Dirhenium Compounds Research Articles

Determination of the anticancer properties of cis- and trans-diadamanthylcarboxylates of dirhenium(III)

The aim of the study. The aim of the work was to investigate in vivo anticancer activity of cis- and trans-diadamanthylcarboxylates of dirhenium(III) alone and together with cisplatin in form of nanobins.Materials and methods. Model of tumor growth, Guerin’s carcinoma; intraperitoneal administration of cisplatin, dirhenium(III) compounds in liposomes and of binary liposomes, containing both cytostatics; volumes and final weights of tumors were measured.Results. In vivo antitumor properties of two dirhenium(III) dicarboxylates with 1-adamantanecarboxylic acid moieties as ligands with cis- (I) and trans- (II) orientation of the carboxylic groups around a cluster fragment alone and together with cisplatin were presented; an attempt to understand differences in a possible mechanism of anticancer activity of the substances were undertaken. Antiradical and DNA-binding properties of I and II were the matter of consideration.Conclusions. Cis- and trans- compounds of dirhenium I and II had close antitumor activity in vivo with a little bit superiority of the cis- analog. Mechanisms of anticancer activity of I and II are different and may also include monofunctional adduct formation and subsequent interstrand cross-linking for the II substance, formation of protein-DNA cross-links, etc.

COMPARISON OF CYTOTOXIC ACTIVITY OF CISPLATIN AND A CLUSTER RHENIUM(III) COMPOUND

Due to the earlier data about anticancer activity of the cluster rhenium(III) compounds and their synergism with cisplatin, the comparison investigations of influence of this compounds with cisplatin on the human leukemic cells is of great interest. The aim of the work was to compare the cytotoxic activity of the cluster rhenium compound Re2Cl2(C3H7CO2)4(I) in the solutions and nanoliposomes alone and together with cisplatin in Jurkat cells. Cytotoxicity of the substances were investigated against T-cells of acute lymphoblastic leukemia (Jurkat cells) by conventional methods. We have shown that the cytotoxic activity of I and cisplatin was close and the cytotoxic activity of the rhenium-platinum system was much more effective than that of I and cisplatin. In the range of low concentrations I is more effective in solutions than cisplatin that may be the explanation of much lower toxicity of the rhenium compounds and their efficacy in experiments in vivo. Liposomal formulations of investigated preparations are more effective than their solutions, due to a simplified transport mechanism and prevention of the deactivation before penetration to the cancer cell. Liposomal I and antitumor system on its base have LC50 in the range of10-8 M, that is comparable with the LC50 values for the known antitumor drugs and underlines the importance of further investigations of the rhenium cluster compounds as anticancer species. The obtained results underline perspectives of the use of dirhenium compounds in medicines and emphasize the need of further investigations of mechanisms of anticancer activity of the cluster dirhenium(III) compounds. Keywords: cluster rhenium compound; rhenium-platinum antitumor system; cytotoxic activity; apoptosis.

Activation of Heteroaromatic C-H Bonds in Furan and 2,5-Dimethylfuran.

The reaction of Re2(CO)8(μ-C6H5)(μ-H) (1) with furan in CH2Cl2 at 40 °C yielded two new isomeric dirhenium compounds, Re2(CO)8(μ-η2-2,3-C4H3O)(μ-H) (2) and Re2(CO)8(μ-η2-3,2-C4H3O)(μ-H) (3), which contain a bridging (σ + π)-coordinated furyl ligand formed by activation of the C-H bond at the 2 and 3 positions of furan, respectively. Compound 3 is the first example of a compound formed by C-H bond activation at the 3 position of a furan ring. Compound 3 was isomerized to 2 by heating to 80 °C for 7 days. The reaction of compound 2 with a second 1 equiv of 1 in CH2Cl2 at 40 °C yielded the doubly metalated furan-bis[Re2(CO)8(μ-H)] product [Re2(CO)8(μ-H)]2(μ-η2-2,3-μ-η2-5,4-C4H2O) (4) containing a 2,5-furdiyl ligand that is (σ + π)-coordinated to two Re2(CO)8(μ-H) groups by activation of the C-H bond at the 5 position of the furyl ligand in 2. Compound 2 can also be formed as the major isomer, together with a small quantity of 4 by heating furan with Re2(CO)8(μ-H)[μ-η2-C(H)═C(H)Bu n] in toluene to reflux. An isomer of 4, [Re2(CO)8(μ-H)]2(μ-η2-2,3-μ-η2-4,5-C4H2O) (5), was obtained from the reaction of 3 with 1 through C-H activation at the 4 position of the furyl ring in 3. Compound 4 was also obtained from 5 by heating to 110 °C for 24 h. The reaction of 1 with 2,5-dimethylfuran (DMFUR) in CH2Cl2 at 40 °C yielded the new compound [Re2(CO)8(μ-η2-3,2-(CH3)2C4H2O)](μ-H) (6), which contains a bridging (σ + π)-coordinated 2,5-dimethylfuryl ligand formed by activation of the C-H bond at the 3 position of DMFUR. All of the new compounds were characterized structurally by single-crystal X-ray diffraction analysis.

Coordination chemistry of thioether-carboranes in polynuclear metal carbonyl cluster complexes. B-H activation of thioether-carboranes by dirhenium carbonyl complexes

Two new dirhenium compounds Re2(CO)8[μ-η2-1,3-C2B10H10(1-SCH3)](μ-H), 1 (3.2 % yield) and Re2(CO)8[μ-η2-1,4-C2B10H10(1-SCH3)](μ-H), 2 (31 % yield) were obtained from the reaction of closo-o-(1-SCH3)C2B10H11 with Re2(CO)8[μ-η2-C(H)C(H)Bun](μ-H) in an octane solution heated to reflux. Both compounds contain a C2B10H10(1-SCH3) ligand that bridges the pair of rhenium atoms by the sulfur atom and one of the boron atoms of the carborane cage. The Re – B bonds were formed by oxidative addition of one of the B – H bonds of the carborane to one of the Re atoms. The isomers differ by which boron atom, B(3) for 1 and B(4) for 2, has been added to the Re atom. Compound 1 was isomerized to 2 by heating to 107 °C, but 2 does not isomerize back to 1. A mechanism for the isomerization that involves a reductive-elimination of B(3) and the hydride ligand of 1 followed by an oxidative-addition of the neighboring B(4)-H bond to form 2 is proposed. The new compound Re2(CO)7[μ-η3-C2B10H9(1,2-(SCH3)2](μ-H), 3 was obtained in 38% yield from the reaction of [o-1,2-(SCH3)2]C2B10H10 with Re2(CO)8[μ-η2-C(H)C(H)Bun](μ-H) in an octane solution heated to reflux for 2h. The bridging C2B10H9(1,2-(SCH3)2 ligand is coordinated to one of the rhenium atoms by the two sulfur atoms at one of the Re atoms and the carborane boron atom B(3) also underwent cleavage at the B(3) – H bond to form the Re – B(3) bond to the other Re atom.

Changes in oxidative stress intensity in blood of tumor-bearing rats following different modes of administration of rhenium-platinum system.

Effects of the different modes of administration of dichlorotetra-μ-isobutyratodirhenium(ІІІ) – І – (in water solution, liposomes, nanoliposomes and together with cisplatin – in the rhenium-platinum system) on the intensity of lipid peroxidation (LP) in blood plasma and the activity of the erythrocyte antioxidant enzymes were investigated on the model of tumor growth. A decrease in the concentration of TBA-active substances caused by dirhenium compounds was shown to be independent of the administration mode and the extent of the tumor growth inhibition. I was four-times more effective in inhibition of the LP burst than any known antioxidant. I induced the increasing activity of erythrocyte superoxide dismutase and decreasing activity of catalase. In vitro experiments with native superoxide dismutase, the interaction of І with following activation of the active center of the enzyme was confirmed and the superoxide dismutase activity of І was shown, that may contribute to the enhancement of the enzyme activity in vivo. The cluster rhenium compounds may be promising nontoxic potent antioxidants capable of deactivating superoxide radicals.

Liposomes loaded with a dirhenium compound and cisplatin: preparation, properties and improved in vivo anticancer activity

Liposomes loaded with the rhenium compound (bis-dimethylsulfoxido-cis-tetrachlorodi-μ-pivalatodirhenium(III) (cis–Re2((CH3)3CCOO)2Cl4ċ2DMSO, I) and cisplatin in the molar ratio of 4:1 as well as those loaded only with I were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering and electronic absorption spectroscopy. The relative stability of liposomes loaded with I is reflected by a minimal change in the electronic absorption spectra over a period of 8 days whereas the stability of those loaded with both drugs is lower, which we ascribe to the formation of new Re-Pt species inside the liposomes. Furthermore, the investigations of the co-encapsulation effects on the anticancer activity of the Re-Pt system were undertaken. Importantly, the co-encapsulated liposomes exhibit synergistic or additive anticancer activities in vivo, e.g. introduction of these liposomes into tumor-bearing rats demonstrated their antianemic, nephro- and hepato-protecting effects. These liposomes, which are active in cancer treatment, protect the dirhenium compounds from hydrolysis and preserve the biological properties of the Re-Pt hybrid. This study reveals the importance of combined therapy in nanotechnology and medicine.

Dirhenium Compounds Supported by N,N ′-Dimethylbenzamidinate: Formation of Linear Polymers via Axial Ligation

The reaction between Re2(DMBA)4Cl2 and NaN(CN)2 resulted in Re2(DMBA)4(N(CN)2)2 (1a), where DMBA is N,N′-dimethylbenzamidinate. Molecular compounds Re2(DMBA)4(ReO4)2 (1b) and Re2(DMBA)4(OP(O)(OH)Ph)2 (1c) were obtained through the reactions between Re2(DMBA)4(NO3)2 and the respective monoanion. The dirhenium(III) coordination polymers [Re2(DMBA)4(μ-O,O′-WO4)·2H2O]∞ (2a), [Re2(DMBA)4(μ-O,O′-MoO4)·2H2O]∞ (2b), and [Re2(DMBA)4(μ-O,O′-1,4-(O2C)2C6H4)·2H2O]∞ (2c) were similarly prepared through slow diffusion of Re2(DMBA)4(NO3)2 in acetonitrile into aqueous solution containing the respective dianion. All new compounds were characterized with single crystal X-ray diffraction, which revealed the retention of the essential structural features of Re2(DMBA)4 unit upon the formation of coordination polymers.

Reactivity of [Re 2(CO) 8(MeCN) 2] with thiazoles: Hydrido bridged dirhenium compounds bearing thiazoles in different coordination modes

Reactions of the labile compound [Re 2(CO) 8(MeCN) 2] with thiazole and 4-methylthiazole in refluxing benzene afforded the new compounds [Re 2(CO) 7{μ-2,3-η 2-C 3H(R)NS}{η 1-NC 3H 2(4-R)S}(μ-H)] ( 1, R = H; 2, R = CH 3), [Re 2(CO) 6{μ-2,3-η 2-C 3H(R)NS}{η 1-NC 3H 2(4-R)S} 2(μ-H)] ( 3, R = H; 4, R = CH 3) and fac-[Re(CO) 3(Cl){η 1-NC 3H 2(4-R)S} 2] ( 5, R = H; 6, R = CH 3). Compounds 1 and 2 contain two rhenium atoms, one bridging thiazolide ligand, coordinated through the C(2) and N atoms and a η 1-thiazole ligand coordinated through the nitrogen atom to the same Re as the thiazolide nitrogen. Compounds 3 and 4 contain a Re 2(CO) 6 group with one bridging thiazolide ligand coordinated through the C(2) and N atoms and two N-coordinated η 1-thiazole ligands, each coordinated to one Re atom. A hydride ligand, formed by oxidative-addition of C(2)–H bond of the ligand, bridges Re–Re bond opposite the thiazolide ligand in compounds 1– 4. Compound 5 contains a single rhenium atom with three carbonyl ligands, two N-coordinated η 1-thiazole ligands and a terminal Cl ligand. Treatment of both 1 and 2 with 5 equiv. of thiazole and 4-methylthiazole in the presence of Me 3NO in refluxing benzene afforded 3 and 4, respectively. Further activation of the coordinated η 1-thiazole ligands in 1– 4 is, however, unsuccessful and results only nonspecific decomposition. The single-crystal XRD structures of 1– 5 are reported.

The Synthesis and Characterization of Re2(Xap)4Cl2 Compounds

Five dirhenium(III) compounds, Re2(3,5-(CH3)2ap)4Cl2 (1), Re2(ap)4Cl2 (2), Re2(3-MeOap)4Cl2 (3), Re2(3-Clap)4Cl2 (4), and Re2(3,5-Cl2ap)4Cl2 (5), were synthesized and characterized, where 3,5-(CH3)2ap, ap, 3-MeOap, 3-Clap and 3,5-Cl2ap are 2-(3,5-dimethylanilino)pyridinate, 2-anilinopyridinate, 2-(3-methoxyanilino)pyridinate, 2-(3-chloroanilino)pyridinate and 2-(3,5-dichloroanilino)pyridinate, respectively. Structural studies revealed the Re–Re bond lengths ranging from 2.2214(4) to 2.2262(11) A, signifying that the dirhenium core maintains its quadruple bond. The asymmetric nature of 2-anilinopyridinate ligands resulted in several possible regioisomers: compounds 1 and 4 adopt a cis-(2,2) arrangement, while compounds 2 and 5 assume trans-(2,2) and (3,1) arrangements, respectively. All five compounds display three (quasi)reversible one electron couples, two oxidations and one reduction, and their electrode potentials correlate linearly with the Hammett constant of the aniline substituent.

Synthesis and structural characterization of several dirhenium(III) compounds

Reaction between Re 2(OAc) 4Cl 2 and N, N′-dicyclohexylbenzamidine (HDCyBA) under molten conditions yielded Re 2(DCyBA) 2Cl 4 ( 1); reaction of [Bu 4N] 2[Re 2Cl 8] with N, N′-di(3-methoxyphenyl)formamidine (HDmAniF) resulted in Re 2(DmAniF) 2Cl 4 ( 2); reaction of cis-Re 2(OAc) 2Cl 4 with HDmAniF under reflux conditions resulted in cis-Re 2(OAc) 2(DmAniF) 2Cl 2 ( 3). Reaction between Re 2(OAc) 4Cl 2 and α,α,α′,α′-tetramethyl-1,3-benzenedipropionic acid (H 2esp) under reflux conditions led to Re 2(esp) 2Cl 2 ( 4). Crystallographic studies of compounds 1– 4 revealed Re–Re bond lengths of 2.1679(6), 2.1804(5), 2.2468(7), and 2.2304(6) Å, respectively, which are consistent with the presence of Re–Re quadruple bond. Also reported are electrochemical properties of compounds 1– 4.

Dirhenium Paddlewheel Compounds Supported by N,N‘-Dialkylbenzamidinates: Synthesis, Structures, and Photophysical Properties

Dirhenium(III,III) compounds Re2(DMBA)4Cl2 (1, DMBA=N,N'-dimethylbenzamidinate) and Re2(DEBA)4Cl2 (2, DEBA=N,N'-diethylbenzamidinate) were synthesized via molten reactions between Re2(OAc)4Cl2 and the corresponding amidine. Re2(DMBA)4(NO3)2 (3) was obtained through reacting Re2(DMBA)4Cl2 with AgNO3. Single crystal X-ray diffraction studies revealed that the Re-Re distances in compounds 1-3 are 2.212(1), 2.217(1), and 2.173(1) A, respectively, which are consistent with the presence of a Re-Re quadruple bond. Voltammetric studies revealed that compound 2 exhibits two quasireversible couples, an oxidation and a reduction, and an irreversible reduction, while compound 1 displays irreversible couples at similar potentials. The three complexes exhibit 1deltadelta* absorption as a shoulder at approximately 440 nm (epsilon approximately 1500 M(-1) cm(-1)). Upon excitation of solid samples or CH2Cl2 solutions of 2 with visible light, emission is observed at 824 nm (77 K) and 833 nm (298 K), respectively. The luminescence is assigned as arising from the 3deltadelta* excited state.

Reactions of the triply-bonded complex cis-Re2(μ-O2CCH3)2Cl2(μ-dppm)2with pyridine carboxylic acids. The isolation and structural characterization of a third structural isomer of Re2(dipic)Cl2(μ-dppm)2(dipic = pyridine-2,6-dicarboxylate)

The diamagnetic dirhenium(II) complexes Re2(pic)Cl3(μ-dppm)2 (2), Re2(dipic)Cl2(μ-dppm)2 (3), Re2(HnicO)2Cl2(μ-dppm)2 (4) and Re2(picO)2(μ-dppm)2 (5) that are formed by the reactions of cis-Re2(μ-O2CCH3)2Cl2(μ-dppm)2 (1) with picolinic acid (Hpic), dipicolinic acid (H2dipic), 2-hydroxynicotinic acid (HnicOH) and 6-hydroxypicolinic acid (HpicOH) represent four different types of reaction products from the displacement of the cis acetate groups of 1. All four compounds have been characterized by X-ray crystallography. Compound 2 can be prepared more logically and in higher yield from Re2Cl4(μ-dppm)2. Compound 3, which retains the same cis,cis coordination of μ-dppm ligands that is present in 1, is the third structural isomer of Re2(dipic)Cl2(μ-dppm)2; the other two, which are prepared from Re2Cl4(μ-dppm)2, contain trans,trans and trans,cis ligation by the pair of μ-dppm ligands. Compounds 4 and 5 are the first dirhenium(II) compounds that contain bridging 2-pyridonate ligands; in 4 the carboxylic acid group of μ-HnicO does not coordinate, whereas the μ-picO ligands in 5 are bound in a tridentate fashion and, consequently, the two axial Re–Cl bonds of 1 have been replaced by axial Re–O (carboxylate) coordination. Complexes 3–5 have quite accessible oxidation chemistry as shown by cyclic voltammetric measurements.

The synthesis, crystal structure, and spectroscopic characterization of a tetrakis(μ- N, N′-diarylformamidinato)chlorodirhenium(III,III) cationic complex

A variety of dirhenium compounds has been synthesized with (ArNC(H)NAr) − where Ar is a substituted C 6H 5 or C 6H 4 aryl ring with different electron withdrawing and electron donating substituents. Reactivity studies of AgBF 4 with tetrakis(μ- N,N′-diarylformamidinato)dichlorodirhenium(III,III) complex with a p-MeO substituted aryl ring result in the loss of a single axial chloride from the Re 2Cl 2(III,III) species to yield a cationic complex, [Re 2Cl[( p-MeOC 6H 4)NCHN( p-MeOC 6H 4)] 4][BF 4] and AgCl. The X-ray crystal structure, UV–Vis and NMR spectroscopy, and electrochemical characterization of the cationic Re 2Cl(III,III) derivative [Re 2Cl[( p-MeOC 6H 4)NCHN( p-MeOC 6H 4)] 4][BF 4] are compared to the parent neutral Re 2Cl 2(III,III) complex, Re 2Cl 2[( p-MeOC 6H 4)NCHN( p-MeOC 6H 4)] 4.

Synthesis and crystal structure of amidato-bridged dirhenium(III,III) compounds

Four amidato-bridged dirhenium(III,III) compounds ( 1– 4) have been synthesized through reactions between Re 2(O 2CCH 3) 4Cl 2 and four different molten amides and their strutures determined by X-ray crystallography. In 1, 2 and 3, the nitrogen and oxygen atoms bonded to the same Re atom are cis to each other, and the virtual symmetry of the Re 2(NCO) 4 units is C 2 h . In 4, the trans arrangement of ligands yields a D 2 d virtual symmetry of the Re 2(NCO) 4 unit. All these compounds contain quadruple bonds between two rhenium atoms, with Re—Re distances 2.2304(6) Å, 2.2218(8) Å, 2.2181(6) Å, 2.2350(4) Å and 2.2364(5) Å for 1, 2a, 2b, 3 and 4, respectively. The electronic spectra and 1H NMR were measured. Reaction chemistry and structures of these compounds are compared with those of carboxylato bridged and amidinato bridged compounds. It is concluded that the amidato compounds all have a σ 2π 4δ 2 electron configuration, like their carboxylato analogs, but with larger δ—δ * orbital energy separations.

Acetonitrile and cyanide compounds containing metal-metal bonds: syntheses, structures and applications to solid-state chemistry

Compounds with acetonitrile and cyanide ligands have been prepared from mild substitution reactions of well- known metal-metal bonded precursors. Facile non-redox substitution of the carboxylate ligands in Mo 2(O 2CCH 3) 4 occurs in chlorinated solvents treated with excess [R 4N][CN] (R=Et, Bu n) to produce the salts [R 4N] 4[Mo 2(CN) 8] (R=Et ( 3); Bu n ( 1)) in high yields. These reactions were found to be solvent dependent, with the major product isolated from reactions performed in THF being [Bu n 4N] 3[Mo 2(O 2CCH 3)(CN) 6] ( 2). The chloride ligands in multiply-bonded dirhenium compounds are readily displaced by cyanide as demonstrated by the reaction between Re 2Cl 4(dppm) 2 and [Bu n 4N]CN to give [Bu n 4N] 2(Re 2(CN) 6(dppm) 2] ( 4). Compounds 1– 4 were characterized by IR and electronic spectroscopies; single crystal X-ray data were collected for 1, 2 and 4. 1·8CHCl 3: orthorhombic, Pbca, a=20.526(8), b=28.122(5), c=19.855(7) Å, V=11461(4) Å 3, R=0.082, R w=0.083; 2: monoclinic, P2 1, a=12.046(3), b=16.050(10), c=16.854(3) Å, β=94.11(2)°, V=3250(2) Å 3, R=0.067, R w=0.067; 4·8CH 2Cl 2: triclinic, P 1 , a=13.835(2), b=18.172(2), c 12.261(1) Å, α=106.788(8), β=107.850(9), γ=93.894(9)°, V=2767.5(6) Å 3, R=0.041, R w=0.045. The molecular structure of [Bu n 4N] 4[Mo 2(CN) 8] contains dimolybdenum(II) centers ligated by eight CN − ligands in the familiar unbridged M 2L 8 arrangement, with the two Mo(CN) 4 units being perfectly eclipsed as expected for a molecule with a δ component to the MM bond. The MoMo distance of 2.122(2) Å is the shortest reported distance for an unbridged homoleptic Mo 2 II,IIL 8 compound. The related salt, (Bu n 4N] 3[Mo 2(O 2CCH 3)(CN 6] ( 2), contains an anion displaying a structure similar to 1, but with one bridging acetate ligand, the presence of which results in a slight contraction of the MoMo bond to 2.114(2) Å. The hexacyanodirhenium compound, 4, is reminiscent of M(III) complexes of the type M 2X 6(dppm) 2 with one important exception, namely it is of the type [M 2X 6(dppm) 2] 2− with divalent metal centers. The equatorial plane in 4, bisected by two trans dppm ligands, consists of four unidentate terminal cyanide ligands and two cyanide groups that adopt an unusual η 2-(σ,π) bridging arrangement. The ReRe distance of 3.0505(6) Å is formally a single bond based on the conventional overlap scheme for a d 5d 5 M 2L 10 compound, viz. σ 2π 2(σ 2π *2)π *2 this assignment is supported by the diamagnetism of the compound as revealed by NMR and magnetic susceptibility studies. With the exception of the bridging cyanides in 4, the v(CN) stretches in the new compounds 1– 4 occur at higher frequencies than free CN −, indicating that they are acting purely as donors. In related chemistry, the alkylcyanide CH 3CN is used as the sole supporting ligand in dinuclear metal cations. The compounds [Bu n 4N] 2[Re 2Cl 8] and Re 2Cl 4(PPr n 3) 4 react with HBF 4 etherate solutions to yield the hitherto unknown compound [Re 2(MeCN) 10][BF 4] 4 ( 5), containing a triply-bonded solvated cation. Compound 5 and the previously reported salts [M 2(MeCN) 10][BF 4] 4 (M=Mo, Rh) were metathesized with [Bu n 4N] 2[M 6O 19] (M=Mo, W) and [Bu n 4N] 4[Mo 8O 26] in MeCN to give [M 2(MeCN) 10][M′ 6O 19] 2 (M=Re, M′=Mo ( 6); M=Rh, M′=Mo ( 7); M=Rh, M′=W ( 9); M=M′=Mo ( 10); M=Mo, M′=W ( 12)) and [M 2(MeCN) 10][M′ 8O 26] (M=Rh ( 8); M′=Mo ( 11)). The products were isolated directly from acetonitrile solutions as insoluble salts and characterized primarily by IR and UV-Vis spectroscopies which are diagnostic tools for the presence of the MM bonded chromophore with coordinated nitrile ligands as well as the intact polyoxometallate anions. Layering of the two separate salt solutions led to the isolation of single crystals in two cases. Crystal data for representative salts are: 6·4CH 3CN·2H 2O: monoclinic C2/ c, a=18.36(2), b=22.67(2), c=17.45(2) Å, β=90.31(9)°, V=7263(13) Å 3, R=O.066, R w=0.083; 7·4CH 3CN: monoclinic C2/ c, a=18.457(2), b=22.723(2), c=17.190(2) Å, β=90.07(1)°, V=7209(2) Å 3, R=0.079, R w=0.059. Compounds 6 and 7 were subjected to thermal gravimetric analysis and found to undergo quantitative loss of acetonitrile solvent ligands to give amorphous metal oxide materials of empirical composition MMo 6O 19 (M=Rh ( 13); Re ( 15)). The anaerobic thermal treatment of [Mo 2(MeCN) 10][Mo 6O 19] 2 ( 10) leads to a crystalline material of empirical formula Mo′Mo 6O 19 ( 14) whose powder X-ray pattern revealed tetragonal symmetry with unit cell dimensions a= b=10.811(1), c=2.819(8) Å, V=329.56(6) Å 3. These results will be discussed along with the cyanide chemistry in light of the design of new ordered materials starting from metal-metal bonded molecules.

Edge-sharing bioctahedral dimolybdenum and dirhenium compounds with polydentate phosphines

The edge-sharing bioctahedral (ESBO) compounds 1,2,7,8-Mo 2 Cl 4 (meso-eLTTP).C 6 H 6 (1), (eLTTP=Et 2 PCH 2 -CH 2 P(Ph)CH 2 P(Ph)CH 2 CH 2 PEt 2 ), 1,2,5,6-meso-Mo 2 Cl 4 [Et 2 PCH 2 CH 2 P(Ph)CH 2 P(Ph)] 2 .2C 6 H 6 (4), 1,2,7,8-Re 2 -Cl 6 (meso-tetraphos-1) (5) (tetraphos-1=Ph 2 PCH 2 CH 2 P(Ph)CH 2 CH 2 P(Ph)CH 2 CH 2 PPh 2 ), and 1,2,7,8-Re 2 -Cl 6 (meso-tetraphos-1)-(CH 3 CH 2 ) 2 O (6) have been synthesized and structurally determined, and they represent new isomeric forms for the Mo 2 (μ-Y) 2 X 4 P 4 core

Preparation and structural characterization of two isomers of the rhenium phosphine complexes of stoichiometry Re2Cl5(PR3)3, where R = Me or Et

The paramagnetic dirhenium compounds of stoichiometry Re 2 Cl 5 (PMe 3 ) 3 have been prepared from the reactions of Re 2 Cl 4 (PMe 3 ) 4 with Cl 2 (g) or with PhI•Cl 2 . Two isomers have been isolated and their structures determined

Some new types of quadruply bonded dirhenium compounds containing bridging carboxylato groups

Some new types of quadruply bonded dirhenium compounds containing bridging carboxylato groups

Quadruply bonded pairs of metal atoms bridged by amidines. II. Preparation and structures of two dirhenium compounds, including the shortest rhenium-rhenium bond yet observed

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuadruply bonded pairs of metal atoms bridged by amidines. II. Preparation and structures of two dirhenium compounds, including the shortest rhenium-rhenium bond yet observedF. Albert. Cotton and Larry W. ShiveCite this: Inorg. Chem. 1975, 14, 9, 2027–2031Publication Date (Print):September 1, 1975Publication History Published online1 May 2002Published inissue 1 September 1975https://doi.org/10.1021/ic50151a002RIGHTS & PERMISSIONSArticle Views83Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (647 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts