Structures and solvatochromic phosphorescence of dicationic terpyridyl-platinum(II) complexes with foldable oligo(ortho-phenyleneethynylene) bridging ligands

A series of binuclear organoplatinum(II) complexes, [(tBu3tpy)Pt--(C[triple chemical bond]C--1,2-C6H4)n--C[triple chemical bond]C--Pt(tBu3tpy)][ClO4]2 (1-7, n=1, 2, 3, 4, 5, 6, 8; tBu3tpy=4,4',4'-tri-tert-butyl-2,2':6',2'-terpyridine) with foldable oligo(ortho-phenyleneethynylene) linkers were prepared and characterized by spectroscopic methods and/or X-ray crystallographic analyses. In the crystal structures of 32.5 CH3OH, 5CH3CN, and 64 CH3CN, each of the bridging ortho-phenyleneethynylene ligands has a partially folded conformation. In aerated water/acetonitrile mixtures with water percentages larger than 40 %, the emission of complexes 3-7 are red-shifted and enhanced when compared to those recorded in acetonitrile. The red-shift in emission energy and enhanced emission intensity can be attributed to the inter- and/or intramolecular interactions induced by the addition of water to solutions of the platinum(II) complexes in acetonitrile. Data from dynamic light scattering and transmission electron microscopy studies revealed that these binuclear platinum(II) complexes aggregated into nanosized particles in acetonitrile/water mixtures. Hydrophobic folding of the ortho-phenyleneethynylene linkers in acetonitrile/water mixtures is postulated.     

Tetrameric molecular bowl assembled from glycoluril building blocks

Glycoluril derivative--whose bulky Ph-C[triple bond]C- substituents prevent formation of H-bonded tapes--undergoes solvent dependent assembly in the crystal; a tetrameric molecular bowl is formed by R(24) H-bonding interactions from CH(2)Cl(2) whereas DMF results in H-bond dimerization followed by oligomerization via C-H...pi interactions.     

Synthesis, characterization and photophysics of a new series of anionic C,N,C cyclometalated platinum complexes

A novel series of anionic mononuclear terdentate dicyclometalated complexes (NBu4)[Pt(CwedgeNwedgeC)X] (HCwedgeNwedgeCH=2,6-diphenylpyridine) containing acetylide (X=C[triple bond]CR, R=tBu, 1; Ph, 2; Tol, 3; (4-OMe)C6H4, 4) or another anionic ligand (X=CN, 5; S-2Py, 6; CH2COCH3, 7) have been synthesized and fully characterized. The solid-state structures of complexes 1 and 4-6 have also been determined by X-ray diffraction studies, showing, in all the cases, the presence of several types of weak hydrogen interactions, leading to the generation of supramolecular 2D (1) or 3D (4-6) architectures. All the complexes (1-7) are intensely luminescent at low temperature (solid and glassy CH2Cl2), exhibiting concentration dependence in the emissions of the glassy CH2Cl2 matrix.     

Detailed structural investigation of the grafting of [Ta(=CHtBu)(CH2tBu)3] and [Cp*TaMe4] on silica partially dehydroxylated at 700 degrees C and the activity of the grafted complexes toward alkane metathesis

The reaction of [Ta(=CHtBu)(CH2tBu)3] or [Cp*Ta(CH3)4] with a silica partially dehydroxylated at 700 degrees C gives the corresponding monosiloxy surface complexes [([triple bond]SiO)Ta(=CHtBu)(CH2tBu)2] and [([triple bond]SiO)Ta(CH3)3Cp*] by eliminating a sigma-bonded ligand as the corresponding alkane (H-CH2tBu or H-CH3). EXAFS data show that an adjacent siloxane bridge of the surface plays the role of an extra surface ligand, which most likely stabilizes these complexes as in [([triple bond]SiO)Ta(=CHtBu)(CH2tBu)2([triple bond]SiOSi[triple bond])] (1a') and [([triple bond]SiO)Ta(CH3)3Cp*([triple bond]SiOSi[triple bond])] (2a'). In the case of [(SiO)Ta(=CHtBu)(CH2tBu)2([triple bond]SiOSi[triple bond])], the structure is further stabilized by an additional interaction: a C-H agostic bond as evidenced by the small J coupling constant for the carbenic C-H (JC-H = 80 Hz), which was measured by J-resolved 2D solid-state NMR spectroscopy. The product selectivity in propane metathesis in the presence of [([triple bond]SiO)Ta(=CHtBu)(CH2tBu)2([triple bond]SiOSi[triple bond])] (1a') as a catalyst precursor and the inactivity of the surface complex [([triple bond]SiO)Ta(CH3)3Cp*([triple bond]SiOSi[triple bond])] (2a') show that the active site is required to be highly electrophilic and probably involves a metallacyclobutane intermediate.     

Di-2-pyridyl ketone oxime in copper chemistry: di-, tri-, penta- and hexanuclear complexes

The use of di-2-pyridyl ketone oxime (Hpko)/X- "blends" (X- = OH-, Cl-, ClO4-) in copper chemistry has yielded neutral binuclear and cationic trinuclear, pentanuclear or hexanuclear complexes. Various synthetic procedures have led to the synthesis of compounds [Cu5(pko)7].[ClO4]3.2CH3OH.2H2O (1), [Cu3(pko)3(OH)(Cl)]2[Ph4B]2.4DMF.2H2O (2), [Cu2(pko)4] (3), {[Cu6(pko)6ClO4(CH3CN)6][Cu6(pko)6(ClO4)3(CH3CN)4]}.8ClO4.14CH3CN.H2O (4). The structures of the complexes have been determined by single-crystal X-ray crystallography.     

Reactions of acetonitrile coordinated to a nitrosylruthenium complex with H2O or CH(3)OH under mild conditions: structural characterization of imido-type complexes

The reaction of cis-[Ru(NO)(CH(3)CN)(bpy)(2)](3+) (bpy = 2,2'-bipyridine) in H(2)O at room temperature proceeded to afford two new nitrosylruthenium complexes. These complexes have been identified as nitrosylruthenium complexes containing the N-bound methylcarboxyimidato ligand, cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](2+), and methylcarboxyimido acid ligand, cis-[Ru(NO)(NH=C(OH)CH(3))(bpy)(2)](3+), formed by an electrophilic reaction at the nitrile carbon of the acetonitrile coordinated to the ruthenium ion. The X-ray structure analysis on a single crystal obtained from CH(3)CN-H(2)O solution of cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](PF(6))(3) has been performed: C(22)H(20.5)N(6)O(2)P(2.5)F(15)Ru, orthorhombic, Pccn, a = 15.966(1) A, b = 31.839(1) A, c = 11.707(1) A, V = 5950.8(4) A(3), and Z = 8. The structural results revealed that the single crystal consisted of 1:1 mixture of cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](2+) and cis-[Ru(NO)(NH=C(OH)CH(3))(bpy)(2)](3+) and the structural formula of this single crystal was thus [Ru(NO)(NH=C(OH(0.5))CH(3))(bpy)(2)](PF(6))(2.5). The reaction of cis-[Ru(NO)(CH(3)CN)(bpy)(2)](3+) in dry CH(3)OH-CH(3)CN at room temperature afforded a nitrosylruthenium complex containing the methyl methylcarboxyimidate ligand, cis-[Ru(NO)(NH=C(OCH(3))CH(3))(bpy)(2)](3+). The structure has been determined by X-ray structure analysis: C(25)H(29)N(8)O(18)Cl(3)Ru, monoclinic, P2(1)/c, a = 13.129(1) A, b = 17.053(1) A, c = 15.711(1) A, beta = 90.876(5) degrees, V = 3517.3(4) A(3), and Z = 4.     

The cyanoimido ligand as an oxo analogue. Novel approaches to the preparations of cyano(imino)-aza-phosphorus(V) and N-cyanoaziridine

The known Os(IV)-cyanoimido complexes, mer-Et4N[OsIV(bpy)(Cl)3(NalphaCNbeta)] (mer-[OsIV=N-CN]-) (bpy = 2,2'-bipyridine) and trans-[OsIV(tpy)(Cl)2(NalphaCNbeta)] (trans-[OsIV=N-CN]) (2,2':6',2' '-terpyridine), have formal electronic relationships with high oxidation state Ru and Os-oxo and -dioxo complexes. These include multiple bonding to the metal, the ability to undergo multiple electron transfer, and the availability of nonbonding electron pairs for donation. Thermodynamic, oxo-like behavior is observed for mer-[OsIV=N-CN]- in the pH-dependence of its Os(VI/V) to Os(III/II) redox couples in 1:1 (v/v) CH3CN:H2O. Oxo-like behavior is also observed in the reaction between mer-[OsVI(bpy)(Cl)3(NalphaCNbeta)]PF6 and benzyl alcohol to give mer-[OsIV(bpy)(Cl)3(NalphaCNbetaH2)]PF6 and benzaldehyde. The reaction is first order in each reactant with kbenzyl(CH3CN, 25.0 +/- 0.1 degrees C) = (8.6 +/- 0.2) x 102 M-1 s-1. Formal NCN degrees transfer, analogous to O-atom transfer, occurs in reactions with tertiary phosphine and hexenes. In CH3CN under N2, a rapid reaction occurs between trans-[OsIV=N-CN] and PPh3 (kPPh3(DMF, 25.0 +/- 0.1 degrees C) = 4.06 +/- 0.02 M-1 s-1) to form the nitrilic N-bound Os(II)-(N-cyano)iminophosphorano product, trans-[OsII(tpy)(Cl)2(NalphaCNbetaPPh3)] (trans-[OsII-NalphaC-Nbeta=PPh3]). It undergoes solvolysis at 45 degrees C after 24 h to give trans-[OsII(tpy)(Cl)2(NCCH3)] and (N-cyano)iminophosphorane (NalphaC-Nbeta=PPh3). The analogue to epoxidation, N-cyanoaziridination of cyclohexene and 1-hexene by mer-[OsIV=N-CN]- and trans-[OsIV=N-CN], occurs at Nbeta to give the Os(IV)-N-cyanoaziridino complexes, mer-Et4N[OsII(bpy)(Cl)3(NalphaCNbetaC6H10)] and trans-[OsII(tpy)(Cl)2(NalphaCNbetaC6H11)], respectively. Oxidation to mer-[OsV(bpy)(Cl)3(NalphaCNbeta)]- greatly accelerates N-cyanoaziridination of cyclohexene, which is followed by slow solvolysis to give mer-[OsIII(bpy)(Cl)3(NCCH3)] and N-cyanoaziridine (NC-NC6H10). The Os-(N-cyano)aziridino complexes are the first well-characterized examples of coordinated cyanoaziridines.     

Synthesis and luminescence behaviour of novel heterodecanuclear silver(I)-rhenium(I) alkynyl complexes. X-ray crystal structures of [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Me2bpy)(CO)3]4](PF6)2 and [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Br2phen)(CO)3]4](PF6)2

A novel series of luminescent heterodecanuclear mixed-metal alkynyl complexes, [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(N--N)(CO)3]4](PF6)2, (N--N = tBu2bpy, Me2bpy, phen, Br2phen), have been successfully synthesized; the X-ray crystal structures of [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Me2bpy)(CO)3]4](PF6)2 and [Ag6(mu-dppm)4[mu3-C[triple bond]CC[triple bond]C-Re(Br2phen)(CO)3]4](PF6)2 have also been determined.     

Interdependence of redox state,hydrogen bonding,anion recognition and charge partition in crystals of (EDT-TTF-CONHMe)6 [Re6Se8(CN)6] (CH3CN)2(CH2Cl2)2

Neutral pi-conjugated molecules and their radical cations co-exist in [(EDT-TTF-CONHMe+*)4(EDT-TTF-CONHMe0)2] [Re6Se8(CN)6]4- (CH3CN)2(CH2Cl2)2 whose crystal structure reveals that, upon one-electron oxidation, an activation of the N-H and C-H hydrogen bond donor ability is coupled to a deactivation of the hydrogen bond acceptor character of the carbonyl oxygen atom: this is expressed in the supramolecular hydrogen bond pattern and, ultimately, into charge localisation and partition in the solid state.     

Primary and secondary phosphine complexes of iron porphyrins and ruthenium phthalocyanine: synthesis, structure, and P-H bond functionalization

Reduction of [Fe(III)(Por)Cl] (Por = porphyrinato dianion) with Na2S2O4 followed by reaction with excess PH2Ph, PH2Ad, or PHPh2 afforded [Fe(II)(F20-TPP)(PH2Ph)2] (1a), [Fe(II)(F20-TPP)(PH2Ad)2] (1b), [Fe(II)(F20-TPP)(PHPh2)2] (2a), and [Fe(II)(2,6-Cl2TPP)(PHPh2)2] (2b). Reaction of [Ru(II)(Pc)(DMSO)2] (Pc = phthalocyaninato dianion) with PH2Ph or PHPh2 gave [Ru(II)(Pc)(PH2Ph)2] (3a) and [Ru(II)(Pc)(PHPh2)2] (4). [Ru(II)(Pc)(PH2Ad)2] (3b) and [Ru(II)(Pc)(PH2Bu(t))2] (3c) were isolated by treating a mixture of [Ru(II)(Pc)(DMSO)2] and O=PCl2Ad or PCl2Bu(t) with LiAlH4. Hydrophosphination of CH2=CHR (R = CO2Et, CN) with [Ru(II)(F20-TPP)(PH2Ph)2] or [Ru(II)(F20-TPP)(PHPh2)2] in the presence of (t)BuOK led to the isolation of [Ru(II)(F20-TPP)(P(CH2CH2R)2Ph)2] (R = CO2Et, 5a; CN, 5b) and [Ru(II)(F20-TPP)(P(CH2CH2R)Ph2)2] (R = CO2Et, 6a; CN, 6b). Similar reaction of 3a with CH2=CHCN or MeI gave [Ru(II)(Pc)(P(CH2CH2CN)2Ph)2] (7) or [Ru(II)(Pc)(PMe2Ph)2] (8). The reactions of 4 with CH2=CHR (R = CO2Et, CN, C(O)Me, P(O)(OEt)2, S(O)2Ph), CH2=C(Me)CO2Me, CH(CO2Me)=CHCO2Me, MeI, BnCl, and RBr (R = (n)Bu, CH2=CHCH2, MeC[triple bond]CCH2, HC[triple bond]CCH2) in the presence of (t)BuOK afforded [Ru(II)(Pc)(P(CH2CH2R)Ph2)2] (R = CO2Et, 9a; CN, 9b; C(O)Me, 9c; P(O)(OEt)2, 9d; S(O)2Ph, 9e), [Ru(II)(Pc)(P(CH2CH(Me)CO2Me)Ph2)2] (9f), [Ru(II)(Pc)(P(CH(CO2Me)CH2CO2Me)Ph2)2] (9g), and [Ru(II)(Pc)(PRPh2)2] (R = Me, 10a; Bu(n), 10b; Bn, 10c; CH2CH=CH2, 10d; CH2C[triple bond]CMe, 10e; CH=C=CH2, 10f). X-ray crystal structure determinations revealed Fe-P distances of 2.2597(9) (1a) and 2.309(2) A (2bx 2 CH2Cl2) and Ru-P distances of 2.3707(13) (3b), 2.373(2) (3c), 2.3478(11) (4), and 2.3754(10) A (5b x 2 CH2Cl2). Both the crystal structures of 3b and 4 feature intermolecular C-H...pi interactions, which link the molecules into 3D and 2D networks, respectively.     

Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes

We report a high yield, two-step synthesis of fac-[Ru(bpy)(CH3CN)3NO2]PF6 from the known complex [(p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). [(p-cym)Ru(bpy)NO2]PF6 is prepared by reacting [(p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from [(p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives [Ru(bpy)(CH3CN)3NO2]PF6. The new complexes [(p-cym)Ru(bpy)NO2]PF6 and fac-[Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of [Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes [Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), [Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared [Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes [Ru(bpy)TpNO][PF6]2 and [Ru(bpy)(Tpm)NO][PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for [Ru(bpy)TpNO][PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.     

2-（羟甲基）-N-甲基咪唑桥联Mn2ⅡMn2Ⅲ四核配合物的合成、结构和磁性简

报道了3个2-(羟甲基)-N-甲基咪唑(Hhmmi)桥联的Mn2ⅡMn2Ⅲ四核配合物[Mn4(hmmi)6(DMF)2·(N3)2](ClO4)2(1),[Mn4(hmmi)6(H2O)2(N3)2](ClO4)2(2)和[Mn4(hmmi)6Cl4]·6CH3CN(3·6CH3CN)的合成、晶体结构和磁性. 在配合物1~3中,中心结构皆为四核蝶形混合价Mn结构,2个MnⅡ占据蝶形两翼位置,2个MnⅢ占据蝶形中间位置. MnⅢ离子间通过hmmi-上的μ3-烷氧原子桥联,相应MnⅢ-O-MnⅢ键角为101.3°~103.4°;而MnⅢ-MnⅡ离子间通过hmmi-上的μ3-和μ2-烷氧原子桥联,相应MnⅢ-O-MnⅡ键角为92.5°~113.7°. 对配合物1~3进行变温磁化率拟合,结果表明,MnⅢ-MnⅢ间呈铁磁相互作用,而MnⅢ-MnⅡ间以及Mn4分子间存在较弱的铁磁或反铁磁耦合.     

Intermolecular C-H bond activation reactions promoted by transient titanium alkylidynes. Synthesis, reactivity, kinetic, and theoretical studies of the Ti[triple bond]C linkage

The neopentylidene-neopentyl complex (PNP)Ti=CH(t)Bu(CH2(t)Bu) (2; PNP(-) = N[2-P(CHMe2)(2-)4-methylphenyl]2), prepared from the precursor (PNP)Ti[triple bond]CH(t)Bu(OTf) (1) and LiCH2(t)Bu, extrudes neopentane in neat benzene under mild conditions (25 degrees C) to generate the transient titanium alkylidyne, (PNP)Ti[triple bond]C(t)Bu (A), which subsequently undergoes 1,2-CH bond addition of benzene across the Ti[triple bond]C linkage to generate (PNP)Ti=CH(t)Bu(C6H5) (3). Kinetic, mechanistic, and theoretical studies suggest the C-H activation process to obey pseudo-first-order in titanium, the alpha-hydrogen abstraction to be the rate-determining step (KIE for 2/2-d(3) conversion to 3/3-d(3) = 3.9(5) at 40 degrees C) with activation parameters DeltaH = 24(7) kcal/mol and DeltaS = -2(3) cal/mol.K, and the post-rate-determining step to be C-H bond activation of benzene (primary KIE = 1.03(7) at 25 degrees C for the intermolecular C-H activation reaction in C6H6 vs C6D6). A KIE of 1.33(3) at 25 degrees C arose when the intramolecular C-H activation reaction was monitored with 1,3,5-C6H3D3. For the activation of aromatic C-H bonds, however, the formation of the sigma-complex becomes rate-determining via a hypothetical intermediate (PNP)Ti[triple bond]C(t)Bu(C6H5), and C-H bond rupture is promoted in a heterolytic fashion by applying standard Lewis acid/base chemistry. Thermolysis of 3 in C6D6 at 95 degrees C over 48 h generates 3-d(6), thereby implying that 3 can slowly equilibrate with A under elevated temperatures with k = 1.2(2) x 10-5 s(-1), and with activation parameters DeltaH = 31(16) kcal/mol and DeltaS = 3(9) cal/mol x K. At 95 degrees C for one week, the EIE for the 2 --> 3 reaction in 1,3,5-C6H3D3 was found to be 1.36(7). When 1 is alkylated with LiCH2SiMe3 and KCH2Ph, the complexes (PNP)Ti=CHtBu(CH2SiMe3) (4) and (PNP)Ti=CHtBu(CH2Ph) (6) are formed, respectively, along with their corresponding tautomers (PNP)Ti=CHSiMe3(CH2tBu) (5) and (PNP)Ti=CHPh(CH2tBu) (7). By means of similar alkylations of (PNP)Ti=CHSiMe3(OTf) (8), the degenerate complex (PNP)Ti=CHSiMe3(CH2SiMe3) (9) or the non-degenerate alkylidene-alkyl complex (PNP)Ti=CHPh(CH2SiMe3) (11) can also be obtained, the latter of which results from a tautomerization process. Compounds 4/5 and 9, or 6/7 and 11, also activate benzene to afford (PNP)Ti=CHR(C6H5) (R = SiMe3 (10), Ph (12)). Substrates such as FC6H5, 1,2-F2C6H4, and 1,4-F2C6H4 react at the aryl C-H bond with intermediate A, in some cases regioselectively, to form the neopentylidene-aryl derivatives (PNP)Ti=CHtBu(aryl). Intermediate A can also perform stepwise alkylidene-alkyl metatheses with 1,3,5-Me3C6H3, SiMe4, 1,2-bis(trimethylsilyl)alkyne, and bis(trimethylsilyl)ether to afford the titanium alkylidene-alkyls (PNP)Ti=CHR(R') (R = 3,5-Me2C6H2, R' = CH2-3,5-Me2C6H2; R = SiMe3, R' = CH2SiMe3; R = SiMe2CCSiMe3, R' = CH2SiMe2CCSiMe3; R = SiMe2OSiMe3, R' = CH2SiMe2OSiMe3).     

First row divalent transition metal complexes of aryl-appended tris((pyridyl)methyl)amine ligands: syntheses, structures, electrochemistry, and hydroxamate binding properties

Divalent manganese, cobalt, nickel, and zinc complexes of 6-Ph(2)TPA (N,N-bis((6-phenyl-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine; [(6-Ph(2)TPA)Mn(CH(3)OH)(3)](ClO(4))(2) (1), [(6-Ph(2)TPA)Co(CH(3)CN)](ClO(4))(2) (2), [(6-Ph(2)TPA)Ni(CH(3)CN)(CH(3)OH)](ClO(4))(2) (3), [(6-Ph(2)TPA)Zn(CH(3)CN)](ClO(4))(2) (4)) and 6-(Me(2)Ph)(2)TPA (N,N-bis((6-(3,5-dimethyl)phenyl-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine; [(6-(Me(2)Ph)(2)TPA)Ni(CH(3)CN)(2)](ClO(4))(2) (5) and [(6-(Me(2)Ph)(2)TPA)Zn(CH(3)CN)](ClO(4))(2) (6)) have been prepared and characterized. X-ray crystallographic characterization of 1A.CH(3)()OH and 1B.2CH(3)()OH (differing solvates of 1), 2.2CH(3)()CN, 3.CH(3)()OH, 4.2CH(3)()CN, and 6.2.5CH(3)()CN revealed mononuclear cations with one to three coordinated solvent molecules. In 1A.CH(3)()OH and 1B.2CH(3)()OH, one phenyl-substituted pyridyl arm is not coordinated and forms a secondary hydrogen-bonding interaction with a manganese bound methanol molecule. In 2.2CH(3)()CN, 3.CH(3)()OH, 4.2CH(3)()CN, and 6.2.5CH(3)()CN, all pyridyl donors of the 6-Ph(2)TPA and 6-(Me(2)Ph)(2)TPA ligands are coordinated to the divalent metal center. In the cobalt, nickel, and zinc derivatives, CH/pi interactions are found between a bound acetonitrile molecule and the aryl appendages of the 6-Ph(2)TPA and 6-(Me(2)Ph)(2)TPA ligands. (1)H NMR spectra of 4 and 6 in CD(3)NO(2) solution indicate the presence of CH/pi interactions, as an upfield-shifted methyl resonance for a bound acetonitrile molecule is present. Examination of the cyclic voltammetry of 1-3 and 5 revealed no oxidative (M(II)/M(III)) couples. Admixture of equimolar amounts of 6-Ph(2)TPA, M(ClO(4))(2).6H(2)O, and Me(4)NOH.5H(2)O, followed by the addition of an equimolar amount of acetohydroxamic acid, yielded the acetohydroxamate complexes [((6-Ph(2)TPA)Mn)(2)(micro-ONHC(O)CH(3))(2)](ClO(4))(2) (8), [(6-Ph(2)TPA)Co(ONHC(O)CH(3))](ClO(4))(2) (9), [(6-Ph(2)TPA)Ni(ONHC(O)CH(3))](ClO(4))(2) (10), and [(6-Ph(2)TPA)Zn(ONHC(O)CH(3))](ClO(4))(2) (11), all of which were characterized by X-ray crystallography. The Mn(II) complex 8.0.75CH(3)()CN.0.75Et(2)()O exhibits a dinuclear structure with bridging hydroxamate ligands, whereas the Co(II), Ni(II), and Zn(II) derivatives all exhibit mononuclear six-coordinate structures with a chelating hydroxamate ligand.     

New dicarboxylic acid bipyridine ligand for ruthenium polypyridyl sensitization of TiO2

An ambidentate dicarboxylic acid bipyridine ligand, (4,5-diazafluoren-9-ylidene) malonic acid (dfm), was synthesized for coordination to Ru(II) and mesoporous nanocrystalline (anatase) TiO(2) thin films. The dfm ligand provides a conjugated pathway from the pyridyl rings to the carbonyl carbons of the carboxylic acid groups. X-ray crystal structures of [Ru(bpy)(2)(dfm)]Cl(2) and the corresponding diethyl ester compound, [Ru(bpy)(2)(defm)](PF(6))(2), were obtained. The compounds displayed intense metal-to-ligand charge transfer (MLCT) absorption bands in the visible region (ε > 11,000 M(-1) cm(-1) for [Ru(bpy)(2)(dfm)](PF(6))(2) in acetonitrile). Significant room temperature photoluminescence, PL, was absent in CH(3)CN but was observed at 77 K in a 4:1 EtOH:MeOH (v:v) glass. Cyclic voltammetry measurements revealed quasi-reversible Ru(III/II) electrochemistry. Ligand reductions were quasi-reversible for the diethyl ester compound [Ru(bpy)(2)(defm)](2+), but were irreversible for [Ru(bpy)(2)(dfm)](2+). Both compounds were anchored to TiO(2) thin films by overnight reactions in CH(3)CN to yield saturation surface coverages of 3 × 10(-8) mol/cm(2). Attenuated total reflection infrared measurements revealed that the [Ru(bpy)(2)(dfm)](2+) compound was present in the deprotonated carboxylate form when anchored to the TiO(2) surface. The MLCT excited states of both compounds injected electrons into TiO(2) with quantum yields of 0.70 in 0.1 M LiClO(4) CH(3)CN. Micro- to milli-second charge recombination yielded ground state products. In regenerative solar cells with 0.5 M LiI/0.05 M I(2) in CH(3)CN, the Ru(bpy)(2)(dfm)/TiO(2) displayed incident photon-to-current efficiencies of 0.7 at the absorption maximum. Under the same conditions, the diethylester compound was found to rapidly desorb from the TiO(2) surface.     

The remarkable reactivity of high oxidation state ruthenium and osmium polypyridyl complexes

There is a remarkable redox chemistry of higher oxidation state M(IV)-M(VI) polypyridyl complexes of Ru and Os. They are accessible by proton loss and formation of oxo or nitrido ligands, examples being cis-[RuIV(bpy)2(py)(O)]2+ (RuIV=O2+, bpy=2,2'-bipyridine, and py=pyridine) and trans-[OsVI(tpy)(Cl)2(N)]+ (tpy=2,2':6',2' '-terpyridine). Metal-oxo or metal-nitrido multiple bonding stabilizes the higher oxidation states and greatly influences reactivity. O-atom transfer, hydride transfer, epoxidation, C-H insertion, and proton-coupled electron-transfer mechanisms have been identified in the oxidation of organics by RuIV=O2+. The Ru-O multiple bond inhibits electron transfer and promotes complex mechanisms. Both O atoms can be used for O-atom transfer by trans-[RuVI(tpy)(O)2(S)]2+ (S=CH3CN or H2O). Four-electron, four-proton oxidation of cis,cis-[(bpy)2(H2O)RuIII-O-RuIII(H2O)(bpy)2]4+ occurs to give cis,cis-[(bpy)2(O)RuV-O-RuV(O)(bpy)2]4+ which rapidly evolves O2. Oxidation of NH3 in trans-[OsII(tpy)(Cl)2(NH3)] gives trans-[OsVI(tpy)(Cl)2(N)]+ through a series of one-electron intermediates. It and related nitrido complexes undergo formal N- transfer analogous to O-atom transfer by RuIV=O2+. With secondary amines, the products are the hydrazido complexes, cis- and trans-[OsV(L3)(Cl)2(NNR2)]+ (L3=tpy or tpm and NR2-=morpholide, piperidide, or diethylamide). Reactions with aryl thiols and secondary phosphines give the analogous adducts cis- and trans-[OsIV(tpy)(Cl)2(NS(H)(C6H4Me))]+ and fac-[OsIV(Tp)(Cl)2(NP(H)(Et2))]. In dry CH3CN, all have an extensive multiple oxidation state chemistry based on couples from Os(VI/V) to Os(III/II). In acidic solution, the OsIV adducts are protonated, e.g., trans-[OsIV(tpy)(Cl)2(N(H)N(CH2)4O)]+, and undergo proton-coupled electron transfer to quinone to give OsV, e.g., trans-[OsV(tpy)(Cl)2(NN(CH2)4O)]+ and hydroquinone. These reactions occur with giant H/D kinetic isotope effects of up to 421 based on O-H, N-H, S-H, or P-H bonds. Reaction with azide ion has provided the first example of the terminal N4(2-) ligand in mer-[OsIV(bpy)(Cl)3(NalphaNbetaNgammaNdelta)]-. With CN-, the adduct mer-[OsIV(bpy)(Cl)3(NCN)]- has an extensive, reversible redox chemistry and undergoes NCN(2-) transfer to PPh3 and olefins. Coordination to Os also promotes ligand-based reactivity. The sulfoximido complex trans-[OsIV(tpy)(Cl)2(NS(O)-p-C6H4Me)] undergoes loss of O2 with added acid and O-atom transfer to trans-stilbene and PPh3. There is a reversible two-electron/two-proton, ligand-based acetonitrilo/imino couple in cis-[OsIV(tpy)(NCCH3)(Cl)(p-NSC6H4Me)]+. It undergoes reversible reactions with aldehydes and ketones to give the corresponding alcohols.     

LZnX complexes of tripodal ligands with intramolecular RN-H hydrogen bonding groups: structural implications of a hydrogen bonding cavity, and of X/R in the hydrogen bonding geometry/strength

Tripodal ligands N(CH2Py)3-n(CH2Py-6-NHR)n(R=H, n=1-3 L1-3, n=0 tpa; R=CH2tBu, n=1-3 L'1-3) are used to investigate the effect of different hydrogen bonding microenvironments on structural features of their LZnX complexes (X=Cl-, NO3-, OH-). The X-ray structures of [(L2)Zn(Cl)](BPh4)2.0.5(H2O.CH3CN), [(L3)Zn(Cl)](BPh4)3.CH3CN, [(L'1)Zn(Cl)](BPh4) 1', [(L'2)Zn(Cl)](BPh4)2'.CH3OH, and [(L'3)Zn(Cl)](BPh4)3' have been determined and exhibit trigonal bipyramidal geometries with intramolecular (internal) N-HCl-Zn hydrogen bonds. The structure of [(L'2)Zn(ONO2)]NO3 4'.H2O with two internal N-HO-Zn hydrogen bonds has also been determined. The axial Zn-Cl distance lengthens from 2.275 A in [(tpa)Zn(Cl)](BPh4) to 2.280-2.347 A in 1-3, 1'-3'. Notably, the average Zn-N(py) distance is also progressively lengthened from 2.069 A in [(tpa)Zn(Cl)](BPh4) to 2.159 and 2.182 A in the triply hydrogen bonding cavity of 3 and 3', respectively. Lengthening of the Zn-Cl and Zn-N(py) bonds is accompanied by a progressive shortening of the trans Zn-N bond from 2.271 A in [(tpa)Zn(Cl)](BPh4) to 2.115 A in 3 (2.113 A in 3'). As a result of the triply hydrogen bonding microenvironment the Zn-Cl and Zn-N(py) distances of 3 are at the upper end of the range observed for axial Zn-Cl bonds, whereas the axial Zn-N distance is one of shortest among N4 ligands that induce a trigonal bipyramidal geometry. Despite the rigidity of these tripodal ligands, the geometry of the intramolecular RN-HX-Zn hydrogen bonds (X=Cl-, OH-, NO3-) is strongly dependent on the nature of X, however, on average, similar for R=H, CH2tBu.     

Syntheses and reactivity studies of solvated dirhenium acetonitrile complexes

Fully and partially solvated triply-bonded [Re2]4+ complexes have been synthesized and their X-ray structures are described. A fully solvated dirhenium salt with BArf [tetrakis(3,5-bis(trifluoromethyl)phenyl)borate] as the counter anion [Re2(CH3CN)10][BArf]4 () has been characterized. The solubility of the complex in CH2Cl2 and THF in addition to CH3CN offers the possibility of improved reactivity. The structure of [Re2(micro-O)(CH3CN)10][BF4]4 () that possesses a linear [Re(III)-O-Re(III)]4+ unit is reported. Protonation reactions of cis-Re2Cl2(dppm)2(O2CCH3)2 and trans-Re2Cl4(dppm)2 with HBF4.Et2O in acetonitrile afforded cis and trans [Re2(dppm)2(CH3CN)6][BF4]4 ( and ), respectively. Prolonging the reaction time, however, does not lead to fully solvated complex [Re2(CH3CN)10][BF4]4. The neutral nitrogen donor ligands pynp (2-(2-pyridyl)-1,8-naphthyridine) and tznp (2-(2-thiazolyl)-1,8-naphthyridine) react readily with [Re2(CH3CN)10][BF4]4 to provide trans-[Re2(pynp)2(CH3CN)4][BF4]4 and trans-[Re2(tznp)2(CH3CN)4][BF4]4. The X-ray structures trans-[Re2(pynp)2(CH3CN)4][BF4]4 () and trans-[Re2(tznp)2(CH3CN)4][BF4]3[PF6] () have been determined.     

Supramolecular assembly and solution properties of bis(bipyridyl)ruthenium(II) coordination complexes of aryl(2-pyridyl)methanones

A series of mono- and bis(2-pyridyl)-arylmethanone ligands were prepared by utilizing the reaction between either bromobenzonitrile or dicyanobenzene and 2-lithiopyridine in either a 1:1 or a 2:1 mol ratio, respectively. They react with [Ru(bpy)2(EtOH)2][PF6]2 to yield the new complexes [N,O-PhC(O)(2-py)Ru(bpy)2][PF6]2 (6), [p-N,O-BrC6H4C-(O)(2-py)Ru(bpy)2][PF6]2 (7), [m-N,O-BrC6H4C(O)(2-py)Ru(bpy)2][PF6]2 (8), [p-[N,O-C(O)(2-py)2Ru(bpy)2]2(C6H4)]-[PF6]4 (9), and [m-[N,O-C(O)(2-py)2Ru(bpy)2]2(C6H4)][PF6]4 (10). The solid state structures of 6 and 7 show that the octahedral cations are arranged in sinusoidal chains by pi-pi stacking and CH-pi interactions between bipyridyl groups. Substitution of bromine for hydrogen at the para position of the aryl group in 7 causes the aryl group to become involved in pi-pi stacking interactions that organize the chains into a sheet structure. The complicated 1H and 13C NMR spectra of the complexes have been fully assigned using 2D methods. The optical spectra show two absorption maxima near 434 and 564 nm due to MLCT transitions. The compounds were found to be nonluminescent. Electrochemical data acquired for CH3CN solutions of the bimetallic derivatives indicate that there is no electronic communication between metal centers mediated either through space or through ligand orbitals. Crystallographic information: 6.0.5CH3CN is monoclinic, C2/c, a = 24.3474(11) A, b = 13.7721(6) A, c = 21.3184(10) A, beta = 103.9920(10) degrees, Z = 8; 7 is monoclinic, P2(1)/c, a = 10.6639(11) A, b = 23.690(3) A, c = 13.7634(14) A, beta = 91.440(2) degrees, Z = 4.     

C-H cleavage and double alkyl additions to the disulfido ligand in dicyanido-bridged Ru2S2 complexes

Novel dicyanido-bridged dicationic RuIIISSRuIII complexes [{Ru(P(OCH3)3)2}2(mu-S2)(mu-X)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (4, X=Cl, Br) were synthesized by the abstraction of the two terminal halide ions of [{RuX(P(OCH3)3)2}2(mu-S2)(mu-X)2] (1, X=Cl, Br) followed by treatment with m-xylylenedicyanide. 4 reacted with 2,3-dimethylbutadiene to give the C4S2 ring-bridged complex [{Ru(P(OCH3)3)2}2{mu-SCH2C(CH3)=C(CH3)CH2S}(mu-X)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (6, X=Cl, Br). In addition, 4 reacted with 1-alkenes in CH3OH to give alkenyl disulfide complexes [{Ru(P(OCH3)3)2}2{mu-SS(CH2C=CHR)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3) (7: R=CH2CH3, 9: R=CH2CH2CH3) and alkenyl methyl disulfide complexes [{Ru(P(OCH3)3)2}2{mu-S(CH3)S(CH2C=HR)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (8: R=CH2CH3, 10: R=CH2CH2CH3) via the activation of an allylic C-H bond followed by the elimination of H+ or condensation with CH3OH. Additionally, the reaction of 4 with 3-penten-1-ol gave [{Ru(P(OCH3)3)2}2{mu-SS(CH2C=CHCH2OH)}(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3) (11) via the elimination of H+ and [{Ru(P(OCH3)3)2}2(mu-SCH2CH=CHCH2S)(mu-Cl)2{mu-m-C6H4(CH2CN)2}](CF3SO3)2 (12) via the intramolecular elimination of a H2O molecule. 12 was exclusively obtained from the reaction of 4 with 4-bromo-1-butene.