Poly[octa-carbonyl-heptakis-(tetra-hydro-furan)-diironmanganesedisodium(2 Mn-Fe)].

The reaction of Na2Fe(CO)4 with an excess of MnCl2 in tetra-hydro-furan (THF) produced {Fe2Mn(C4H8O)2Na2(C4H8O)5(CO)8] n or C36H56Fe2MnNa2O15. The compound is a xenophilic dianion with short iron-manganese bond lengths of 2.6274 (10) and 2.6294 (10) Å. The sodium cations of the dianion are coordinated to THF ligands and have isocarbonyl inter-actions forming a polymeric (two-dimensional) structure in the crystal. One of the THF mol-ecules was modeled with the carbon atoms being statistically disordered.

Bioactive hydroperoxyl cembranoids from the Red Sea soft coral Sarcophyton glaucum.

A chemical investigation of an ethyl acetate extract of the Red Sea soft coral Sarcophyton glaucum has led to the isolation of two peroxide diterpenes, 11(S) hydroperoxylsarcoph-12(20)-ene (1), and 12(S)-hydroperoxylsarcoph-10-ene (2), as well as 8-epi-sarcophinone (3). In addition to these three new compounds, two known structures were identified including: ent-sarcophine (4) and sarcophine (5). Structures were elucidated by spectroscopic analysis, with the relative configuration of 1 and 2 confirmed by X-ray diffraction. Isolated compounds were found to be inhibitors of cytochrome P450 1A activity as well as inducers of glutathione S-transferases (GST), quinone reductase (QR), and epoxide hydrolase (mEH) establishing chemo-preventive and tumor anti-initiating activity for these characterized metabolites.

Remote exo/endo selectivity in selective monohydrolysis of dialkyl bicyclo[2.2.1]heptane-2,3-dicarboxylate derivatives.

High exo-facial selectivity was observed in the selective monohydrolysis of a series of near-symmetric diesters that possess an exo-ester group and an endo-ester group attached on a norbornane or norbornene skeleton. The selectivities were found to be clear-cut, although the reaction center in these reactions is one covalent bond distant from the norbornane or norbornene ring, where the difference of the environment between the exo face and endo face is therefore expected to be negligible. The effect of the co-solvent we studied earlier for the selective monohydrolysis reaction was also confirmed and contributed to improvement of the yields of the half-esters.

Crystal Structure, Physical Properties, and Hydrolysis Kinetics of [(O)(tmpa)V(IV)(&mgr;-O)V(V)(tmpa)(O)](3+).

We report the synthesis, crystal structure, physical properties and hydrolysis kinetics of [(O)(tmpa)V(IV)(&mgr;-O)V(V)(tmpa)(O)](3+) (tmpa = tris(2-pyridylmethyl)amine), the first cation in its class for which both solid state and solution-phase characteristics are fully consistent with expectations for a Robin-Day type III mixed-valence complex. [V(2)(tmpa)(2)(O)(3)](ClO(4))(3).CH(3)CN crystallizes in the triclinic, P&onemacr; (No. 2) space group with a = 10.719(2) Å, b = 11.609(1) Å, c = 19.516(2) Å, alpha = 87.876(9) degrees, beta = 79.295(9) degrees, gamma = 68.743(9) degrees, and V = 2222.6(6) Å(3); Z = 2. The two vanadium centers are crystallographically equivalent in a linear, oxo-bridged cation with V-O(b) and V=O bond lengths of 1.800(1) and 1.597(4) Å, respectively. A 15-hyperfine line EPR spectrum (g = 1.9704, A = 46.4 x 10(-4) cm(-1)) was observed for [V(2)(tmpa)(2)(O)(3)](3+), consistent with coupling of a single electron to two equivalent (51)V atoms. The mixed-valence complex exhibits an intervalence transfer (IT) band at 1.05 x 10(4) cm(-1) (epsilon = 2.1 x 10(3) M(-1) cm(-1), CH(3)CN) whose energy is insensitive to variations in the solvent; d-d transitions are observed at 1.25 x 10(4) cm(-1) ((2)E <-- (2)B(2)) and 1.44 x 10(4) cm(-1) ((2)B(1) <-- (2)B(2)). [V(2)(tmpa)(2)(O)(3)](2+), [V(2)(tmpa)(2)(O)(3)](3+), and [V(2)(tmpa)(2)(O)(3)](4+) comprise a redox family related by vanadium (IV,V/IV,IV) and (V,V/IV,V) half-wave reduction potentials of 0.25 and 1.62 V vs NHE (25 degrees C, CH(3)CN, I = 0.1 M), respectively. The hydrolysis reaction: [V(2)(tmpa)(2)(O)(3)](3+) + H(2)O --> [V(IV)(tmpa)(O)(OH)](+) + [V(V)(tmpa)(O)(2)](+) + H(+) proceeds with an acid-independent rate constant of 2.37 x 10(-3) s(-1) (25 degrees C; DeltaH() = 71 kJ/mol, DeltaS() = -59 J/mol K). [V(4)O(5)(tmpa)(4){Fe(CN)(6)}](ClO(4))(4).H(2)O was isolated as an unexpected product from the reaction of [V(2)(tmpa)(2)(O)(3)](ClO(4))(2).2H(2)O with equimolar K(3)[Fe(CN)(6)] in aqueous solution. It is proposed that pairs of V(IV)=O and V(V)=O units aggregate with [Fe(CN)(6)](4-) into a charge transfer complex. Hexacyanoferrate(II)-to-vanadium IT charge transfer bands are observed at 1.98 x 10(4) cm(-1) (epsilon = 5.3 x 10(3) M(-1) cm(-1)) and 2.72 x 10(4) cm(-1) (epsilon = 9.3 x 10(3) M(-1) cm(-1)); a 29-line EPR spectrum (g = 1.9737, A = 22.0 x 10(-4) cm(-1)) demonstrates equal delocalization of unpaired electron density over all four V atoms (CH(3)CN solution).

Calixarenes Derivatized with Sulfur-Containing Functionalities as Selective Extractants for Heavy and Precious Metal Ions.

The calix[4]arenes 5,11,17,23-tert-butyl-25,26,27,28-(2-methylthioethoxy)calix[4]arene, 25,26,27,28-(2-methylthioethoxy)calix[4]arene, and 5,11,17,23-tert-butyl-25,26,27,28-(2-(2-thiophenecarboxy)ethoxy)calix[4]arene have been prepared. The structure of 25,26,27,28-(2-methylthioethoxy)calix[4]arene has been verified by X-ray crystallography. The crystals with the empirical formula C(40)H(48)O(4)S(4) are monoclinic C2/c with a = 20.428(2) Å, b = 10.581(1) Å, c = 20.445(2) Å, beta = 118.461(5) degrees, Z = 4. These calix[4]arenes are effective extractants for transferring heavy metal ions from aqueous solution into chloroform. The extraction of Sn(II), Hg(II), Ag(I), Pd(II), Au(III), MeHg(II), Pb(II) and Cd(II) into chloroform with these calix[4]arenes is compared with that performed with 5,11,17,23-tert-butyl-25,26,27,28-(2-N,N-dimethyldithiocarbamoylethoxy)calix[4]arene, 25,26,27,28-(2,N,N-dimethyldithiocarbamoylethoxy)calix[4]arene, and 5,11,17,23-tert-butyl-25,26,27,28-(2-mercaptoethoxy)calix[4]arene.

Terminal Coordination of a Gallium(I) Species to a Transition Metal. Syntheses and Crystal Structures of Ru{GaCl(THF)(2)}{GaCl(2)(THF)}(2)(CO)(3).0.5THF and Ru(2){GaCl(2)(THF)}(2)(CO)(8).

The reaction of Ru(3)(CO)(12) with Ga(2)Cl(4) in the presence of gallium metal in refluxing toluene, followed by crystallization from tetrahydrofuran, produces Ru{GaCl(THF)(2)}{GaCl(2)(THF)}(2)(CO)(3).0.5 THF (1) and Ru(2){GaCl(2)(THF)}(2)(CO)(8) (2) (THF = tetrahydrofuran). The ruthenium atom in 1 has an approximately octahedral coordination environment, with meridinal arrangements of carbonyl ligands and gallium atoms. The GaCl(THF)(2) group is in a position trans to one of the GaCl(2)(THF) groups. The crystal structure of 2 consists of a linear arrangement of metal atoms in which two GaCl(2)(THF) groups are in axial positions with respect to the metal-metal bond of an Ru(2)(CO)(8) unit. Crystal data for 1: monoclinic space group P2(1)/c (No. 14), a = 17.367(3) Å, b = 12.054(2) Å, c = 16.049(3) Å, beta = 95.18(1) degrees, Z = 4, R = 0.0527, R(w) = 0.0718. Crystal data for 2: monoclinic space group P2(1)/c (No. 14), a = 11.980(1) Å, b = 6.944(1) Å, c = 16.097(3) Å, beta = 96.81(1) degrees, Z = 2, R = 0.0300, R(w) = 0.0510. The title complexes are the first compounds to contain ruthenium-gallium bonds, and compound 1 is the second structurally-characterized example of a complex in which a gallium(I) species is terminally coordinated to a transition metal.