Synthesis and characterization of oxorhenium-`3+1' mixed-thiolate complexes. Crystal and molecular structures of [ReO{η3-(SCH2CH2)2S}(C6H4X-4-CH2S)] (X=F, Cl, Br, OMe) and of the pendant thiolate compounds [ReO{η3-(SCH2CH2)2S}(η1-SCH2CH2SCH2CH2SH)] and [ReO{η3-(SCH2CH2)2S}{η1-SCH2CH(OH)CH(OH)CH2SH}]

Mixed-valence dimolybdenum complexes containing hard oxo and soft carbonyl ligands: synthesis, structure, and electrochemistry of Mo2(O)(CO)2(μ-κ2-S(CH2)nS)2(κ2-diphosphine)

Mixed-valence dimolybdenum complexes Mo2(O)(CO)2{μ-κ2-S(CH2)nS}2(κ2-Ph2P(CH2)mPPh2) (n = 2, 3; m = 1, 2) (1-4) have been synthesized from one-pot reactions of fac-Mo(CO)3(NCMe)3 and dithiols, HS(CH2)nSH, in the presence of diphosphines. The dimolybdenum framework is supported by two thiolate bridges, with one molybdenum carrying a terminal oxo ligand and the second two carbonyls. The dppm (m = 1) products exist as a pair of diastereomers differing in the relative orientation of the two carbonyls (cis and trans) at the Mo(CO)2(dppm) center, while dppe (m = 2) complexes are found solely as the trans isomers. Small amounts of Mo(CO){κ3-S(CH2CH2S)2}(κ2-dppe) (5) also result from the reaction using HS(CH2)2SH and dppe. The bonding in isomers of 1-4 has been computationally explored by DFT calculations, trans diastereomers being computed to be more stable than the corresponding pair of cis diastereomers for all. The calculations confirm the existence of Mo[triple bond, length as m-dash]O and Mo-Mo bond orders and suggest that the new dimeric compounds are best viewed as Mo(v)-Mo(i) mixed-valence systems. The electrochemical properties of 1 have been investigated by CV and show a reversible one-electron reduction associated with the Mo(v) centre, while two closely spaced irreversible oxidation waves are tentatively assigned to oxidation of the Mo(i) centre of the two isomers as supported by DFT calculations.

Probing the effect of arm length and inter- and intramolecular interactions in the formation of Cu(ii) complexes of Schiff base ligands derived from some unsymmetrical tripodal amines

Mononuclear and dinuclear Cu(ii) complexes, [Cu^IILaldi](ClO₄) and [Cu^IILaldi]₂(ClO₄)₂, derived from unsymmetrical tripodal amines (1–6) are reported.

Controlled assembly of ruthenium complexes through ortho-carborane dithiolate and polysulfide ligands

Treatment of ortho-carborane, n-butyl lithium, sulfur, and [(p-cymene)RuCl(2)](2) in varying ratio led to four new compounds (p-cymene)Ru[S(3)(C(2)B(10)H(10))(2)] (3), [(p-cymene)Ru(2)(μ(2)-S(2)C(2)B(10)H(9))(μ(3)-S(2)C(2)B(10)H(10))](2) (4), [(p-cymene)Ru](2)Ru(μ(2)-η(2):η(2)-S(2)) (μ(2)-η(2):η(1)-S(2)Cl)(μ(2)-S(2)C(2)B(10)H(10))(2) (5), and [(p-cymene)Ru](2)Ru(μ(2)-η(1):η(1)-S(2))(μ(3)-η(2):η(2)-S(4)) (μ(2)-S(2)C(2)B(10)H(10))(2) (6), respectively. In 3, the ruthenium atom is coordinated by three S atoms from a in situ generated tridentate [S(3)(C(2)B(10)H(10))(2)](2-) ligand. 4 consists of two identical dinuclear (p-cymene)Ru(2)(μ(2)-S(2)C(2)B(10)H(9))(μ(3)-S(2)C(2)B(10)H(10)) subunits which connect to each other via the Ru-Ru bond and two bridging o-carborane-1,2-dithiolate ligands. In 4, a Ru-B bond is present. 5 contains a Ru(3)(μ(2)-S)(2)(μ(2)-S(2))(μ(2)-S(2)Cl) core, and the central ruthenium atom is coordinated by seven S atoms in a distorted pentagonal bipyramidal geometry. In 5, a S-Cl bond is generated. 6 has a novel Ru(3)(μ(2)-S)(2)(μ(2)-S(2))(μ(3)-S(4)) core, and the three ruthenium atoms are connected through the two terminal sulfur atoms of the S-S-S-S chain in a μ(3) binding fashion. All the four complexes have been characterized by elemental analysis, mass, NMR, and X-ray crystallography.

Arene-ruthenium complexes of an acyclic thiolate-thioether and tridentate thioether derivatives resulting from ring-closure reactions

The reaction of [(eta(6)-arene)RuCl(2)](2) (arene = C(6)Me(6), 1,4-MeC(6)H(4)CHMe(2)) with a large excess of the dianion of bis(2-mercaptoethyl) sulfide, (HSCH(2)CH(2))(2)S, obtained from deprotonation of the dithiol with freshly prepared NaOMe, gives the deep red, monomeric complexes [(eta(6)-arene)Ru(eta(3)-C(4)H(8)S(3))] (arene = C(6)Me(6) (5), 1,4-MeC(6)H(4)CHMe(2) (6)) in which the dianion is bound to the metal atom through one thioether and two thiolate sulfur atoms. Complex 5 reacts with [(eta(6)-C(6)Me(6))RuCl(2)](2) (4) in a 2:1 mole ratio to give a quantitative yield of the chloride salt of a binuclear cation [((eta(6)-C(6)Me(6))Ru)(2)Cl(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](+) (7) in which the thiolate sulfur atoms of the [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(8)S(3))] group bridge to a (eta(6)-C(6)Me(6))RuCl unit. This compound is also obtained directly from the reaction of 4 with the dithiolate, if the Ru dimer is used in large excess. The binuclear complex [((eta(6)-C(6)Me(6))Ru)(2)(MeCN)(mu(2)-eta(2):eta(3)-C(4)H(8)S(3))](PF(6))(2).MeCN, (9)(PF(6))(2).MeCN, is obtained by treatment of (7)Cl with NH(4)PF(6) in acetonitrile. Protonation of 5 with HCl gave the mono- and diprotonated derivatives viz. [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(9)S(3))]Cl, (8)Cl, and [(eta(6)-C(6)Me(6))Ru(eta(3)-C(4)H(10)S(3))]Cl(2), (10)Cl(2), respectively. The reaction of 5 with methyl iodide gives both the mono- and di-S-methylated derivatives. Treatment of 5 with dibromoalkanes, Br(CH(2))(n)Br (n = 1-5), effects ring closure to give the (eta(6)-C(6)Me(6))Ru dications containing the trithia mesocyclic zS3 (z = 8-12) ligands, isolated as their PF(6) salts. The X-ray crystal structures of 5, 6, the solvates of (7)Cl and (9)(PF(6))(2), and the trithia mesocyclic Ru complexes (eta(6)-C(6)Me(6))Ru(zS3)(PF(6))(2) (z = 8-11) are reported.

Schiff base chemistry of the rhenium(V)-oxo core with '3+2' ligand donor sets

Reactions of [ReOCl(3)(PPh(3))(2)] with the bidentate ligands 2-(2-hydroxyphenyl) benzoxazole and (2'-hydroxyphenyl)-2-thiazoline resulted in the isolation of the complexes [ReOCl(2)(OC(6)H(4)-2-C=NC(6)H(4)-2-O)(PPh(3))] (1) and [ReOCl(2)(OC(6)H(4)-2-C=NCH(2)CH(2)S)(PPh(3))] (2). Reactions of 1 with the tridentate Schiff base ligands salicylaldehyde 2-hydroxyanil (H(2)L(1b)), salicylaldehyde 2-mercaptoanil (H(2)L(2b)) afnd S-benzyl-2-[(2-hydroxyphenyl)methylene] dithiocarbazate (H(2)L(3b)) yielded the '3+2' rhenium(V) oxo species [ReO(OC(6)H(4)-2-C=NC(6)H(4)O) (OC(6)H(4)CH=NC(6)H(4)O)] (3), [ReO(OC(6)H(4)-2-C=NC(6)H(4)O)-(OC(6)H(4)CH=NC(6)H(4)S)] (4) and [ReO(OC(6)H(4)-2-C=NC(6)H(4)O){OC(6)H(4)CH=N-N=C(SCH(2)C(6)H(5))S}] (5). Similarly, the reactions of [ReOCl(2)(OC(6)H(4)-2-C=NC(6)H(4)S)(PPh(3))] (2) with H(2)L(2b), H(2)L(3b) and 2-[(2-hydroxyphenyl) methylene]-N-phenyl-hydrazinecarbothioamide (H(2)L(4b)) were exploited to prepare [ReO(OC(6)H(4)-2-C=NC(6)H(4)S)(OC(6)H(4)CH=NC(6)H(4)O)] (6), [ReO(OC(6)H(4)C=NC(6)H(4)S){OC(6)H(4)CH=N-N=C (SCH(2)C(6)H(5))S}] (7) and [ReO(OC(6)H(4)-2-C=NC(6)H(4)S){OC(6)H(4)CH=N-N=C(NHC(6)H(5))}] (8), respectively.

The syntheses and structures of '3+2' and '2+2+1' oxorhenium mixed-ligand complexes employing 8-hydroxy-5-nitroquinoline as the bidentate N,O donor ligand

The syntheses and structural characterizations of a series of novel '3+2' and '2+2+1' mixed-ligand complexes carrying 8-hydroxy-5-nitroquinoline (HL) as the bidentate N,O donor atom system are reported. Thus one-pot reactions of [ReOCl(3)(PPh(3))(2)] with dianionic tridentate ligands H(2)L(n) (where H(2)L(1)=HOC(6)H(4)-2-CH=NC(6)H(4)-2-OH; H(2)L(2)=HOC(6)H(4)-2-CH=N-C(6)H(4)-2-SH; H(2)L(3)=HOC(6)H(4)-2-CH=NN=C(NHC(6)H(5))-SH; H(2)L(4)=2-CH(2)OH-C(5)H(3)N-6-CH(2)SH; and H(2)L(5)=2-CO(2)H-C(5)H(3)N-6-CO(2)H) and HL afforded a series of '3+2' oxorhenium complexes of the type [ReO(H(2)L(n))(L)] 2-6, which exhibit distorted octahedral geometries. Crystals of 1 are monoclinic space group C2/c, a=16.702(1), b=14.275(1), c=22.363(2) A, beta=108.083(1) degrees V=5068.2(7) A(beta) and Z=8; those of 2 are monoclinic space group P2(1)/n, a=8.5093(4) b=38.518(2), c=11.6092(5) A, beta=97.708(1) degrees , V=3770.7(3) A(3) and Z=8; those of 5 are triclinic, space group P1-, a=7.5899(8), b=10.322(1), c=11.905(1) A, alpha=78.636(2) degrees , beta=74.229(2) degrees , gamma=71.391(2) degrees , V=844.3(2) A(3), and Z=2. Upon reaction of 2,6-pyridinedimethanol (H(2)L(6)) with the intermediate complex [ReOCl(2)(L)(PPh(3))] (1), only one of the two methylene hydroxy group was deprotonated and a new '2+2+1' complex [ReO(OCH(3))(HL(6))(L)].CH(3)OH (7) was obtained. Crystal data for 7: monoclinic P2(1)/n, a=12.0579(6), b=11.0993(6), c=14.9262(8) A, beta=107.872(1) degrees , V=1901.2(2) A(3), and Z=8. In the preparation of complex 3, cleavage of the C=N bond of the Schiff base H(2)L(2) was observed and the '2+2+1' complex 8 [ReO(PPh(3))(eta(2)-NHC(6)H(4)-2-S)(L)].CH(2)Cl(2) having 2-aminothiophenol as a dianionic bidentate ligand was isolated. Crystals of 8 are monoclinic space group C2/c, a=25.627(2), b=8.1305(6) c=31.404(2) A beta=96.147(1) degrees , V=6505.7(8) A(3), and Z=8. Reduction of HL to 8-hydroxy-5-aminoquinoline was realized during the formation of complex 6, and a new complex 9 was thus isolated involving the coordination of two sets of N,O donor atoms from L and 8-hydroxy-5-aminoquinoline while a methoxy oxygen atom completes the octahedral coordination geometry. Crystals of 9 are monoclinic space group P2(1)/n, a=7.5330(6), b=15.095(1), c=16.394(1) A, beta=99.690(2) degrees , V=1837.7(3) A(3), and Z=4.

Exploring oxorhenium '3+1' mixed-ligand complexes carrying the S-benzyl-3-[(2-hydroxyphenyl)methylene]dithiocarbazate [ONS]/monothiol [S] donor set: synthesis and characterization

The reaction of ReOCl(3)(PPh(3))(2) with the potentially tridentate ligand S-benzyl-3-[(2-hydroxyphenyl)methylene]dithiocarbazate ([ONS] donor set) and para-substituted benzenethiols [C(6)H(4)X-4-SH] (where X=H, F, Cl, Br and OCH(3)) in the presence of Et(3)N afforded a series of integrated '3+1' oxorhenium(V) complexes with general formula [ReO{eta(3)-OC(6)H(4)-2-CH=N-N=C(SCH(2)Ph)-S}(eta(1)-C(6)H(4)X-4-S)]. The molecular structure of [ReO{eta(3)-OC(6)H(4)-2-CH=N-N=C(SCH(2)Ph)-S}(eta(1)-C(6)H(4)F-4-S)] (4) was determined by single-crystal X-ray analysis. Complex 4 consists of a central oxorhenium(V) core with phenolic oxygen, azomethine nitrogen and thiol sulfur donor from the thiosemicarbazone Schiff base ligand and one sulfur donor from monothiol ligand completing a distorted square pyramidal environment. Crystal data for 4, C(21)H(16)FN(2)O(2)S(3)Re: orthorhombic, P2(1)2(1)2(1), a=5.6682(3), b=11.6600(6), c=31.697(2) A, V=2094.9(2) A(3), Z=4.

Schiff base chemistry of the {ReO} core: structural characterization of the unusual '3 + 2' complex [ReO(eta-OC(6)H(4)-CH=NC(6)H(4)-2-S)(eta-OC(6)H(4))]

The reaction of [ReOCl(3)(PPh(3))(2)] with salicylaldehyde-2-mercaptoanil (1) in methanol yields [ReO(OCH(3))(PPh(3))(eta(3)-OC(6)H(4)CH=NC(6)H(4)S)] (3). Reaction of 3 with 2-(2-hydroxyphenyl)benzothiazole (2) produces [ReO(eta(3)-OC(6)H(4)CH=NC(6)H(4)S)( eta(2)-OC(6)H(4))] (4) in good yield. Compound 4 may also be prepared directly from the reaction of [ReOCl(3)(PPh(3))(2)] with excess 1, after prolonged reaction times in the presence of atmospheric oxygen. The structure of 3 exhibits a distorted octahedral Re(V) center coordinated to a terminal oxo-group, a methoxy ligand, a triphenylphosphine ligand, and the N, O and S donors of the tridentate Schiff base ligand. The octahedral geometry of 4 is defined by the terminal oxo-group, the N, O and S donors of the tridentate Schiff base ligand, and the N and O donors of the bidentate 2-(2-hydroxophenyl)benzothiazole ligand. Oxidation and cyclization of the Schiff base salicylaldehyde-2-mercaptoanil to produce 2-(2-hydroxyphenyl)benzothiazole is precedented and in this instance may be driven by the formation of the robust '3+2' complex 4.

Synthesis and characterization of oxorhenium(V)-'3+1' mixed thiolate [SNS]/[S] and [ONS]/[S] complexes. Crystal and molecular structures of [ReO(eta-SCH(2)C(5)H(3)NCH(2)S)(eta-C(6)H(4)Br-4-S)], [ReO(eta-SCH(2)C(5)H(3)NCH(2)O)(eta-C(6)H(4)X-4-S)] (X=Cl, OMe), [ReO(eta-SCH(2)C(5)H(3)NCH(2)O)(eta-C(6)H(4)OCH(3)-4-CH(2)S)] and [ReO(eta-SCH(2)C(5)H(3)NCH(2)S)(eta-C(5)H(4)NH-2-S)][Cl]

The reaction of [ReOCl(3)(PPh(3))(2)] with the tridentate ligands 2,6-dithiomethylpyridine (4) or 6-thiomethyl-2-pyridinemethanol (5) and the appropriate monothiols, such as para-substituted benzenethiols (C(6)H(4)X-4-SH) (where X=F, Cl, Br and OCH(3)) and para-substituted benzylmercaptans (C(6)H(4)X-4-CH(2)SH) (where X=F, Cl and OCH(3)) in the presence of Et(3)N leads to the isolation of a series of integrated '3+1' oxorhenium(V) complexes. Similarly, reaction of [ReOCl(3)(PPh(3))(2)] with 2-mercaptopyridine and 4 afforded a cationic oxorhenium(V) complex, [ReO(eta(3)-SCH(2)C(5)H(3)NCH(2)S)(eta(1)-C(5)H(4)NH-2-S)][Cl] (22). Crystal data for 10, C(13)H(11)BrNOS(3)Re: triclinic, P1, a=7.2909(5), b=14.1978(9), c=15.991(1) A, alpha=77.184(1), beta=86.588(1), gamma=75.507(1) degrees , V=1562.69(18) A(3), Z=4. For 16, C(13)H(11)ClNO(2)S(2)Re: orthorhombic, P2(1)2(1)2(1), a=6.9728(6), b=13.477(1), c=15.761(1) A, V=1481.1(2) A(3), Z=4. For 18, C(14)H(14)NO(3)S(2)Re: monoclinic, P2(1)/c, a=15.6512(14), b=7.6678(7), c=13.732(1) A, beta=112.489(1) degrees , V=1522.7(2) A(3), Z=4. For 21, C(15)H(16)NO(3)S(2)Re: monoclinic, P2(1)/c, a=13.929(1), b=7.741(1), c=15.583(2) A, beta=103.600(2) degrees , V=1633.1(3) A(3), Z=4. For 22, C(12)H(11)ClN(2)OS(3)Re: monoclinic, C2(1)/(c), a=27.827(3), b=8.529(1), c=14.957(2) A, beta=119.314(2) degrees , V=3095.3(6) A(3), Z=8.

Investigations of the {ReO} core: A '2+2' complex from bidentate and potentially trident ligands: [ReO(η-HOC(6)H(4)-2-CH(2)NC(6)H(4)S)(η-SC(5)H(4)N)(PPh(3))]

The reaction of [ReOCl(3)(PPh(3))(2)] with N-(2-hydroxybenzyl)-2-mercaptoaniline (H(3)hbma) (2) and 2-mercaptopyridine in hot CHCl yields [ReO(η(2)-HOC(6)H(4)-2-CH(2)NC(6)H(4)S)(η(2)-SC(5)H(4)N)(PPh(3))] (3). The structure of 3 consists of distorted octahedral Re(V) monomers. The coordination geometry at the rhenium is defined by a terminal oxo-group, the nitrogen and sulfur donors of the chelating mercaptopyridine, the nitrogen and sulfur donors of a bidentate (Hhbma)(2-) ligand, and the phosphorus of the PPh(3) group. The -C(6)H(4)OH arm of (Hhbma)(2-) is pendant, and the coordinated nitrogen of this ligand is present as a deprotonated amido nitrogen.

Structural characterizations of an Re(IV) complex [ReCl(4)(OPPh(3))(2)] and of an imino species [ReOCl(2)(PPh(3))(eta-OC(6)H(4)-2-CH=NH)] prepared from the reaction of [ReOCl(3)(PPh(3))(2)] with salicylaldoxime

The reaction of [ReOCl(3)(PPh(3))(2)] with salicylaldoxime unexpectedly yields [ReCl(4)(OPPh(3))(2)] (1) and [ReOCl(2)(PPh(3))(eta(2)-OC(6)H(4)-2-CH=NH)] (2). The crystal structure of the Re(IV) complex 1 consists of discrete mononuclear units. The Re site is bound to four chlorides and two trans oxygens of the OPPh(3) groups. The crystal structure of 2 is also mononuclear with the geometry of the Re(V) center defined by a terminal oxo-group, two cis chlorides, the phosphorus of the PPh(3), and the nitrogen and oxygen donors of the phenoxyimino ligand [OC(6)H(4)-2-CH=NH](-).

Synthesis and characterization of complexes of the {ReO} core with SNS and S donor ligands

The reaction of [ReOCl(3)(PPh(3))(2)] with N,N-bis(2-mercaptoethyl)benzylamine and 4-bromobenzenethiol allowed for the isolation of [ReO{eta(3)-(SCH(2)CH(2))(2)N(CH(2)C(6)H(5))}-(eta(1)-C(6)H(4)Br-4-S)] (1). The reaction of [ReOCl(3)(PPh(3))(2)] with [(HSCH(2)CH(2))(2)N(CH(2)C(5)H(4)N)] and the appropriate thiol in chloroform treated with triethylamine has led to the isolation of a series of neutral rhenium complexes of the type [ReO{eta(3)-(SCH(2)CH(2))(2)N(CH(2)C(5)H(4)N)}(eta(1)-C(6)H(4)X-4-S)] (X = Br (2), Cl (3), F (4), and OCH(3) (5)) and [ReO{eta(3)-(SCH(2)CH(2))(2)N(CH(2)C(5)H(4)N)}(eta(1)-C(6)H(4)OCH(3)-4-CH(2)S)] (6). Likewise, under similar reaction conditions, the use of the related tridentate ligand, [(HSCH(2)CH(2))(2)N(CH(2)CH(2)C(5)H(4)N)], has led to the isolation of a series of rhenium complexes of the type [ReO{eta(3)-(SCH(2)CH(2))(2)N(CH(2)CH(2)C(5)H(4)N)}(eta(1)-C(6)H(4)X-4-S)] (X=Br (7), Cl (8), OCH(3) (9)), as well as [ReO{eta(3)-(SCH(2)CH(2))(2)N(CH(2)CH(2)C(5)H(4)N)}(eta(1)-C(6)H(4)Cl-4-CH(2)S)].0.5CH(3)(CH(2))(4)CH(3) (10). These compounds are extensions of the '3+1' approach to the synthesis of materials with the {MO}(3+) core (M=Tc and Re), which have applications in nuclear medicine. The ligands chosen allow systematic exploration of the consequences of para-substitution on the monodentate thiolate ligand [S] and of derivatization of the substituent R on the tridentate aminodithiol ligand [SNS] of the type (HSCH(2)CH(2))(2)NR. Such modifications can influence lipophilicity, charge, size and molecular weight of the complex and consequently the biodistribution.

Oxorhenium(V) complexes containing tridentate Schiff-base and monothiol coligands

The reaction of [n-(C(4)H(9))(4)N][ReOBr(4)(OPPh(3))] with the tridentate Schiff-base [HOC(6)H(4)C(H)NC(6)H(4)SH] allows for the isolation of [ReOBr{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)}] (1). The reaction of [n-(C(4)H(9))(4)N][ReOBr(4)(OPPh(3))] with [HOC(6)H(4)C(H)NC(6)H(4)SH] and the appropriate benzenethiol (C(6)H(4)X-4-SH) where X=H, Br, Cl, F, and OCH(3) in methanol-acetonitrile treated with triethylamine has led to the isolation of a series of rhenium complexes of the type [ReO{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)} (eta(1)-C(6)H(4)X-4-S)] (X=H (2), Br (3), Cl (4), F (5), and OCH(3) (6)). Likewise, under similar reaction conditions, the use of benzylmercaptan ligands of the type (C(6)H(4)X-4-CH(2)SH) where X=H, Cl, F, and OCH(3) has led to the isolation of a series of rhenium complexes of the type [ReO{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)} (eta(1)-C(6)H(4)X-4-CH(2)S)] (X=H (7), Cl (8), F (9), and OCH(3) (10)). The incorporation of the appropriate amine functionality into the substituent R of the monodentate ligand allows for the isolation of a cationic oxorhenium(V) species, namely, [ReO{eta(3)-(OC(6)H(4)C(H)NC(6)H(4)S)} (eta(1)-C(5)H(4)NH-2-S)][Br] (11).