Solution and solid-state dynamics of metal-coordinated white phosphorus

The dynamic behavior in solution of eight mono-hapto?tetraphosphorus transition metal-complexes, trans-[Ru(dppm)(2) (H)(η(1) -P(4) )]BF(4) ([1]BF(4) ), trans-[Ru(dppe)(2) (H)(η(1) -P(4) )]BF(4) ([2]BF(4) ), [CpRu(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([3]PF(6) ), [CpOs(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([4]PF(6) ), [Cp*Ru(PPh(3) )(2) (η(1) -P(4) )]PF(6) ([5]PF(6) ), [Cp*Ru(dppe)(η(1) -P(4) )]PF(6) ([6]PF(6) ), [Cp*Fe(dppe)(η(1) -P(4) )]PF(6) ([7]PF(6) ), [(triphos)Re(CO)(2) (η(1) -P(4) )]OTf ([8]OTf), and of three bimetallic Ru(μ,η(1:2) -P(4) )Pt species [{Ru(dppm)(2) (H)}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([1-Pt]BF(4) ), [{Ru(dppe)(2) (H)}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([2-Pt]BF(4) ), [{CpRu(PPh(3) )(2) )}(μ,η(1:2) -P(4) ){Pt(PPh(3) )(2) }]BF(4) ([3-Pt]BF(4) ), [dppm=bis(diphenylphosphanyl)methane; dppe=1,2-bis(diphenylphosphanyl)ethane; triphos=1,1,1-tris(diphenylphosphanylmethyl)ethane; Cp=η(5) -C(5) H(5) ; Cp*=η(5) -C(5) Me(5) ] was studied by variable-temperature (VT) NMR and (31) P{(1) H} exchange spectroscopy (EXSY). For most of the mononuclear species, NMR spectroscopy allowed to ascertain that the metal-coordinated P(4) molecule experiences a dynamic process consisting, apart from the free rotation about the M?P(4) axis, in a tumbling movement of the P(4) cage while remaining chemically coordinated to the central metal. EXSY and VT (31) P?NMR experiments showed that also the binuclear complex cations [1-Pt](+) -[3-Pt](+) are subjected to molecular motions featured by the shift of each metal from one P to an adjacent one of the P(4) moiety. The relative mobility of the metal fragments (Ru vs. Pt) was found to depend on the co-ligands of the binuclear complexes. For complexes [2]BF(4) and [3]PF(6) , MAS, (31) P?NMR experiments revealed that the dynamic processes observed in solution (i.e., rotation and tumbling) may take place also in the solid state. The activation parameters for the dynamic processes of complexes 1(+) , 2(+) , 3(+) , 4(+) , 6(+) , 8(+) in solution, as well as the X-ray structures of 2(+) , 3(+) , 5(+) , 6(+) are also reported. The data collected suggest that metal-coordinated P(4) should not be considered as a static ligand in solution and in the solid state.     

Dithiocarboxylate complexes of ruthenium(II) and osmium(II)

The ruthenium(II) complexes [Ru(R)(κ(2)-S(2)C·IPr)(CO)(PPh(3))(2)](+) (R = CH=CHBu(t), CH=CHC(6)H(4)Me-4, C(C≡CPh)=CHPh) are formed on reaction of IPr·CS(2) with [Ru(R)Cl(CO)(BTD)(PPh(3))(2)] (BTD = 2,1,3-benzothiadiazole) or [Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh(3))(2)] in the presence of ammonium hexafluorophosphate. Similarly, the complexes [Ru(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·ICy)(CO)(PPh(3))(2)](+) and [Ru(C(C≡CPh)=CHPh)(κ(2)-S(2)C·ICy)(CO)(PPh(3))(2)](+) are formed in the same manner when ICy·CS(2) is employed. The ligand IMes·CS(2) reacts with [Ru(R)Cl(CO)(BTD)(PPh(3))(2)] to form the compounds [Ru(R)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+) (R = CH=CHBu(t), CH=CHC(6)H(4)Me-4, C(C≡CPh)=CHPh). Two osmium analogues, [Os(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+) and [Os(C(C≡CPh)=CHPh)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+) were also prepared. When the more bulky diisopropylphenyl derivative IDip·CS(2) is used, an unusual product, [Ru(κ(2)-SC(H)S(CH=CHC(6)H(4)Me-4)·IDip)Cl(CO)(PPh(3))(2)](+), with a migrated vinyl group, is obtained. Over extended reaction times, [Ru(CH=CHC(6)H(4)Me-4)Cl(BTD)(CO)(PPh(3))(2)] also reacts with IMes·CS(2) and NH(4)PF(6) to yield the analogous product [Ru{κ(2)-SC(H)S(CH=CHC(6)H(4)Me-4)·IMes}Cl(CO)(PPh(3))(2)](+)via the intermediate [Ru(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·IMes)(CO)(PPh(3))(2)](+). Structural studies are reported for [Ru(CH=CHC(6)H(4)Me-4)(κ(2)-S(2)C·IPr)(CO)(PPh(3))(2)]PF(6) and [Ru(C(C≡CPh)=CHPh)(κ(2)-S(2)C·ICy)(CO)(PPh(3))(2)]PF(6).     

Regioselective nucleophilic addition of triphenylphosphine to the nitrosylruthenium alkynyl complexes having a hydrotris(pyrazol-1-yl)borate: formation of phosphonio-alkenyl, alkynyl, and allenyl species

A nitrosylruthenium alkynyl complex of TpRuCl(C[triple bond]CPh)(NO)(1a) was reacted with PPh3 in the presence of HBF4.Et2O at room temperature to give a beta-phosphonio-alkenyl complex (E)-[TpRuCl{CH=C(PPh3)Ph}(NO)]BF4(2.BF4). On the other hand, for gamma-hydroxyalkynyl complexes TpRuCl{C[triple bond]CC(R)2OH}(NO)(R = Me (1b), Ph (1c), H (1d)), similar treatments with PPh3 were found to give gamma-phosphonio-alkynyl [TpRuCl{C[triple bond]CC(Me)2PPh3}(NO)]BF4(3.BF4),alpha-phosphonio-allenyl [TpRuCl{C(PPh3)=C=CPh2}(NO)]BF4(4.BF4), and a novel product of gamma-hydroxy-beta-phosphonio-alkenyl (E)-[TpRuCl{CH=C(PPh3)CH2OH}(NO)]BF4(5.BF4), respectively. Dominant factors for the selectivity in affording 3-5 were associated with the steric congestion and electronic properties at the gamma-carbons, along with those around the metal fragment. From the bis(alkynyl) complex TpRu(C[triple bond]CPh)2(NO)6, a bis(beta-phosphonio-alkenyl)(E,E)-[TpRu{CH=C(PPh3)Ph}2(NO)](BF4)2{7.(BF4)2} was produced at room temperature. However, similar reactions at 0 degrees C gave an alkynyl beta-phosphonio-alkenyl complex (E)-[TpRu(C[triple bondCPh){CH=C(PPh3)Ph}(NO)]BF4(8.BF4) as a sole product, of which additional hydration in the presence of HBF4.Et2O afforded a [small beta]-phosphonio-alkenyl ketonyl (E)-[TpRu{CH2C(O)Ph}{CH=C(PPh3)Ph}(NO)]BF(.9BF4). Five complexes, 2-5 and 7 were crystallographically characterized.     

Group 11 complexes containing the [C5(CN)5]- ligand; 'coordination-analogues' of molecular organometallic systems

The reactions of Na[C(5)(CN)(5)] (Na[1]) with group 11 phosphine complexes [(P)(n)MCl] (M = Cu, Ag, Au, P = Ph(3)P; M = Cu, P = dppe (Ph(2)PCH(2)CH(2)PPh(2))] give a range of compounds containing the pentacyanocyclopentadienide ligand, [C(5)(CN)(5)](-) (1). The new complexes [(Ph(3)P)(2)M{1}](2) [M = Cu (3); M = Ag (5)], [(Ph(3)P)(3)Ag{1}] (4), [(dppe)(3)Cu(2){1}(2)] (6) and [Au(PPh(3))(2)][1] (7) include the first complete series of group 11 complexes of any cyclopentadienide ligand to be structurally characterised.     

Mixed-valence nickel-iron dithiolate models of the [NiFe]-hydrogenase active site

A series of mixed-valence nickel-iron dithiolates is described. Oxidation of (diphosphine)Ni(dithiolate)Fe(CO)(3) complexes 1, 2, and 3 with ferrocenium salts affords the corresponding tricarbonyl cations [(dppe)Ni(pdt)Fe(CO)(3)](+) ([1](+)), [(dppe)Ni(edt)Fe(CO)(3)](+) ([2](+)) and [(dcpe)Ni(pdt)Fe(CO)(3)](+) ([3](+)), respectively, where dppe = Ph(2)PCH(2)CH(2)PPh(2), dcpe = Cy(2)PCH(2)CH(2)PCy(2), (Cy = cyclohexyl), pdtH(2) = HSCH(2)CH(2)CH(2)SH, and edtH(2) = HSCH(2)CH(2)SH. The cation [2](+) proved unstable, but the propanedithiolates are robust. IR and EPR spectroscopic measurements indicate that these species exist as C(s)-symmetric species. Crystallographic characterization of [3]BF(4) shows that Ni is square planar. Interaction of [1]BF(4) with P-donor ligands (L) afforded a series of substituted derivatives of type [(dppe)Ni(pdt)Fe(CO)(2)L]BF(4) for L = P(OPh)(3) ([4a]BF(4)), P(p-C(6)H(4)Cl)(3) ([4b]BF(4)), PPh(2)(2-py) ([4c]BF(4)), PPh(2)(OEt) ([4d]BF(4)), PPh(3) ([4e]BF(4)), PPh(2)(o-C(6)H(4)OMe) ([4f]BF(4)), PPh(2)(o-C(6)H(4)OCH(2)OMe) ([4g]BF(4)), P(p-tol)(3) ([4h]BF(4)), P(p-C(6)H(4)OMe)(3) ([4i]BF(4)), and PMePh(2) ([4j]BF(4)). EPR analysis indicates that ethanedithiolate [2](+) exists as a single species at 110 K, whereas the propanedithiolate cations exist as a mixture of two conformers, which are proposed to be related through a flip of the chelate ring. M?ssbauer spectra of 1 and oxidized S = 1/2 [4e]BF(4) are both consistent with a low-spin Fe(I) state. The hyperfine coupling tensor of [4e]BF(4) has a small isotropic component and significant anisotropy. DFT calculations using the BP86, B3LYP, and PBE0 exchange-correlation functionals agree with the structural and spectroscopic data, suggesting that the SOMOs in complexes of the present type are localized in an Fe(I)-centered d(z(2)) orbital. The DFT calculations allow an assignment of oxidation states of the metals and rationalization of the conformers detected by EPR spectroscopy. Treatment of [1](+) with CN(-) and compact basic phosphines results in complex reactions. With dppe, [1](+) undergoes quasi-disproportionation to give 1 and the diamagnetic complex [(dppe)Ni(pdt)Fe(CO)(2)(dppe)](2+) ([5](2+)), which features square-planar Ni linked to an octahedral Fe center.     

Reactions of the tetrafluoroborate complex [Mo2Cp2(κ(2)-F2BF2)(μ-PPh2)2(CO)]BF4 with mono- and bidentate ligands having E-H bonds (E = O, S, Se, N, P)

The title compound reacted rapidly with CN(t)Bu at room temperature by displacing the BF(4)(-) ligand and incorporating three molecules of isocyanide to yield the electron-precise complex [Mo(2)Cp(2)(μ-PPh(2))(2)(CN(t)Bu)(3)(CO)](BF(4))(2), which was obtained as a mixture of cis and trans isomers. Reaction with several HER(n) molecules (HER(n) = HSPh, HSePh, H(2)PCy) took place with formal elimination of HBF(4) and spontaneous carbonylation to give the electron-precise cations [Mo(2)Cp(2)(μ-ER(n))(μ-PPh(2))(2)(CO)(2)](+). Reactions with several bidentate ligands (L(2)H) having acidic E-H bonds (2-hydroxypyridine, 2-mercaptopyridine, cathecol, 2-aminophenol, and 2-aminothiophenol) proceeded analogously with deprotonation of these bonds with the preference E = S > O > N. The N,O-donor ligands yielded 32-electron chelate derivatives of the type [Mo(2)Cp(2)(O,N-L(2))(μ-PPh(2))(2)(CO)]BF(4) (L(2) = OC(5)H(4)N, OC(6)H(4)NH(2)), whereas the S,N-donors yielded 34-electron, S-bridged complexes [Mo(2)Cp(2)(μ-S:S,N-L(2))(μ-PPh(2))(2)(CO)]BF(4) [L(2) = SC(5)H(4)N (Mo-Mo = 2.8895(8) ?), SC(6)H(4)NH(2)]. However, reaction with catechol gave a monodentate derivative [Mo(2)Cp(2)(O-OC(6)H(4)OH)(μ-PPh(2))(2)(CO)]BF(4). In contrast, reactions of the title complex with several carboxylic acids and related species (acetic, benzoic, and thioacetic acids, acetamide, thioacetamide, and sodium diethyldithiocarbamate) were insensitive to the nature of the donor atoms and gave in all cases 32-electron chelate derivatives of type [Mo(2)Cp(2)(κ(2)-L(2))(μ-PPh(2))(2)(CO)]BF(4). All of the above cations having Mo-bound OH, NH, or NH(2) groups were easily deprotonated upon reaction with 1,8-diazabicycloundec-7-ene (DBU) or other bases to give neutral complexes which exhibited different coordination motifs depending on the donor atoms, including chelate complexes of the type [Mo(2)Cp(2)(κ(2)-L(2)')(μ-PPh(2))(2)(CO)] (L(2)' = OC(6)H(4)O, OC(6)H(4)NH), the bridged complexes [Mo(2)Cp(2)(μ-S,N:S,N-SC(6)H(4)NH)(μ-PPh(2))(2)] and [Mo(2)Cp(2){μ-S,N-N(S)CMe}(μ-PPh(2))(2)], and the terminal acetylimido complex [Mo(2)Cp(2){N-N(O)CMe}(μ-PPh(2))(2)(CO)].     

Syntheses, reactions, and ethylene polymerization of titanium complexes with [N,N,S] ligands

Tridentate dianionic arylsulfide free ligands [ArNHCH(2)C(6)H(4)NHC(6)H(4)-2-SPh] (Ar = Ph (3a); Ar = 2,4,6-trimethylphenyl (3b); Ar = 2,6-diisopropylphenyl (3c)) have been prepared by reduction of the corresponding imine compounds [ArN[double bond, length as m-dash]CHC(6)H(4)NHC(6)H(4)-2-SPh] (Ar = Ph (2a); Ar = 2,4,6-trimethylphenyl (2b); Ar = 2,6-diisopropylphenyl (2c)) with LiAlH(4) in high yields. Reactions of TiCl(4) with the tridentate dianionic arylsulfide free ligands (3a-3c) afford five-coordinate and four-coordinate titanium complexes [κS, κ(2)N-(ArNHCH(2)C(6)H(4)NHC(6)H(4)-2-SPh)TiCl(2)] (Ar = Ph (4a); Ar = 2,4,6-trimethylphenyl (4b)] and [κ(2)N-(ArNHCH(2)C(6)H(4)NHC(6)H(4)-2-SPh)TiCl(2)] (Ar = 2,6-diisopropylphenyl (4c)], respectively. The molecular structures of compounds 2b, 2c, 3b and 3c·HCl have been characterized by single crystal X-ray diffraction analyses. Complexes 2a-4c are characterized by IR,(1)H-NMR spectra, and elemental analysis. EXAFS spectroscopy performed on complexes 4b and 4c reveals the expected different coordination geometry due to steric hindrance effect. When activated by excess methylaluminoxane (MAO), 4a-4c can be used as catalysts for ethylene polymerization and exhibit moderate to good activities.     

A convenient route to dinuclear chloro-bridged platinum(II) derivatives via nitrile complexes

The syntheses of the complexes [PtCl(2)(NCR)L] [R = Me, Et; L = PPh(3); R = Et, L = Py, CO] and [PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] are described starting from the easily available [PtCl(2)(NCR)(2)]. The stability of the products under different experimental conditions is discussed as well as their use as precursors to dinuclear complexes [Pt(μ-Cl)ClL](2). The crystal and molecular structures of cis-[PtCl(2)(NCEt)(PPh(3))], [SP-4-2]-[PtCl{(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}(NCEt)] and trans-[Pt(μ-Cl){(κ(2)-P,C)P(OC(6)H(4))(OPh)(2)}](2) are reported.     

Sulfido-bridged dinuclear molybdenum-copper complexes related to the active site of CO dehydrogenase: [(dithiolate)Mo(O)S2Cu(SAr)]2- (dithiolate = 1,2-S2C6H4, 1,2-S2C6H2-3,6-Cl2, 1,2-S2C2H4)

The [MoCu] carbon monoxide dehydrogenase (CODH) is a Cu-containing molybdo-flavoprotein, the active site of which contains a pterin-dithiolene cofactor bound to a sulfido-bridged dinuclear Mo-Cu complex. In this paper, the synthesis and characterization of dinuclear Mo-Cu complexes relevant to the active site of [MoCu]-CODH are described. Reaction of [MoO2S2]2- with CuCN affords the dinuclear complex [O2MoS2Cu(CN)]2- (1), in which the CN- ligand can be replaced with various aryl thiolates to give rise to a series of dinuclear complexes [O2MoS2Cu(SAr)]2- (Ar = Ph (2), o-Tol (3), and p-Tol (4)). An alternative synthesis of complex 2 is the reaction of [MoO2S2]2- with [Cu(SPh)3]2-. Similarly, [O2MoS2Cu(PPh3)]- (5), [O2MoS2Cu(dppe)]- (dppe = 1,2-bis(diphenylphosphino)ethane) (6), and [O2MoS2Cu(triphos)]- (triphos = 1,1,1-tris[(diphenylphosphino)methyl]ethane) (7) were prepared from the reactions of [MoO2S2]2- with the Cu(I) phosphine complexes. Treatment of 1, 2, 4, or 5 with dithiols (1,2-(SH)2C6H4, 1,2-(SH)2C6H2-3,6-Cl2, and 1,2-(SH)2C2H4), in acetonitrile, leads to the replacement of a molybdenum-bound oxo ligand to yield [(dithiolate)Mo(O)S2CuL]2- (L = CN, SAr; dithiolate = 1,2-S2C6H4, 1,2-S2C6H2-3,6-Cl2, or 1,2-S2C2H4) (8-13) or [(1,2-S2C6H4)Mo(O)S2Cu(PPh3)]- (14) complexes.     

Syntheses and structures of dinuclear gold(I) dithiophosphonate complexes and the reaction of the dithiophosphonate complexes with phosphines: diverse coordination types

The dinuclear gold(I) dithiophosphonate complex, [Au(2)(dtp)(2)] (1), where dtp = [S(2)P(R)(OR')](-) with R = p-C(6)H(4)OCH(3); R'= c-C(5)H(9), has been synthesized and its reaction studied with the phosphine ligands PPh(3) and Ph(2)P(CH(2))(n)PPh(2) (n = 1-4). Compound 1 contains two gold atoms homobridged by the anionic dithiophosphonate ligand, forming an eight-membered ring complex in a chair form. After the reaction of 1 with diphosphine ligands, the dinuclear open-ring complexes Au(2)(dppm)(dtp)(2) (2), Au(2)(dppe)(dtp)(2) (3), Au(2)(dppp)(dtp)(2) (4), Au(2)(dppb)(dtp)(2) (5) were formed (dppm = diphenylphosphinomethane; dppe = diphenylphosphinoethane; dppp = diphenylphosphinopropane; dppb = diphenylphosphinobutane). The reaction with dppm is stoichiometry-dependent. Thus, when 1 reacts with 2 equiv of dppm, the ionic complex [Au(2)(dppm)(2)(dtp)]dtp forms. This dtp counterion was exchanged with tetrafluoroborate to yield [Au(2)(dppm)(2)(dtp)]BF(4), the crystallization of which afforded two interconvertible isomers, 6-yellow and 7-white. Reaction of 1 with PPh(3) affords the tetracoordinate mononuclear complex [Au(dtp)(PPh(3))(2)] (8). The molecular structures of 1-8 were confirmed by X-ray crystallography and show multiple coordination modes and geometries. The crystal structures of 1 and its reaction products with dppm (2, 6, 7) show short intramolecular Au.Au aurophilic bonding interactions of 2.95-3.10 A while no intermolecular interactions were discernible. However, reaction products of 1 with longer-chain Ph(2)P(CH(2))(n)PPh(2) ligands, n = 2-4, exhibit structures that lack both intra- and intermolecular Au.Au interactions.     

Active-site models for the nickel-iron hydrogenases: effects of ligands on reactivity and catalytic properties

Described are new derivatives of the type [HNiFe(SR)(2)(diphosphine)(CO)(3)](+), which feature a Ni(diphosphine) group linked to a Fe(CO)(3) group by two bridging thiolate ligands. Previous work had described [HNiFe(pdt)(dppe)(CO)(3)](+) ([1H](+)) and its activity as a catalyst for the reduction of protons (J. Am. Chem. Soc. 2010, 132, 14877). Work described in this paper focuses on the effects on properties of NiFe model complexes of the diphosphine attached to nickel as well as the dithiolate bridge, 1,3-propanedithiolate (pdt) vs 1,2-ethanedithiolate (edt). A new synthetic route to these Ni-Fe dithiolates is described, involving reaction of Ni(SR)(2)(diphosphine) with FeI(2)(CO)(4) followed by in situ reduction with cobaltocene. Evidence is presented that this route proceeds via a metastable μ-iodo derivative. Attempted isolation of such species led to the crystallization of NiFe(Me(2)pdt)(dppe)I(2), which features tetrahedral Fe(II) and square planar Ni(II) centers (H(2)Me(2)pdt = 2,2-dimethylpropanedithiol). The new tricarbonyls prepared in this work are NiFe(pdt)(dcpe)(CO)(3) (2, dcpe = 1,2-bis(dicyclohexylphosphino)ethane), NiFe(edt)(dppe)(CO)(3) (3), and NiFe(edt)(dcpe)(CO)(3) (4). Attempted preparation of a phenylthiolate-bridged complex via the FeI(2)(CO)(4) + Ni(SPh)(2)(dppe) route gave the tetrametallic species [(CO)(2)Fe(SPh)(2)Ni(CO)](2)(μ-dppe)(2). Crystallographic analysis of the edt-dcpe compund [2H]BF(4) and the edt-dppe compound [3H]BF(4) verified their close resemblance. Each features pseudo-octahedral Fe and square pyramidal Ni centers. Starting from [3H]BF(4) we prepared the PPh(3) derivative [HNiFe(edt)(dppe)(PPh(3))(CO)(2)]BF(4) ([5H]BF(4)), which was obtained as a ～2:1 mixture of unsymmetrical and symmetrical isomers. Acid-base measurements indicate that changing from Ni(dppe) (dppe = Ph(2)PCH(2)CH(2)PPh(2)) to Ni(dcpe) decreases the acidity of the cationic hydride complexes by 2.5 pK(a)(PhCN) units, from ～11 to ～13.5 (previous work showed that substitution at Fe leads to more dramatic effects). The redox potentials are more strongly affected by the change from dppe to dcpe, for example the [2](0/+) couple occurs at E(1/2) = -820 for [2](0/+) vs -574 mV (vs Fc(+/0)) for [1](0/+). Changes in the dithiolate do not affect the acidity or the reduction potentials of the hydrides. The acid-independent rate of reduction of CH(2)ClCO(2)H by [2H](+) is about 50 s(-1) (25 °C), twice that of [1H](+). The edt-dppe complex [2H](+) proved to be the most active catalyst, with an acid-independent rate of 300 s(-1).     

Hydride-containing models for the active site of the nickel-iron hydrogenases

The [NiFe]-hydrogenase model complex NiFe(pdt)(dppe)(CO)(3) (1) (pdt = 1,3-propanedithiolate) has been efficiently synthesized and found to be robust. This neutral complex sustains protonation to give the first nickel-iron hydride [1H]BF(4). One CO ligand in [1H]BF(4) is readily substituted by organophosphorus ligands to afford the substituted derivatives [HNiFe(pdt)(dppe)(PR(3))(CO)(2)]BF(4), where PR(3) = P(OPh)(3) ([2H]BF(4)); PPh(3) ([3H]BF(4)); PPh(2)Py ([4H]BF(4), where Py = 2-pyridyl). Variable temperature NMR measurements show that the neutral and protonated derivatives are dynamic on the NMR time scale, which partially symmetrizes the phosphine complex. The proposed stereodynamics involve twisting of the Ni(dppe) center, not rotation at the Fe(CO)(2)(PR(3)) center. In MeCN solution, 3, which can be prepared by deprotonation of [3H]BF(4) with NaOMe, is about 10(4) stronger base than is 1. X-ray crystallographic analysis of [3H]BF(4) revealed a highly unsymmetrical bridging hydride, the Fe-H bond being 0.40 ? shorter than the Ni-H distance. Complexes [2H]BF(4), [3H]BF(4), and [4H]BF(4) undergo reductions near -1.46 V vs Fc(0/+). For [2H]BF(4), this reduction process is reversible, and we assign it as a one-electron process. In the presence of trifluoroacetic acid, proton reduction catalysis coincides with this reductive event. The dependence of i(c)/i(p) on the concentration of the acid indicates that H(2) evolution entails protonation of a reduced hydride. For [2H](+), [3H](+), and [4H](+), the acid-independent rate constants are 50-75 s(-1). For [2H](+) and [3H](+), the overpotentials for H(2) evolution are estimated to be 430 mV, whereas the overpotential for the N-protonated pyridinium complex [4H(2)](2+) is estimated to be 260 mV. The mechanism of H(2) evolution is proposed to follow an ECEC sequence, where E and C correspond to one-electron reductions and protonations, respectively. On the basis of their values for its pK(a) and redox potentials, the room temperature values of ΔG(H?) and ΔG(H-) are estimated as respectively as 57 and 79 kcal/mol for [1H](+).     

A series of dinuclear homo- and heterometallic complexes with two or three bridging sulfido ligands derived from the tungsten tris(sulfido) complex [Et(4)N][(Me(2)Tp)WS(3)] (Me(2)Tp = hydridotris(3,5-dimethylpyrazol-1-yl)borate)

The generation of heterobimetallic complexes with two or three bridging sulfido ligands from mononuclear tris(sulfido) complex of tungsten [Et(4)N][(Me(2)Tp)WS(3)] (1; Me(2)Tp = hydridotris(3,5-dimethylpyrazol-1-yl)borate) and organometallic precursors is reported. Treatment of 1 with stoichiometric amounts of metal complexes such as [M(PPh(3))(4)] (M = Pt, Pd), [(PtMe(3))(4)(micro(3)-I)(4)], [M(cod)(PPh(3))(2)][PF(6)] (M = Ir, Rh; cod = 1,5-cyclooctadiene), [Rh(cod)(dppe)][PF(6)] (dppe = Ph(2)PCH(2)CH(2)PPh(2)), [CpIr(MeCN)(3)][PF(6)](2) (Cp = eta(5)-C(5)Me(5)), [CpRu(MeCN)(3)][PF(6)], and [M(CO)(3)(MeCN)(3)] (M = Mo, W) in MeCN or MeCN-THF at room temperature afforded either the doubly bridged complexes [Et(4)N][(Me(2)Tp)W(=S)(micro-S)(2)M(PPh(3))] (M = Pt (3), Pd (4)), [(Me(2)Tp)W(=S)(micro-S)(2)M(cod)] (M = Ir, Rh (7)), [(Me(2)Tp)W(=S)(micro-S)(2)Rh(dppe)], [(Me(2)Tp)W(=S)(micro-S)(2)RuCp] (10), and [Et(4)N][(Me(2)Tp)W(=S)(micro-S)(2)W(CO)(3)] (12) or the triply bridged complexes including [(Me(2)Tp)W(micro-S)(3)PtMe(3)] (5), [(Me(2)Tp)W(micro-S)(3)IrCp][PF(6)] (9), and [Et(4)N][(Me(2)Tp)W(micro-S)(3)Mo(CO)(3)] (11), depending on the nature of the incorporated metal fragment. The X-ray analyses have been undertaken to clarify the detailed structures of 3-5, 7, and 9-12.     

Pyridine-2-thionate as a versatile ligand in Pd(II) and Pt(II) chemistry: the presence of three different co-ordination modes in [Pd2(micro2-S,N-C5H4SN)(micro2-kappa2S-C5H4SN)(micro2-dppm)(S-C5H4SN)2

Reactions of [MCl2(L-L)], M = Pt, Pd; L-L = bis(diphenylphosphino)methane (dppm) or bis(diphenylphosphino)ethane (dppe), with NaC5H4SN in a 1 : 2 molar ratio lead to mononuclear species [M(S-C5H4SN)2(P-P)], M = Pt; L-L = dppm (1) or dppe (2) and M = Pd; L-L = dppe (3), as well as to the dinuclear [Pd2(micro2-S,N-C5H4SN)(micro2-kappa2S-C5H4SN)(micro2-dppm)(S-C5H4SN)2] (4). In contrast, reaction of [MCl2(dppm)] with NaC5H4SN in a 1 : 1 molar ratio leads to [Pd2(micro2-S,N-C5H4SN)3(micro2-dppm)]Cl (5) and trans-[Pt(S-C5H4SN)2(PPh2Me)2] (6) respectively. The latter is formed in low yield by cleavage of the dppm ligand. The dinuclear derivatives 4 and 5 present an A-frame and lantern structure, respectively. The former showing three different co-ordination modes in the same molecule with a short Pd-Pd distance of 2.9583 (9) A and the latter with three bridging S,N thionate ligands showing a shorter Pd-Pd distance of 2.7291 (13) A. Both distances could be imposed by the bridging ligands or point to some sort of metal-metal interaction.     

Metal-hydride bond activation and metal-metal interaction in dinuclear iron complexes with linking dinitriles: a synthetic,electrochemical, and theoretical study

The dinuclear iron(II)-hydride complexes [[FeH(dppe)(2)](2)(mu-LL)][BF(4)](2) (LL = NCCH=CHCN (1a), NCC(6)H(4)CN (1b), NCCH(2)CH(2)CN (1c); dppe = Ph(2)PCH(2)CH(2)PPh(2)) and the corresponding mononuclear ones, trans-[FeH(LL)(dppe)(2)][BF(4)] (2a-c) were prepared by treatment of trans-[FeHCl(dppe)(2)], in tetrahydrofuran (thf) and in the presence of Tl[BF(4)], with the appropriate dinitrile (in molar deficiency or excess, respectively). Metal-metal interaction was detected by cyclic voltammetry for 1a, which, upon single-electron reversible oxidation, forms the mixed valent Fe(II)/Fe(III) 1a(+) complex. The latter either undergoes heterolytic Fe-H bond cleavage (loss of H(+)) or further oxidation, at a higher potential, also followed by hydride-proton evolution, according to ECECE or EECECEC mechanistic processes, respectively, which were established by digital simulation. Anodically induced Fe-H bond rupture was also observed for the other complexes and the detailed electrochemical behavior, as well as the metal-metal interaction (for 1a), were rationalized by ab initio calculations for model compounds and oxidized derivatives. These calculations were used to generate the structural parameters (full geometry optimization), the most stable isomeric forms, the ionization potentials, the effective atomic charges, and the molecular orbital diagrams, as well as to predict the nature of the other electron-transfer induced chemical steps, i.e. geometric isomerization and nucleophilic addition, by BF(4)(-), to the unsaturated iron center resulting from hydride-proton loss. From the values of the oxidation potential of the complexes, the electrochemical P(L) and E(L) ligand parameters were also estimated for the dinitrile ligands (LL) and for their mononuclear complexes 2 considered as ligands toward a second binding metal center.     

Synthesis and Ligand Substitution Reactions of a Mesitylphosphido-Bridged Platinum(II) Dimer

The stable primary phosphine complexes trans-M(PH(2)Mes)(2)Cl(2) (1, M = Pd; 2, M = Pt; Mes = 2,4,6-(t-Bu)(3)C(6)H(2)) were prepared from Pd(PhCN)(2)Cl(2) and K(2)PtCl(4), respectively. Reaction of Pt(COD)Cl(2) (COD = 1,5-cyclooctadiene) with less bulky arylphosphines gives the unstable cis-Pt(PH(2)Ar)(2)Cl(2) (3, Ar = Is = 2,4,6-(i-Pr)(3)C(6)H(2); 4, Ar = Mes = 2,4,6-Me(3)C(6)H(2)). Spontaneous dehydrochlorination of 4 or direct reaction of K(2)PtCl(4) with 2 equiv of PH(2)Mes gives the insoluble primary phosphido-bridged dimer [Pt(PH(2)Mes)(&mgr;-PHMes)Cl](2) (5), which was characterized spectroscopically, including solid-state (31)P NMR studies. The reversible reaction of 5 with PH(2)Mes gives [Pt(PH(2)Mes)(2)(&mgr;-PHMes)](2)[Cl](2) (6), while PEt(3) yields [Pt(PEt(3))(2)(&mgr;-PHMes)](2)[Cl](2) (7), which on recrystallization forms [Pt(PEt(3))(&mgr;-PHMes)Cl](2) (8). Complex 5 and PPh(3) afford [Pt(PPh(3))(&mgr;-PHMes)Cl](2) (9). Addition of 1,2-bis(diphenylphosphino)ethane (dppe) to 5 gives the dicationic [Pt(dppe)(&mgr;-PHMes)](2)[Cl](2) (10-Cl), which was also obtained as the tetrafluoroborate salt 10-BF(4)() by deprotonation of [Pt(dppe)(PH(2)Mes)Cl][BF(4)] (11) with Et(3)N or by reaction of [Pt(dppe)(&mgr;-OH)](2)[BF(4)](2) with 2 equiv of PH(2)Mes. Complexes 8, 9, and 10-Cl.2CH(2)Cl(2).2H(2)O were characterized crystallographically.     

Mixed dinitrogen-organocyanamide complexes of molybdenum(0) and their protic conversion into hydrazide and amidoazavinylidene derivatives

Organocyanamides, Ntbd1;CNR(2) (R = Me or Et), react with trans-[Mo(N(2))(2)(dppe)(2)] (1, dppe = Ph(2)PCH(2)CH(2)PPh(2)), in THF, to give the first mixed molybdenum dinitrogen-cyanamide complexes trans-[Mo(N(2))(NCNR(2))(dppe)(2)] (R = Me 2a or Et 2b) which are selectively protonated at N(2) by HBF(4) to yield the hydrazide(2-) complexes trans-[Mo(NNH(2))(NCNR(2))(dppe)(2)][BF(4)](2) (R = Me, 3a, or Et, 3b). On treatment with Ag[BF(4)], oxidation and metal fluorination occur, and the ligating cyanamide undergoes an unprecedented beta-protonation at the unsaturated C atom to form trans-[MoF(NCHNR(2))(dppe)(2)][BF(4)](2) (R = Me, 4a, or Et, 4b) compounds which present the novel amidoazavinylidene (or amidomethyleneamide) ligands. Complexes 4 are also formed from the corresponding compounds 3, with liberation of ammonia and hydrazine. The crystal structure of 2b was determined by single-crystal X-ray diffraction analysis which indicates that the N atom of the amide group has a trigonal planar geometry.     

Syntheses, structures, and reactivities of mono- and dinuclear iridium thiolato complexes containing nitrosyl ligands

Reactions of the iridium(III) nitrosyl complex [Ir(NO)Cl2(PPh3)2] (1) with hydrosulfide and arenethiolate anions afforded the square-pyramidal iridium(III) complex [Ir(NO)(SH)2(PPh3)2] (2) with a bent nitrosyl ligand and a series of the square-planar iridium(I) complexes [Ir(NO)(SAr)2(PPh3)] (3a, Ar = C6H2Me3-2,4,6 (Mes); 3b, Ar = C6H3Me2-2,6 (Xy); 3c, Ar = C6H2Pri3-2,4,6) containing a linear nitrosyl ligand, respectively. Complex 1 also reacted with alkanethiolate anions or alkanethiols to give the thiolato-bridged diiridium complexes [Ir(NO)(mu-SPri)(SPri)(PPh3)]2 (4) and [Ir(NO)(mu-SBut)(PPh3)]2 (5). Complex 4 contains two square-pyramidal iridium(III) centers with a bent nitrosyl ligand, whereas 5 contains two tetrahedral iridium(0) centers with a linear nitrosyl ligand and has an Ir-Ir bond. Upon treatment with benzoyl chloride, 3a and 3b were converted into the (diaryl disulfide)- and thiolato-bridged dichlorodiiridium(III) complexes [[IrCl(mu-SC6HnMe4-nCH2)(PPh3)]2(mu-ArSSAr)] (6a, Ar = Mes, n = 2; 6b, Ar = Xy, n = 3) accompanied by a loss of the nitrosyl ligands and cleavage of a C-H bond in an ortho methyl group of the thiolato ligands. Similar treatment of 4 gave the dichlorodiiridium complex [Ir(NO)(PPh3)(mu-SPri)3IrCl2(PPh3)] (7), which has an octahedral dichloroiridium(III) center and a distorted trigonal-bipyramidal Ir(I) atom with a linear nitrosyl ligand. The detailed structures of 3a, 4, 5, 6a, and 7 have been determined by X-ray crystallography.     

Cyclometalated organoplatinum(II) complexes: first example of a monodentate benzo[h]quinolyl ligand and a complex with bridging bis(diphenylphosphino)ethane

The cyclometalated complexes [Pt(ppy)R(SMe(2))] or [Pt(bhq)R(SMe(2))], where ppyH = 2-phenylpyridine, bhqH = benzo[h]quinoline and R = methyl or p-tolyl, react with bis(diphenylphosphino)ethane, dppe, in a 1:1 ratio to give the corresponding complexes [Pt(κ(1)-C-ppy)R(dppe)] or [Pt(κ(1)-C-bhq)R(dppe)], in which the ppy or bhq ligands are monodentate and dppe is chelating. The similar reaction in a 2:1 ratio gives the binuclear complexes [{Pt(ppy)R}(2)(μ-dppe)] or [{Pt(bhq)R}(2)(μ-dppe)], in which the dppe ligands are in the unusual bridging bidentate bonding mode.     

Formation of diphenylphosphanylbutadienyl complexes by insertion of two P-coordinated alkynylphosphanes into a PtbondC6F5 bond: detection of intermediate and reaction products

The reactions between cis-[M(C(6)F(5))(2)(PPh(2)CtriplebondCR)(2)] (M=Pt, Pd; R=Ph, tBu, Tol 2, 3) or cis-[Pt(C(6)F(5))(2)(PPh(2)CtriplebondCR)(PPh(2)CtriplebondCtBu)] (R=Ph 4, Tol 5) and cis-[Pt(C(6)F(5))(2)(thf)(2)] 1 have been investigated. Whereas [M](PPh(2)CtriplebondCtBu)(2) ([M]=cis-M(C(6)F(5))(2)) is inert towards 1, the analogous reactions starting from [M](PPh(2)CtriplebondCR)(2) or [Pt](PPh(2)CtriplebondCR)(PPh(2)CtriplebondCtBu) (R=Ph, Tol) afford unusual binuclear species [Pt(C(6)F(5))(S)mu-[C(R')dbondC(PPh(2))C(PPh(2))doublebondC(R)(C(6)F(5))]M(C(6)F(5))(2)] (R=R'=Ph, Tol, M=Pt 6 a,c, M=Pd 7 a,c; M=Pt, R'=tBu, R=Ph 8, Tol 9) containing a bis(diphenylphosphanyl)butadienyl bridging ligand formed by an unprecedented sequential insertion reaction of two P-coordinated PPh(2)CtriplebondCR ligands into a PtbondC(6)F(5) bond. Although in solution the presence of coordinated solvent S (S=(thf)(x)(H(2)O)(y)) in 6, 7 is suggested by NMR spectroscopy, X-ray diffraction analyses of different crystals of the mixed complex [Pt(C(6)F(5))mu-[C(tBu)doublebondC(PPh(2))C(PPh(2))doublebondC(Tol)(C(6)F(5))]Pt(C(6)F(5))(2)] 9 unequivocally establish that in the solid state the steric crowding of the new diphenylbutadienyl ligand formed stabilizes an unusual coordinatively unsaturated T-shaped 3-coordinated platinum(II) center. Structure determinations of the mononuclear precursors cis-[Pt(C(6)F(5))(2)(PPh(2)CtriplebondCR)(2)] (R=Ph, tBu, Tol) have been carried out to evaluate the factors affecting the insertion processes. The reactions of the platinum complexes 6 towards neutral ligands (L=CO, py, PPh(2)H, CNtBu) in a 1:1 molar ratio afford related diplatinum derivatives 10-13, whereas treatment with CNtBu (1:2 molar ratio) or 2,2'-bipy (1:1 molar ratio) results in the opening of the chelating ring to give cis,cis-[Pt(C(6)F(5))(L)(2)mu-[1-kappaC(1):2-kappaPP'-C(R)doublebondC(PPh(2))C(PPh(2))doublebondC(R)(C(6)F(5))]Pt(C(6)F(5))(2)] (14, 15). The unsaturated or solvento complexes are unstable in solution evolving firstly, through an unexpected formal 4-1 R (Ph, Tol) migration, to the intermediate diphosphanylbutadienyl isomer derivatives [Pt(C(6)F(5))(S)mu-[C(C(6)F(5))doublebondC(PPh(2))C(PPh(2))doublebondC(R)(2)]M(C(6)F(5))(2)] (16, 18) (X-ray, R=Ph, M=Pt) and, finally, to 1-pentafluorophenyl-2,3-bis(diphenylphosphanyl)naphthalene mononuclear complexes (17, 19) by annulation of a phenyl or tolyl group.