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Bis(diphenylphosphino)methane dioxide (dppmO2) forms eight-coordinate cations [M(dppmO2)4]Cl3 (M = La, Ce, Pr, Nd, Sm, Eu, Gd) on reaction in a 4:1 molar ratio with the appropriate LnCl3 in ethanol. Similar reaction in a 3:1 ratio produced seven-coordinate [M(dppmO2)3Cl]Cl2 (M = Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), whilst LuCl3 alone produced six-coordinate [Lu(dppmO2)2Cl2]Cl. The complexes have been characterised by IR, 1H and 31P{1H}-NMR spectroscopy. X-ray structures show that [M(dppmO2)4]Cl3 (M = Ce, Sm, Gd) contain square antiprismatic cations, whilst [M(dppmO2)3Cl]Cl2 (M = Yb, Dy, Lu) have distorted pentagonal bipyramidal structures with apical Cl. The [Lu(dppmO2)2Cl2]Cl has a cis octahedral cation. The structure of [Yb(dppmO2)3(H2O)]Cl3&middot, dppmO2 is also reported. The change in coordination numbers and geometry along the series is driven by the decreasing lanthanide cation radii, but the chloride counter anions also play a role.

Two di-N-functionalized macrocyclic complexes, [Ni(C-racemic-L3)]2+ bearing two N CH2CH2C( NH)OCH3 pendant arms and [Ni(C-racemic-L8)]2+ bearing two N CH2C( NH)OCH3 pendant arms, have been prepared by the reaction of methanol with [Ni(C-racemic-L2)(OAc)]+ (L2 = 1,8-bis(N-cyanoethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) or [Ni(C-racemic-L7)(OAc)]+ (L7 = 1,8-bis(N-cyanomethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Both complexes have somewhat distorted cis-octahedral coordination geometry. Their hydrolysis has been investigated under various experimental conditions. The complex [Ni(C-racemic-L3)]2+ is hydrolyzed to [Ni(C-racemic-L4)]2+ bearing two N CH2CH2COOCH3 groups in acidic aqueous solutions (pH ⩽6), but to [Ni(C-racemic-L5)]2+ bearing two N (CH2)2CONH2 pendant arms in basic aqueous solutions (pH ⩾9). Very interestingly, two N (CH2)2C( NH)OMe groups in [Ni(C-racemic-L3)]2+ undergo different reactions at pH 7 to yield [Ni(C-racemic-L6)]2+ bearing one N (CH2)2CONH2 and one N (CH2)2CN pendant arms. Although the N CH2C( NH)OCH3 groups in [Ni(C-racemic-L8)]2+ undergo hydrolysis to form [Ni(C-racemic-L9)]2+ bearing two N CH2CONH2 pendant arms in basic aqueous solutions (pH ⩾9), they are quite inert against hydrolysis in neutral and acidic aqueous solutions (pH ⩽7).

Substitution of the acetylacetonate ligands in [MO2(acac)2] (M = Mo or W) by 2-oxy-1-naphthaldehyde izonicotinoyl hydrazonate (NIH2−) or 3-methoxy-2-oxybenzaldehyde izonicotinoyl hydrazonate (VIH2−) gives rise to either zigzag chain polymers, [MO2(NIH)]n (1 and 2), square complexes [MO2(VIH)]4 (3 and 4), mononuclear complexes [MO2(VIH)(C2H5OH)] (5 and 6), or to polyoxomolybdate hybrid compounds [{; ; ; MoO2(HNIH)}; ; ; 2Mo6O19] (7) and [MoO2(HVIH)(H2O)]2Mo6O19 (8), depending on the reaction conditions. In all of these compounds the ligand is coordinated to the cis-MO22+ core via phenolic-oxygen, azomethine-nitrogen and enolic-oxygen atoms, while the remaining sixth coordination site is occupied either by the nitrogen atom of the izonicotinyl part, or by an oxygen atom from the solvent molecule, or by an oxygen atom from the hexanuclear anion. Crystal and molecular structures of the molybdenum(VI) compounds [MoO2(NIH)]n (1), [MoO2(VIH)]4 (3), [{; ; ; MoO2(HNIH)}; ; ; 2Mo6O19] (7) and [MoO2(HVIH)(H2O)]2Mo6O19 (8) were determined by the single crystal X-ray diffraction method. Dioxotungsten(VI) compounds [WO2(NIH)]n (2) and [WO2(VIH)]4 (4) were structurally characterized by the X-ray powder diffraction method. All of the investigated compounds were further characterized by elemental analysis, thermogravimetric analyses, cyclic voltammetry, FT-IR, UV-Vis and NMR spectroscopy.

Three chiral cis -octahedral Grignard reagents have been synthesized and structurally characterized by X-ray diffraction methods. Crystals of cis -[( n -Pr)MgBr(dme) 2 ] ( 1 ), cis -[( i -Pr)MgBr(dme) 2 ] ( 2 ) and cis -[(allyl)MgBr(dme) 2 ] ( 3 ) were prepared from neat 1,2-dimethoxyethane (DME) and are all racemic. Synthesis and structural characterization of trans -[MgBr 2 (tmeda) 2 ] ( 4 ) and cis -[MgBr 2 (dme) 2 ] ( 5 ) indicated that bidentate tertiary amino ligands may be less well suited for the preparation of cis -octahedral Grignard reagents. On the other hand, the crystal structures of cis -[MgBr 2 (trigly)] ( 6 ) and [Mg 2 (μ-Br) 2 (trigly) 2 ][Mg 2 (μ-Me) 2 Br 4 ] ( 7 ) {trigly=triglyme)}, suggest that the triglyme ligand may be ideally suited for this purpose.

The synthesis of a homogeneous series of cis bis substituted iron complexes is described. These complexes which display the [M]{[C(O)] x R}{[C(O)) y R′]} ( x + y =0, 1, 2, 3, 4; x , y ⩽2) pattern are models for the study of carbon–carbon coupling processes including mono- and polycarbonylations. Their reactivity is reviewed and particularly that of bis alkoxycarbonyl, bis carbamoyl and metalla γ ketoester iron compounds.

Several diorgano- and dihalotin(IV) derivatives of new β-diketonate donors, 1,3-dimethyl-4-R(CO)pyrazol-5-ones (R=Me, QDH; R=Ph, QMH) have been synthesized and characterized with analytical and spectroscopic methods. They are stable monomeric species, very soluble not only in aromatic and chlorohydrocarbon solvents, but also in alcohols and hydroalcoholic solutions. In the solid state, the diorganotin(IV) derivatives adopt a skewed trapezoidal bipyramidal geometry. The X-ray structure of bis(1,3-dimethyl-4-acetylpyrazolon-5-ato)dicyclohexyltin(IV) shows marked distortion of the organometallic C–Sn–C angle (155°) and two different sets of Sn–O distances. The factors affecting the distortion of this type of complex are discussed. The dihalotin(IV) derivatives (Q)2SnX2 (X=F, Cl, Br and I) are likely cis octahedral in the solid state, whereas in solution they exist as a mixture of cis and trans isomers. 119Sn-NMR solution data are discussed and related to electronic and steric properties of the β-diketonate donor, and also to the nature of the halo and organic groups bound to tin.

Ethyl-5-methyl-4-imidazolecarboxylate (emizco) is an important intermediate in the synthesis of pharmacological ac- tive compounds. In this work, there were synthetized and char- acterized the following coordination compounds with emizco: trans-(Co(emizco)2(H2O)2)(NO3)2 1, trans-(Ni(emizco)2(H2O)2)(NO3)2 2, trans-(Cd(emizco)2(H2O)2)(NO3)2 (3) and cis-(Cd(emizco)2Br2) (4). 2D or 3D supramolecular arrangements were stabilized. All nitrate trans octahedral compounds stabilized a 3D supramolecular arrange- ment via hydrogen bonding, throughout the nitrate anions, the ligand and the coordinated water molecules; the cis-octahedral halide com- plex formed a 2D pleated sheet arrangement, by intermolecular π stacking and halide-hydrogen bonding. Resumen. El etil 5-metil-4-imidazolcarboxilato (emizco) es un in- termediario importante en la sintesis de compuestos con activi- dad farmacologica. En el presente trabajo se sintetizaron y carac- terizaron los siguientes compuesto de coordinacion con emizco: trans-(Co(emizco)2(H2O)2)(NO3)2 1, trans-(Ni(emizco)2(H2O)2)(NO3)2 2, trans-(Cd(emizco)2(H2O)2)(NO3)2 (3) y cis-(Cd(emizco)2Br2) (4). Estos compuestos estabilizan estructuras supramoleculares en 2D o 3D; todos los compuestos de nitrato con geometria trans octaedrica estabilizan arreglos en 3D por medio de puentes de hidrogeno entre los iones nitrato, emizco y las moleculas de H2O; mientras que el compuesto de coordinacion del haluro cis octaedrico tiene un arreglo en forma de hoja plegada en 2D, por medio de interacciones intermo- leculares de tipo apilamiento-π y puente de hidrogeno-haluro. Palabras clave: Emizco, cobalto(II), niquel(II), cadmio(II), compues- to de coordinacion, arreglos supramoleculares.

The reaction of [MoO2(acac)2] (where acac = acetylacetonate ligand) with the salicylaldehyde isonicotinyl hydrazonate ligand (SIH2−) yielded a zigzag chain polymer [MoO2(SIH)]n (1), an interwoven hexagon [MoO2(SIH)]6 (2), or the mononuclear complexes [MoO2(SIH)(C2H5OH)] (3EtOH) and [MoO2(SIH)(C3H7OH)] (3PrOH). Diversity in the formation of dioxomolybdenum(VI) compounds illustrates their sensitivity to the reaction conditions. Crystal and molecular structures of all of the investigated molybdenum(VI) compounds were determined by the single crystal X-ray diffraction method. Solid-state reactions lead to the transformation of the supramolecular hexagon or the mononuclear complexes into the chain coordination polymer. These thermally induced conversions were characterized by the X-ray powder diffraction method. All of the investigated compounds were further characterized by elemental analysis, thermogravimetric analyses, Fourier transform infrared (FT-IR), and NMR spectroscopy.

1,4,8,11-Tetrakis(methyldiphenylphosphino)-1,4,8,11-tetraazacyclotetradecane (TPTA) reacts with molybdenum(0) and tungsten(0) hexacarbonyls to give yellow crystalline diamagnetic complexes of the formula [M(CO) 4 ] 2 TPTA. Each metal atom in these binuclear species is coordinated by two phosphorus atoms from the pendant methyldiphenylphosphino groups and by four carbonyls in a cis octahedral arrangement.

α-Hydroxyiminophosphonic acid derivatives are widely known not only as intermediates in the synthesis of the important aminophosphonic acids,1,2 but also as phosphorylating agents,3 potential metalloenzyme inhibitors,4 and as compounds having fungicidal activity.5 In this work the scope of these compounds has been extended considerably by the synthesis of a number of novel dialkyl derivatives. Novel lanthanide (LaIII, PrIII, NdIII, GdIII and DyIII) and transition metal (CoII and NiIII) complexes of dialkyl α-hydroxyiminophosphonates (RO)2P(O)C(R')N(OH) where R = Et. Pri and R′ = Me, Et have been prepared and the NMR shift properties of the PrIII complex (R = Et; R′ = Et) indicate the potential of these compounds as NMR shift reagents for the analysis of geometric isomers.6,7 X-ray crystal structure analysis of [Ni(L1)2C12] (L1: R = Et; R′ = Et) shows a distorted cis octahedral coordination at the nickel atom giving two symmetry related diethyl-(E)-α-hydroxyiminopropanephosphonate ligands and two ...

Olique-texture electron diffraction examination of K-saturated dioctahedral smectites after 70-100 wetting-drying cycles allows the determination of cation distribution between trans and cis octahedra of the 2:1 layers. Studies of smectites with different compositions has revealed a wide variety of occupancies of the available octahedral sites. In dioctahedral phyllosilicates only two of the three symmetrically independent octahedral positions are occupied by cations. The 2:1 layer will have a centre of symmetry if the trans octahedra are vacant (model 1, Fig. la) and it will have none if the cations occupy trans octahedral sites as well as cis octahedral positions, forming one of the two regular systems of points (model 2, Fig. lb). Numerous structure refinements of dioctahedral layer-silicates have shown that the octahedral cations occupy only the cis octahedrat positions of the 2:1 layers if the total number of these cations per unit cell is equal to 4. The probable existence of two-layer micas with non-centrosymmetrical layers was noted by B. B. Zvyagin et al. (1979); these authors also specified the possible polytypes of micas with such layers and calculated their diffraction data for ideal models.

IR- und elektronenspektroskopische Untersuchungen an [Co(phen)2X2]-Komplexen (XF−, Cl−, Br−, J−, NCS−, NCO−, NO3−, SO−, ClO4−, HCOO−, H3CCOO−, H5C2COO−, n-H7C3COO− und Salicylat) wurden zur weiteren Charakterisierung dieses Koordinationstyps durchgefuhrt. Die Untersuchungsergebnisse deuten auf cis-oktaedrische Ligandenanordnung in diesen Verbindungen hin. Aus den v1- und v3-Ubergangen der Elektronenspektren wurden die Ligandenfeldparameter B und Dq berechnet sowie die Lage des Zweielektronenubergangs v2 bestimmt. Die [Co(phen)2X2]-Verbindungen unterliegen in Losung Symmetriegleichgewichten zwischen pseudooktaedrischer und -tetraedrischer Ligandenanordnung, die auf Komplexdisproportionierung zuruckzufuhren ist. Die grune Form des Chloridkomplexes konnte isoliert und als [Co(phen)Cl2] identifiziert werden. On Bis(phenanthroline) cobalt(II) Complexes Spectrophotometric investigations of [Co(phen)2X2] complexes in the IR and UV/VIS region are described. The results of this investigations show cis octahedral arrangement of the ligands. From the v1- and v3-transitions of the electronic spectra the LF parameters B and Dq are calculated and from this the two electron transition v2 is estimated. [Co(phen)2X2] complexes show symmetry equilibria between octahedral and tetrahedral forms in solutions by reason of complex disproportionation reactions. The green form of the chloride complex could be isolated and identificated as [Co(phen)Cl2].

The dynamic aspects of the stereoisomerizations of some bis(β-diketonato) complexes have been investigated with the aid of permutational analysis and topological representations. The analysis indicates that the lowest energy rearrangement mode (M4) occuring in such complexes, and involving a reversal of the helecity of the structure, is permutationally equivalent to the “one-ring flip” mechanism of diaryl derivatives of the type Ar2ZX, which are shown to be stereochemically correspondent to the bis-chelate molecules. The activation energies associated with such arrangements have been determined by variable temperature NMR studies. Only for bis(acetylacetonato) bis-(triphenylphosphine)ruthenium(II) is the activation barrier high enough to allow resolution of the two enantiomers at ambient temperatures.

IR- und elektronenspektroskopische Untersuchungen an [Co(phen)2X2]-Komplexen (XF−, Cl−, Br−, J−, NCS−, NCO−, NO3−, SO−, ClO4−, HCOO−, H3CCOO−, H5C2COO−, n-H7C3COO− und Salicylat) wurden zur weiteren Charakterisierung dieses Koordinationstyps durchgefuhrt. Die Untersuchungsergebnisse deuten auf cis-oktaedrische Ligandenanordnung in diesen Verbindungen hin. Aus den v1- und v3-Ubergangen der Elektronenspektren wurden die Ligandenfeldparameter B und Dq berechnet sowie die Lage des Zweielektronenubergangs v2 bestimmt. Die [Co(phen)2X2]-Verbindungen unterliegen in Losung Symmetriegleichgewichten zwischen pseudooktaedrischer und -tetraedrischer Ligandenanordnung, die auf Komplexdisproportionierung zuruckzufuhren ist. Die grune Form des Chloridkomplexes konnte isoliert und als [Co(phen)Cl2] identifiziert werden. On Bis(phenanthroline) cobalt(II) Complexes Spectrophotometric investigations of [Co(phen)2X2] complexes in the IR and UV/VIS region are described. The results of this investigations show cis octahedral arrangement of the ligands. From the v1- and v3-transitions of the electronic spectra the LF parameters B and Dq are calculated and from this the two electron transition v2 is estimated. [Co(phen)2X2] complexes show symmetry equilibria between octahedral and tetrahedral forms in solutions by reason of complex disproportionation reactions. The green form of the chloride complex could be isolated and identificated as [Co(phen)Cl2].

The dynamic stereochemistry of phenylchlorobis(benzoylacetonato)tin has been investigated in solution with the aid of variable temperature 1 H NMR spectroscopy. The results, analyzed in terms of permutational analysis and topological representations, reveal that in this complex at least two different rearrangement modes are necessary in order to give exchange of all the isomers and diastereotopic signals. The free energies associated with each mode have been determined and have shown to be very similar to each other. The residual isomerism is discussed in the light of the results.

A re-examination of the electronic properties and structure of [Cu(dmphen)2(O2NO)][CCl3CO2]·CCl3CO2H (dmphen = 2,9-dimethyl-1,10-phenanthroline) suggests that it is best described as a distorted squarepyramidal cis octahedral CuN4O2 chromophore (4 + 1 + 1*) as suggested by the electronic reflectance spectrum, but involving a novel sense of distortion.