Cubane-type heterometallic sulfido clusters: incorporation of two metal fragments into a dinuclear ReS(mu-S)2ReS core affording bimetallic M2Re2(mu 3-S)4 clusters (M = Ru,Pt, Cu) or trimetallic MM'Re2(mu 3-S)4 clusters via incomplete cubane-type MRe2(mu 3-S)(mu 2-S)3 intermediates (M = Ru,Rh, Ir; M' = Mo,W, Pd,Ru, Rh)

Reactions of a dirhenium tetra(sulfido) complex [PPh(4)](2)[ReS(L)(mu-S)(2)ReS(L)] (L = S(2)C(2)(SiMe(3))(2)) with a series of group 8-11 metal complexes in MeCN at room temperature afforded either the cubane-type clusters [M(2)(ReL)(2)(mu(3)-S)(4)] (M = CpRu (2), PtMe(3), Cu(PPh(3)) (4); Cp = eta(5)-C(5)Me(5)) or the incomplete cubane-type clusters [M(ReL)(2)(mu(3)-S)(mu(2)-S)(3)] (M = (eta(6)-C(6)HMe(5))Ru (5), CpRh (6), CpIr (7)), depending on the nature of the metal complexes added. It has also been disclosed that the latter incomplete cubane-type clusters can serve as the good precursors to the trimetallic cubane-type clusters still poorly precedented. Thus, treatment of 5-7 with a range of metal complexes in THF at room temperature resulted in the formation of novel trimetallic cubane-type clusters, including the neutral clusters [[(eta(6)-C(6)HMe(5))Ru][W(CO)(3)](ReL)(2)(mu(3)-S)(4)], [(CpM)[W(CO)(3)](ReL)(2)(mu(3)-S)(4)] (M = Rh, Ir), [(Cp*Ir)[Mo(CO)(3)](ReL)(2)(mu(3)-S)(4)], [[(eta(6)-C(6)HMe(5))Ru][Pd(PPh(3))](ReL)(2)(mu(3)-S)(4)], and [(Cp*Ir)[Pd(PPh(3))](ReL)(2)(mu(3)-S)(4)] (13) along with the cationic clusters [(Cp*Ir)(CpRu)(ReL)(2)(mu(3)-S)(4)][PF(6)] (14) and [(Cp*Ir)[Rh(cod)](ReL)(2)(mu(3)-S)(4)][PF(6)] (cod = 1,5-cyclooctadiene). The X-ray analyses have been carried out for 2, 4, 7, 13, and the SbF(6) analogue of 14 (14') to confirm their bimetallic cubane-type, bimetallic incomplete cubane-type, or trimetallic cubane-type structures. Fluxional behavior of the incomplete cubane-type and trimetallic cubane-type clusters in solutions has been demonstrated by the variable-temperature (1)H NMR studies, which is ascribable to both the metal-metal bond migration in the cluster cores and the pseudorotation of the dithiolene ligand bonded to the square pyramidal Re centers, where the temperatures at which these processes proceed have been found to depend upon the nature of the metal centers included in the cluster cores.     

Alkyl-eta2-alkene niobocene and tantalocene complexes with the allyldimethylsilyl-eta5-cyclopentadienyl ligand: synthesis, NMR studies and DFT calculations

Group 5 metal complexes [M(eta5-C5H5)[eta5-C5H4SiMe2(CH2-eta]2-CH=CH2)]X] (M = Nb, X = Me, CH2Ph, CH2SiMe3; M = Ta, X = Me, CH2Ph) and [Ta(eta5-C5Me5)[eta5-C5H4SiMe2(CH2-eta2-CH=CH2)]X] (X = Cl, Me, CH2Ph, CH2SiMe3) containing a chelating alkene ligand tethered to a cyclopentadienyl ring have been synthesized in high yields by reduction with Na/Hg (X = Cl) and alkylation with reductive elimination (X = alkyl) of the corresponding metal(iv) dichlorides [M(eta5-Cp)[eta5-C5H4SiMe2(CH2CH=CH2)]Cl2] (Cp = C5H5, M = Nb, Ta, Cp = C5Me5, M = Ta). These chloro- and alkyl-alkene coordinated complexes react with CO and isocyanides [CNtBu, CN(2,6-Me2C6H3)] to give the ligand-substituted metal(III) compounds [M(eta5-Cp)[eta5-C5H4SiMe2(CH2CH=CH2)]XL] (X = Cl, Me, CH2Ph, CH2SiMe3). Reaction of the chloro-alkene tantalum complex with LiNHtBu results in formation of the imido hydride derivative [Ta(eta5-C5Me5)[eta5-C5H4SiMe2(CH2CH=CH2)]H(NtBu)]. NMR studies for all of the new compounds and DFT calculations for the alkene-coordinated metal complexes are compared with those known for related group 4 metal cations.     

Synthesis, structure, and dynamics of nickelacarboranes incorporating the [nido-7,9-C(2)B(9)H(11)](2)(-) ligand

The nickelacarboranes [NEt(4)][2-(eta(3)-C(3)H(4)R)-closo-2,1,7-NiC(2)B(9)H(11)] (R = H (1a), Ph (1b)) have been synthesized via reaction between [Na](2)[nido-7,9-C(2)B(9)H(11)] and [Ni(2)(micro-Br)(2)(eta(3)-C(3)H(4)R)(2)] in THF (THF = tetrahydrofuran), followed by addition of [NEt(4)]Cl. Protonation of 1a in the presence of a donor ligand L affords the complexes [2,2-L(2)-closo-2,1,7-NiC(2)B(9)H(11)] (L = CO (2), CNBu(t) (3)). Addition of PEt(3) (1 equiv) to 2 produces quantitative conversion to [2-CO-2-PEt(3)-closo-2,1,7-NiC(2)B(9)H(11)], 4. Species 2-4 exhibit in solution hindered rotation of the NiL(2) fragment with respect to the eta(5)-C(2)B(9) cage unit. Protonation of 1a in the presence of a diene affords the neutral complexes [2-(eta(2):eta(2)-diene)-closo-2,1,7-NiC(2)B(9)H(11)] (diene = C(5)Me(5)H (5), dcp (6), cod (7), nbd (8), chd (9), and cot (10a); dcp = dicyclopentadiene, cod = 1,5-cyclooctadiene, nbd = norbornadiene, chd = 1,3-cyclohexadiene, and cot = cyclooctatetraene). Variable temperature (1)H NMR experiments show that the [Ni(diene)] fragments are freely rotating even at 193 K. A small quantity of the di-cage species [2,2'-micro-(1,2:5,6-eta-3,4:7,8-eta-cot)-(closo-2,1,7-NiC(2)B(9)H(11))(2)] (10b) is formed as a coproduct in the synthesis of 10a. This species can be rationally synthesized by protonation of 1a and subsequent addition of 10a.     

Transition metal complexes of the chelating phosphine borane ligand Ph2PCH2Ph2P.BH3

Chromium and ruthenium complexes of the chelating phosphine borane H(3)B.dppm are reported. Addition of H(3)B.dppm to [Cr(CO)(4)(nbd)](nbd = norbornadiene) affords [Cr(CO)(4)(eta1-H(3)B.dppm)] in which the borane is linked to the metal through a single B-H-Cr interaction. Addition of H(3)B.dppm to [CpRu(PR(3))(NCMe)(2)](+)(Cp =eta5)-C(5)H(5)) results in [CpRu(PR(3))(eta1-H(3)B.dppm)][PF(6)](R = Me, OMe) which also show a single B-H-Ru interaction. Reaction with [CpRu(NCMe)(3)](+) only resulted in a mixture of products. In contrast, with [Cp*Ru(NCMe)(3)](+)(Cp*=eta5)-C(5)Me(5)) a single product is isolated in high yield: [Cp*Ru(eta2-H(3)B.dppm)][PF(6)]. This complex shows two B-H-Ru interactions. Reaction with L = PMe(3) or CO breaks one of these and the complexes [Cp*Ru(L)(eta1-H(3)B.dppm)][PF(6)] are formed in good yield. With L = MeCN an equilibrium is established between [Cp*Ru(eta2-H(3)B.dppm)][PF(6)] and the acetonitrile adduct. [Cp*Ru (eta2-H(3)B.dppm)][PF(6)] can be considered as being "operationally unsaturated", effectively acting as a source of 16-electron [Cp*Ru (eta1-H(3)B.dppm)][PF(6)]. All the new compounds (apart from the CO and MeCN adducts) have been characterised by X-ray crystallography. The solid-state structure of H(3)B.dppm is also reported.     

Resolution of chiral, tetrahedral M4L6 metal-ligand hosts

The supramolecular metal-ligand assemblies of M416 stoichiometry are chiral (M = GaIII, AlIII, InIII, FeIII, TiIV, or GeIV, H41 = N,N'-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene). The resolution process of delta delta delta delta- and lambda lambda lambda lambda-[M(4)1(6)]12- by the chiral cation S-nicotinium (S-nic+) is described for the Ga(III), Al(III), and Fe(III) assemblies, and the resolution is shown to be proton dependent. From a methanol solution of M(acac)3, H(4)1, S-nicI, and KOH, the delta delta delta delta-KH3(S-nic)7[(S-nic) subset M(4)1(6)] complexes precipitate, and the lambda lambda lambda lambda-K6(S-nic)5[(S-nic) subset M(4)1(6)] complexes subsequently can be isolated from the supernatant. Ion exchange enables the isolation of the (NEt4(+))(12), (NMe4(+))(12), and K+(12) salts of the resolved structures, which have been characterized by CD and NMR spectroscopies. Resolution can also be accomplished with 1 equiv of NEt4+ blocking the cavity interior, demonstrating that external binding sites are responsible for the difference in S-nic+ enantiomer interactions. Circular dichroism data demonstrate that the (NMe4(+))(12) and (NEt4(+))(12) salts of the resolved [Ga(4)1(6)]12- and [Al(4)1(6)]12- structures retain their chirality over extended periods of time (>20 d) at room temperature; heating the (NEt4(+))(12)[Ga(4)1(6)] assembly to 75 degrees C also had no effect on its CD spectrum. Finally, experiments with the resolved K(12)[Ga(4)1(6)] assemblies point to the role of a guest in stabilizing the resolved framework.     

Synthesis, structural characterization, reactivity, and thermal stability of [eta(5):sigma-Me2C(C5H4)(C2B10H10)]Ti(R)(NMe2)

Reaction of [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]TiCl(NMe2) (1) with 1 equiv of PhCH2K, MeMgBr, or Me3SiCH2Li gave corresponding organotitanium alkyl complexes [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(R)(NMe2) (R = CH2Ph (2), CH2SiMe3 (4), or Me (5)) in good yields. Treatment of 1 with 1 equiv of n-BuLi afforded the decomposition product {[eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti}2(mu-NMe)(mu:sigma-CH2NMe) (3). Complex 5 slowly decomposed to generate a mixed-valence dinuclear species {[eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti}2(mu-NMe2)(mu:sigma-CH2NMe) (6). Complex 1 reacted with 1 equiv of PhNCO or 2,6-Me2C6H3NC to afford the corresponding monoinsertion product [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(Cl)[eta(2)-OC(NMe2)NPh] (7) or [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(Cl)[eta(2)-C(NMe2)=N(2,6-Me2C6H3)] (8). Reaction of 4 or 5 with 1 equiv of R'NC gave the titanium eta(2)-iminoacyl complexes [eta:(5)sigma-Me2C(C5H4)(C2B10H10)]Ti(NMe2)[eta(2)-C(R)=N(R')] (R = CH2SiMe3, R' = 2,6-Me2C6H3 (9) or tBu (10); R = Me, R' = 2,6-Me2C6H3 (11) or tBu (12)). The results indicated that the unsaturated molecules inserted into the Ti-N bond only in the absence of the Ti-C(alkyl) bond and that the Ti-C(cage) bond remained intact. All complexes were fully characterized by various spectroscopic techniques and elemental analyses. Molecular structures of 2, 3, 6-8, and 10-12 were further confirmed by single-crystal X-ray analyses.     

Chiral bisphosphinite metalloligands derived from a P-chiral secondary phosphine oxide

Interaction of PdCl(2)(MeCN)(2) with 2 equiv of (S(P))-(t)BuPhP(O)H (1H) followed by treatment with Et(3)N gave [Pd((1)(2)H)](2)(micro-Cl)(2) (2). Reaction of 2 with Na[S(2)CNEt(2)] or K[N(PPh(2)S)(2)] afforded Pd[(1)(2)H](S(2)CNEt(2)) (3) or Pd[(1)(2)H)[N(PPh(2)S)(2)] (4), respectively. Treatment of 3 with V(O)(acac)(2) (acac = acetylacetonate) and CuSO(4) in the presence of Et(3)N afforded bimetallic complexes V(O)[Pd(1)(2)(S(2)CNEt(2))](2) (5) or Cu[Pd(1)(2)(S(2)CNEt(2))](2) (6), respectively. X-ray crystallography established the S(P) configuration for the phosphinous acid ligands in 3 and 6, indicating that 1H binds to Pd(II) with retention of configuration at phosphorus. The geometry around Cu in 6 is approximately square planar with the average Cu-O distance of 1.915(3) A. Treatment of 2 with HBF(4) gave the BF(2)-capped compound [Pd((1)(2)BF(2))](2)(micro-Cl)(2) (7). The solid-state structure of 7 containing a PdP(2)O(2)B metallacycle has been determined. Chloride abstraction of 7 with AgBF(4) in acetone/water afforded the aqua compound [Pd((1)(2)BF(2))(H(2)O)(2)][BF(4)] (8) that reacted with [NH(4)](2)[WS(4)] to give [Pd((1)(2)BF(2))(2)](2)[micro-WS(4)] (9). The average Pd-S and W-S distances in 9 are 2.385(3) and 2.189(3) A, respectively. Treatment of [(eta(6)-p-cymene)RuCl(2)](2) with 1H afforded the phosphinous acid adduct (eta(6)-p-cymene)RuCl(2)(1H) (10). Reduction of [CpRuCl(2)](x)() (Cp = eta(5)-C(5)Me(5)) with Zn followed by treatment with 1H resulted in the formation of the Zn(II) phosphinate complex [(CpRu(eta(6)-C(6)H(5)))(t)BuPO(2))](2)(ZnCl(2))(2) (11) that contains a Zn(2)O(4)P(2) eight-membered ring.     

Diastereospecific and diastereoselective syntheses of Ruthenium(II) complexes using N,N' bidentate ligands aryl-pyridin-2-ylmethyl-amine ArNH-CH2-2-C5H4N and their oxidation to imine ligands

Coordination of N,N' bidentate ligands aryl-pyridin-2-ylmethyl-amine ArNH-CH2-2-C5H4N 1 (Ar = 4-CH3-C6H4, 1a; 4-CH3O-C6H4, 1b; 2,6-(CH3)2-C6H3, 1c; 4-CF3-C6H4, 1d) to the moieties [Ru(bipy)2]2+, [Ru(eta5-C5H5)L]+ (L = CH3CN, CO), or [Ru(eta6-arene)Cl]2+ (arene = benzene, p-cymene) occurs under diastereoselective or diastereospecific conditions. Detailed stereochemical analysis of the new complexes is included. The coordination of these secondary amine ligands activates their oxidation to imines by molecular oxygen in a base-catalyzed reaction and hydrogen peroxide was detected as byproduct. The amine-to-imine oxidation was also observed under the experimental conditions of cyclic voltammetry measurements. Deprotonation of the coordinated amine ligands afforded isolatable amido complexes only for the ligand (1-methyl-1-pyridin-2-yl-ethyl)-p-tolyl-amine, 1e, which doesn't contain hydrogen atoms in a beta position relative to the N-H bond. The structures of [Ru(2,2'-bipyridine)2(1b)](PF6)2, 2b; [Ru(2,2'-bipyridine)(2)(1c)](PF6)2, 2c; trans-[RuCl2(COD)(1a)], 3; and [RuCl2(eta6-C6H6)(1a)]PF6, 4a, have been confirmed by X-ray diffraction studies.     

Titanium imido complexes of cyclooctatetraenyl ligands

Reaction of [Ti(NR)Cl2(py)3] (R=tBu or 2,6-iPr2C6H3) with K(2)[COT] (COT=C8H8) or Li2[COT'] (COT'=1,4-C8H6(SiMe3)2) gave the monomeric complexes [Ti(NR)(eta8-COT)] or [Ti(NR)(eta8-COT')], respectively. The pseudo-two coordinate, "pogo stick" geometry for these complexes is unique in both early transition-metal and cyclooctatetraenyl ligand chemistry. In contrast, reaction of [Ti(N-2,6-Me2C6H3)Cl2(py)3] with K2[COT] gave the mu-imido-bridged dimer [Ti2(mu-N-2,6-Me2C6H3)2(eta8-COT)2]. It appears that as the steric bulk of the imido and C8 ring substituents are decreased, dimerisation becomes more favourable. Aryl imido COT complexes were also prepared by imido ligand exchange reactions between anilines and [Ti(NtBu)(eta(8)-COT)] or [Ti(NtBu)(eta(8)-COT')]. The complexes [Ti(NtBu)(eta(8)-COT)], [Ti(N-2,6-iPr2C6H3)2(eta8-COT)] and [Ti2(mu-N-2,6-Me2C6H3)2(eta8-COT)2] have been crystallographically characterised. The electronic structures of both the monomeric and dimeric complexes have been investigated by using density functional theory (DFT) calculations and gas-phase photoelectron spectroscopy. The most striking aspect of the bonding is that binding to the imido nitrogen atom is primarily through sigma and pi interactions, whereas that to the COT or COT' ring is almost exclusively through delta symmetry orbitals. A DFT-based comparison between the bonding in [Ti(NtBu)(eta8-COT)] and the bonding in the previously reported late transition-metal "pogo stick"complexes [Os(NtBu)(eta6-C6Me6)], [Ir(NtBu)(eta5-C5Me5)] and [Ni(NO)(eta5-C5H5)] has also been undertaken.     

Eta6-mesityl,eta1-imidazolinylidene-carbene-ruthenium(II) complexes: catalytic activity of their allenylidene derivatives in alkene metathesis and cycloisomerisation reactions

The reaction of electron-rich carbene-precursor olefins containing two imidazolinylidene moieties [(2,4,6-Me(3)C(6)H(2)CH(2))NCH(2)CH(2)N(R)Cdbond;](2) (2a: R=CH(2)CH(2)OMe, 2 b R=CH(2)Mes), bearing at least one 2,4,6-trimethylbenzyl (R=CH(2)Mes) group on the nitrogen atom, with [RuCl(2)(arene)](2) (arene=p-cymene, hexamethylbenzene) selectively leads to two types of complexes. The cleavage of the chloride bridges occurs first to yield the expected (carbene) (arene)ruthenium(II) complex 3. Then a further arene displacement reaction takes place to give the chelated eta(6)-mesityl,eta(1)-carbene-ruthenium complexes 4 and 5. An analogous eta(6)-arene,eta(1)-carbene complex with a benzimidazole frame 6 was isolated from an in situ reaction between [RuCl(2)(p-cymene)](2), the corresponding benzimidazolium salt and cesium carbonate. On heating, the RuCl(2)(imidazolinylidene) (p-cymene) complex 8, with p-methoxybenzyl pendent groups attached to the N atoms, leads to intramolecular p-cymene displacement and to the chelated eta(6)-arene,eta(1)-carbene complex 9. On reaction with AgOTf and the propargylic alcohol HCtbond;CCPh(2)OH, compounds 4-6 were transformed into the corresponding ruthenium allenylidene intermediates (4-->10, 5-->11, 6-->12). The in situ generated intermediates 10-12 were found to be active and selective catalysts for ring-closing metathesis (RCM) or cycloisomerisation reactions depending on the nature of the 1,6-dienes. Two complexes [RuCl(2)[eta(1)-CN(CH(2)C(6)H(2)Me(3)-2,4,6)CH(2)CH(2)N- (CH(2)CH(2)OMe)](C(6)Me(6))] 3 with a monodentate carbene ligand and [RuCl(2)[eta(1)-CN[CH(2)(eta(6)-C(6)H(2)Me(3)-2,4,6)]CH(2)CH(2)N-(CH(2)C(6)H(2)Me(3)-2,4,6)]] 5 with a chelating carbene-arene ligand were characterised by X-ray crystallography.     

Bi- and poly-metallic cyanide-bridged complexes of the redox-active cyanomanganese nitrosyl unit [Mn(CN)(PR3)(NO)(eta-C5H4Me)

Cationic nitrile complexes and neutral halide and cyanide complexes, with the general formula [MnL1L2(NO)(eta-C5H4Me)]z, undergo one-electron oxidation at a Pt electrode in CH2Cl2. Linear plots of oxidation potential, Eo', vs. nu(NO) or the Lever parameters, EL, for L1 and L2, allow Eo' to be estimated for unknown analogues. In the presence of TlPF6, [MnIL'(NO)(eta-C5H4Me)] reacts with [Mn(CN)L(NO)(eta-C5H4Me)] to give [(eta5-C5H4Me)(ON)LMn(mu-CN)MnL'(NO)(eta5-C5H4Me)][PF6] which undergoes two reversible one-electron oxidations; DeltaE, the difference between the potentials for the two processes, differs significantly for stable cyanide-bridged linkage isomers. Novel pentametallic complexes such as [Mn[(mu-NC)Mn(CNBut)(NO)(eta5-C5H4Me)]4(OEt2)][PF6]2 and [Mn[(mu-NC)Mn(CNXyl)(NO)(eta5-C5H4Me)]4(NO3-O,O')][PF6], containing a trigonal bipyramidal and a distorted octahedral Mn(II) centre, respectively, result either from slow decomposition of the binuclear cyanide-bridged species or from the reaction of anhydrous MnI2 with four equivalents of [Mn(CN)L(NO)(eta5-C5H4Me)] in the presence of TlPF6.     

Molybdenum amido complexes with single Mo-N bonds: synthesis,structure, and reactivity

Reactions of the complex [MoCl(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (1) (phen=1,10-phenanthroline) with potassium arylamides were used to synthesize the amido complexes [Mo(N(R)Ar)(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (R=H, Ar=Ph, 2 a; R=H, Ar=p-tolyl, 2 b; R=Me, Ar=Ph; 2 c). For 2 b the Mo-N(amido) bond length (2.105(4) A) is consistent with it being a single bond, with which the metal attains an 18-electron configuration. The reaction of 2 b with HOTf affords the amino complex [Mo(eta(3)-C(3)H(4)-Me-2)(NH(2)(p-tol))(CO)(2)(phen)]OTf (3-OTf). Treatment of 3-OTf with nBuLi or KN(SiMe(3))(2) regenerates 2 b. The new amido complexes react with CS(2), arylisothiocyanates and maleic anhydride. A single product corresponding to the formal insertion of the electrophile into the Mo-N(amido) bond is obtained in each case. For maleic anhydride, ring opening accompanied the formation of the insertion product. The reaction of 2 b with maleimide affords [Mo(eta(3)-C(3)H(4)-Me-2)[NC(O)CH=CHC(O)](CO)(2)(phen)] (7), which results from simple acid-base metathesis. The reaction of 2 b with (p-tol)NCO affords [[Mo(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)](2)(eta(2)-MoO(4))] (8), which corresponds to oxidation of one third of the metal atoms to Mo(VI). Complex 8 was also obtained in the reactions of 2 b with CO(2) or the lactide 3,6-dimethyl-1,4-dioxane-2,5-dione. The structures of the compounds 2 b, 3-OTf, [Mo(eta(3)-C(3)H(4)-Me-2)[SC(S)(N(H)Ph)](CO)(2)(phen)] (4), [Mo(eta(3)-C(3)H(4)-Me-2)[SC(N(p-tol))(NH(p-tol))](CO)(2)(phen)] (5 a), and [Mo(eta(3)-C(3)H(4)-Me-2)[OC(O)CH=CHC(O)(NH(p-tol))](CO)(2)(phen)] (6), 7, and 8 (both the free complex and its N,N'-di(p-tolyl)urea adduct) were determined by X-ray diffraction.     

On the prospects of polynuclear complexes with acetylenedithiolate bridging units

The generation of polynuclear complexes with one, two, or four acetylenedithiolate bridging units via the isolation of eta2-alkyne complexes of acetylenedithiolate K[Tp'M(CO)(L)(C2S2)] (Tp'=hydrotris(3,5-dimethylpyrazolyl)borate, M=W, L=CO (K-3a), M=Mo, L=CNC6H3Me2 (K-3b)) is reported. The strong electronic cooperation of Ru and W in the heterobimetallic complexes [(eta5-C5H5)(PPh3)Ru(3a)] (4a) and [(eta5-C5H5)(Me2C6H3NC)Ru(3a)] (4b) has been elucidated by correlation of the NMR, IR, UV-vis, and EPR-spectroscopic properties of the redox couples 4a/4a+ and 4b/4b+ with results from density functional calculations. Treatment of M(II) (M=Ni, Pd, Pt) with K-3a and K-3b afforded the homoleptic bis complexes [M(3a)2] (M=Ni (5a), Pd (5b), Pt (5c)), and [M(3b)2] (M=Pd (6a) and Pt (6b)), in which the metalla-acetylendithiolates exclusively serve as S,S'-chelate ligands. The vibrational and electronic spectra as well as the cyclic voltammetry behavior of all the complexes are compared. The structural analogy of 5a/5b/5c and 6a/6b with dithiolene complexes is only partly reflected in the electronic structures. The very intense visible absorptions involve essential d orbital contributions of the central metal, while the redox activity is primarily attributed to the alkyne complex moiety. Accordingly, stoichiometric reduction of 5a/5b/5c yields paramagnetic complex anions with electron-rich alkyne complex moieties being indistinguishable in the IR time scale. K-3a forms with Cu(I) the octanuclear cluster [Cu(3a)]4 (7) exhibiting a Cu4(S2C2)4W4 core. The nonchelating bridging mode of the metalla-acetylenedithiolate 3a- in 7 is recognized by a high-field shift of the alkyne carbon atoms in the 13C NMR spectrum. X-ray diffraction studies of K[Tp'(CO)(Me3CNC)Mo(eta2-C2S2)] (K-3c), 4b, 6a, 6b, and 7 are included. Comparison of the molecular structures of K-3c and 7 on the one hand with 4b and 6a/6b on the other reveals that the small bend-back angles in the latter are a direct consequence of the chelate ring formation.     

DNA binding and topoisomerase II inhibitory activity of water-soluble ruthenium(II) and rhodium(III) complexes

Water-soluble piano-stool arene ruthenium complexes based on 1-(4-cyanophenyl)imidazole (CPI) and 4-cyanopyridine (CNPy) with the formulas [(eta6-arene)RuCl2(L)] (L = CPI, eta6-arene = benzene (1), p-cymene (2), hexamethylbenzene (3); L = CNPy, eta6-arene = benzene (4), p-cymene (5), hexamethylbenzene (6)) have been prepared by our earlier methods. The molecular structure of [(eta6-C6Me6)RuCl2(CNPy)] (6) has been determined crystallographically. Analogous rhodium(III) complex [(eta5-C5Me5)RhCl2(CPI)] (7) has also been prepared and characterized. DNA interaction with the arene ruthenium complexes and the rhodium complex has been examined by spectroscopic and gel mobility shift assay; condensation of DNA and B-->Z transition have also been described. Arene ruthenium(II) and EPh3 (E = P, As)-containing arene ruthenium(II) complexes exhibited strong binding behavior, however, rhodium(III) complexes were found to be Topo II inhibitors with an inhibition percentage of 70% (7) and 30% (7a). Furthermore, arene ruthenium complexes containing polypyridyl ligands also act as mild Topo II inhibitors (10%, 3c and 40%, 3d) in contrast to their precursor complexes. Complexes 4-6 also show significant inhibition of beta-hematin/hemozoin formation activity.     

Phosphaallyl complexes of Ru(II) derived from dicyclohexylvinylphosphine (DCVP)

The complexes [(eta5-RC5H4)Ru(CH3CN)3]PF6(R = H, CH3) react with DCVP (DCVP = Cy2PCH=CH2) at room temperature to produce the phosphaallyl complexes [(eta5-C5H5)Ru(eta1-DCVP)(eta3-DCVP)]PF6 and [(eta5-MeC5H4)Ru(eta1-DCVP)(eta3-DCVP)]PF6. Both compounds react with a variety of two-electron donor ligands displacing the coordinated vinyl moiety. In contrast, we failed to prepare the phosphaallyl complexes [(eta5-C5Me5)Ru(eta1-DCVP)(eta3-DCVP)]PF6, [(eta5-MeC5H4)Ru(CO)(eta3-DCVP)]PF6 and [(eta5-C5Me5)Ru(CO)(eta3-DPVP)]PF6(DPVP = Ph2PCH=CH2).The compounds [(eta5-MeC5H4)Ru(CO)(CH3CN)(DPVP)]PF6 and [(eta5-C5Me5)Ru(CO)(CH3CN)(DPVP)]PF6 react with DMPP (3,4-dimethyl-1-phenylphosphole) to undergo [4 + 2] Diels-Alder cycloaddition reactions at elevated temperature. Attempts at ruthenium catalyzed hydration of phenylacetylene produced neither acetophenone nor phenylacetaldehyde but rather dimers and trimers of phenylacetylene. The structures of the complexes described herein have been deduced from elemental analyses, infrared spectroscopy, 1H, 13C{1H}, 31P{1H} NMR spectroscopy and in several cases by X-ray crystallography.     

Bimetallic cluster complexes: the synthesis, structures, and bonding of ruthenium carbonyl cluster complexes containing palladium and platinum with the bulky tri-tert-butyl-phosphine ligand

The bis-phosphine compounds M(PBut3)2, M = Pd and Pt, readily eliminate one PBut3 ligand and transfer MPBut3 groups to the ruthenium-ruthenium bonds in the compounds Ru3(CO)12, Ru6(CO)17(micro6-C), and Ru6(CO)14(eta6-C6H6)(micro6-C) without displacement of any of the ligands on the ruthenium complexes. The new compounds, Ru3(CO)12[Pd(PBut3)]3, 10, and Ru6(CO)17(micro6-C)[Pd(PBut3)]2, 11, Ru6(CO)17(micro6-C)[Pt(PBut3)]n, n = 1 (12), n = 2 (13), and Ru6(CO)14(eta6-C6H6)(micro6-C)[Pd(PBut3)]n, n = 1 (15), n = 2 (16), have been prepared and structurally characterized. In most cases the MPBut3 groups bridge a pair of mutually bonded ruthenium atoms, and the associated Ru-Ru bond distance increases in length. Fenske-Hall calculations were performed on 10 and 11 to develop an understanding of the electron deficient metal-metal bonding. 10 undergoes a Jahn-Teller distortion to increase bonding interactions between neighboring Ru(CO)4 and Pd(PBut3) fragments. 11 has seven molecular orbitals important to cluster bonding in accord with cluster electron-counting rules.     

Synthesis, characterization, and photochemical behavior of {Ru(arene)}2+ derivatives of alpha-[PW11O39]7-: an organometallic way to ruthenium-substituted heteropolytungstates

Reaction of [Ru(arene)Cl(2)](2) (arene = benzene, toluene, p-cymene, hexamethylbenzene) with K(7)[PW(11)O(39)].14H(2)O provided two series of organometallic derivatives of heteropolytungstates: type-1 and type-2 complexes of general formulas [PW(11)O(39){Ru(arene)(H(2)O)}](5-) and [{PW(11)O(39){Ru(arene)}}(2){WO(2)}](8-), respectively. All compounds were characterized by infrared and multinuclear NMR ((1)H, (31)P, (183)W) spectroscopies. The crystal structures of Na(4)K(4)[{PW(11)O(39){Ru(benzene)}}(2){WO(2)}].6H(2)O (NaK-2a.6H(2)O), K(7)H[{PW(11)O(39){Ru(toluene)}}(2){WO(2)}].4H(2)O (K-2b.4H(2)O), and Cs(3)K(2)[PW(11)O(39){Ru(p-cymene)(H(2)O)}].4H(2)O (CsK-1c.4H(2)O) were obtained and revealed that the {Ru(arene)} fragment is supported on the oxometallic framework. Photochemical reactivity of [PW(11)O(39){Ru(arene)(H(2)O)}](5-) (arene = toluene, p-cymene) in the presence of various ligands L (L = H(2)O, dimethyl sulfoxide, tetramethylene sulfoxide, and diphenyl sulfoxide) was investigated, and led to the formation of [PW(11)O(39){Ru(L)}](5-), in which the ruthenium is incorporated into the lacunary [PW(11)O(39)](7-) anion.     

Molecular nitrides containing group 4 and 5 metals: single and double azatitanocubanes

Treatment of [[Ti(eta(5)-C(5)Me(5))(micro-NH)](3)(micro(3)-N)] (1) with the imido complexes [Ti(NAr)Cl(2)(py)(3)] (Ar=2,4,6-C(6)H(2)Me(3)) and [Ti(NtBu)Cl(2)(py)(3)] in toluene affords the single azatitanocubanes [[Cl(2)(ArN)Ti]( micro(3)-NH)(3)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]].(C(7)H(8)) (2.C(7)H(8)) and [[Cl(2)Ti](micro(3)-N)(2)(micro(3)-NH)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]] (3), respectively. Similar reactions of complex 1 with the niobium and tantalum imido derivatives [[M(NtBu)(NHtBu)Cl(2)(NH(2)tBu)](2)] (M=Nb, Ta) in toluene give the single azaheterometallocubanes [[Cl(2)(tBuN)M](micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]] (M=Nb (4), Ta (5)), both complexes react with 2,4,6-trimethylaniline to yield the analogous species [[Cl(2)(ArN)M](micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]].(C(7)H(8)) (Ar=2,4,6-C(6)H(2)Me(3), M=Nb (6.C(7)H(8)), Ta (7.C(7)H(8))). Also the azaheterodicubanes [M[micro(3)-N)(2)(micro(3)-NH)](2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)](2)].2C(7)H(8) [M=Ti (8.2C(7)H(8)), Zr (9.2C(7)H(8))], and [M[(micro(3)-N)(5)(micro(3)-NH)][Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)](2)].2 C(7)H(8) (Nb (10.2C(7)H(8)), Ta (11.2C(7)H(8))) were prepared from 1 and the homoleptic dimethylamido complex [M(NMe(2))(x)] (x=4, M=Ti, Zr; x=5, M=Nb, Ta) in toluene at 150 degrees C. X-ray crystal structure determinations were performed for 6 and 10, which revealed a cube- and double-cube-type core, respectively. For complexes 2 and 4-7 we observed and studied by DNMR a rotation or trigonal-twist of the organometallic ligands [[Ti(eta(5)-C(5)Me(5))(micro-NH)](3)(micro(3)-N)] (1) and [(micro(3)-N)(micro(3)-NH)(2)[Ti(3)(eta(5)-C(5)Me(5))(3)(micro(3)-N)]](1-). Density functional theory calculations were carried out on model complexes of 2, 3, and 8 to establish and understand their structures.     

Interplay of cubic building blocks in (et6-arene)ruthenium-containing tungsten and molybdenum oxides

A series of molybdenum and tungsten organometallic oxides containing [Ru(arene)]2+ units (arene =p-cymene, C6Me6) was obtained by condensation of [[Ru(arene)Cl2]2] with oxomolybdates and oxotungstates in aqueous or nonaqueous solvents. The crystal structures of [[Ru(eta6-C6Me6]]4W4O16], [[Ru(eta6-p-MeC6H4iPr]]4W2O10], [[[Ru-(eta6-p-MeC6H4iPr)]2(mu-OH)3]2][[Ru(eta6-p-MeC6H4iPr)]2W8O28(OH)2[Ru(eta6-p-MeC6H4iPr)(H2O)]2], and [[Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) have been determined. While the windmill-type clusters [[Ru(eta6-arene)]4(MO3)4(mu3-O)4] (M = Mo, W; arene =p-MeC6H4iPr, C6Me6), the face-sharing double cubane-type cluster [[Ru(eta6-p-MeC6H4iPr)]4(WO2)2(mu3-O)4(mu4-O)2], and the dimeric cluster [[Ru(eta6-p-MeC6H4iPr)(WO3)3(mu3-O)3(mu3-OH)Ru(eta6-pMeC6H4iPr)(H2O)]2(mu-WO2)2]2- are based on cubane-like units, [(Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) are more properly described as lacunary Lindqvist-type polyoxoanions supporting three ruthenium centers. Precubane clusters [[Ru(eta6-arene)](MO3)2(mu-O)3(mu3-O)]6- are possible intermediates in the formation of these clusters. The cluster structures are retained in solution, except for [[Ru(eta6-p-MeC6H4iPr)]4Mo4O16], which isomerizes to the triple-cubane form.     

Novel dimetal bridging carbene complexes derived from a terminal carbonyl dimetal compound. Syntheses, structures and reactivities of 7H-indene-coordinated diiron bridging carbene complexes

Pentacarbonyl-7H-indenediiron, [Fe2(CO)5(eta3,eta5-C9H8)] (1), reacts with aryllithium, ArLi (Ar = C6H5, p-C6H5C6H4), followed by alkylation with Et3OBF4 to give novel 7H-indene-coordinated diiron bridging alkoxycarbene complexes [Fe2{mu-C(OC2H5)Ar}(CO)4(eta4,eta4-C9H8)] (2, Ar = C6H5; 3, Ar = p-C6H5C6H4). Complexes 2 and 3 react with HBF4.Et2O at low temperature to yield cationic bridging carbyne complexes [Fe2(mu-CAr)(CO)4(eta4,eta4-C9H8)]BF4 (4, Ar = C6H5; 5, Ar = p-C6H5C6H4). Cationic 4 and 5 react with NaBH4 in THF at low temperature to afford diiron bridging arylcarbene complexes [Fe2{mu-C(H)Ar}(CO)4(eta4,eta4-C9H8)] (6, Ar = C6H5; 7, Ar = p-C6H5C6H4). The similar reactions of 4 and 5 with NaSC6H4CH3-p produce the bridging arylthiocarbene complexes [Fe2{mu-C(Ar)SC6H4CH3-p}(CO)4(eta4,eta4-C9H8)] (8, Ar = C6H5; 9, Ar = p-C6H5C6H4). Cationic 4 and 5 can also react with anionic carbonylmetal compounds Na[M(CO)5(CN)] (M = Cr, Mo, W) to give the diiron bridging aryl(pentacarbonylcyanometal)carbene complexes [Fe2{mu-C(Ar)NCM(CO)5}(CO)4(eta4,eta4-C9H8)] (10, Ar = C6H5, M = Cr; 11, Ar = p-C6H5C6H4, M = Cr; 12, Ar = C6H5, M = Mo; 13, Ar = p-C6H5C6H4, M = Mo; 14, Ar = C6H5, M = W; 15, Ar = p-C6H5C6H4, M = W). Interestingly, in CH2Cl2 solution at room temperature complexes 10-15 were transformed into the isomerized 7H-indene-coordinated monoiron complexes [Fe(CO)2(eta5-C9H8)C(Ar)NCM(CO)5] (16, Ar = C6H5, M = Cr; 17, Ar = p-C6H5C6H4, M = Cr; 18, Ar = C6H5, M = Mo; 19, Ar = p-C6H5C6H4, M = Mo; 20, Ar = C6H5, M = W; 21, Ar = p-C6H5C6H4, M = W), while complex 3 was converted into a novel ring addition product [Fe2{C(OC2H5)C6H4C6H5-p-(eta2,eta5-C9H8)}(CO)5] (22) under the same conditions. The structures of complexes 2, 6, 8, 14, 18 and 22 have been established by X-ray diffraction studies.