Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds::the role of iodine Lewis basicity

The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols RfnCH2OH (Rfn = CF3(CF2)n–1; n = 11, 13, 15) are converted to the triflates RfnCH2OTf (Tf2O, pyridine; 22–61%) and then to RfnCH2I (NaI, acetone; 58–69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides RfnCH2ICl2 (n = 11, 13; 33–81%), which slowly evolve Cl2. The ethereal fluorous alcohols CF3CF2CF2O(CF(CF3)CF2O)xCF(CF3)CH2OH (x = 2–5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail. Substrates lacking a methylene group, RfnI, are also inert, but additions of TMSCl to bis(trifluoroacetates) RfnI(OCOCF3)2 appear to generate RfnICl2, which rapidly evolve Cl2. The aromatic fluorous iodides 1,3-Rf6C6H4I, 1,4-Rf6C6H4I, and 1,3-Rf10C6H4I are prepared from the corresponding diiodides, copper, and RfnI (110–130 °C, 50–60%), and afford quite stable RfnC6H4ICl2 species upon reaction with NaOCl/HCl (80–89%). Iodinations of 1,3-(Rf6)2C6H4 and 1,3-(Rf8CH2CH2)2C6H4 (NIS or I2/H5IO6) give 1,3,5-(Rf6)2C6H3I and 1,2,4-(Rf8CH2CH2)2C6H3I (77–93%). The former, the crystal structure of which is determined, reacts with Cl2 to give a 75:25 ArICl2/ArI mixture, but partial Cl2 evolution occurs upon work-up. The latter gives the easily isolated dichloride 1,2,4-(Rf8CH2CH2)2C6H3ICl2 (89%). The relative thermodynamic ease of dichlorination of these and other iodine(I) compounds is probed by DFT calculations

Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

Theoretical Aspects of Werner Complexes and Molecular Devices

This dissertation begins with the first comprehensive review of molecular gyroscopes. The following two chapters feature combined experimental/computational studies. In the first, equilibria involving gyroscope-like complexes and geometric isomers are measured and the data interpreted with molecular dynamics simulations and DFT calculations. In the second, trigonal bipyramidal diiron tetraphosphorus complexes that have parallel P–Fe–P axes and the potential for coupled Fe(CO)3 rotators are examined. Here the DFT studies focus mainly on electronic structure and IR properties. The rotators can be removed from the gyroscope-like complexes to give unprecedented dibridgehead diphosphines with long (CH2)n linkers. Their conformational, dynamic, and NMR properties are interrogated by simulated annealing and DFT calculations, helping to rationalize observed behavior and predicting properties of molecules that remain to be synthesized. Another major class of molecules investigated is polyynes H(C≡C)n'H which are of special interest at long chain lengths (models for the polymeric sp carbon allotrope carbyne). Nucleus independent chemical shifts are revealing an absence of special shielding regions and DFT calculations provide highly accurate chemical shift values, including polyynes with platinum endgroups. Complexes with four platinum corners and four –(C≡C)2– edges can be accessed. Electrostatic potential maps show highly negatively charged cores that explain the strong affinities of these species for ammonium salts. DFT calculations also establish very similar energies for planar vs. puckered conformations, both of which have been observed crystallographically: electronic structures and equilibria involving Pt3 and Pt5 homologs are also thoroughly explored. Werner complexes of the type [Co(en)3]3+ 3X– (en = 1,2-ethylenediamine) have also been extensively investigated. In one study, the intricate stereochemical and conformation properties are reviewed including substituted derivatives using conventions from both organic and inorganic chemistry. In another, >150 crystal structures of [Co(en)3]3+ salts have been analyzed with respect to hydrogen bonding between the NH groups and the counteranions. Diverse motifs could be identified and a nomenclature syntax developed

Partially Shielded Fe(CO)₃ Rotors: Syntheses, Structures, and Dynamic Properties of Complexes with Doubly <i>trans</i> Spanning Diphosphines, <i>trans</i>-Fe(CO)₃(PhP((CH₂)_<i>n</i>)₂PPh)

Reactions of Fe­(CO)₃(η⁴-benzylideneacetone) and PhP­((CH₂)_<i>m</i>CHCH₂)₂ (<i>m</i> = <b>a</b>, 4; <b>b</b>, 5; <b>c</b>, 6) give <i>trans</i>-Fe­(CO)₃(PhP­((CH₂)_<i>m</i>CHCH₂)₂)₂ (<b>2a</b>–<b>c</b>, 28–70%), which are treated with Grubbs’ catalyst (15 mol %; refluxing CH₂Cl₂). NMR analyses of the crude <i>inter</i>ligand metathesis products <i>trans</i>-Fe­(CO)₃(PhP­((CH₂)_<i>m</i>CHCH­(CH₂)_<i>m</i>)₂PPh) (<b>3a</b>–<b>c</b>, 30–31%) suggest <i>Z</i>/<i>E</i> CC mixtures and/or byproducts from <i>intra</i>ligand metathesis or oligomers. Subsequent hydrogenations (5 bar/cat. Rh­(Cl)­(PPh₃)₃ or PtO₂) afford <i>trans</i>-Fe­(CO)₃(PhP­((CH₂)_<i>n</i>)₂PPh) (<b>4a</b>–<b>c</b>, 69–77%; <i>n</i> = 2<i>m</i> + 2, <i>synperiplanar</i> phenyl groups), which density functional theory calculations show to be more stable than isomers derived from other metathesis modes. Crystallizations give (<i>E</i>,<i>E</i>)-<b>3a</b> and <b>4b</b>, the X-ray structures of which are determined and analyzed. Variable-temperature ¹³C­{¹H} NMR experiments show that rotation of the Fe­(CO)₃ moiety in <b>4b</b> is rapid on the NMR time scale (RT to 0 °C; Δ<i>G</i>^⧧_273 K ≤ 12.8 kcal/mol), but that in <b>4a</b> is not (RT to 105 °C; Δ<i>G</i>^⧧_378 K ≥ 17.9 kcal/mol). These data indicate rotational barriers lower than those in analogues in which three methylene chains connect the phosphorus atoms, <i>trans</i>-Fe­(CO)₃(P­((CH₂)_<i>n</i>)₃P)

Ruthenium(ii) arene complexes with chelating chloroquine analogue ligands: Synthesis, characterization and in vitro antimalarial activity.

Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η(6)-cym)(L(1))Cl]Cl (1, cym = p-cymene, L(1) = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η(6)-cym)(L(2))Cl]Cl (2, L(2) = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η(6)-cym)(L(3))Cl] (3, L(3) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine) have been synthesized and characterized. In addition, the X-ray crystal structure of 2 is reported. The antimalarial activity of complexes 1-3 and ligands L(1), L(2) and L(3), as well as the compound N-(2-(bis((pyridin-2-yl)methyl)amino)ethyl)-7-chloroquinolin-4-amine (L(4)), against chloroquine sensitive and chloroquine resistant Plasmodium falciparum malaria strains was evaluated. While 1 and 2 are less active than the corresponding ligands, 3 exhibits high antimalarial activity. The chloroquine analogue L(2) also shows good activity against both the chloroquine sensitive and the chloroquine resistant strains. Heme aggregation inhibition activity (HAIA) at an aqueous buffer/n-octanol interface (HAIR(50)) and lipophilicity (D, as measured by water/n-octanol distribution coefficients) have been measured for all ligands and metal complexes. A direct correlation between the D and HAIR(50) properties cannot be made because of the relative structural diversity of the complexes, but it may be noted that these properties are enhanced upon complexation of the inactive ligand L(3) to ruthenium, to give a metal complex (3) with promising antimalarial activity

Legislative Documents

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Three-Fold Intramolecular Ring Closing Alkene Metatheses of Square Planar Complexes with <i>cis</i> Phosphorus Donor Ligands P(X(CH₂)_<i>m</i>CHCH₂)₃ (X = −, <i>m</i> = 5–10; X = O, <i>m</i> = 3–5): Syntheses, Structures, and Thermal Properties of Macrocyclic Dibridgehead Diphosphorus Complexes

Reactions of <i>cis</i>-PtCl₂(P­((CH₂)_<i>m</i>CHCH₂)₃)₂ and Grubbs’ first generation catalyst and then hydrogenations afford <i>cis</i>-PtCl₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>2</b>; <i>n</i> = 2<i>m</i> + 2 = 12 (<b>b</b>), 14 (<b>c</b>), 16 (<b>d</b>), 18 (<b>e</b>), 20 (<b>f</b>), 22 (<b>g</b>); 6–40%), derived from 3-fold <i>interligand</i> metatheses. The phosphite complexes <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>m</i>*CHCH₂)₃)₂ are similarly converted to <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>n</i>*O)₃P) (<i>cis</i>-<b>5</b>; <i>n*</i> = 8 (<b>a</b>), 10 (<b>b</b>), 12 (<b>c</b>), 10–20%). The substitution products <i>cis</i>-PtPh₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>6c</b>,<b>d</b>) and <i>cis</i>-PtI₂(P­(O­(CH₂)₁₀O)₃P) are prepared using Ph₂Zn and NaI, respectively. Crystal structures of <i>cis</i>-<b>2c</b>,<b>d</b>,<b>f</b>, <i>cis</i>-<b>5a</b>,<b>b</b>, and <i>cis</i>-<b>6c</b> show one methylene bridge that roughly lies in the platinum coordination plane and two that are perpendicular. The thermal behavior of the complexes is examined. When the bridges are sufficiently long, they rapidly exchange via an unusual “triple jump rope” motion over the PtX₂ moieties. NMR data establish Δ<i>H</i>^⧧, Δ<i>S</i>^⧧, and Δ<i>G</i>_298K^⧧/Δ<i>G</i>_393K^⧧ values of 7.8 kcal/mol, −27.9 eu, and 16.1/18.8 kcal/mol for <i>cis</i>-<b>2d</b>, and a Δ<i>G</i>_393K^⧧ of ≥19.6 kcal/mol for the shorter bridged <i>cis</i>-<b>2c</b>. While <i>cis</i>-<b>2c</b>,<b>g</b> gradually convert to <i>trans</i>-<b>2c</b>,<b>g</b> at 150–185 °C in haloarenes, <i>trans</i>-<b>2c</b>,<b>g</b> give little reaction under analogous conditions, establishing the stability order <i>trans</i> > <i>cis</i>. Similar metathesis/hydrogenation sequences with octahedral complexes containing two <i>cis</i> phosphine ligands, <i>fac</i>-ReX­(CO)₃(P­((CH₂)₆CHCH₂)₃)₂ (X = Cl, Br), give <i>fac</i>-ReX­(CO)₃(P­(CH₂)₁₃CH₂)­((CH₂)₁₄)­(P­(CH₂)₁₃CH₂) (19–50%), which are derived from a combination of <i>interligand</i> and <i>intraligand</i> metathesis. The relative stabilities of <i>cis</i>/<i>trans</i> and other types of isomers are probed by combinations of molecular dynamics and DFT calculations

Three-Fold Intramolecular Ring Closing Alkene Metatheses of Square Planar Complexes with <i>cis</i> Phosphorus Donor Ligands P(X(CH₂)_<i>m</i>CHCH₂)₃ (X = −, <i>m</i> = 5–10; X = O, <i>m</i> = 3–5): Syntheses, Structures, and Thermal Properties of Macrocyclic Dibridgehead Diphosphorus Complexes

Reactions of <i>cis</i>-PtCl₂(P­((CH₂)_<i>m</i>CHCH₂)₃)₂ and Grubbs’ first generation catalyst and then hydrogenations afford <i>cis</i>-PtCl₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>2</b>; <i>n</i> = 2<i>m</i> + 2 = 12 (<b>b</b>), 14 (<b>c</b>), 16 (<b>d</b>), 18 (<b>e</b>), 20 (<b>f</b>), 22 (<b>g</b>); 6–40%), derived from 3-fold <i>interligand</i> metatheses. The phosphite complexes <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>m</i>*CHCH₂)₃)₂ are similarly converted to <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>n</i>*O)₃P) (<i>cis</i>-<b>5</b>; <i>n*</i> = 8 (<b>a</b>), 10 (<b>b</b>), 12 (<b>c</b>), 10–20%). The substitution products <i>cis</i>-PtPh₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>6c</b>,<b>d</b>) and <i>cis</i>-PtI₂(P­(O­(CH₂)₁₀O)₃P) are prepared using Ph₂Zn and NaI, respectively. Crystal structures of <i>cis</i>-<b>2c</b>,<b>d</b>,<b>f</b>, <i>cis</i>-<b>5a</b>,<b>b</b>, and <i>cis</i>-<b>6c</b> show one methylene bridge that roughly lies in the platinum coordination plane and two that are perpendicular. The thermal behavior of the complexes is examined. When the bridges are sufficiently long, they rapidly exchange via an unusual “triple jump rope” motion over the PtX₂ moieties. NMR data establish Δ<i>H</i>^⧧, Δ<i>S</i>^⧧, and Δ<i>G</i>_298K^⧧/Δ<i>G</i>_393K^⧧ values of 7.8 kcal/mol, −27.9 eu, and 16.1/18.8 kcal/mol for <i>cis</i>-<b>2d</b>, and a Δ<i>G</i>_393K^⧧ of ≥19.6 kcal/mol for the shorter bridged <i>cis</i>-<b>2c</b>. While <i>cis</i>-<b>2c</b>,<b>g</b> gradually convert to <i>trans</i>-<b>2c</b>,<b>g</b> at 150–185 °C in haloarenes, <i>trans</i>-<b>2c</b>,<b>g</b> give little reaction under analogous conditions, establishing the stability order <i>trans</i> > <i>cis</i>. Similar metathesis/hydrogenation sequences with octahedral complexes containing two <i>cis</i> phosphine ligands, <i>fac</i>-ReX­(CO)₃(P­((CH₂)₆CHCH₂)₃)₂ (X = Cl, Br), give <i>fac</i>-ReX­(CO)₃(P­(CH₂)₁₃CH₂)­((CH₂)₁₄)­(P­(CH₂)₁₃CH₂) (19–50%), which are derived from a combination of <i>interligand</i> and <i>intraligand</i> metathesis. The relative stabilities of <i>cis</i>/<i>trans</i> and other types of isomers are probed by combinations of molecular dynamics and DFT calculations