superposition of cyclic dimeric complexes and of chain like polymeric complexes. The shortest nonbonding Pb…Pb distances are 4.0 Å.     

Kohlenwasserstoffverbrückte Metallkomplexe. L Dicarbonyl‐cyclopentadienyl‐pyridoyl‐eisen‐Komplexe als Liganden

Hydrocarbon‐bridged Metal Complexes. L Dicarbonyl Cyclopentadienyl Pyridoyl Iron Complexes as Ligands Dicarbonyl‐cyclopentadienyl‐2‐ and 3‐pyridoyl‐iron (L¹, L²) and 2,6‐dicarbonyl‐pyridine‐bis(dicarbonyl‐cyclopentadienyl‐iron) (L³) function as ligands in metal complexes and the N,O‐chelates [(OC)₄M(L¹)] (M = Mo, W, 8 a, b ) and [(Ph₃P)₂Cu(L¹)]⁺BF₄^– ( 9 ) were prepared. Monodentate coordination of L¹ and L² through the pyridine N‐atom occurs in the palladium(II) complexes [Cl₂Pd(PnBu₃)(L¹)] ( 10 ), [Cl₂Pd(PnBu₃)(L²)] ( 11 ) and [Cl₂Pd(L²)₂] ( 12 ). Ligand L³ forms the O,N,O‐bis(chelate) [Cl₂Zn(L³)] ( 13 ). The crystal and molecular structures of L¹, 8 b (M = W), 9–11 and 13 were determined by X‐ray diffraction.     

Reduktive Dimerisierung von NO an Dirutheniumkomplexen und Bildung eines tridentaten 2, 2‐Bis(diphenylphosphanyl)ethanolato‐Liganden

The reaction of the trans‐hyponitrito complex [Ru₂(CO)₄(μ‐η²‐ONNO)(μ‐H)(μ‐PtBu₂)(μ‐dppen)] ( 1 , dppen = Ph₂PC(=CH₂)PPh₂) with tetrafluorido boric acid afforded the new complex salt [Ru₂(CO)₄(μ‐η²‐ONNOH)(μ‐H)(μ‐PtBu₂)(μ‐dppen)]BF₄ ( 2 ) containing the monoprotonate hyponitrous acid as the ligand in the cationic complex. Complex 1 showed a nucleophilic reactivity towards the trimethyloxonium cation resulting in the monoester derivative of the hyponitrous acid [Ru₂(CO)₄(μ‐η²‐ONNOMe)(μ‐H)(μ‐PtBu₂)(μ‐dppen)]BF₄ ( 3 ). During heating of compound 2 in ethanol under reflux for a short time nitrous oxide was liberated affording unexpectedly a new tridentate 2, 2‐bis(diphenylphosphanyl)ethanolato ligand formed by an intramolecular attack of an intermediate hydroxido ligand towards the unsaturated carbon carbon double bond in the bridging dppen ligand. Thus the complex salt [Ru₂(CO)₄{μ‐η³‐OCH₂CH(PPh₂)₂}(μ‐H)(μ‐PtBu₂)]BF₄ ( 4 ) was formed in good yields. The new compounds 2 , 3 , and 4 were characterized by spectroscopic means as well as their molecular structures were determined in the crystal.     

Metallkomplexe mit N2O2S2‐Koordinationssphäre. Synthese und Charakterisierung der Cobalt(II)‐, Nickel(II)‐ und Kupfer(II)‐Komplexe eines 15‐ und eines 16‐gliedrigen N,N′‐bis(2‐hydroxyethyl)‐funktionalisierten makrocyclischen Liganden

Metal Complexes with N₂O₂S₂ Donor Set. Synthesis and Characterization of the Cobalt(II), Nickel(II), and Copper(II) Complexes of a 15‐ and a 16‐Membered Bis(2‐hydroxyethyl) Pendant Macrocyclic Ligand The macrocyclic ligands 6, 10‐bis(2‐hydroxyethyl)‐7, 8, 9, 11, 17, 18‐hexahydro‐dibenzo‐[e, n][1, 4, 8, 12]‐dithiadiaza‐cyclopentadecine ( 1 ) (L¹) and 5, 13‐bis(2‐hydroxyethyl)‐7, 8, 9, 10, 16, 17, 18, 19, 20‐nonahydro‐dibenzo‐[g, o][1, 9, 5, 13]‐dithiadiaza‐cyclohexadecine (L⁴) have been prepared. They form the stable complexes [CoL¹(‐H)CoL¹](ClO₄)₃ ( 2 ), [NiL¹](ClO₄)₂·MeOH ( 3 ), Λ‐[CuL¹](ClO₄)₂·MeOH ( 4a ) and rac‐[CuL¹](ClO₄)₂·MeOH ( 4b ), [NiL⁴](ClO₄)₂ ( 5 ), and [CuL⁴](ClO₄)₂ ( 6 ). The compounds 1 to 6 have been characterized by standard methods and single‐crystal X‐ray diffraction. In the complexes 2 to 6 the metal atoms are octahedrally coordinated by the N₂O₂S₂ donor set of the ligands. L¹ and L⁴ are folded herein along the N···M···S‐ and the N···M···N′‐axes, respectively. This results at the metal atom in a all‐cis‐configuration for the complexes of L¹ and a trans‐N₂‐cis‐O₂‐cis‐S₂‐configuration for the complexes of L⁴. The cobalt(II) complex 2 is a dimer, bridged by a rather short hydrogen bridge of 2.402(12)Å length. The copper(II) complexes of L¹ and L⁴ differ with respect to the Jahn‐Teller‐distortion.     

Pyridinderivate als Komplexbildner VIII Die Herstellung je eines neuen vier- und sechszähnigen Liganden

The synthesis of the new complexing agents tris-(2-pyridylmethyl)-amine and N,N,N′,N′-tetrakis-(2-pyridylmethyl)-ethylenediamine is described, and their protonation constants are given.     

Ein Thiolato‐Zink‐Komplex mit einem Zn4O4‐Bicyclooctan‐Gerüst

A Thiolate‐Zinc Complex with a Zn₄O₄ Bicyclooctane Framework The reaction of diethyl zinc with 2,4,6‐triisopropyl thiophenol (HSR*) and N‐methyl‐2‐hydroxymethyl imidazole (ImCH₂OH) in methanol yields the complex Zn₄(SR*)₄ (ImCH₂O)₃(OMe) with terminal SR* and bridging ImCH₂O and MeO ligands. The structure of its Zn₄O₄ framework is that of a bicyclo[2.2.2]octane with Zn and O at the two apices.     

Metallkomplexe mit biologisch wichtigen Liganden. CLXV N,O‐Chelat‐Komplexe von α‐Aminosäureanionen mit cyclopalladiertem N,N‐Dimethylferrocencarbothiamid

Metal Complexes of Biologically Important Ligands. CLXV N,O‐Chelate Complexes of α‐Amino Acid Anions with Cyclopalladated N,N‐Dimethylferrocenecarbothioamide A short literature review on the reactions of various chlorobridged complexes with α‐aminoacidates, α‐amino acid esters, peptide ester or derivatives of amino acids is given. The chloro bridged o‐palladated N,N‐dimethylferrocenecarbothioamide [(fct)Pd(μ‐Cl)₂Pd(fct)] reacts with the anions of glycine, L‐alanine, L‐proline, L‐valine, L‐phenylalanine, L‐leucine, L‐isoleucine to give the N,O‐chelates [(fct)Pd(N,O‐α‐aminocarboxylate)] ( 1 – 7 ). Due to the planary chirality of the unsymmetrically disubstituted cyclopentadienyl iron moiety of fct the complexes 2 – 7 with optically active amino acidate ligands are formed as a mixture of two diastereoisomers, which can be detected by their NMR spectra.     

Catalytic,Cascade Ring‐Opening Benzannulations of 2,3‐Dihydrofuran O,O‐ and N,O‐Acetals

An Al(OTf)₃‐catalyzed intramolecular cascade ring‐opening benzannulation of 2,3‐dihydrofuran O,O‐ and N,O‐acetals is described. The cascade sequence involves the dihydrofuran ring‐opening by acetal hydrolysis, an intramolecular Prins‐type cyclization, and aromatization to generate an array of benzo‐fused (hetero)aromatic systems in up to 95 % yield. This method represents the first example of dihydrofuran acetal usage in benzannulation reactions. The approach provides excellent regiocontrol based on the choice of alkenes used to form the requisite dihydrofuran acetals.     

Metallkomplexe mit biologisch wichtigen Liganden. CLXVI Metallkomplexe mit Ferrocenylmethyl‐L‐cysteinat und 1,1′‐Ferrocenylbis‐(methyl‐L‐cysteinat) als Liganden

Metal Complexes of Biologically Important Ligands. CLXVI Metal Complexes with Ferrocenylmethylcysteinate and 1,1′‐Ferrocenylbis‐(methylcysteinate) as Ligands A series of complexes of transition metal ions ( Cr³⁺, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ ) and of lanthanide ions ( La³⁺, Nd³⁺, Gd³⁺, Dy³⁺, Lu³⁺ ) with the anions of ferrocenylmethyl‐L‐cysteine [(C₅H₅)Fe(C₅H₄CH(R)SCH₂CH(NH₃⁺)CO₂^?] (L¹) and with the dianions of 1,1′‐ferrocenylbis(methyl‐L‐cysteine) [Fe(C₅H₄CH(R)SCH₂CH(NH₃⁺) CO₂^?)₂] (R = H, Me, Ph) (L²) as N,O,S‐donors were prepared. With the monocysteine ferrocene derivative L¹ as ligands complexes [M^IIL¹₂] or [Cr^IIIL¹₂]Cl type complexes are formed whereas the bis(cysteine) ligand L² yields insoluble complexes of type [ML²]_n, presumably as coordination polymers. The magnetic moments of [Mn^IIL²]_n, [Pr^IIIL²]_n(OH)_n and [Dy^IIIL²]_n(OH)_n exhibit “normal” paramagnetism.