Metal complexes of 2,4-diamino-5-(3′,4′,5′-trimethoxybenzyl)pyrimidine, (trimethoprim). Part II. Synthesis,magnetic characterization and X-ray structure of [Cu2(O2CCH3)4(trimethoprim)2]·2C6H6·CH3OH

The reaction of [Cu₂(O₂CCH₃)₄·2H₂O] with trimethoprim is reported. In methanol a green solution was obtained, which, on adding benzene, yielded tetrakis(μ-acetato)bis(trimethoprim)dicopper(II) di-benzene methanol solvate. The compound crystallizes with four molecules per cell in the monoclinic space group C2/c, with a = 24.109(5), b = 15.256(3), c = 16.532(3) Å, β = 116.89(2) for λ(Mo-Kα) = 0.71073 Å. The copper atoms are bridged by four acetate groups to form the binuclear molecule [Cu₂-(O₂CCH₃)₄(TMP)₂]·2C₆H₆·CH₃OH. The TMP ligand acts as a donor molecule through one pyrimidinic nitrogen atom.     

Tris(1-methylcytosine-N3)ammineplatinum(II) perchlorate monohydrate,a model for simultaneous binding of three nucleobases to a single metal ion

A Pt(II) complex containing three 1-methylcytosine ligands (C), [Pt(NH₃)C₃] (CIO₄)₂· H₂], has been prepared starting with cis-Pt(NH₃)₂Cl₂, and its crystal structure has been determined. The title compound represents a model of a hypothetical interaction of cis.Pt(II) with three biomolecules which proceeds via an intermediate monochloro complex, cis-[Pt(NH₃)₂CCl]Cl, and loss of ammonia from this compound. [Pt(NH₃)C₃](ClO₄)₂·H₂O crystallizes in space group P2₁/c (No. 14) with a = 15.296(3), b = 4.666(3), c = 14.025(2) Å, β = 122.61(1)° and has 4 formula units in the unit cell. Data were collected with use of a Syntex P2₁ diffractometer and MoKα radiation. The crystal structure was determined by standard methods and refined to R₁ = 0.043 and R₂ = 0.056 based on 2925 independent reflections. The compound contains the three 1-methylcytosine ligands bound through N(3) with the three ligands almost perpendicular to the Pt coordination plane. The two C ligands trans to each other have identical orientations with respect to the platinum square plane whereas the cytosine trans to NH₃ has the opposite orientation. Bond lengths and angles are normal.     

The structure of (μ3-sulfido)(μ3-p-tolyphosphido)tris(tricarbonyliron)(2FeFe)

Compounds of the type (μ₃-S)(μ₃-RP)Fe₃(CO)₉ have been prepared by the reaction of Fe₃(CO)₁₂ with [RP(S)S]₂ or RP(S)Cl₃. In this paper we report the synthesis of (μ₃-S)(μ₃-CH₃OC₆H₄P)Fe₃(CO)₉ using Lawesson's reagents, and the three dimensional structure of (μ₃-S)(μ₃-p-CH₃C₆H₄P)Fe₃(CO)₉. This material crystallizes in the space group P2₁/n with a = 8.558(2) Å, b = 9.022(2) Å, c = 27.506(6) Å, β = 95.40(2)°, Z = 4. The cluster is a nido structure as found commonly for (μ₃-X)(μ₃-Y)Fe₃(CO)₉ complexes.     

Synthesis and crystal structure of bis(tetramethylammonium) aquotetra-fluorodioxouranate(VI) dihydrate, [(CI3)4 N]2[UO2 F4(H2 O)]·2H2O

The title compound has been synthesized and subjected to crystal structure analysis. M_r = 548.50, m.p. 108.1 °C (decom.), orthorhombic, Im2m,a = 7.006(2), b = 8.938(2), c = 13.619(2) Å V = 852.8(3) ų, Z = 2, D_x = 2.136, D_m, (flotation in CCl₄/CH₂I₂) = 2.128 g cm^?3, λ(Mo-Kα) = 0.71069 Å, μ = 90.79 cm^?1, F(000) = 519.89, T = 295 K, final R_F = 0.036 and R_G = 0.044 for 566 observed reflections. The discrete [UO₂F₄(H₂0)]^2? anion has site symmetry m2m, its virtually linear uranyl moiety being surrounded by fluoro and aquo ligands occupying the vertices of a pentagon in the equatorial plane. Watet molecules serve to link the complex anions by hydrogen bonds into layers, between which the organic cations are accommodated.     

An inspection into the class of bis(alkyne)-undecacarbonyl-quadro-tetraruthenium complexes. Crystal structure and dynamic behaviour of Ru4(CO)11 (μ4, η2-MeC2Ph)2

The reactions of the butterfly complex Ru₄(CO)₁₂(MeC₂Ph) with several alkynes give the quasiplanar derivatives Ru₄(CO)₁₁(MeC₂Ph)(Alkyne) in almost quantitative yields.The structure of Ru₄(CO)₁₁(MeC₂Ph)₂ has been determined by X-ray methods. Crystals are monoclinic, space group C2/c, with Z = 4 in a unit cell of dimensions a 22.383(16), b 9.048(8), c 18.268(12) Å, β = 127.25(4)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.034 for 1420 observed reflections. The complex, having an imposed C₂ symmetry, presents a tetranuclear metal cluster in which the Ru atoms are in a tetrahedrally-distorted square arrangement. Ten carbonyls are terminal and one symmetrically bridges an edge of the cluster. Each of the two alkyne ligands is σ-bonded to two Ru atoms on the opposite vertices of the cluster and π-bonded to the other two. The organometallic cluster has a Ru₄C₄ core in which the metal and carbon atoms occupy the vertices of a triangulated dodecahedron.     

Non-adiabatic electronic energy transfer from the (3CTRu(bpy)2(CN)2 excited state to Cr(III) complexes

The quenching of the luminescence lifetime of cis-Ru(bpy)₂(CN)₂ (bpy = 2,2′-bipyridine) by complexes of the cis- and trans-Cr(en)₂(XY)⁺ families (en = ethylenediamine; X and Y = F, Cl, Br, NCS, ONO) has been studied in aqueous solution and the results obtained have been discussed together with those previously reported for the quenching of the Ru(bpy)₃²⁺ luminescene by the same Cr(III) complexes. Experimental results and theoretical considerations show that the quenching process occurs by exchange electronic energy transfer. Since in all cases the process is sufficiently exoergonic to make up for the small intrinsic barriers, the lowest diffusion values of the quenching constants indicate a non-adiabatic behavior. The degree of adiabaticity of the energy transfer process is larger for the neutral Ru(bpy)₂(CN)₂ donor than for the positively charged Ru(bpy)₃²⁺ donor. The X and Y ligands can be ordered in the following adiabaticity series: ONO^?, F^? < Cl^? <NCS^? <Br^?. The geometry of the acceptor is a discriminating parameter only for energy transfer from the charged donor. These results show that the electronic term of exchange energy transfer in non-adiabatic processess is governed by a delicate balance of factors related to the composition and structure of the encounter complex [1].     

An assessment of the cis-influence in coenzyme B12 Models. The structure of the mixed schiff-base/oxime complex: Aquo(3,9-dimethyl-2,10-diethyl-1,4,8,1 1-tetra-azaundeca-1,3,8,10-tetraen-11-ol-1-olato)(methyl)cobalt(III)hexafluorophosphate

The title compound is the first accurately determined structure in the general class of ‘Costa’ B₁₂ models. The data permit comparisons of structural results to other relevant B₁₂ models and the construction of a cis effect series.Crystal Data: C₁₄H₂₀CoF₆N₄O₃P, M = 504.4, monoclinic, space group P2₁/c, a = 14.316(3), b = 6.819(1), c = 22.741(5) Å and β = 99.91(2)°, V = 2186.9 ų, D_m = 1.52, Z = 4, D_c = 1.53 g cm^?3, μ(MoKα) = 9.2 cm^?1, λ(MoKα) = 0.7107 Å. Unit cell parameters were refined and intensity data collected on a CAD4 computer-controlled diffractometer, using graphite-monochromated MoKα radiation. A total of 5803 reflections were collected and corrected for Lorentz-polarization factor, 2802 independent reflections with I > 3σ(I) being used in the subsequent calculations.The CoO bond length to the axial water is 2.102- (3) Å. This value places the Costa model structural cis influence as being comparatively close to corrin based systems, somewhat greater than cobaloximes and definitely lower than Schiff-base complexes.     

Preparation and crystal structure of manganese(II) isothiocyanate tetrahydrate

Crystals of Mn(NCS)₂·4H₂O were isolated from an aqueous solution obtained by mixing solutions of barium thiocyanate and manganese(II) sulphate tetrahydrate. The crystals are monoclinic with a = 7.827(7), b = 9.208(1), c = 7.456(5) Å, β = 112.57(5)°, space group P2₁/c. The structure consists of discrete centrosymmetric trans-[Mn(NCS)₂(H₂O)₄] octahedra linked by hydrogen bonds.     

Lanthanide ion catalysis of the trans-cis isomerization of trans-bis(oxalato)-diaquochromate(III) and trans-bis(malonato)diaquochromate(III) [1]

The lanthanide ion catalyzed trans-cis isomerizations of trans-bis(oxalato)diaquochromate(II) and trans-bis(malonato)diaquochromate(III) have been studied. A linear free energy relationship was found correlating the catalytic rate constants for the oxalate reaction with the corresponding formation constants of complexes formed between simple monocarboxylic acids and the light (LaGd) members of the lanthanide series. The results indicates that for this portion of the series, the reaction mechanism is related to the formation of monocarboxylate complex intermediates. When the ionic radius of the lanthanide ion decreases below a particular value (as in the latter half of the series), the metal ion remains coordinated to both carboxylates of the oxalate ion rather than simply binding to only one carboxylate. In either situation, isomerization to the cis product eventually occurs, and the lanthanide ion is released.The reaction rates associated with the trans-bis(malonato)diaquochromate(III) reaction were found to be significantly slower than those of the corresponding oxalate system. However, in the malonate system, no linear free energy relationship was found relating the catalytic rate constants with the corresponding formation constants of monocarboxylic acids. One does find a linear relationship between the catalytic rate constants for the malonate reaction and the log K₁ values for the corresponding lanthanide/malonate complexes. During the course of the trans-cis isomerization, the lanthanide ion chelates the dissociated malonate group of a pentavalent Cr(III) intermediate. In the mechanism the lanthanide ion does not aid in ring opening, and neither does it singly bond to the intermediate     

Macrocyclic polyphosphane ligands: cobalt(II) and nickel(II) complexes of 1,10-dipropyl-4RS, 7SR, 13SR, 16RS-tetraphenyl-1,10-diaza-4,7,13,16-tetraphospha-cyclooctadecane and crystal structure of the cobalt tetraphenylborate monohydrate complex

The X-ray crystal structure of the title compound has been carried out. The crystals are triclinic, space group P$\text{1}$, a = 13.252(2), b = 13.943(2), c = 24.316(5) Å, α = 70.660(14), β = 75.219(14), γ = 69.231(13)° for Z = 2. The structure has been refined to an R factor of 0.069 by the least-squares technique. The cobalt atom is five-coordinated by the four phosphorus atoms of the macrocycle and by a water molecule forming a distorted square-pyramidal geometry. The stereochemistry of some cobalt(II) and nickel(II) complexes of the same ligand were investigated, in the solid state and in solution, by electronic spectroscopy.     

Crystal structure of (theophyllinato)methylmercury(II) monohydrate

The title compound belongs to space group P2₁/c, a = 10.884 Å, b = 9.187 Å, c = 14.458 Å, β = 131.02°, Z = 4. The structure was refined on 1355 nonzero reflections to an R factor of 0.059. The crystal contains discrete [CH₃Hg(theophyllinate)] molecules in which the proton initially bound to N7 is replaced by the CH₃Hg⁺ ion. The water molecule forms hydrogen bonds with both carbonyl oxygens, whereas an intermolecular contact of 2.98 Å is established between mercury and N9. The intramolecular Hg?O6 distance of 3.18 Å is consistent with the absence of significant Hg?carbonyl bonding interactions in the present structure.     

Uranyl(VI), copper(II) and nickel(II) complexes derived from a new compartmental ligand

A new heptadentate compartmental ligand has been synthesized by condensation of 3-formylsalicylic acid and 1,5-diamino-3-thiapentane in methanol (H₄L_a). This Schiff base contains an inner N₂SO₂ and an outer O₂O₂ site and gives, by reaction with copper(II), nickel(II) and uranyl(VI) diacetate, mononuclear, homo- and heterobinuclear complexes. In the mononuclear copper and nickel complexes, the metal ion is in the inner N₂SO₂ site, while it is in the outer O₂O₂ for uranyl; a solvent molecule fills the fifth equatorial coordination position in this last complex. The physico-chemical properties of the compounds are discusscd on the basis of infrared, electronic and magnetic data and by comparison with the analogous complexes with the ligand obtained by reaction of 3- formylsalicylic acid and diethylenetriamine (H₄L_b). The mononuclear copper and the heterodinuclear copper-uranyl complexes show anomalously low magnetic moments.     

Preparation and characterization of (9-methyladenine)triammineplatinum(II) and trans-dihydroxo(9-methyladenine)triammineplatinum(IV) complexes

The preparation is reported of [(NH₃)₃Pt(9- MeA)] X₂ (9-MeA = 9-methyladenine) with XCl (1a) and XClO₄ (1b) and of trans-[(OH)₂Pt(NH₃)₃- (9-MeA)]X₂ with XCl (2a) and XClO₄ (2b), and the crystal structure of 1b. [(NH₃)₃Pt(C₆H₇N₅)](ClO₄)₂ crystallizes in space group P2₁/n with a = 20.810(7) Å, b = 7.697(3) Å, c = 10.567(4) Å, β = 91.57(6)°, Z = 4. The structure was refined to R = 0.054, R_w = 0.063. In all four compounds Pt coordination is through N7 of 9-MeA, as is evident from ³J coupling between H8 of the adenine ring and ¹⁹⁵Pt. Pt(II) and Pt(IV) complexes can be differentiated on the basis of different ³J values, larger for Pt(II) than for Pt(IV) by a factor of 1.57 (av). In Me₂SO-d₆, hydrogen bonding occurs between Cl^? and C(8)H of 9-MeA as weil as between Cl^? and the NH₃ groups in the case of the Pt(II) complex 1a. Protonation of the 9-MeA ligands was followed using ¹H NMR spectroscopy and pK_a values for the N1 protonated 9-MeA ligands were determined in D₂O. They are 1.9 for 1a and 1.8 for 2a, which compares with 4.5 for the non-platinated 9-MeA. Possible consequences for hydrogen bonding with the complementary bases thymine or uracil are discussed briefly. Protonation of the OH groups in the Pt(IV) complexes has been shown not to occur above pH 1.     

Interaction of metal ions with humic-like models. Part VII. Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of 2,5-dihydroxybenzoic acid

Complexes of formula M(2,5-DHB)₂4H₂O (M = Mn, Co, Ni, Zn, Cu and Cd; 2,5-DHB = 2,5-dihydroxybenzoate) were prepared and characterized by means of infrared and electronic spectroscopy, and by electron spin resonance. For the Zn complex the crystal and molecular structure was also determined by single-crystal X-ray diffraction analysis. The crystal is orthorhombic, space group Pbca (No. 61), with a = 18.503(4), b = 13.536(3), c = 6.900(2) Å, and Z = 4. The final refinement used 877 reflections and gave a residual R value of 0.041. The complex has slightly compressed octahedral coordination, with the zinc atom bound to two monodentate carboxylate groups lying in trans positions and four water molecules. X-ray data and infrared spectra show the Mn, Co, Ni, Zn and Cd complexes to be isostructural with the Zn compound. The electronic, infrared and ESR spectra of the copper(II) complex are consistent with a CuO_4? based chromophore involving two water molecules and two monodentate carboxylate groups in the metal plane, and long axial contacts.     

Metal-penicillamine interactions. Part 1. Preparation and crystal structure of a 1:1 complex of mercuric chloride with d-penicillamine, 2[μ3-Cl){HgSC(CH3)2CH(NH3)COO}3·3(μ2-Cl)· 2(H3O)·(H2O·Cl)3

A 1:1 complex of mercuric chloride with D-peniccillamine has been isolated and characterised as 2[(μ₃-Cl){HgSC(CH₃)₂CH(NH₃)COO}3]·3(μ₂-Cl)·2(H₃O)·(H₂O·Cl)₃. The compound crystallises in cubic space group P4₁32, with a = 18.679(5) Å and Z = 4. The structure, refined to R_F = 0.086 for 443 observed Mo-Kα diffractometer data, features a triply bridging chloride ion linking three equivalent [HgSC(CH₃)₂CH(NH₃)COO]⁺ units [Hg-Cl = 2.37(1) Å, Hg-Cl-Hg′ = 98.5(9)°]. The carboxylate groups of a pair of adjacent penicillamine ligands are strongly linked via a symmetrical O?H?O hydrogen bond of length 2.24(8) Å, and neighboring pyramidal trinuclear [μ₃-Cl){HgSC(CH₃)₂CH(NH₃)-COO}₃]²⁺ moieties are further connected by symmetrical chloride bridges [Hg-Cl = 3.06(2) Å; HgClHg′' = 79.6(7)°] to form a three-dimensional network. The voids in the lattice are filled by hydronium ions and novel planar cyclic hydrogen-bonded (H₂O·Cl^?)₃ rings of edge O-H?Cl = 2.46(4) Å.     

Crystal and molecular structure of Δ-cis-α-ethylenebis-S-prolinato(1,2-diamino-ethane)cobalt(III) perchlorate dihydrate, Δ-cis-α-[Co(ss-EBP)(en)] ClO4·2H2O

The crystal and molecular structure of Δ- cis-α- ethylenebis-S-prolinato(1,2-diaminoethane)cobalt(III) perchlorate dihydrate, Δ-cis-α-[Co(SS-EBP)(en)] ClO₄· 2H₂O, was determined from three-dimensional X-ray diffractometer data. The complex crystallizes in the orthorhombic system, space group P2₁2₁2₁ with a = 7.879(4) Å, b = 13.738(9) Å, c = 19.445(2) Å, V = 2104(2) ų. With Z = 4, the observed and calculated densities are 1.60(2) and 1.605 g cm^?3, respectively. The structure was refined by the block- diagonal least-squares technique to a final R = 0.0560 for 1604 observed reflections. The geometry about the cobalt atom is roughly octahedral with the tetradentate SS-EBP (= ethylenebis-S-prolinate ion), assuming cis-α configuration in which the complex possesses two out-of-plane amino acidate (R) rings and the backbone ethylenediamine (E) ring. The E ring conformation is δ. On the other hand, the R rings have λ conformation as well as the en ring. Δ-R_NR_N?(δ_E  λ_R1  λ_R2)(λ_en)-cis-α-[Co(SS-EBP)(en)]⁺ is one of two possible isomers of this compound which have been isolated and whose absolute configurations have been tentatively assigned by spectroscopy. The crystal and molecular structure determination confirms these assignments.     

Proton nuclear magnetic resonance study of N,N-diethylformamide exchange on (N,N-diethylformamide)2,2′2″-tris(dimethylamino)triethylamine)cobalt(II) and its copper(II) analogue

Proton NMR studies of N,N-diethylformamide (def) exchange on [M(Me₆tren)def]²⁺ where M = Co and Cu yield: k_ex (298.2K) = 26.3 ± 2.2, 980 ± 70 s⁻¹; ΔH^≠ = 58.3 ± 1.7, 36.3 ± 0.9 kJ mol⁻¹; ΔS^≠= −22.2 ± 4.6, −65.9 ± 2.5 J K⁻¹ mol⁻¹; and ΔV^≠ = −1.3 ± 0.2, 5.3 ± 0.3 cm³ mol⁻¹ respectively. These data which are consistent with a and d activation modes operating when M = Co and Cu respectively are compared with data for related systems.     

Reaction of PtOH complexes with CO2: synthesis and X-ray structure of (PBz3)4Pt2(Ph)2(η1,η1,μ-CO3)·(toluene)

The reaction of (diphoe)Pt(CH₂CN)(OH) and trans-(PBz₃)₂Pt(Ph)(OH) with CO₂ is reported as producing dimeric, bridged carbonato complexes of the type: P₄Pt₂(R)₂(CO₃). The crystal and molecular structure of (PBz₃)₄Pt₂(Ph)₂(μ-CO₃)·(toluene) is also reported, showing η¹, η¹ bonding. The reaction is recognized to proceed in a stepwise fashion through bicarbonato intermediates.