Ligand Substitution Reactions on Aquapentachloro‐ and Hexachloroplatinic Acid — Synthesis and Characterization of Tetrachloroplatinum(IV) Complexes with Heterocyclic N,N Donors

Reactions of aquapentachloroplatinic acid, (H₃O)[PtCl₅(H₂O)]·2(18C6)·6H₂O ( 1 ) (18C6 = 18‐crown‐6), and H₂[PtCl₆]·6H₂O ( 2 ) with heterocyclic N, N donors (2, 2′‐bipyridine, bpy; 4, 4′‐di‐tert‐butyl‐2, 2′‐bipyridine, tBu₂bpy; 1, 10‐phenanthroline, phen; 4, 7‐diphenyl‐1, 10‐phenanthroline, Ph₂phen; 2, 2′‐bipyrimidine, bpym) afforded with ligand substitution platinum(IV) complexes [PtCl₄(N∩N)] (N∩N = bpy, 3a ; tBu₂bpy, 3b ; Ph₂phen, 5 ; bpym, 7 ) and/or with protonation of N, N donor yielding (R₂phenH)₂[PtCl₆] (R = H, 4a ; Ph, 4b ) and (bpymH)⁺ ( 8 ). With UV irradiation Ph₂phen and bpym reacted with reduction yielding platinum(II) complexes [PtCl₂(N∩N)] (N∩N = Ph₂phen, 6 ; bpym, 9 ). Identities of all complexes were established by microanalysis as well as by NMR (¹H, ¹³C, ¹⁹⁵Pt) and IR spectroscopic investigations. Molecular structures of [PtCl₄(bpym)]·MeOH ( 7 ) and [PtCl₂(Ph₂phen)] ( 6 ) were determined by X‐ray diffraction analyses. Differences in reactivity of bpy/bpym and phen ligands are discussed in terms of calculated structures of complexes [PtCl₅(N∩N)]^— with monodentately bound N, N ligands (N∩N = bpy, 10a ; phen, 10b ; bpym, 10c ).     

Mixed‐ligand MnII and CuII complexes with alternating 2,2′‐bipyrimidine and terephthalate bridges

The novel polymeric complexes catena‐poly[[diaquamanganese(II)]‐μ‐2,2′‐bipyrimidine‐κ⁴N¹,N^1′:N³,N^3′‐[diaquamanganese(II)]‐bis(μ‐terephthalato‐κ²O¹:O⁴)], [Mn₂(C₈H₄O₄)₂(C₈H₆N₄)(H₂O)₄]_n, (I), and catena‐poly[[[aquacopper(II)]‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ²O¹:O^1′‐copper(II)‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ²O¹:O^1′‐[aquacopper(II)]‐μ‐2,2′‐bipyrimidine‐κ⁴N¹,N^1′:N³,N^3′] tetrahydrate], {[Cu₃(C₈H₄O₄)₂(OH)₂(C₈H₆N₄)(H₂O)₄]·4H₂O}_n, (II), containing bridging 2,2′‐bipyrimidine (bpym) ligands coordinated as bis‐chelates, have been prepared via a ligand‐exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht²⁻) anions were found. In (I), two tpht²⁻ anions acting as bis‐monodentate ligands bridge the Mn^II centres in a parallel fashion. In (II), the tpht²⁻ anions act as endo‐bridges and connect two Cu^II centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn₂(tpht)₂(bpym)(H₂O)₄] entity in (I) and the trinuclear [Cu₃(tpht)₂(OH)₂(bpym)(H₂O)₄]·4H₂O coordination entity in (II) build up one‐dimensional polymeric chains along the b axis. In (I), the Mn^II cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central Cu^II cation is also on a special position (site symmetry ). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face‐to‐face π–π interactions [in (I)], forming three‐dimensional metal–organic frameworks. The Mn^II cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu^II cations in (II) are in distorted octahedral environments. The Cu^II polyhedra are inclined relative to each other and share common edges.     

A zinc–lithium complex of 4,7‐bis(2‐aminoethyl)‐1,4,7‐triazacyclononane‐1‐acetate

The asymmetric unit of {[4,7‐bis(2‐amino­ethyl)‐1,4,7‐tri­aza­cyclo­nonan‐1‐yl]acetato}zinc(II) triaqua{μ‐[4,7‐bis(2‐amino­ethyl)‐1,4,7‐tri­aza­cyclo­nonan‐1‐yl]acetato}lithium(I)zinc(II) chloride diperchlorate, [Zn(C₁₂H₂₆N₅O₂)][LiZn(C₁₂H₂₆N₅O₂)(H₂O)₃]Cl(ClO₄)₂, obtained from the reaction between the lithium salt of 4,7‐bis(2‐amino­ethyl)‐1,4,7‐tri­aza­cyclo­nonane‐1‐acetate and Zn(ClO₄)₂, contains two Zn^II complexes in which each Zn^II ion is six‐coordinated by five N‐atom donors and one O‐­atom donor from the ligand. One carboxyl­ate O‐atom donor is not involved in coordination to a Zn^II atom, but coordinates to an Li⁺ ion, the tetrahedral geometry of Li⁺ being completed by three water mol­ecules. The two complexes are linked via a hydrogen bond between a primary amine N—H group and the carboxyl­ate‐O atom not involved in coordination to a metal.     

(μ‐Tri‐tert‐butoxysilanethiol­ato)­bis[(tetra­hydro­furan)lithium(I)] and catena‐poly[[bis­(μ‐tri‐tert‐butoxy­silanethiol­ato)dilithium(I)]‐μ‐dimethoxy­ethane]: solvent coordination as the structure‐forming factor

The title compounds, μ‐(tri‐tert‐butoxy­silanethiol­ato‐κ²S:S)‐bis[(tetra­hydro­furan‐κO)lithium(I)], [Li₂(C₁₂H₂₇O₃SSi)₂(C₄H₈O)₂], (I), and catena‐poly[[bis­(μ‐tri‐tert‐butoxysilanethiol­ato)‐1:2κ²S;1κS:2κS,O‐dilithium(I)]‐μ‐dimethoxy­ethane‐κ²O:O′], [Li₂(C₁₂H₂₇O₃SSi)₂(C₄H₁₀O₂)]_n, (II), were obtained by the reaction of tri‐tert‐butoxy­silanethiol with metallic lithium. The crude product, when recrystallized from tetra­hydro­furan (THF) yields (I), and when recrystallized from 1,2‐dimethoxy­ethane (DME) gives (II). Compound (I) forms centrosymmetric dimers in the solid state with an Li₂S₂ central core, whereas (II) forms infinitely long chains, in which the centrosymmetric dimeric units are linked together by the bidentate DME ligand (also residing on an inversion centre), thus forming a coordination polymer. The formation of a one‐dimensional structure in (II) is a consequence of replacement of a monodentate THF solvent mol­ecule with a bidentate DME mol­ecule.     

1,1‐Di(9‐fluorenyl)­ethanol,a ­by‐­product from the acetyl­ation of 9‐fluorenyl­lithium

Treatment of 9‐fluorenyl­lithium with acetyl chloride produces 9‐acetyl­fluorene, (I), and several by‐products. Among them is a compound unequivocally identified for the first time as the addition product of (I) with 9‐fluorenyl­lithium, 1,1‐di(9‐fluorenyl)­ethanol, C₂₈H₂₂O, (II). The two fluorene‐ring planes of (II) are essentially perpendicular [89.90 (9)°]. A number of intermolecular non‐bonding distances are well within or close to the sum of their respective van der Waals radii and may be responsible for the rarely observed large bowing of one of the fluorene rings. This bowing apparently arises from two mol­ecules impinging on the convex face of the bowed ring, augmented by hydrogen bonding between the peripheral π electrons of the concave face and the hydroxyl H atom of another mol­ecule adjacent to that face.     

9‐(1‐Acetoxy­ethyl­idene)­fluorene (`diacetyl­fluorene'), a by‐product from the acetyl­ation of 9‐fluorenyl­lithium

Treatment of 9‐fluorenyl­lithium with acetyl chloride produces 9‐acetyl­fluorene, (I), and several by‐products, among which is `di­acetyl­fluorene', now characterized definitively as 9‐(1‐acetoxy­ethyl­idene)­fluorene [IUPAC name: (1‐fluoren‐9‐yl­idene­)ethyl acetate], (II), C₁₇H₁₄O₂, derived from acetyl­ation of initially formed (I). Various parameters disclose substantial structural distortion within (II) emanating from A^(1,3) strain associated with the 9‐(acetoxy­ethyl­idenyl)­fluorene system.     

Synthesis and characterization of crown ether–containing N‐phosphorylated thioureas RC(S)NHP(O)(OiPr)2 (R = 1‐aza‐15‐crown‐5, 1‐aza‐12‐crown‐4) and their Co(II) and Ni(II) complexes

The reaction of the lithium salts of N‐phosphorylated thioureas RC(S)NHP(O)(OiPr)₂ (R = 1‐aza‐15‐crown‐5, HL ^I ; 1‐aza‐12‐crown‐4, HL ^II ) with Co(II) or Ni(II) leads to the chelate complexes [ ML ^I,II ₂ ]. The metal center is found in a tetrahedral ([ CoL ^I,II ₂ ]) or square planar ([ NiL ^I,II ₂ ]) O₂S₂ environment formed by the CS sulfur atoms and the PO oxygen atoms of two deprotonated ligands L . The molecular structure of [ CoL ^I ₂ ] was elucidated by X‐ray diffraction and the extraction properties of HL ^I,II and [ ML ^I,II ₂ ] toward alkali metal and ammonium picrates were investigated. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:486–491, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20637     

Die konjugative Verbrückung metallorganischer Reaktionszentren in Heterozweikernkomplexen [(OC)3ClRe(μ‐L)MCl(C5Me5)]+, M = Rh oder Ir ‐ Spektroskopische Konsequenzen reduktiver Aktivierung

The Conjugative Bridging of Organometallic Reaction Centers in Heterodinuclear Complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)]⁺, M = Rh or Ir ‐ Spectroscopic Consequences of Reductive Activation Heterodinuclear complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)](PF₆), M = Rh or Ir and L = 2, 5‐bis(1‐phenyliminoethyl)pyrazine (bpip), 3, 6‐bis(2‐pyridyl)‐1, 2, 4, 5‐tetrazine (bptz) or 2, 2′‐bipyrimidine (bpym), were synthesized via mononuclear rhenium compounds (L)Re(CO)₃Cl. The stepwise reductive activation under chloride dissociation was studied through cyclic voltammetry and spectroelectrochemistry in the range of CO stretching vibrations (IR), charge transfer absorptions (UV/Vis) and electron spin resonance (ESR) for paramagnetic intermediates of the mono‐ and heterodinuclear compounds. While complexes of bpip and bptz form one‐electron reduced radical intermediates [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)] ^˙ , the compounds with bpym react under MCl‐dissociative two‐electron reduction directly to [(OC)₃ClRe(μ‐L)M(C₅Me₅)].     

Nickel(I)‐Komplexe mit 1,1′‐Bis(phosphino)ferrocenen als Liganden

Nickel(I) Complexes with 1,1′‐Bis(phosphino)ferrocenes as Ligands The thermically stable monomeric Nickel(I) complexes [(d^tbpf)Ni(acac)] ( 1 ) and [(dⁱppf)NiCl] ( 2 ) were synthesized and characterized by elemental analyses, EPR spectroscopy, and by X‐ray crystal structure analyses of single crystals (d^tbpf: 1,1′‐bis(di‐tertbutylphosphino)ferrocene; dⁱppf: 1,1′‐bis(diisopropylphosphino)ferrocene). 1 is formed by reduction of Ni(acac)₂ with triethylaluminium in the presence of d^tbpf, together with the nickel(0) complex [(d^tbpf)Ni(C₂H₄)]. 1 contains a Ni^I atom surrounded of two O‐ and two P donor atoms in a distorted tetrahedral coordination. 2 was obtained by reduction of [(dⁱppf)NiCl₂] with NaBH₄. In 2 the nickel(I) atom adopts trigonal planar coordination.     

Hexanuclear Wheel‐Shaped Lithium N‐(2,6‐Diisopropylphenyl)‐N′‐(2‐pyridylethyl)benzamidinate

Lithiation of N‐(2,6‐diisopropylphenyl)‐N′‐(2‐pyridylethyl)benzamidine ( 1 ) with LiN(SiMe₃)₂ in a solvent mixture of toluene and TMEDA yields hexameric lithium N‐(2,6‐diisopropylphenyl)‐N′‐(2‐pyridylethyl)benzamidinate ( 2 ), which can be purified by recrystallization from a solvent mixture of toluene and THF. The three‐coordinate lithium ions have T‐shaped coordination spheres. The negative charge is delocalized within the 1,3‐diazaallylic system, which adopts a (syn‐Z)‐arrangement.     

A novel one‐dimensional double‐chain‐like ZnII coordination polymer: poly[bis(1‐benzyl‐1H‐imidazole‐κN3)tris(μ‐cyanido‐κ2C:N)(cyanido‐κC)disilver(I)zinc(II)]

One of most interesting systems of coordination polymers constructed from the first‐row transition metals is the porous Zn^II coordination polymer system, but the numbers of such polymers containing N‐donor linkers are still limited. The title double‐chain‐like Zn^II coordination polymer, [Ag₂Zn(CN)₄(C₁₀H₁₀N₂)₂]_n, presents a one‐dimensional linear coordination polymer structure in which Zn^II ions are linked by bridging anionic dicyanidoargentate(I) units along the crystallographic b axis and each Zn^II ion is additionally coordinated by a terminal dicyanidoargentate(I) unit and two terminal 1‐benzyl‐1H‐imidazole (BZI) ligands, giving a five‐coordinated Zn^II ion. Interestingly, there are strong intermolecular Ag^I…Ag^I interactions between terminal and bridging dicyanidoargentate(I) units and C—H…π interactions between the phenyl rings of BZI ligands of adjacent one‐dimensional linear chains, providing a one‐dimensional linear double‐chain‐like structure. The supramolecular three‐dimensional framework is stabilized by C—H…π interactions between the phenyl rings of BZI ligands and by Ag^I…Ag^I interactions between adjacent double chains. The photoluminescence properties have been studied.     

Zur Reaktion der Alkin‐Kupfer(I)‐Komplexe [CuCl(S‐Alkin)] und [Cu2Br2(S‐Alkin)(dms)] (S‐Alkin = 3,3,6,6‐Tetramethyl‐1‐thia‐4‐cycloheptin,dms = Dimethylsulfid) mit den Lithiumorganylen Phenyllithium und Fluorenyllithium

Organometallic Compounds of Copper. XX On the Reaction of the Alkyne Copper(I) Complexes [CuCl(S‐Alkyne)] and [Cu₂Br₂(S‐Alkyne)(dms)] (S‐Alkyne = 3,3,6,6‐Tetramethyl‐1‐thiacyclohept‐4‐yne; dms = Dimethylsulfide) with the Lithiumorganyls Phenyllithium und Fluorenyllithium The alkyne copper(I) bromide complex [Cu₂Br₂(S‐Alkyne)(dms)] ( 3 b ) (S‐Alkyne = 3,3,6,6‐tetramethyl‐1‐thiacyclohept‐4‐yne; dms = dimethylsulfide) reacts with phenyllithium to form a tetranuclear copper(I) complex of the composition [Cu₄(C₆H₅)₂(S‐Alkenyl)₂] ( 7 ) in low yield (4%). The reaction of the alkyne copper(I) chloride complex [CuCl(S‐Alkyne)] ( 2 a ) with fluorenyllithium in tetrahydrofuran (thf) affords a lithium cuprate of the composition [Li(thf)₄]⁺ [Cu₂(fluorenyl)₃(S‐Alkyne)₂]^– ( 8 ) (yield 32%). The structures of both new complexes 7 and 8 were determined by X–ray diffraction.     

Planarity of benzoylthiocarbazate tuberculostatics. IV. Polymorphs of N′‐(1,3‐dithiolan‐2‐ylidene)‐4‐nitrobenzohydrazide

The search for new tuberculostatics is important considering the occurrence of drug‐resistant strains of Mycobacterium tuberculosis . Three polymorphs of N ′‐(1,3‐dithiolan‐2‐ylidene)‐4‐nitrobenzohydrazide (a potentially tuberculostatic agent), C₁₀H₉N₃O₃S₂, denoted (I1), (I2) and (I3), and the monohydrate of this compound, C₁₀H₉N₃O₃S₂·H₂O, (I4), have been characterized by single‐crystal X‐ray diffraction. The conformations of the molecules in all these structures are very similar. Structures (I1), (I2) and (I3) provide an example of packing polymorphism resulting from different intermolecular interactions.     

Molecular Structures of Dibromo[(E)2‐bromo‐2‐phenylvinyl]‐(phenyl) tellurium (IV) and Dibromo [(Z)‐2‐bromo‐2‐phenyl‐vinyl] (p‐tulyl) tellurium (IV) hydrate methanolate

The structures of title compounds, [TeBr₂(C₈H₆Br)(C₆H₅)] (I) and [TeBr₂(C₈H₆Br)(C₇H₉)](H₂O)(CT₃OH) (II), have been determined by X‐ray diffraction. The structures confirm that E‐ or Z‐type configuration of vinylic telluride depends on the polarity of solvent employed. In either structure, Te atom is in a trigonal dipyramide configuration with the lone pair of electrons in the equatorial position.     

1,2,3‐Trimethoxy‐4‐[(E)‐2‐phenylvinyl]benzene and (E,E)‐1,4‐bis(2,3,4‐trimethoxyphenyl)buta‐1,3‐diene

The stilbene derivative 1,2,3‐trimethoxy‐4‐[(E)‐2‐phenylvinyl]benzene, C₁₇H₁₈O₃, (I), and its homocoupling co‐product (E,E)‐1,4‐bis(2,3,4‐trimethoxyphenyl)buta‐1,3‐diene, C₂₂H₂₆O₆, (II), both have double bonds in trans conformations in their conjugated linkages. In the structure of stilbene (I), the aromatic rings deviate significantly from coplanarity, in contrast with coproduct (II), the core of which is rigorously planar. The deviation in stilbene (I) seems to be driven by intermolecular electrostatic interactions. Diene (II) sits on a crystallographic inversion centre, which bisects the conjugated linkage.     

Synthesis and characterization of three dinuclear copper(I) complexes of 1,2‐bis(diphenylphosphino)‐1,2‐dicarba‐closo‐dodecaborane

Three dinuclear copper(I) complexes, [Cu₂(µ‐Cl)₂(1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀)₂]·2CH₂Cl₂ ( 1 ), [Cu₂(µ‐Br)₂(1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀)₂]·2THF ( 2 ) and {Cu₂(µ‐I)₂[1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀]₂} ( 3 ) have been synthesized by the reactions of CuX (X = Cl, Br and I) with the closo ligand 1,2‐(PPh₂)₂‐1,2‐C₂B₁₀H₁₀. All these complexes were characterized by elemental analysis, FT‐IR, ¹H and ¹³C NMR spectroscopy and X‐ray structure determination. Single crystal X‐ray structure determinations show that every complex contained di‐µ‐X‐bridged structure involving a crossed parallelogram plane formed by two Cu atoms and two X atoms (X = Cl, Br, I). The geometry at the Cu atom was a distorted tetrahedron, in which two positions were occupied by two P atoms of the PPh₂ groups connected to the two C atoms of carborane (Cc), and the other two resulted from two X atoms which bridged the other Cu atom at the same time. To the best of our knowledge, this is the first example of copper(I) complexes with 1,2‐diphenylphosphino‐1,2‐dicarba‐closo‐dodecaborane as ligand characterized by X‐ray diffraction. The catalytic property of the complex 3 for the amination of iodobenzene with aniline was also investigated. Copyright © 2005 John Wiley & Sons, Ltd.     

Die Reaktion des Digalliumsubiodids R(I)Ga‐Ga(I)R [R = C(SiMe3)3] mit Lithium‐diphenylphosphanid – radikalische Öffnung der Ga‐Ga‐Bindung

The Reaction of the Digallium Subiodide R(I)Ga‐Ga(I)R [R = C(SiMe₃)₃] with Lithium Diphenylphosphanide – Radical Cleavage of the Ga‐Ga Bond The easily available organoelement digallium(II) subiodide R(I)Ga‐Ga(I)R ( 1 ) [R = C(SiMe₃)₃] reacted with two equivalents of lithium diphenylphosphanide in toluene by the replacement of both iodine atoms by two phosphanido groups. The product, [R(H)Ga‐P(C₆H₅)₂]₂ ( 2 ), contains a four‐membered Ga₂P₂ heterocycle without direct Ga‐Ga bonding interactions and the gallium atoms exclusively in an oxidation state of +III. They are attached to hydrogen atoms, which may result from a reaction of a reactive intermediate with the solvent.     

Low‐dimensional coordination polymeric structures in alkali metal complex salts of the herbicide (2,4‐dichlorophenoxy)acetic acid (2,4‐D)

The Li, Rb and Cs complexes with the herbicide (2,4‐dichlorophenoxy)acetic acid (2,4‐D), namely poly[[aqua[μ₃‐(2,4‐dichlorophenoxy)acetato‐κ³O¹:O¹:O^1′]lithium(I)] dihydrate], {[Li(C₈H₅Cl₂O₃)(H₂O)]·2H₂O}_n, (I), poly[μ‐aqua‐bis[μ₃‐(2,4‐dichlorophenoxy)acetato‐κ⁴O¹:O^1′:O^1′,Cl²]dirubidium(I)], [Rb₂(C₈H₅Cl₂O₃)₂(H₂O)]_n, (II), and poly[μ‐aqua‐bis[μ₃‐(2,4‐dichlorophenoxy)acetato‐κ⁵O¹:O^1′:O^1′,O²,Cl²]dicaesium(I)], [Cs₂(C₈H₅Cl₂O₃)₂(H₂O)]_n, (III), respectively, have been determined and their two‐dimensional polymeric structures are described. In (I), the slightly distorted tetrahedral LiO₄ coordination involves three carboxylate O‐atom donors, of which two are bridging, and a monodentate aqua ligand, together with two water molecules of solvation. Conjoined six‐membered ring systems generate a one‐dimensional coordination polymeric chain which extends along b and interspecies water O—H...O hydrogen‐bonding interactions give the overall two‐dimensional layers which lie parallel to (001). In hemihydrate complex (II), the irregular octahedral RbO₅Cl coordination about Rb⁺ comprises a single bridging water molecule which lies on a twofold rotation axis, a bidentate O_carboxy,Cl‐chelate interaction and three bridging carboxylate O‐atom bonding interactions from the 2,4‐D ligand. A two‐dimensional coordination polymeric layer structure lying parallel to (100) is formed through a number of conjoined cyclic bridges, including a centrosymmetric four‐membered Rb₂O₂ ring system with an Rb...Rb separation of 4.3312 (5) Å. The coordinated water molecule forms intralayer aqua–carboxylate O—H...O hydrogen bonds. Complex (III) comprises two crystallographically independent (Z′ = 2) irregular CsO₆Cl coordination centres, each comprising two O‐atom donors (carboxylate and phenoxy) and a ring‐substituted Cl‐atom donor from the 2,4‐D ligand species in a tridentate chelate mode, two O‐atom donors from bridging carboxylate groups and one from a bridging water molecule. However, the two 2,4‐D ligands are conformationally very dissimilar, with one phenoxyacetate side chain being synclinal and the other being antiperiplanar. The minimum Cs...Cs separation is 4.4463 (5) Å. Structure extension gives coordination polymeric layers which lie parallel to (001) and are stabilized by intralayer water–carboxylate O—H...O hydrogen bonds.     

(E)‐N′‐(4‐Chlorobenzylidene)‐, (E)‐N′‐(4‐bromobenzylidene)‐ and (E)‐N′‐[4‐(diethylamino)benzylidene]‐ derivatives of 4‐hydroxybenzohydrazide

The 4‐chloro‐ [C₁₄H₁₁ClN₂O₂, (I)], 4‐bromo‐ [C₁₄H₁₀BrN₂O₂, (II)] and 4‐diethylamino‐ [C₁₈H₂₁N₃O₂, (III)] derivatives of benzylidene‐4‐hydroxybenzohydrazide, all crystallize in the same space group (P2₁/c), (I) and (II) also being isomorphous. In all three compounds, the conformation about the C=N bond is E. The molecules of (I) and (II) are relatively planar, with dihedral angles between the two benzene rings of 5.75 (12) and 9.81 (17)°, respectively. In (III), however, the same angle is 77.27 (9)°. In the crystal structures of (I) and (II), two‐dimensional slab‐like networks extending in the a and c directions are formed via N—H...O and O—H...O hydrogen bonds. The molecules stack head‐to‐tail viaπ–π interactions involving the aromatic rings [centroid–centroid distance = 3.7622 (14) Å in (I) and 3.8021 (19) Å in (II)]. In (III), undulating two‐dimensional networks extending in the b and c directions are formed via N—H...O and O—H...O hydrogen bonds. The molecules stack head‐to‐head viaπ–π interactions involving inversion‐related benzene rings [centroid–centroid distances = 3.6977 (12) and 3.8368 (11) Å].     

Diiodobis(2‐hydroxymethyl‐1‐methyl‐1‐imidazole‐N3)cadmium(II)

The Cd atom in Cd(Hmmi)₂I₂ is five‐coordinate with a trigonal bipyramidal geometry in which the apical sites are occupied by I and O atoms. Copyright © 2005 John Wiley & Sons, Ltd.