Ghassoub Rima

Stable germanium analogs of carbenes, imines, ketones, thiones, selones and tellones

Abstract The chemistry of low coordinate germanium compounds has made important advances in recent years and a rather large number of these species have been isolated in a monomeric state owing to both electronic and/or steric effects. This review reports with their synthetic routes the stable germylenes Ge and the stable germanimines, germanone, germanethiones, -selones and -tellones GeY (Y=N–, O, S, Se, Te) prepared up to now, focusing particularly on compounds whose structures have been determined.

Synthesis, antioxidant properties and radioprotective effects of new benzothiazoles and thiadiazoles

In this work, we report the synthesis and characterization of new compounds derived from benzothiazoles and thiadiazoles. We observed that structural modifications on these skeletons affected the antioxidant activity. Thiol and aminothiol compounds derived from thiadiazoles and benzothiazoles showed an interesting antioxidant property. The radioprotective activity has also been evaluated in mice. Some of these compounds could be good radioprotectors.

Three coordinate divalent Group 14 element compounds with a β-diketiminate as supporting ligand L2MX [L2=PhNC(Me)CHC(Me)NPh, X=Cl, I; M=Ge, Sn]

Abstract The new heteroleptic divalent germanium and tin compounds L2MX [L2=PhNC(Me)CHC(Me)NPh. X=Cl; M=Ge (1), Sn (2). X=I; M=Ge (3), Sn (4)] have been synthesized and physicochemically and structurally (2) characterized. The halide ligand of all compounds can either be removed by reaction with NaBPh4 leading to the cationic Ge(II) and Sn(II) species L2M+ or may be replaced by other groups after nucleophilic substitution giving L2MR compounds [R=N(SiMe3)2; M=Ge, Sn. M=Sn; R=OSO2CF3, N3]. Reactions of 1 and 2 with elemental S8, Se or transition metal complexes M′(CO)5·THF have resulted in the isolation of the new complexes L2(Cl)ME (E=S; M=Ge, Sn. E=Se, M=Ge) and L2(Cl)MM′(CO)5 (M′=Cr, W; M=Ge, Sn).

Heteronuclear bonding between heavier Group 14 elements and transition-metals: novel halogermylene- and stannylene transition-metal complexes L2(X)MM'L'n [L2 = PhNC(Me)CHC(Me)NPh; X = Cl, I; M = Ge, Sn; M'L'n = W(CO)5, Fe(CO)4]

Abstract Reactions of the stable heteroleptic halodivalent species L 2 (X)M [L 2 =PhNC(Me)CHC(Me)NPh; M=Ge, X=Cl ( 1 ); X=I ( 2 ); M=Sn, X=Cl ( 5 )] with the intermediate metal complexes W(CO) 5 THF and Fe(CO) 4 have provided the new halogermylene- or stannylenetungsten- and iron-complexes L 2 (X)MM′L′ n [M′L′ n =W(CO) 5 , M=Ge, X=Cl ( 3 ), X=I ( 4 ); M′L′ n =Fe(CO) 4 , X=Cl, M=Ge ( 6 ), M=Sn ( 7 )] respectively; complexes 3 , 4 and 6 , 7 have been characterized via X-ray crystallography and a detailed discussion of their structures is presented. All the MM′ bonds are very short but calculations are consistent with the L 2 MX ligands being good σ-donors and very poor π-acceptors in complexes 3 , 4 and 6 , 7 . Selective metathesis reaction between 3 and MeLi resulted in the formation of the stable monomeric complex L 2 (Me)GeW(CO) 5 ( 8 ).

Low coordinate germanium and tin compounds (ArO)2ME and (ArO)2MM′Ln M=Ge, Sn; E=S, Se, –NSiMe3 M′=Cr, W, Fe, Pt [Ar=2,4,6-tris((dimethylamino)methyl)phenyl-]

Abstract The reactions of the divalent species (ArO) 2 M (Ar=2,4,6-[(CH 3 ) 2 NCH 2 ] 3 C 6 H 2 ; M=Ge, Sn) with either Me 3 SiN 3 , elemental S 8 , Se or transition metal complexes M′(CO) n +1 (M′=Fe, n =4; M′=Cr, W; n =5) (Ph 3 P) 2 Pt·C 2 H 4 have resulted in the isolation of either the new stable formal metallanimines (ArO) 2 MN–SiMe 3 , germanethione, -selone (ArO) 2 GeE (E=S, Se) (the expected formations of the stannanethione and -selone were not observed), or the (ArO) 2 MM′(CO) n , (ArO) 2 MPt(PPh 3 ) 2 complexes, respectively. The direct oxidation of the (ArO) 2 M species with various oxidizing agents led to the formation of the corresponding metalloxanes [(ArO) 2 M–O–] 2 . All of the chalcogenido- and transition metal–metal 14 complexes have been physicochemically and chemically characterized. The reactions of the (ArO) 2 GeE (E=S, Se) compounds with 3,5-di- tert -butyl-1,2-benzoquinone produced, by extrusion of sulfur or selenium, the dioxametalloles corresponding to the formal addition of the divalent species (ArO) 2 M to the benzoquinone. A substitution reaction of chalcogen (S/Se) has been observed permitting to go from germaneselone to germanethione.

Stable heterocyclic (Schiff base) divalent Group 14 element species (M=Ge, Sn, Pb)

Abstract The synthesis and characterization of new stable divalent germanium, tin and lead homoleptic species L2M [L2=2,2′-N,N′-bis(salicylidene)ethylenediamine, M=Ge (1), Sn (2), Pb (3); (R,R)-(−)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine, M=Ge (4), Sn (5), Pb (6) and N-methyl-2,2′-imino-bis(8-hydroxyquinoline), M=Ge (7), Sn (8)] are described. Compounds 1–8 were obtained in good yields by alcoholysis of the MN bonds of the divalent precursors [(Me3Si)2N]2M by diols with bis(salicylidene)diamine and 2,2′-imino-bis-quinoline structures. They have been isolated as solids at ambient temperature and are monomeric. NMR, IR and UV spectra are suggestive of N⋯M intramolecular coordination. The chemistry of 1–8 is illustrated through their reactions with iodine and 1,2-benzoquinones. The X-ray structure of the L2Sn-quinone adduct reveals a distorted octahedral coordination geometry around tin with remarkably short SnN distances. Various RCHO insertion reactions into the MO bonds of 1–8 and MO cleavage reactions with organic acids and acyl halides are also described; they provide a convenient procedure for the generation of new heteroleptic divalent species.

Synthèse et activité radioprotectrice de germatranes, silatranes, oxydes et sulfures germaniés à ligande chlorhydrate de cystéamine, méthylcystéamine et N(thio-2 éthyl)diamino-1,3 propane

Resume De nouvelles structures organogermaniees et siliciees de type germatranes ou silatranes, oxydes ou sulfures de germanium a ligande chlorhydrate de cysteamine, de methylcysteamine et N (thio-2 ethyl)diamino-1,3 propane, ont ete synthetisees. Leur toxicite aigue et leur activite radioprotectrice ont ete determinees. Les germatranes semblent etre les structures les plus actives dans ce dernier domaine. La toxicite de ces derives (y compris celle des silatranes) est generalement faible.

New bivalent germanium, tin and lead compounds with MO bond

The syntheses of new stable bivalent germanium, tin and lead homoleptic species (ArO)2M: (ArO = 2,4,6-[(CH3)2NCH2]3C6H2O; M = Ge (1), Sn (2), Pb(3), Ge(OSO2CF3)2·C4H8O2 (4) and heteroleptic species M(OAr) [N(SiMe3)2] (M = Ge (5), Sn (6)) are described. New organometallic heterocycles, stable metalla-imines and germathione (ArO)2M = X (X = NSiMe3, S) and metal(II)-transition metal complexes are obtained starting from 1 and 2.

Thermolyse, pyrolyse et photolyse d'hétérocycles germaniés et soufrés à 4 et 5 chainons: espèces intermédiaires à germanium doublement lié

Abstract The thermolysis, pyrolysis and photolysis of thiagermetane Me2G eCH 2 SC H2, dithiagermolane Me2G eCH 2 SSC H2 and thiagermetane dioxide Me2G eCH 2 SO 2 C H2 have been studied. Thiagermetane and dithiagermolane decompose leading to various new germylated heterocycles: Me2G eSCH 2 GeMe 2 S , Me2G eSCH 2 GeMe 2 SC H2 and Me2G eSGeMe 2 CH 2 GeMe 2 S probably proceed by two competitive mechanisms which involve the transient species germaethene [Me2GeCH2], germathione [Me2GeS], thiagermirane [Me2G eCH 2 S ] and thiadigermetane Me2G eCH 2 GeMe 2 S . Pyrolysis of thiagermetane dioxide also involves germaethene [Me2GeCH2] and probably a new doubly-bonded germanium species, the germasulfene [Me2GeSO2] (by mass spectroscopy), which finally gives germoxanes (Me2GeO)n (n = 3, 4).

Synthèse et activité radioprotectrice de nouveaux trithiagermatranes, trithiasilatranes, oxyde et sulfure germaniés à substituant chlorhydrate de cystéamine et N(2-thioéthyl)-1,3-diaminopropane

Resume De nouvelles structures organogermaniees et siliciees des types: trithiagermatranes ou trithiasilatranes, bicyclodithiazagermolidines et 6-aza, 1,3-dithia, 2-germaperhydrocines a ligands chlorhydrates de cysteamine et de N(2-thioethyl)-1,3-diaminopropane et oxyde ou sulfure de germanium a substituant chlorhydrate de N(2-thioethyl)-1,3-diaminopropane ont ete synthetisees. Leur toxicite aigue et leur activite radioprotectrice ont ete determinees.