Synthesis, structure, and electrochemical properties of copper(I) complexes with S/N homoscorpionate and heteroscorpionate ligands

Dinuclear Cu(I) complexes with bifunctionalized homoscorpionate ligands, hydrotris(thioxotriazolyl)borato [Li(Tr(Me,o)(-)(Py)) (1) and Li(Tr(Mes,Me)) (2)], and the heteroscorpionate ligand hydro[bis(thioxotriazolyl)-3-(2-pyridyl)pyrazolyl]borato [K(Br(Mes)pz(o)(-)(Py))] (3) were synthesized and crystallographically characterized. The complexes [Cu(Tr(Mes,Me))](2) (4) and [Cu(Tr(Me,o)(-)(Py))](2) (5) exhibit a similar coordination geometry where every metal is surrounded by three thioxo groups in a trigonal arrangement. The presence of a [B-H...Cu] three-center-two-electron interaction in both compounds causes the overall coordination to become tetrahedrally distorted (S(3)H coordination for each metal). The complex [Cu(Br(Mes)pz(o)(-)(Py))](2) (6) presents a trigonal geometry in which the metals interact with two thioxo groups and a bridging pyrazolyl nitrogen atom. A weak contact with a pyridine nitrogen atom completes the coordination of the metals (S(2)N,N' coordination for each metal). [Cu(Tr(Mes,Me))](2), [Cu(Tr(Me,o)(-)(Py))](2), and [Cu(Br(Mes)pz(o)(-)(Py))](2) exhibit fluxional behavior in solution as evidenced by variable-temperature NMR spectroscopy, and for 5 and 6 two species in equilibrium [in the ratio 2/1 for 5 (CDCl(3)) and 3/2 for 6 (CD(2)Cl(2))] are distinguishable in the (1)H NMR spectra at 270 K. 2D-NOESY spectra recorded at 270 K assisted in the attribution of solution molecular geometries for each isomer of 5 and 6. The free energy of activation (DeltaG()(Tc)) was determined for both equilibria from the evaluation of the coalescence temperature. DFT calculations were performed to describe plausible molecular geometry for the minor isomer of 5 and 6 and to propose a possible mechanism of interconversion between major and minor isomers. Cyclic voltammograms were recorded in CH(2)Cl(2) (3 and 6) or CH(2)Cl(2)/CH(3)CN (1/1, v/v) (2, 4, and 5) solutions using 0.1 M TBAHFP or TBAOTf as supporting electrolytes. [Cu(Tr(Mes,Me))](2), [Cu(Tr(Me,o)(-)(Py))](2), and [Cu(Br(Mes)pz(o)(-)(Py))](2) exhibit a quasi-reversible Cu(I)/Cu(II) redox behavior with E(pa) = +719 mV and E(pc) = +538 mV for 4, E(pa) = +636 mV and E(pc) = -316 mV for 5, and E(pa) = +418 mV and E(pc) = -319 mV for 6.     

Proton-induced reactivities of ruthenium azido complexes: the first example of boron-carbon bond formation by methylene insertion into a B-H bond

Whereas the reaction of Tp(PhCN)(PPh(3))Ru-N(3) {Tp = HB(pz)(3), pz = pyrazolyl} with CH(3)I in CH(2)Cl(2) led to the cationic ruthenium methyleneimine complex [Tp(PPh(3))(PhCN)Ru(NH=CH(2))]I, the analogous reaction with HCl gave rise to the ruthenium chloride complex containing a methyl tris(pyrazolyl)borate ligand (Me)Tp(PPh(3))(PhCN)RuCl, as a result of the highly unusual methylene insertion into a B-H bond of the Tp ligand.     

Coinage metal complexes of a boron-substituted soft scorpionate ligand

An improved synthesis of lithium phenyltris(methimazolyl)borate, Li[PhTm(Me)], (methimazole = 1-methylimidazole-2-thione) is described, and the structure of the methanol-solvated [Li(OHMe)4][PhTm(Me)] has been determined. The syntheses and characterization of complexes [M(PhTm(Me))(PR3)] (M = Cu, Ag, Au; R = Et, Ph;) are reported, and the complexes [Cu(PhTm(Me))(PPh3)], [Ag(PhTm(Me))(PEt3)] and [Au(PhTm(Me))(PEt3)] are crystallographically characterized, showing a progression from pseudo-tetrahedral geometry (copper, S3P coordination) to trigonal planar geometry (silver, S2P coordination) to linear geometry (gold, SP coordination). In addition, the copper(I) and silver(I) triphenylphosphine complexes of the adventitiously formed phenylhydrobis(methimazolyl)borate ligand, [M(PhBm(Me))(PPh3)], have been crystallographically characterized, showing both species to have a trigonal planar primary coordination sphere, with a secondary M...H-B interaction. Finally, reaction of copper(II) chloride with Li[PhTm(Me)] results in formation of a compound analyzing as [Cu(II)(PhTm(Me))Cl], although its extreme insolubility and marked instability have precluded its complete characterization. Attempts to prepare this by ultra-slow diffusion of the reactants through solvent blanks has led to isolation of a mixed-valence copper(I/II) methimazolate cluster, [Cu(I)10Cu(II)2(mt)12Cl2] and a copper(I) dimeric complex [Cu2(PhTm(Me))2], indicating that copper(II) ions oxidatively decompose the phenyltris(methimazolyl)borate anion.     

Coordination features of a hybrid scorpionate/phosphane ligand exemplified with Iridium

Although the pentacoordinated complex [Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}(cod)] (1; pz=pyrazolyl, cod=1,5-cyclooctadiene), isolated from the reaction of [{Ir(mu-Cl)(cod)}(2)] with [Li(tmen)][B(allyl)(CH(2)PPh(2))- (pz)(2)] (tmen=N,N,N',N'-tetramethylethane-1,2-diamine), shows behavior similar to that of the related hydridotris(pyrazolyl)borate complex, the carbonyl derivatives behave in a quite different way. On carbonylation of 1, the metal--metal-bonded complex [(Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}CO)(2)(mu-CO)] (2) that results has a single ketonic carbonyl bridge. This bridging carbonyl is labile such that upon treatment of 2 with PMe(3) the pentacoordinated Ir(I) complex [Ir(CO){(pz)B(eta(2)-CH(2)CH=CH(2))(CH(2)PPh(2))(pz)}(PMe(3))] (3) was isolated. Complex 3 shows a unique fac coordination of the hybrid ligand with the allyl group eta(2)-bonded to the metal in the equatorial plane of a distorted trigonal bipyramid with one pyrazolate group remaining uncoordinated. This unusual feature can be rationalized on the basis of the electron-rich nature of the metal center. The related complex [Ir(CO){(pz)B(eta(2)-CH(2)CH=CH(2))(CH(2)PPh(2))(pz)}(PPh(3))] (4) was found to exist in solution as a temperature-dependent equilibrium between the cis-pentacoordinated and trans square planar isomers with respect to the phosphorus donor atoms. Protonation of 3 with different acids is selective at the iridium center and gives the cationic hydrides [Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}(CO)H(PMe(3))]X (X=BF(4) (5), MeCO(2) (6), and Cl (7)). Complex 7 further reacts with HCl to generate the unexpected product [Ir(CO)Cl{(Hpz)B(CH(2)PPh(2))(pz)CH(2)CH(Me)}(PMe(3))]Cl (9; Hpz=protonated pyrazolyl group) formed by the insertion of the hydride into the Ir-(eta(2)-allyl) bond. In contrast, protonation of complex 4 with HCl stops at the hydrido complex [Ir{(allyl)B(CH(2)PPh(2))(pz)(2)}(CO)H(PPh(3))]Cl (8). X-ray diffraction studies carried out on complexes 2, 3, and 9 show the versatility of the hybrid scorpionate ligand in its coordination.     

Versatile ligand behavior of hydrotris(4-ethyl-3-methyl-5-thioxo-1,2,4-triazolyl)borate. Syntheses and crystal structures of Cu(I) and Bi(III) complexes

Preparations of copper(I) and bismuth(III) complexes of hydrotris(4-ethyl-3-methyl-5-thioxo-1,2,4-triazolyl)borate (Tr(Et,Me)) are described. These complexes have been characterized by means of spectroscopy and microanalysis. Molecular structures of [Cu(Tr(Et,Me))](2) x 2.5CH(3)CN x 0.5H(2)O (3a) and [Bi(Tr(Et,Me))(2)]NO(3) x 2CHCl(3) (4a) have been determined by single-crystal X-ray diffraction. In the centrosymmetric dimeric copper(I) complex, Tr(Et,Me) acts in the k(3)S,S',H:kS' ' coordination mode. The metal is found in a distorted trigonal geometry as the ligand exhibits an "S(3)-inverted" conformation at the boron center so that a weak [B-H.Cu] agostic interaction renders the overall coordination of the (3 + 1) type. On the other hand, in the bismuth complex, Tr(Et,Me) presents the k(3)S,S',S' ' coordination mode and the "S(3)-normal" conformation. The metal is found in a regular octahedral geometry bound by six thioxo groups of two ligands. Species distributions in solution have been studied using electrospray ionization mass spectrometry upon dissolution of 3a and 4a crystals in acetonitrile. Monomeric and polynuclear copper(I) complexes with different M:L ratios are present in solution, while for 4a only the monomeric species is present.     

Cobalt half-sandwich, sandwich, and mixed sandwich complexes with soft tripodal ligands

Reaction of sodium hydrotris(methimazolyl)borate (NaTm(Me)) with cobalt halides leads to the formation of paramagnetic pseudotetrahedral [Co(Tm(Me))X] (X = Cl, Br, I), of which the bromide has been crystallographically characterized. Mass spectrometry reveals the presence of higher molecular weight fragments [Co(Tm(Me))(2)](+) and [Co(2)(Tm(Me))(2)X](+) in solution. Aerial oxidation in donor solvents (e.g. MeCN) leads to formation of the [Co(Tm(Me))(2)](+) cation, which has been crystallographically characterized as the BF(4)(-), ClO(4)(-), Br(-), and I(-), salts. Attempts to prepare the mixed sandwich complex, [Co(Cp)(Tm(Me))](+), resulted in ligand decomposition to yield [Co(mtH)(3)I]I (mtH = 1-methylimidazole-2-thione), but with the more electron donating methylcyclopentadienyl (Cp(Me)) ligand, [Co(Cp(Me))(Tm(Me))]I was isolated and characterized. Electrochemical measurements reveal that the cobalt(III) Tm(Me) complexes are consistently more difficult to reduce than their Tp and Cp congeners.     

Isomerism in rhodium(I) N,S-donor heteroscorpionates: ring substituent and ancillary ligand effects

The heteroscorpionate ligands [HB(taz)(2)(pz(R))](-) (pz(R) = pz, pz(Me2), pz(Ph)) and [HB(taz)(pz)(2)](-), synthesised from the appropriate potassium hydrotris(pyrazolyl)borate salt and 4-ethyl-3-methyl-5-thioxo-1,2,4-triazole (Htaz), react with [{Rh(cod)(μ-Cl)}(2)] to give [Rh(cod)Tx] {Tx = HB(taz)(2)(pz), HB(taz)(2)(pz(Me2)), HB(taz)(2)(pz(Ph)), HB(taz)(pz)(2)}; the heteroscorpionate rhodaboratrane [Rh{B(taz)(2)(pz(Me2))}{HB(taz)(2)(pz(Me2))}] is the only isolable product from the reaction of [{Rh(nbd)(μ-Cl)}(2)] with K[HB(taz)(2)(pz(Me2))]. Carbonylation of the cod complexes gave a mixture of [Rh(CO)(2)Tx] and [(RhTx)(2)(μ-CO)(3)] which reacts with PR(3) to give [Rh(CO)(PR(3))Tx] (R = Cy, NMe(2), Ph, OPh). In the solid state the complexes are square planar with the particular structure dependent on the steric and/or electronic properties of the scorpionate and ancillary ligands. The complex [Rh(cod){HB(taz)(pz)(2)}] has the heteroscorpionate κ(2)[N(2)]-coordinated to rhodium with the B-H bond directed away from the rhodium square plane while [Rh(cod){HB(taz)(2)(pz(Me2))}] is κ(2)[SN]-coordinated, with the B-H bond directed towards the metal. The complexes [Rh(CO)(PPh(3)){HB(taz)(2)(pz)}] and [Rh(CO)(PPh(3)){HB(taz)(2)(pz(Me2))}] are also κ(2)[SN]-coordinated but with the pyrazolyl ring cis to PPh(3); in the former the B-H bond is directed towards rhodium while in the latter the ring is pseudo-parallel to the rhodium square plane, as also found for [Rh(CO)(2){HB(taz)(2)(pz(Me2))}]. The analogues [Rh(CO)(PR(3)){HB(taz)(2)(pz(Me2))}] (R = Cy, NMe(2)) have the phosphines trans to the pyrazolyl ring. Uniquely, [Rh(CO)(PPh(3)){HB(taz)(2)(pz(Ph))}] is κ(2)[S(2)]-coordinated. A qualitative mechanism is given for the rapid ring-exchange, and hence isomerisation, observed in solution.     

A mechanistic investigation of oxidative addition of methyl iodide to [Tp*Rh(CO)(L)

Reaction of methyl iodide with square planar [kappa(2)-Tp*Rh(CO)(PMe(3))] 1a (Tp* = HB(3,5-Me(2)pz)(3)) at room temperature affords [kappa(3)-Tp*Rh(CO)(PMe(3))(Me)]I 2a, which was fully characterized by spectroscopy and X-ray crystallography. The pseudooctahedral geometry of cationic 2a, which contains a kappa(3)-coordinated Tp* ligand, indicates a reaction mechanism in which nucleophilic attack by Rh on MeI is accompanied by coordination of the pendant pyrazolyl group. In solution 2a transforms slowly into a neutral (acetyl)(iodo) rhodium complex [kappa(3)-Tp*Rh(PMe(3))(COMe)I] 3a, for which an X-ray crystal structure is also reported. Kinetic studies on the reactions of [kappa(2)-Tp*Rh(CO)(L)] (L = PMe(3), PMe(2)Ph, PMePh(2), PPh(3), CO)] with MeI show second-order behavior with large negative activation entropies, consistent with an S(N)2 mechanism. The second-order rate constants correlate well with phosphine basicity. For L = CO, reaction with MeI gives an acetyl complex, [kappa(3)-Tp*Rh(CO)(COMe)I]. The bis(pyrazolyl)borate complexes [kappa(2)-Bp*Rh(CO)(L)] (L = PPh(3), CO) are much less reactive toward MeI than the Tp* analogues, indicating the importance of the third pyrazolyl group and the accessibility of a kappa(3) coordination mode. The results strengthen the evidence in favor of an S(N)2 mechanism for oxidative addition of MeI to square planar d(8) transition metal complexes.     

Solution behavior and structural properties of Cu(I) complexes featuring m-terphenyl isocyanides

The synthesis of the m-terphenyl isocyanide ligand CNAr (Mes2) (Mes = 2,4,6-Me 3C 6H 2) is described. Isocyanide CNAr (Mes2) readily functions as a sterically encumbering supporting unit for several Cu(I) halide and pseudo halide fragments, fostering in some cases rare structural motifs. Combination of equimolar quantities of CNAr (Mes2) and CuX (X = Cl, Br and I) in tetrahydrofuran (THF) solution results in the formation of the bridging halide complexes (mu-X) 2[Cu(THF)(CNAr (Mes2))] 2. Addition of CNAr (Mes2) to cuprous chloride in a 2:1 molar ratio generates the complex ClCu(CNAr (Mes2)) 2 in a straightforward manner. Single-crystal X-ray diffraction has revealed ClCu(CNAr (Mes2)) 2 to exist as a three-coordinate monomer in the solid state. As determined by solution (1)H NMR and FTIR spectroscopic studies, monomer ClCu(CNAr (Mes2)) 2 resists tight binding of a third CNAr (Mes2) unit, resulting in rapid isocyanide exchange. Contrastingly, addition of 3 equiv of CNAr (Mes2) to cuprous iodide readily affords the tris-isocyanide species, ICu(CNAr (Mes2)) 3, as determined by X-ray diffraction. Similar coordination behavior is observed in the tris-isocyanide salt [(THF)Cu(CNAr (Mes2)) 3]OTf (OTf = O 3SCF 3), which is generated upon treatment of (C 6H 6)[Cu(OTf)] 2 with 6 equiv of CNAr (Mes2) in THF. The disparate coordination behavior of the [CuCl] fragment relative to both [CuI] and [CuOTf] is rationalized in terms of structure and Lewis acidity of the Cu-containing fragments. The putative triflate species [Cu(CNAr (Mes2)) 3]OTf itself serves as a good Lewis acid and is found to weakly bind C 6H 6 in an eta (1)- C manner in the solid-state. Density Functional Theory is used to describe the bonding and energetics of the eta (1)- C Cu-C 6H 6 interaction.     

Coinage metal complexes of tris(pyrazolyl)methanide [C(3,5-Me2pz)3]-: kappa3-coordination vs. backbone functionalisation

Tris(pyrazolyl)methanides, [C(3,5-R2pz)3]-, contain an unassociated tetrahedral carbanionic centre in the bridgehead position. In addition to nitrogen donor centres for transition metal coordination, an accessible reactive site for further manipulations is available in the backbone of the ligand. The coordination variability of the ambidental C-/N ligand [C(3,5-Me2pz)3]- was elucidated by investigating its coinage metal complexes. Two principle coordination modes were found for complexes of general formula [LMPR3] (with M = Cu(I), Ag(I), Au(I); L =[C(3,5-Me2pz)3]-; R = Ph, OMe). While for Cu(I) (2,3) and Ag(I) (4) complexes the anionic ligand acts as a face-capping, six electron N3-donor, gold(I) (5) is coordinated by the bridging carbanion yielding a two coordinate Au(I) complex comprising a covalent Au-C bond. The complexes featuring the kappa3-coordinated N3-donor ligand were investigated by 31P CP (MAS) NMR in the solid state.     

Copper complexes of mono- and ditopic [(methylthio)methyl]borates: missing links and linked systems en route to copper enzyme models

TMEDA-free (TMEDA: tetramethylethylenediamine) LiCH(2)SMe is a suitable reagent for the selective introduction of (methylthio)methyl groups into PhBBr(2) and its p-silylated derivative Me(3)Si--C(6)H(4)--BBr(2). The resulting compounds, R*--C(6)H(4)--B(Br)(CH(2)SMe) (R*=H: 2; R*=SiMe(3): 7) and PhB(CH(2)SMe)(2) (3), form cyclic dimers through B--S adduct bonds in solution and in the solid state. Compounds 2 and 3 have successfully been used for preparing the (N(2)S) scorpionate [PhBpz(2)(CH(2)SMe)](-) ([5](-)) (pz: pyrazol-1-yl) and the (NS(2)) scorpionate [PhBpz(CH(2)SMe)(2)](-), respectively. Compound 7 proved to be an excellent building block for the heteroditopic poly(pyrazol-1-yl)borate p-[pz(3)B--C(6)H(4)--Bpz(2)(CH(2)SMe)](2-) ([10](2-)) that mimics the two ligation sites of the copper enzymes peptidylglycine alpha-hydroxylating monooxygenase and dopamine beta-monooxygenase. Treatment of the monotopic tripod [5](-) with CuCl and CuBr(2) results in the formation of complexes K[Cu(5)(2)] and [Cu(5)(2)]. An X-ray crystallography study of K[Cu(5)(2)] revealed a tetrahedral (N(2)S(2)) coordination environment for the Cu(I) ion, whereas the Cu(II) ion of [Cu(5)(2)] possesses a square-pyramidal (N(4)S) ligand sphere (S-atom in the axial position). The remarkable redox properties of K[Cu(5)(2)] and [Cu(5)(2)] have been assessed by cyclic voltammetry and quantum chemical calculations. The reaction of K[Cu(5)(2)] with dry air leads to the Cu(II) species [Cu(5)(2)] and to a tetranuclear Cu(II) complex featuring [PhB(O)pz(2)](2-) ligands. Addition of CuCl to K(2)[10] gives the complex K(3)[Cu(10)(2)] containing two ligand molecules per Cu(I) center. The Cu(I) ion binds to both heteroscorpionate moieties and thereby establishes a coordination environment similar to that of the Cu(I) ion in K[Cu(5)(2)].     

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.     

Synthetic applications of (Me3SiNSN)2E (E = S, Se) in chalcogen-nitrogen chemistry: formation and structural characterization of Cl2TeESN2 (E = S, Se) and [PPh4]2[Pd2(mu-Se2N2S)X4] (X = Cl, Br)

The reaction of (Me3SiNSN)2S with TeCl4 in CH2Cl2 affords Cl2TeS2N2 (1) and that of (Me3SiNSN)2Se with TeCl4 produces Cl2TeSeSN2 (2) in good yields. The products were characterized by X-ray crystallography, as well as by NMR and vibrational spectroscopy and EI mass spectrometry. The Raman spectra were assigned by utilizing DFT molecular orbital calculations. The pathway of the formation of five-membered Cl2TeESN2 rings by the reactions of (Me3SiNSN)2E with TeCl4 (E = S, Se) is discussed. The reaction of (Me3SiNSN)2Se with [PPh4]2[Pd2X6] yields [PPh4]2[Pd2(mu-Se2N2S)X4] (X = Cl, 4a; Br, 4b), the first examples of complexes of the (Se2N2S)2- ligand. In both cases, this ligand bridges the two palladium centers through the selenium atoms.     

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.     

Platinum complexes of naphthalene-1,8-dichalcogen and related polyaromatic hydrocarbon ligands

Platinum bisphosphine complexes bearing dichalcogen-derivatised naphthalene, acenaphthene or phenanthrene ligands have been prepared by either oxidative addition to zero-valent platinum species or from [PtCl(2)(PPhR(2))] (R=Ph or Me) and the disodium or dilithium salts of the parent disulfur, diselenide or mixed S/Se species. The parent naphthalene, acenaphthene and phenanthrene chalcogen compounds were treated with either [Pt(PPh(3))(4)] or [Pt(C(2)H(4))(PMe(3))(2)] (prepared in situ from [PtCl(2)(PMe(3))(2)], ethene and sodium naphthalide or super hydride [LiBEt(3)H]) to give the appropriate platinum(II) species. The dilithium salts of 1,8-E(2)-naphthalene (E=S or Se) prepared in situ by reduction of the E-E bond with [LiBEt(3)H] were treated with [PtCl(2)(PPh(3))(2)] to give [Pt(1,8-E(2)-nap)(PPh(3))(2)]. The tetraoxides [Pt(1,8-(S(O)(2))(2)-nap)(PR(3))(2)] (PR(3)=PPh(3) or PMe(2)Ph) were prepared in a similar metathetical manner from the appropriate [PtCl(2)(PR(3))] complexes and the disodium salt of naphthalene 1,8-disulfinic acid (1,8-(S(O)ONa)(2)-nap). The X-ray structures of selected examples reveal bidentate coordination with the naphthalene-E(2) unit hinged (111-137 degrees) with respect to the coordination plane. The naphthalene ring suffers significant distortion from planarity.     

Unprecedented formation of novel phosphonodithioate ligands from diferrocenyldithiadiphosphetane disulfide

The reaction of the phosphetane disulfide, FcP(S)S 2P(S)Fc ( 1) (Fc = (eta (5)-C 5H 5)Fe(eta (5)-C 5H 4)), the ferrocenyl analogue of the Lawesson reagent, with gold and palladium complexes leads to the unprecedented formation of phosphonodithioate ligands upon coordination to the metal centers. The reaction of 1 with gold complexes such as [AuCl(PR 3)] affords the species [Au{S 2P(OH)Fc}(PR 3)] (PR 3 = PPh 3 ( 2), PPh 2Me ( 3)), in which the phosphonodithioate ligand Fc(OH)PS 2 (-) has been formed. The same ligand is present in the compound [Au 2{S 2P(OH)Fc} 2].[N(PPh 3) 2]Cl ( 4), obtained by reaction of 1 with [N(PPh 3) 2][AuCl 2]. It crystallizes with one molecule of [N(PPh 3) 2]Cl, whereby complex 4 acts as an anion receptor and forms strong hydrogen bonds between the chloro and the hydroxyl groups. The reaction with palladium derivatives is different; two complexes, [Pd 2(S 4OP 2Fc 2) 2] ( 5) and [Pd 4Cl 4(S 4OP 2Fc 2) 2] ( 6), are obtained in molar ratio 2:1 and 1:1, respectively. In these complexes a new phosphonodithioate ligand is present and probably arises from the condensation of two molecules of Fc(OH)PS 2 (-). Complex 5 has also been characterized by X-ray methods.     

Synthesis and structural characterization of configurational isomers of tungsten-palladium complexes with bridging diphenyl(dithioalkoxycarbonyl)phosphine as a ligand and phosphine transfer from tungsten to palladium

Treatment of the complex [W(CO)5[PPh2(CS2Me)]] (2) with [Pd(PPh3)4] (1) affords binuclear complexes such as anti-[(Ph3P)2Pd[mu-eta 1,eta 2-(CS2Me)PPh2]W(CO)5] (3), syn-[(Ph3P)2Pd[mu-eta 1,eta 2-(CS2Me)PPh2]W(CO)5] (4), and trans-[W(CO)4(PPh3)2] (5). In 3 and 4, respectively, the W and Pd atoms are in anti and syn configurations with respect to the P-CS2 bond of the diphenyl(dithiomethoxycarbonyl)phosphine ligand, PPh2(CS2Me). Complex 3 undergoes extensive rearrangement in CHCl3 at room temperature by transfer of a PPh3 ligand from Pd to W, eliminating [W(CO)5(PPh3)] (7), while the PPh2CS2Me ligand transfers from W to Pd to give [[(Ph3P)Pd[mu-eta 1,eta 2-(CS2Me)PPh2]]2] (6). In complex 6, the [Pd(PPh3)] fragments are held together by two bridging PPh2(CS2Me) ligands. Each PPh2(CS2Me) ligand is pi-bonded to one Pd atom through the C=S linkage and sigma-bonded to the other Pd through the phosphorus atom, resulting in a six-membered ring. Treatment of Pd(PPh3)4 with [W(CO)5[PPh2[CS2(CH2)nCN]]] (n = 1, 8a; n = 2, 8b) in CH2Cl2 affords syn-[(Ph3P)2Pd[mu-eta 1,eta 2-[CS2(CH2)nCN]PPh2]W(CO)5] (n = 1, 9a; n = 2, 9b). Similar configurational products syn-[(Ph3P)2Pd[mu-eta 1,eta 2-(CS2R)PPh2]W(CO)5] (R = C2H5, C3H5, C2H4OH, C3H6CN, 11a-d) are synthesized by the reaction of Pd(PPh3)4 with [W(CO)5[PPh2(CS2R)]] (R = C2H5, C3H5, C2H4OH, C3H6CN, 10a-d). Although complexes 11a-d have the same configuration as 9a,b, the SR group is oriented away from Pd in the former and near Pd in the latter. In these complexes, the diphenyl(dithioalkoxycarbonyl)phosphine ligand is bound to the two metals through the C=S pi-bonding and to phosphorus through the sigma-bonding. All of the complexes are identified by spectroscopic methods, and the structures of complexes 3, 6, 9a, and 11d are determined by single-crystal X-ray diffraction. Complexes 3, 9, and 11d crystallize in the triclinic space group P1 with Z = 2, whereas 6 belongs to the monoclinic space group P2/c with Z = 4. The cell dimensions are as follows: for 3, a = 10.920(3) A, b = 14.707(5) A, c = 16.654(5) A, alpha = 99.98(3) degrees, beta = 93.75(3) degrees, gamma = 99.44(3) degrees; for 6, a = 15.106(3) A, b = 9.848(3) A, c = 20.528(4) A, beta = 104.85(2) degrees; for 9a, a = 11.125(3) A, b = 14.089(4) A, c = 17.947(7) A, alpha = 80.13(3) degrees, beta = 80.39(3) degrees, gamma = 89.76(2) degrees; for 11d, a = 11.692(3) A, b = 13.602(9) A, c = 18.471(10) A, alpha = 81.29(5) degrees, beta = 80.88(3) degrees, gamma = 88.82(1) degrees.     

New bis-, tris- and tetrakis(pyrazolyl)borate ligands with 3-pyridyl and 4-pyridyl substituents: synthesis and coordination chemistry

The new ligands dihydrobis[3-(4-pyridyl)pyrazol-1-yl]borate [Bp(4py)]-, hydrotris[3-(4-pyridyl)pyrazol-1-yl]borate [Tp(4py)]-, tetrakis[3-(4-pyridyl)pyrazol-1-yl]borate [Tkp(4py)]-, dihydrobis[3-(3-pyridyl)pyrazol-1-yl]borate [Bp(3py)]-, hydrotris[3-(3-pyridyl)pyrazol-1-yl]borate [Tp(3py)]- and tetrakis[3-(3-pyridyl)pyrazol-1-yl]borate [Tkp(4py)]- are derivatives of the well known bis-, tris- and tetrakis-(pyrazolyl)borate cores, bearing 4-pyridyl or 3-pyridyl substituents attached to the pyrazolyl C3 positions. These pyridyl groups cannot chelate to the metal ions in the poly(pyrazolyl) cavity but are externally directed. Structural studies on a range of metal complexes show how, in many cases, coordination of these pendant pyridyl groups to the M(pyrazolyl)n core of an adjacent metal complex fragment results in formation of coordination oligomers or polymeric networks. [Tl(Bp(3py))], [Tl(Bp(4py))] and [Tl(Tp(4py))] form one-dimensional polymeric chains via coordination of one of their pendant pyridyl units to the Tl(I) centre of an adjacent complex fragment; in contrast, in [Tl(Tp(3py))] coordination of all three pendant pyridyl units to separate Tl(I) neighbours results in formation of a two-dimensional polymeric sheet. In [Tl(Tkp(3py))] and [Tl(Tkp(4py))] the Tl(I) is coordinated by two or three of the four pyrazolyl arms, respectively; bridging interactions of pendant 4-pyridyl groups with adjacent Tl(I) centres result in a two-dimensional sheet forming in each case. In Ag(Tkp(4py)) each Ag(I) ion is coordinated by two pyrazolyl rings, and two bridging pyridyl ligands from other complex units, resulting in a one-dimensional chain consisting of pairs of cross-linked zigzag chains. In contrast to these polymeric coordination networks, the structures of [Cu(Tp(4py))] and [(Tp(3py))Cd(CH3CO2)] are dimers, with a pendant pyridyl residue from the first metal centre attaching to a vacant coordination site on the second, and vice versa; these dimers are stabilised by pi-stacking interactions between sections of the two ligands. [Ni(Tp(3py))2] is monomeric, with an octahedral coordination geometry arising from two tris(pyrazolyl)borate chelates; the array of pendant 3-pyridyl groups is involved only in intramolecular hydrogen-bonding. [(Tp(4py))Re(CO)3] is also monomeric, with a facial arrangement of three pyrazolyl ligands and three carbonyls, with the pendant 4-pyridyl groups not further coordinated. [(Tp(2py))Re(CO)3], based on the related ligand hydrotris[3-(2-pyridyl)pyrazol-1-yl]borate, has a similar fac-(CO)3(pyrazolyl)3 coordination geometry.     

Unprecedented coordination of dithiocarbimate in multinuclear and heteroleptic complexes

An uncommon coordination protocol induced by the p-tolylsulfonyl dithiocarbimate ligand (L) [L = p-CH(3)C(6)H(4)SO(2)N[double bond, length as m-dash]CS(2)(2-)] in conjunction with PPh(3) allowed the formation of novel homodimetallic, Cu(2)(PPh(3))(4)L (1), trinuclear heterometallic Cu(2)Ni(L)(2)(PPh(3))(4) (2) and heteroleptic complexes of general formula cis-[M(PPh(3))(2)L] [M = Pd(ii) (3), Pt(ii) (4)]. The complexes have been characterized by microanalysis, mass spectrometry, IR, (1)H, (13)C and (31)P NMR and electronic absorption spectra and single-crystal X-ray crystallography. 2 uniquely consists of square planar, trigonal planar and tetrahedral coordination spheres within the same molecule. In both heteroleptic complexes 3 and 4 the orientation of aromatic protons of PPh(3) ligand towards the Pd(ii) and Pt(ii) center reveals C-HPd and C-HPt rare intramolecular anagostic or preagostic interactions. These complexes exhibit photoluminescent properties in solution at room temperature arising mainly from intraligand charge transfer (ILCT) transitions. The assignment of electronic absorption bands has been corroborated by time dependent density functional theory (TD-DFT) calculations. Complexes 1 and 2 with σ(rt) values ～ 10(-6) S cm(-1) show semi-conductor properties in the temperature range 313-403 K whereas 3 and 4 exhibit insulating behaviour.     

Dioxygen activation and substrate oxygenation by a p-nitrothiophenolatonickel complex: unique effects of an acetonitrile solvent and the p-nitro group of the ligand

The nickel(II) complex [Ni(Tp(Me2)) (SC(6)H(4)NO(2))] [1a; Tp(Me2) = hydrotris(3,5-dimethylpyrazol-1-yl)borate] reacts with O(2) to form the ligand oxygenation product ArSO(2)(-) in MeCN, and also 1a catalyzes the oxygenation of external substrates such as triphenylphosphine. The reactivity may correlate to the unique quinoid-like resonance structure of the thiophenolate ligand. The structure is stabilized by a p-nitro group and induced by coordination of MeCN.