Cu(I) dinuclear complexes with tripodal ligands vs monodentate donors: triphenylphosphine, thiourea, and pyridine. A 1H NMR titration study

Complexes [PPh3Cu(Tr(Mes,Me))] (1), [PPh3Cu(Tr(Me,o-Py))] (2), and [PPh3Cu(Br(Mes)pz(o-Py))] (3) (Tr(Mes,Me) = hydrotris[1,4-dihydro-3-methyl-4-mesityl-5-thioxo-1,2,4-triazolyl]borate; Tr(Me,o-Py) = hydrotris[1,4-dihydro-4-methyl-3-(2-pyridyl)-5-thioxo-1,2,4-triazolyl]borate; Br(Mes)pz(o-Py) = hydro[bis(thioxotriazolyl)-3-(2-pyridyl)pyrazolyl]borate; PPh3 = triphenylphosphine) were synthesized by the reaction of dinuclear complexes [Cu(Tr(Mes,Me))]2, [Cu(Tr(Me,o-Py))]2, [Cu(Br(Mes)pz(o-Py))]2, and PPh3. 1-3 were characterized by 1H, 13C, and 31P NMR spectroscopy and ESI-mass spectrometry. Crystal structure analyses were performed for 1 and 2. Both complexes crystallize in the triclinic P space group with the metal in a slightly distorted tetrahedral geometry (S3P coordination) bound by a kappa3-S3 ligand and a PPh3 molecule. The solution molecular structures were investigated by means of variable-temperature (210-310 K, CDCl3, 1-2; 200-310 K, CD2Cl2, 3) and NOESY NMR spectroscopy. The solution structures of 1-2 are in accordance with the X-ray structures, and the complexes do not exhibit fluxional behavior. On the other hand, 3 is subject to an equilibrium between two species with a coalescing temperature of approximately 260 K. DFT geometry optimizations suggest that the major species of 3 consists of the Br(Mes)pz(o-Py) ligand bound to Cu(I) in the kappa3-S2H fashion with two C=S groups and a [Cu...H-B] interaction. A PPh3 completes the copper coordination (S2HP coordination). The complex [TuCu(Tr(Mes,Me))] (4) (Tu = thiourea) was crystallized using an excess of Tu with respect to [Cu(Tr(Me,2-Py))]2 (approximately a 6:1 ratio). The metal adopts a distorted tetrahedral geometry with an overall S3H coordination determined by the bound kappa3-S2H ligand (two C=S groups and a [B-H...Cu] interaction) and by a Tu. The reactivity of dinuclear complexes [Cu(Tr(Mes,Me))]2, [Cu(Tr(Me,o-Py))]2, and [Cu(Br(Mes)pz(o-Py))]2 with monodentate ligands was investigated by means of NMR titrations with PPh3, Tu. and pyridine (Py), and formation constants for the adducts [DCu(L)] (D = monodentate donor, L = tripodal ligand) were determined.     

Nitrogen atom insertion into Ir-S and C-S bonds initiated by photolysis of iridium(III)-azido-dithiocarbamato complexes

Photolysis of acetonitrile solutions of Cp*Ir(R2dtc)(N3) [Cp* = eta5-C5Me5, R2dtc = S2CNR2; R = Me (1) or Et (1')] at temperatures below 0 degrees C afford five-coordinate complexes Cp*Ir{NSC(NR2)S} (2 or 2'), where a nitrogen atom has been inserted into one of the Ir-S bonds. In solution, complex 2 thermally convert to the azaethene-1,2-dithiolate complex, Cp*Ir[SN=C(NMe2)S] (3), which could be crystallized as the corresponding dimer, {Cp*Ir[mu-SN=C(NMe2)S-kappa3S:S,S']}2 (4). As a result, a nitrogen atom that originated in the azide ligand is transferred into a C-S bond of the dithiocarbamate.     

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.     

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.     

Preparation of mononuclear tungsten tris(sulfido) and molybdenum sulfido-tetrasulfido complexes with hydridotris(pyrazolyl)borate coligand and conversion of the former into sulfido-bridged bimetallic complex having Pt(mu-S)2WS core

Treatment of [Et4N][(Me2Tp)W(CO)3] (Me2Tp = HB(3,5-dimethylpyrazol-1-yl)3) with S8 in DMF at room temperature afforded a tris(sulfido) complex [Et4N][(Me2Tp)WS3] (1a), while that of [Et4N][TpW(CO)3] (Tp = HB(pyrazol-1-yl)3) in MeCN resulted in the formation of [Et4N][TpWS3] (1b) along with [Et4N]2[[WO(S2)2]2(mu-S)] (6) as a byproduct. Under similar conditions, [Et4N][(Me2Tp)Mo(CO)3] gave a mixture of a sulfido-tetrasulfido complex [Et4N][(Me2Tp)MoS(S4)] (2a) and its monooxo analogue [Et4N][(Me2Tp)MoO(S4)], although a sulfido-tetrasulfido complex [Et4N][TpMoS(S4)] (2b) was exclusively obtained from [Et4N][TpMo(CO)3]. The reaction of 1a with [PtCl2(cod)] (cod = 1,5-cyclooctadiene) in MeCN at room temperature led to the formation of a sulfido-bridged mixed-metal complex [Et4N][(Me2Tp)WS(mu-S)2PtCl2] (10). The structures of new complexes have been determined in detail by the X-ray analyses for 1a.MeCN, 1b, 2a, 2b, 6, and 10.     

Mononuclear (Pd, Pt), heterodinuclear (PdAg, PtAg), and tetranuclear (Pd2Ag2, Pt2Ag2) 1,1-ethylenedithiolato complexes

lp;&-5q;1 The reactions of [Tl2[S2C=C[C(O)Me]2]]n with [MCl2L2] (1:1) or with [MCl2(NCPh)2] and PPh3 (1:1:2) give complexes [M[eta2-S2C=C[C(O)Me]2]L2] [M = Pt, L2 = 1,5-cyclooctadiene (cod) (1); L2 = bpy, M = Pd (2a), Pt (2b), L = PPh3, M = Pd (3a), Pt (3b)] whereas with MCl2 and QCl (2:1:2) anionic derivatives Q2[M[eta2-S2C=C[C(O)Me]2]2] [M = Pd, Q = NMe4 (4a), Ph3P=N=PPh3 (PPN) (4a'), M = Pt, Q = NMe4 (4b)] are produced. Complexes 1 and 3 react with AgClO4 (1:1) to give tetranuclear complexes [[ML2]2Ag2[mu2,eta2-(S,S')-[S2C=C[C(O)Me]2]2]](ClO4)2 [L = PPh3, M = Pd (5a), Pt (5b), L2 = cod, M = Pt (5b')], while the reactions of 3 with AgClO4 and PPh3 (1:1:2) give dinuclear [[M(PPh3)2][Ag(PPh3)2][mu2,eta2-(S,S')-S2C=C[C(O)Me]2]]]ClO4 [M = Pd (6a), Pt (6b)]. The crystal structures of 3a, 3b, 4a, and two crystal forms of 5b have been determined. The two crystal forms of 5b display two [Pt(PPh3)2][mu2,eta2-(S,S')-[S2C=C[C(O)Me]2]2] moieties bridging two Ag(I) centers.     

Cleavage of X-H bonds (X = N, o, or C) by copper(I) alkyl complexes to form monomeric two-coordinate copper(I) systems

The monomeric copper(I) alkyl complexes (IPr)Cu(R) [R = Me or Et; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] react with substrates that possess N-H, O-H, and acidic C-H bonds to form monomeric systems of the type (IPr)Cu(X) (X = anilido, phenoxide, ethoxide, phenylacetylide, or N-pyrrolyl) and methane or ethane. Solid-state X-ray crystal structures of the anilido, ethoxide, and phenoxide complexes confirm that they are monomeric systems. Experimental studies on the reaction of (IPr)Cu(Me) and aniline to produce (IPr)Cu(NHPh) suggest that a likely reaction pathway is coordination of aniline to Cu(I) followed by proton transfer to produce methane and the copper(I) anilido complex.     

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.     

1,1-ethylenedithiolato complexes of palladium(II) and platinum(II) with isocyanide and carbene ligands

The reactions of [Tl(2)[S(2)C=C[C(O)Me](2)]](n) with [MCl(2)(NCPh)(2)] and CNR (1:1:2) give complexes [M[eta(2)-S(2)C=C[C(O)Me](2)](CNR)(2)] [R = (t)Bu, M = Pd (1a), Pt (1b); R = C(6)H(3)Me(2)-2,6 (Xy), M = Pd (2a), Pt (2b)]. Compound 1b reacts with AgClO(4) (1:1) to give [[Pt(CN(t)Bu)(2)](2)Ag(2)[mu(2),eta(2)-(S,S')-[S(2)C=C[C(O)Me](2)](2)]](ClO(4))(2) (3). The reactions of 1 or 2 with diethylamine give mixed isocyanide carbene complexes [M[eta(2)-S(2)C=C[C(O)Me](2)](CNR)[C(NEt(2))(NHR)]] [R = (t)Bu, M = Pd (4a), Pt (4b); R = Xy, M = Pd (5a), Pt (5b)] regardless of the molar ratio of the reagents. The same complexes react with an excess of ammonia to give [M[eta(2)-(S,S')-S(2)C=C[C(O)Me](2)](CN(t)Bu)[C(NH(2))(NH(t)Bu)]] [M = Pd (6a), Pt (6b)] or [M[eta(2)-(S,S')-S(2)C=C[C(O)Me](2)][C(NH(2))(NHXy)](2)] [M = Pd (7a), Pt (7b)] probably depending on steric factors. The crystal structures of 2b, 4a, and 4b have been determined. Compounds 4a and 4b are isostructural. They all display distorted square planar metal environments and chelating planar E,Z-2,2-diacetyl-1,1-ethylenedithiolato ligands that coordinate through the sulfur atoms.     

Azametallacycles from Ag(I)- or Cu(II)-promoted coupling reactions of dialkylcyanamides with oximes at Pt(II)

The dialkylcyanamide complexes cis-[PtCl(NCNR(2))(PPh(3))(2)][BF(4)] 1 and cis-[Pt(NCNR(2))(2)(PPh(3))(2)][BF(4)](2) 2 (R = Me or Et) have been prepared by treatment of a CH(2)Cl(2) solution of cis-[PtCl(2)(PPh(3))(2)] with the appropriate dialkylcyanamide and one or two equivalents of Ag[BF(4)], respectively. Compounds 2 can also be obtained from 1 by a similar procedure. Their reaction with oximes, HON=CR'R' ' (R'R' ' = Me(2) or C(4)H(8)), in CH(2)Cl(2) and in the presence of Ag[BF(4)] or Cu(CH(3)COO)(2), leads to the novel type of azametallacycles cis-[Pt(NH=C(ON=CR'R")-NR2)(PPh3)2][BF4]2 4 upon an unprecedented coupling of the organocyanamides with oximes, in a process that proceeds via the mixed oxime-organocyanamide species cis-[Pt(NCNR(2))(HON=CR'R' ')(PPh(3))(2)][BF(4)](2) 3, and is catalyzed by either Ag(+) or Cu(2+) which activate the ligating organocyanamide by Lewis acid addition to the amide group. In contrast, in the organonitrile complexes cis-[Pt(NCR)(2)(PPh(3))(2)][BF(4)](2) 5 (R = C(6)H(4)OMe-4 or Et), obtained in a similar way as 2 (but by using NCR instead of the cyanamide), the ligating NCR is not activated by the Lewis acid and does not couple with the oximes. The spectroscopic properties of those complexes are reported along with the molecular structures of 2b (R = Et), 4a1 (R = Me, R'R' ' = Me(2)), and 4b1 (R = Et, R'R' ' = Me(2)), as established by X-ray crystallography which indicates that in the former complex the amide-N-atoms are trigonal planar, whereas in the latter (4a1 and 4b1) the five-membered rings are planar with a localized N=C double bond (imine group derived from the cyanamide) and the exocyclic amide and alkylidene groups (in 4b1) are involved in two intramolecular H-bonds to the oxygen atom of the ring.     

Metallophilic bonding and agostic interactions in gold(I) and silver(I) complexes bearing a thiotetrazole unit

Gold(I) and silver(I) complexes of 1-methyl-5-thio-tetrazole (1) have been prepared and the coordination chemistry of this ligand toward metal-phosphine frameworks has been explored. As indicated by IR and Raman data, ligand 1 is deprotonated and the resulted anion acts as a bidentate (S,N)-tetrazole-5-thiolato unit in the new gold(I) complexes, [Au(SCN(4)Me)(PPh(3))] (2), [{Au(SCN(4)Me)}(2)(μ-dppm)] (3), and [{Au(SCN(4)Me)}(2)(μ-dppe)] (4), while it is coordinated only through the sulfur atom as its neutral tetrazole-5-thione form in the silver(I) derivative, [Ag(HSCN(4)Me)(PPh(3))](2)(OTf)(2) (5). Further characterization of the new compounds was performed using multinuclear ((1)H, (13)C, (31)P, (19)F) NMR spectroscopy, mass spectrometry, and DSC measurements. Single-crystal X-ray diffraction studies revealed basically linear P-M-S arrangements in complexes 3-5. The bidentate (S,N) coordination pattern results in a T-shaped (S,N)PAu core in 3 and 4, whereas, in 5, a similar coordination geometry is achieved in the dimer association based on S-bridging ligand 1. Herein, weak (C)H···Au and (C)H···Ag agostic interactions were observed. An intramolecular Au···Au contact occurs in 3, while in 4 intermolecular aurophilic bonds lead to formation of a chain polymer. An intermolecular Ag···Ag contact is also present in the dimer unit of 5. Low-temperature (31)P NMR data for 5 evidenced the presence of monomer and dimer units in solution. Theoretical calculations on model of the complexes 2 and 4 are consistent with the geometries found by X-ray diffraction studies.     

Aluminum and zinc complexes based on an amino-bis(pyrazolyl) ligand: synthesis, structures, and use in MMA and lactide polymerization

The coordination chemistry of bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]amine (1, LH) with aluminum- and zinc-alkyls has been studied. Reaction of 1 with AlR3 affords the adducts [LH] x AlR3 (R = Me, 2; Et, 3), which undergo alkane elimination upon heating to yield the amido complexes [L]AlR2 (R = Me, 4; Et, 5). Reaction of LiO(iPrO)C=CMe2 with 2 proceeds via N-H deprotonation to give Li[L]AlMe3 (6), while the former enolate adds to 4 to generate [Me2C=C(OiPr)OLi] x [L]AlMe2 (7). Similarly, the 1:1 reaction of ZnEt2 with 1 gives [LH] x ZnEt2 (9), which is transformed into [L]ZnEt (10) upon heating. When an excess of ZnEt2 was used in the latter reaction, the bimetallic complex [L]ZnEt x ZnEt2 (11) was isolated beside 10. Performing the same reaction in the presence of O2 traces yielded selectively the dinuclear ethyl-ethoxide complex [L]Zn2Et2(mu-OEt) (12), which was alternatively prepared from the reaction of 10 and ZnEt(OEt). Zinc chloride complexes [LH] x ZnRCl (R = Et, 13; p-CH3C6H4CH2, 14) and [L]ZnCl (15) were prepared in high yields following similar strategies. Ethyl abstraction from 10 with B(C6F5)3 yields [L]Zn+EtB(C6F5)3- (16). All complexes have been characterized by multinuclear nuclear magnetic resonance (NMR), elemental analysis, and single-crystal X-ray diffraction studies for four-coordinate Al complexes 2, 4, and 6 and Zn complexes 9-12 and 14. Aluminate species 6 and 7 initiate the polymerization of methyl methacrylate, and the monomer conversions are improved in the presence of neutral complexes 2 or 4, respectively; however, these methyl methacrylate (MMA) polymerizations are uncontrolled. Polymerization of rac-lactide takes place at 20 degrees C in the presence of zinc ethoxide complex 12 to yield atactic polymers with controlled molecular masses and relatively narrow polydispersities.     

Novel nucleophilic reactivity of disulfido ligands coordinated parallel to M-M (M = Rh, Ir) bonds

Reaction of trans-[(MCp)(2)(mu-CH(2))(2)Cl(2)] (M = Rh, Ir; Cp = eta(5)-C(5)Me(5)) with Li(2)S(2) afforded the disulfido complexes [(MCp)(2)(mu-CH(2))(2)(mu-S(2)-S:S')] which were easily oxidized by O(2) to give the oxygenated complexes [(MCp)(2)(mu-CH(2))(2)(mu-SSO(2)-S:S')]. Although [(RhCp)(2)(mu-CH(2))(2)(mu-S(2)-S:S')] gave a complicated mixture when reacted with CH(2)Cl(2) or CHCl(3), [(IrCp)(2)(mu-CH(2))(2)(mu-S(2)-S:S')] reacted with both CH(2)Cl(2) and CHCl(3) to give the dithioformato complex [(IrCp)(2)(mu-CH(2))(2)(mu-S(2)CH-S:S')]Cl and the cyclotetrasulfido complex [((IrCp)(2)(mu-CH(2))(2))(2)(mu-S(4)-S:S':S":S"')]Cl(2). The oxygenated complexes [(RhCp)(2)(mu-CH(2))(2)(mu-SSO(2)-S:S')] reacted with hydrocarbyl halides to afford bridging hydrocarbyl thiolato complexes accompanied by the generation of SO(2) gas. These complexes have been characterized by NMR spectroscopy, ESI-MS, and X-ray diffraction.     

The first acetimine gold(I) and gold(III) complexes and the first acetonine complexes

Ketimino(phosphino)gold(I) complexes of the type [Au[NR=C(Me)R']L]X (X = ClO4, R = H, L = PPh3, R'=Me (la), Et (2a); L=PAr3 (Ar=C6H4OMe-4), R'=Me (1b), Et (2b); L=PPh3, R=R'=Me (3); X= CF3SO3 (OTf), L=PPh3, R=R'=Me (3'); R=Ar, R'=Me (4)) have been prepared from [Au(acac)L] (acac = acetyl acetonate) and ammonium salts [RNH3]X dissolved in the appropriate ketone MeC(O)R'. Complexes [Au(NH=CMe2)2]X (X = C1O4 (6), OTf (6')) were obtained from solutions of [Au(NH3)2]X in acetone. The reaction of 6 with PPN[AuCl2] or with PhICl2 gave [AuCl(NH=CMe2)] (7) or [AuCI2(NH=CMe2)2]ClO4 (8), respectively. Complex 7 was oxidized with PhICl2 to give [AuCl3(NH=CMe2)] (9). The reaction of [AuCl(tht)] (tht = tetrahydrothiophene), NaClO4, and ammonia in acetone gave [Au(acetonine)2]ClO4 (10) (acetonine = 2,2,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine) which reacted with PPh3 or with PPN[AuCl2] to give [Au(PPh3)(acetonine)]ClO4 (11) or [AuCl(acetonine)] (12), respectively. Complex 11 reacts with [Au(PPh3)(Me2CO)]ClO4 to give [(AuPPh3)2(mu-acetonine)](ClO4)2 (13). The reaction of AgClO4 with acetonine gave [Ag(acetonine)(OClO3)] (14). The crystal structures of [Au(NH2Ar)(PPh3)]OTf (5), 6' and 10 have been determined.     

Electropolymerization of Pd(II) complexes containing phosphinoterthiophene ligands

A series of Pd complexes of 3'-diphenylphosphino-2,2':5'2' '-terthiophene (1a, dppterth) in which the metal is coordinated in three different modes have been prepared and electropolymerized, resulting in the formation of conductive thin films. In [Pd2(mu-Cl2)(dppterth-P,C3)2] (3a) the metal is P,C-coordinated, in [PdCl2(dppterth-P)2] (4a) the coordination is monodentate via the phosphine, and in [Pd(dppterth-P,C3)(dppterth-P,S1)][PF6] (5a) both P,C- and P,S-coordination modes are found. In 5a, the coordinated thiophene is hemilabile and may be displaced by reaction with more strongly coordinating ligands such as isocyanides. To probe the effect of blocking the alpha-position of the terthienyl moiety with methyl groups, 3'-diphenylphosphino-5-methyl-2,2':5'2' '-terthiophene (1b, Me-dppterth) and 3'-diphenylphosphino-5,5' '-dimethyl-2,2':5'2' '-terthiophene (1c, Me2-dppterth) were prepared, and the corresponding series of Pd complexes was synthesized. One of these complexes, [Pd(Me2-dppterth-P,C3)(Me2-dppterth-P,S1)][PF6] (5c), has been crystallographically characterized. The electropolymerized films prepared from 5a react with isonitriles, and shifts in the absorption spectra of the electropolymerized materials are observed upon reaction. A Pd complex has also been prepared from 5-diphenylphosphino-2,2':5'2' '-terthiophene (2, 5dppterth), and this complex has been electropolymerized. All the electropolymerized thin films have been characterized using EDX analysis, which demonstrates good correspondence with the elemental analysis of the respective monomers, and the maximum conductivities of the films are near 10(-4) S x cm(-1). Comparing the electropolymerization behavior of the complexes, along with their electrochemical and spectroscopic data, allows conclusions to be drawn regarding the involvement of pi-delocalization and the metal group in the conductivity of the materials.     

Synthesis and molecular structure of the dihydrobis(thioxotriazolinyl)borato complexes of zinc(II), bismuth(III), and nickel(II). M...H-B interaction studied by Ab initio calculations

Reacting the heterocycle 5-thioxo-1,4-dihydro-4-ethyl-3-methyl-1,2,4-triazole (thioxotriazoline) with sodium tetrahydroborate in the molar ratio of approximately 2:1 at 130 degrees C provides the new ligand dihydrobis(thioxotriazolinyl)borato, [Bt(Et,Me)](-), as its sodium salt. The neutral complexes of this anionic ligand with zinc(II), bismuth(III), and nickel(II) have been synthesized and characterized by X-ray crystallography. In every complex, the ligand is coordinated to the metal in the S(2) mode, generating eight-membered chelate rings. The bismuth and nickel complexes exhibit two M.H-B interactions responsible for the dodecahedral and octahedral geometries, respectively. For the zinc complex, the trigonal-bipyramidal coordination is achieved with an apical Zn.H-B interaction. The crystal structures for the three complexes are described, and ab initio calculations on Bi(III), Ni(II), and Zn(II) compounds have been performed in order to assess the nature of the M.H-B interaction and its role for the definition of the molecular geometries.     

Structural and electronic differences of copper(I) complexes with tris(pyrazolyl)methane and hydrotris(pyrazolyl)borate ligands

Copper(I) complexes with tripodal nitrogen-containing neutral ligands such as tris(3,5-diisopropyl-1-pyrazolyl)methane (L1') and tris(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)methane (L3'), and with corresponding anionic ligands such as hydrotris(3,5-diisopropyl-1-pyrazolyl)borate (L1-) and hydrotris(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)borate (L3-) were synthesized and structurally characterized. Copper(I) complexes [Cu(L1')Cl] (1), [Cu(L1')(OClO3)] (2), [Cu(L1')(NCMe)](PF6) (3a), [Cu(L1')(NCMe)](ClO4) (3b), [Cu(L1')(CO)](PF6) (4a), and [Cu(L1')(CO)](ClO4) (4b) were prepared using the ligand L1'. Copper(I) complexes [Cu(L3')Cl] (5) and [Cu(L3')(NCMe)](PF6) (6) with the ligand L3' were also synthesized. Copper(I) complexes [Cu(L1)(NCMe)] (7) and [Cu(L1)(CO)] (8) were prepared using the anionic ligand L1-. Finally, copper(I) complexes with anionic ligand L3- and acetonitrile (9) and carbon monoxide (10) were synthesized. The complexes obtained were fully characterized by IR, far-IR, 1H NMR, and 13C NMR spectroscopy. The structures of both ligands, L1' and L3', and of complexes 1, 2, 3a, 3b, 4a, 4b, 5, 6, 7, and 10 were determined by X-ray crystallography. The effects of the differences in (a) the fourth ligand and the counteranion, (b) the steric hindrance at the third position of the pyrazolyl rings, and most importantly, (c) the charge of the N3 type ligands, on the structures, spectroscopic properties, and reactivities of the copper(I) complexes are discussed. The observed differences in the reactivities toward O2 of the copper(I) acetonitrile complexes are traced back to differences in the oxidation potentials determined by cyclic voltammetry. A special focus is set on the carbonyl complexes, where the 13C NMR and vibrational data are presented. Density functional theory (DFT) calculations are used to shed light on the differences in CO bonding in the compounds with neutral and anionic N3 ligands. In correlation with the vibrational and electrochemical data of these complexes, it is demonstrated that the C-O stretching vibration is a sensitive probe for the "electron richness" of copper(I) in these compounds.     

Polynuclear and mixed-ligand mononuclear Cu(I) complexes with N-thiophosphorylated thioureas and 1,10-phenanthroline or PPh3

Deprotonation of the N-thiophosphorylated thioureas RC(S)NHP(S)(OiPr)(2) (R = Me(2)N, HL(I); iPrNH, HL(II); 2,6-Me(2)C(6)H(3)NH, HL(III), 2,4,6-Me(3)C(6)H(2)NH, HL(IV), aza-15-crown-5, HL(V)) and reaction with CuI or Cu(NO(3))(2) in aqueous EtOH leads to the polynuclear complexes [Cu(4)(L(I)-S,S')(4)], [Cu(8)(L(II)-S,S')(8)], and [Cu(3)(L(III-V)-S,S')(3)]. The structures of these compounds were investigated by IR, (1)H, (31)P{(1)H} NMR, UV-vis spectroscopy and elemental analyses. The crystal structures of [Cu(4)L(I)(4)], [Cu(8)L(II)(8)], [Cu(3)L(III,IV)(3)] were determined by single-crystal X-ray diffraction. Reaction of the deprotonated ligands (L(I-V))(-) with a mixture of CuI and 1,10-phenanthroline (phen) or PPh(3) leads to the mixed-ligand mononuclear complexes [Cu(phen)L(I-V)], [Cu(PPh(3))L(I-V)] or [Cu(PPh(3))(2)L(I-V)]. The same mixed-ligand complexes were obtained from the reaction of [Cu(4)L(I)(4)], [Cu(8)L(II)(8)], [Cu(3)L(III-V)(3)] with phen or PPh(3).     

Copper(II/I) Complexes of a Hexakis(bipyridyl)cyclotriveratrylene Ligand: A Redox-Induced Conformational Switch

A series of copper(II) and copper(I) complexes have been synthesized with ligands combining 6-methyl-2,2'-bipyridines with cyclotriveratrylene (CTV) (1) and with catechol (2). The electrochemical, (1)H NMR, and mass spectrometry characterizations of these complexes are described and discussed. The six pendant bipyridines of ligand 1 allow for the formation of two trinuclear copper(I) complexes [(1)Cu(3)](BF(4))(3) differing only in the conformation "vic" or "int" adopted by the ligand to fit the tetrahedral cuprous ions. Similarly, 1 generates two trinuclear copper(II) complexes in which the conformation of the ligand fits the square planar geometry of cupric ions. In both the cuprous and cupric complexes, a conformational equilibrium exists. Ligand 2 bearing two methylbipyridines has proven to be a useful model of the coordinating sites of ligand 1. In this case, two homologous copper(I) complexes are obtained, [(2)Cu]BF(4) and [(2)(2)Cu(2)](BF(4))(2), modeling respectively two possible coordination conformations of ligand 1. With copper(II), ligand 2 yields only one complex [(2)Cu](CF(3)SO(3))(2), which allows for the unambiguous identification of the conformations observed for ligand 1 complexes. The different coordinating modes of ligand 1 in the complexes mentioned are in exchange but exhibit different physical properties, thus representing a new bistable system based on conformational isomerism which exhibits an electrochemical potential hysteresis. An equilibrium constant and thermodynamic data were obtained for this system by variable-temperature cyclic voltammetry. The influence of coordinating vs noncoordinating solvents was also studied.     

Hydridotris(thioxotriazolyl)borate (Tt), an ambidentate (N(3)/S(3)) tripodal ligand. X-ray crystal structures of sodium, bismuth(III), tin(IV), and manganese(I) complexes

Treatment of the heterocycle 5-thioxo-4,5-dihydro-3,4-dimethyl-1,2,4-triazole (thioxotriazole) with sodium tetrahydroborate at 210 degrees C provides the new [N(3)/S(3)] ambidentate tripod ligand hydridotris(thioxotriazolyl)borate (Tt) as its sodium complex salt. Complexes of this ligand with sodium, bismuth(III), tin(IV), and manganese(I) have been synthesized and characterized by X-ray crystallography. The structures of these complexes illustrate the ambidentate character of the ligand with the softer metals bismuth and tin exhibiting sulfur coordination, while sodium and manganese(I) bond via the ligand nitrogen donors. In the [S(3)] coordination mode the ligand creates eight-membered chelate rings with the metal with the consequence that the metal ligand unit adopts a propeller-type conformation with C(3)-symmetry. However, in the [N(3)] mode six-membered chelate rings are formed analogous to the familiar hydrotris(pyrazolyl)borate (Tp) ligand.