Fluorotrithiophosphate Abstraction from the Difluoropentathiodiphosphate Dianion: d8 and d6 Complexes of [η2-S3PF]2.

Coordinative heterolysis of the difluoropentathiodiphosphate dianion [S5P2F2]2- results in the formal elimination of [S2PF] by complexes of the group 10 divalent metals nickel, palladium, and platinum. The remaining fragment of this cleavage, [S3PF]2- coordinates as an η2-ligand. Several complexes with this novel fluorotrithiophosphate were characterized structurally and spectroscopically with X-ray diffraction (XRD), infrared (IR) spectroscopy, and 31P and 19F nuclear magnetic resonance (NMR). In addition to mononuclear η2 chelate complexes, bridging complexes with η2-µ2-S3PF configurations result in binuclear nickel and ruthenium adducts. Facile methylation with methyl triflate of the uncoordinated sulfur atom leads to a complex with the methylthiofluorodithiophosphate ligand in a cationic complex, which hydrolyses with loss of fluoride to give complexed [S2P(O)SMe]2-. Alternatively hydrolysis can also lead to a binuclear Ni2(dppe)2(S3PF)(S2POF) complex. Divalent ruthenium π-aryl's form fluorotrithiophosphate complexes rapidly at room temperature to give bridged dimers with complete chloride substitution.

The Sulfur Rich Fluorothiophosphate Dianions [S5 P2 F2 ]2- and [S3 PF]2- : Cluster and Chelation Control of P-S Heterolysis.

The sulfur rich difluoropentathiodiphosphate dianion [S5 P2 F2 ]2- , from fluoride addition to P4 S10 , has a somewhat checkered history and proves to be the main product of the reaction in acetonitrile. Its optimized synthesis, and structural characterization, as either a tetraphenylphosphonium or a tetrapropylammonium salt, [Nn Pr4 ]2 [S5 P2 F2 ] allows for the first coordination chemistry for this dianion. Reactions of [S5 P2 F2 ]2- with d10 metal ions of zinc(II), and cadmium(II), and d9 copper(II) resulted in a surprising diverse array of binding modes and structural motifs. In addition to the simple bis-chelate coordination of [S5 P2 F2 ]2- with zinc, cleavage of the P-S bond resulted in complexes with the unusual [S3 PF]2- fluorotrithiophosphate dianion. This was observed in two cluster complexes: a trinuclear cadmium complex with mixed [S5 P2 F2 ]2- /[S3 PF]2- ligands, [Cd3 (S5 P2 F2 )3 (S3 PF)2 ]4- as well as an octanuclear copper cluster, [Cu8 (S3 PF)6 ]4- which form rapidly at room temperature. These new metal/sulfur/ligand clusters are of relevance to understanding multimetal binding to metallothionines, and to potential capping strategies for the condensed nanoparticulate cadmium chalcogenide semiconductors CdS and CdSe.

Separation of Isomers and Mechanisms of Inversion of Stereochemistry of Group 9 d6 Tris-Chelate Complexes of Hinokitiol.

Tris-chelate complexes of Co(III), Rh(III), and Ir(III) with 4-isopropyltropolone (hinokitiol or ß-thujaplicin) form by the substitution of carbonate and chloride ligands from group 9 trivalent metal salts. The new complexes are neutral, are readily soluble in most organic solvents, and are brightly colored with strong charge transfer bands. The fac isomers of Co(hino)3 and Rh(hino)3 were isolated from the mixture by fractional recrystallization from ethanol. The remaining mixtures were respectively enriched by 5:3 and 4.4:3 for the mer isomer. The 1H NMR data show that the complexes exhibit remarkable stereochemical lability, which is unusual for diamagnetic d6 group 9 metals, with rotational barriers of 14.2 and 18.2 kcal/mol found for the inversion of stereochemistry of Co(hino)3 and Rh(hino)3. The low activation barriers, as well as the analysis of some key structural parameters, suggest that the inversion of stereochemistry occurs via a trigonal-twist (Bailar) mechanism. Facile substitution of a single hinokitiol ligand in the cobalt complex with ethylenediamine to form [Co(en)(hino)2]Cl also indicates that the tris-chelates are substitutionally and configurationally labile.

Fluxionality in the Tropolone Hinokitiol Chelate.

Tropolonate complexes of Ru(II), Ru(III), and Os(II) with hinokitiol, also termed ß-thuljaplicin, or 4-isopropyltropolone, readily formed by chloride and triarylphosphine substitution in RuCl2(PPh3)3 and MHCl(CO)(PR3)3 (M = Ru, R = Ph; M = Os, R = Ph and p-tolyl). The resulting colorful complexes have variable and strong charge transfer bands and also have a surprising combination of stereochemical selectivity and lability. For the Os(II) d6 examples, the tropolone chelate has a fluxionality with a barrier of only 90 kJ/mol for the R = aryl examples, as determined by variable-temperature 31P NMR. Chlorination with N-chlorosuccinimide results in MCl(CO)(hino)(PPh3)2 (M = Ru and Os). Together these results quantify the fluxionality of this important chelate which in turn has consequences for its biochemistry.

Alterations in bone and erythropoiesis in hemolytic anemia: comparative study in bled, phenylhydrazine-treated and Plasmodium-infected mice.

Sustained erythropoiesis and concurrent bone marrow hyperplasia are proposed to be responsible for low bone mass density (BMD) in chronic hemolytic pathologies. As impaired erythropoiesis is also frequent in these conditions, we hypothesized that free heme may alter marrow and bone physiology in these disorders. Bone status and bone marrow erythropoiesis were studied in mice with hemolytic anemia (HA) induced by phenylhydrazine (PHZ) or Plasmodium infection and in bled mice. All treatments resulted in lower hemoglobin concentrations, enhanced erythropoiesis in the spleen and reticulocytosis. The anemia was severe in mice with acute hemolysis, which also had elevated levels of free heme and ROS. No major changes in cellularity and erythroid cell numbers occurred in the bone marrow of bled mice, which generated higher numbers of erythroid blast forming units (BFU-E) in response to erythropoietin. In contrast, low numbers of bone marrow erythroid precursors and BFU-E and low concentrations of bone remodelling markers were measured in mice with HA, which also had blunted osteoclastogenesis, in opposition to its enhancement in bled mice. The alterations in bone metabolism were accompanied by reduced trabecular bone volume, enhanced trabecular spacing and lower trabecular numbers in mice with HA. Taken together our data suggests that hemolysis exerts distinct effects to bleeding in the marrow and bone and may contribute to osteoporosis through a mechanism independent of the erythropoietic stress.