Mechanism of protonation of [Pt(3)(mu-PBu(t)(2))3(H)(CO)2], yielding the hydride-bridged [Pt(3)(mu-PBu(t)(2))2(mu-H)(PBu(t)(2)H)(CO)2]OTf (Tf=CF(3)SO(2)), and the spectroscopic and theoretical characterization of a kinetic intermediate

The reaction of the Pt(I)Pt(I)Pt(II) triangulo cluster Pt(3)(micro-PBu(t)()(2))(3)(H)(CO)(2) (1) with TfOH (Tf = CF(3)SO(2)) affords the hydride-bridged cationic derivative [Pt(3)(mu-PBu(t)()(2))(2)(mu-H)(PBu(t)()(2)H)(CO)(2)]OTf (2). With TfOD the reaction gives selectively [Pt(3)(mu-PBu(t)(2))(2)(mu-D)(PBu(t)(2)H)(CO)(2)]OTf (2-D(1)), implying that the proton is transferred to a metal center while a P-H bond is formed by the reductive coupling of one of the bridging phosphides and the terminal hydride ligand of the reagent. The reaction proceeds through the formation of a thermally unstable kinetic intermediate which was characterized at low temperatures, and was suggested to be the CO-hydrogen-bonded (or protonated) [Pt(3)(mu-PBu(t)(2))(3)(H)(CO)(2)].HOTf (3). An ab initio theoretical study predicts a hydrogen-bonded complex or a proton-transfer tight ion pair as a possible candidate for the structure of the kinetic intermediate.     

Reaction properties of the trans-hyponitrite complex [Ru2(CO)4(mu-H)(mu-PBu(t)2)(mu-Ph2PCH2PPh2)(mu-eta2-ONNO)

The protonation of [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNO)] (1) with HBF(4) occurs at the oxygen of the noncoordinating side of the trans-hyponitrite ligand to give [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOH)][BF(4)] (2) in good yield. The monoprotonated hyponitrite in 2 is deprotonated easily by strong bases to regenerate 1. Furthermore, 1 reacts with the methylating reagent [Me(3)O][BF(4)] to afford [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOMe)][BF(4)] (3). The molecular structures of 2 and 3 have been determined crystallographically, and the structure of 2 is discussed with the results of the DFT/B3LYP calculations on the model complex [Ru(2)(CO)(4)(mu-H)(mu-PH(2))(mu-H(2)PCH(2)PH(2))(mu-eta(2)-ONNOH)](+) (2a). Moreover, the thermolysis of 2 in ethanol affords [Ru(2)(CO)(4)(mu-H)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)][BF(4)] (4) in high yield, and the deprotonation of 4 by DBU in THF yields the novel complex [Ru(2)(CO)(4)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)] (5).     

Synthesis of Polysiloxane-Bound (Ether-phosphine)palladium Complexes. Stoichiometric and Catalytic Reactions in Interphases(1)

The reaction of two equiv of the monomeric ether-phosphine O,P ligand (MeO)(3)Si(CH(2))(3)(Ph)PCH(2)-Do [1a(T(0)()), 1b(T(0)())] {Do = CH(2)OCH(3) [1a(T(0)())], CHCH(2)CH(2)CH(2)O [1b(T(0)())]} with PdCl(2)(COD) yields the monomeric palladium(II) complexes Cl(2)Pd(P approximately O)(2) [2a(T(0)())(2)(), 2b(T(0)())(2)()]. The compounds 2a(T(0)())(2)() and 2b(T(0)())(2)() are sol-gel processed with variable amounts (y) of Si(OEt)(4) (Q(0)()) to give the polysiloxane-bound complexes 2a(T(n)())(2)()(Q(k)())(y)(), 2b(T(n)())(2)()(Q(k)())(y)() (Table 1) {P approximately O = eta(1)-P-coordinated ether-phosphine ligand; for T(n)() and Q(k)(), y = number of condensed T type (three oxygen neighbors), Q type (four oxygen neighbors) silicon atoms; n and k = number of Si-O-Si bonds; n = 0-3; k = 0-4; 2a(T(n)())(2)()(Q(k)())(y)(), 2b(T(n)())(2)()(Q(k)())(y)() = {[M]-SiO(n)()(/2)(OX)(3)(-)(n)()}(2)[SiO(k)()(/2)(OX)(4)(-)(k)()](y)(), [M] = (Cl(2)Pd)(1/2)(Ph)P(CH(2)Do)(CH(2))(3)-, X = H, Me, Et}. The complexes 2b(T(n)())(2)()(Q(k)())(y)() (y = 4, 12, 36) show high activity and selectivity in the hydrogenation of 1-hexyne and tolan. The dicationic complexes [Pd(P&arcraise;O)(2)][SbF(6)](2) [3a(T(0)())(2)(), 3b(T(0)())(2)()] are formed by reacting Cl(2)Pd(P approximately O)(2) with 2 equiv of a silver salt {P&arcraise;O = eta(2)-O&arcraise;P-coordinated ether-phosphine ligand; 3a(T(0)())(2)(), 3b(T(0)())(2)() = [M]-SiOMe(3); [M] = {[Pd(2+)](1/)(2)P(Ph)(CH(2)CH(2)OCH(3))(CH(2))(3)-}{SbF(6)} (a), {[Pd(2+)](1/)(2)P(Ph)(CH(2)CHCH(2)CH(2)CH(2)O)(CH(2))(3)-}{SbF(6)} (b)}. Their polysiloxane-bound congeners 3a(T(n)())(2)(), 3b(T(n)())(2)() {[M]-SiO(n)()(/2)(OX)(3)(-)(n)} are obtained if a volatile, reversible bound ligand like acetonitrile is employed during the sol-gel process. The bis(chelate)palladium(II) complexes 3a(T(n)())(2)(), 3b(T(n)())(2)() are catalytic active in the solvent-free CO-ethene copolymerization, producing polyketones with chain lengths comparable to those obtained with chelating diphosphine ligands. The polysiloxane-bound palladium(0) complexes 5a(T(n)())(2)()(Q(k)())(4)(), 5b(T(n)())(2)()(Q(k)())(4)() {[M]-SiO(n)()(/)(2)(OX)(3)(-)(n)}(2)[SiO(k)()(/2)(OX)(4)(-)(k)](4), [M] = [(dba)Pd](1/)(2)P(Ph)(CH(2)Do)(CH(2))(3)-} undergo an oxidative addition reaction with iodobenzene in an interphase with formation of the complexes PhPd(I)(P approximately O)(2).4SiO(2) [6a(T(n)())(2)()(Q(k)())(4)(), 6b(T(n)())(2)()(Q(k)())(4)()] {[M]-SiO(n)()(/)(2)(OX)(3)(-)(n)](2)[SiO(k)()(/2)(OX)(4)(-)(k)](4), [M] = [PhPd(I)](1/2)P(Ph)(CH(2)Do)(CH(2))(3)-}, which insert carbon monoxide into the palladium-aryl bond even in the solid state.     

Site selectivity in the reactions of the hexanuclear platinum cluster [Pt6(mu-PtBu2)4(CO)6][CF3SO3]2

The previously reported hexanuclear cluster [Pt(6)(mu-PtBu(2))(4)(CO)(6)](2+)[Y](2) (1-Y(2): Y=CF(3)SO(3) (-)) contains a central Pt(4) tetrahedron bridged at each of the opposite edges by another platinum atom; in turn, four phosphido ligands bridge the four Pt-Pt bonds not involved in the tetrahedron, and, finally, one carbonyl ligand is terminally bonded to each metal centre. Interestingly, the two outer carbonyls are more easily substituted or attacked by nucleophiles than the inner four, which are bonded to the tetrahedron vertices. In fact, the reaction of 1-Y(2) with 1 equiv of [nBu(4)N]Cl or with an excess of halide salts gives the monochloride [Pt(6)(mu-PtBu(2))(4)(CO)(5)Cl](+)[Y], 2-Y, or the neutral dihalide derivatives [Pt(6)(mu-PtBu(2))(4)(CO)(4)X(2)] (3: X=Cl; 4: X=Br; 5: X=I). Moreover, the useful unsymmetrically substituted [Pt(6)(mu-PtBu(2))(4)(CO)(4)ICl] (6) was obtained by reacting equimolar amounts of 2 and [nBu(4)N]I, and the dicationic derivatives [Pt(6)(mu-PtBu(2))(4)(CO)(4)L(2)](2+)[Y](2) (7-Y(2): L=(13)CO; 8-Y(2): L=CNtBu; 9-Y(2): L=PMe(3)) were obtained by reaction of an excess of the ligand L with 1-Y(2). Weaker nitrogen ligands were introduced by dissolving the dichloride 3 in acetonitrile or pyridyne in the presence of TlPF(6) to afford [Pt(6)(mu-PtBu(2))(4) (CO)(4)L(2)](2+)[Z](2) (Z=PF(6) (-), 10-Z(2): L=MeCN; 11-Z(2): L=Py). The "apical" carbonyls in 1-Y(2) are also prone to nucleophilic addition (Nu(-): H(-), MeO(-)) affording the acyl derivatives [Pt(6)(mu-PtBu(2))(4)(CO)(4)(CONu)(2)] (12: Nu=H; 13: Nu=OMe). Complex 12 is slowly converted into the dihydride [Pt(6)(mu-PtBu(2))(4)(CO)(4)H(2)] (14), which was more cleanly prepared by reacting 3 with NaBH(4). In a unique case we observed a reaction involving also the inner carbonyls of complex 1, that is, in the reaction with a large excess of the isocyanides R-NC, which form the corresponding persubstituted derivatives [Pt(6)(mu-tPBu(2))(4)(CN-R)(6)](2+)[Y](2), (15-Y(2): R=tBu; 16-Y(2) (2-): R=-C(6)H(4)-4-C triple bond CH). All complexes were characterized by microanalysis, IR and multinuclear NMR spectroscopy. The crystal and molecular structures of complexes 3, 5, 6 and 9-Y(2) are also reported. From the redox viewpoint, all complexes display two reversible one-electron reduction steps, the location of which depends both upon the electronic effects of the substituents, and the overall charge of the original complex.     

Aggregation of [(tBu3SiS)MX]: structures of {[Br2Fe(mu-SSitBu3)2)FeBr(THF)]Na(THF)4}infinity, cis-[(THF)FeI]2(mu-SSitBu3)2, [(tBu3SiS)Fe]2(mu-SSitBu3)2, and comparative structure and magnetism studies of [(tBu3SiS)MX]n (M = Fe, Co, X = Cl, n = 12; M = Fe, Ni, X = Br, n = 12; M = Fe, X = I, n = 14)

A convenient synthesis of (t)Bu(3)SiSH and (t)Bu(3)SiSNa(THF)(x)() led to the exploration of "(t)Bu(3)SiSMX" aggregation. The dimer, [((t)Bu(3)SiS)Fe](2)(mu-SSi(t)Bu(3))(2) (1(2)), was formed from [{(Me(3)Si)(2)N}Fe](2)(mu-N(SiMe(3))(2))(2) and the thiol, and its dissolution in THF generated ((t)Bu(3)SiS)(2)Fe(THF)(2) (1-(THF)(2)). Metathetical procedures with the thiolate yielded aggregate precursors [X(2)Fe](mu-SSi(t)Bu(3))(2)[FeX(THF)]Na(THF)(4) (3-X, X = Cl, Br) and cis-[(THF)IFe](2)(mu-SSi(t)Bu(3))(2) (4). Thermal desolvations of 3-Cl, 3-Br and 4 afforded molecular wheels [Fe(mu-X)(mu-SSi(t)Bu(3))](12)(C(6)H(6))(n) (5-FeX, X = Cl, Br) and the ellipse [Fe(mu-I)(mu-SSi(t)Bu(3))](14)(C(6)H(6))(n) (6-FeI). Related metathesis and desolvation sequences led to wheels [Co(mu-Cl)(mu-SSi(t)Bu(3))](12)(C(6)H(6))(n) (5-CoCl) and [Ni(mu-Br)(mu-SSi(t)Bu(3))](12)(C(6)H(6))(n) (5-NiBr). The nickel wheel disproportionated to give, in part, [((t)Bu(3)SiS)Ni](2)(mu-SSi(t)Bu(3))(2) (7), which was also synthesized via salt metathesis. X-ray structural studies of 1(2) revealed a roughly planar Fe(2)S(4) core, while 1-(THF)(2), 3-Br, and 4 possessed simple distorted tetrahedral and edge-shared tetrahedral structures. X-ray structural studies revealed 5-MX (MX = FeCl, FeBr, CoCl, NiBr) to be wheels based on edge-shared tetrahedra, but while the pseudo-D(6)(d) wheels of 5-FeCl, 5-CoCl, and 5-FeBr pack in a body-centered arrangement, those of pseudo-C(6)(v)() 5-NiBr exhibit hexagonal packing and two distinct trans-annular d(Br...Br). Variable-temperature magnetic susceptibility measurements were conducted on 5-FeCl, 5-CoCl, 5-FeBr, and 6-FeI, and the latter three are best construed as weakly antiferromagnetic, while 5-FeCl exhibited modest ferromagnetic coupling. Features suggesting molecular magnetism are most likely affiliated with phase changes at low temperatures.     

Syntheses, luminescence behavior, and assembly reaction of tetraalkynylplatinate(II) complexes: crystal structures of [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3) and [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)

A series of tetraalkynylplatinate(II) complexes, (NBu(4))(2)[Pt(Ctbd1;CR)(4)] (R = C(6)H(4)N-4, C(6)H(4)N-3, and C(6)H(3)N(2)-5), and the diynyl analogues, (NBu(4))(2)[Pt(Ctbd1;CCtbd1;CR)(4)] (R = C(6)H(5) and C(6)H(4)CH(3)-4), have been synthesized. These complexes displayed intense photoluminescence, which was assigned as metal-to-ligand charge transfer (MLCT) transitions. Reaction of (Bu(4)N)(2)[Pt(Ctbd1;CC(5)H(4)N-4)(4)] with 4 equiv of [Pt((t)Bu(3)trpy)(MeCN)](OTf)(2) in methanol did not yield the expected pentanuclear platinum product, [Pt(Ctbd1;CC(5)H(4)N)(4)[Pt((t)Bu(3)trpy)](4)](OTf)(6), but instead afforded a strongly luminescent 4-ethynylpyridine-bridged dinuclear complex, [Pt((t)Bu(3)trpy)(Ctbd1;CC(5)H(4)N)Pt((t)Bu(3)trpy)](PF(6))(3,) which has been structurally characterized. The emission origin is assigned as derived from states of predominantly (3)MLCT [d(pi)(Pt) --> pi((t)Bu(3)trpy)] character, probably mixed with some intraligand (3)IL [pi --> pi(Ctbd1;C)], and ligand-to-ligand charge transfer (3)LLCT [pi(Ctbd1;C) --> pi((t)()Bu(3)trpy)] character. On the other hand, reaction of (Bu(4)N)(2)[Pt(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(4)] with [Ag(MeCN)(4)][BF(4)] gave a mixed-metal aggregate, [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)]. The crystal structure of [Pt(2)Ag(4)(Ctbd1;CCtbd1;CC(6)H(4)CH(3)-4)(8)(THF)(4)] has also been determined. A comparison study of the spectroscopic properties of the hexanuclear platinum-silver complex with its precursor complex has been made and their spectroscopic origins were suggested.     

Platinum(II) hydrazido complexes

Reaction of 1,2-dimethylhydrazine with the platinum hydroxo complex [(dppp)Pt(mu-OH)](2)(BF(4))(2) gives the bridging 1,2-dimethylhydrazido(-2) product [(dppp)(2)Pt(2)(mu-eta(2):eta(2)-MeNNMe)](BF(4))(2) 1. Crystals of 1.CH(2)Cl(2) from CH(2)Cl(2)/Et(2)O are monoclinic (C/2) with a = 19.690(1), b = 18.886(1), c = 17.170 (1) A, and beta = 92.111(1) degrees. Treatment of [(dppp)Pt(mu-OH)](2)(OTf)(2) with 1,1-dimethylhydrazine gives [(dppp)(2)Pt(2)(mu-OH)(mu-NHNMe(2))](OTf)(2) 2. Crystals of 2.CH(2)Cl(2) from CH(2)Cl(2)/Et(2)O are triclinic (P-1) with a = 12.910 (3), b = 13.927(3), c = 17.5872 (3) A, alpha = 87.121(3), beta = 89.997(4), and gamma = 84.728(3) degrees. Reaction of [(dppp)Pt(mu-OH)](2)(OTf)(2) with 1 equiv of phenylhydrazine in CH(2)Cl(2) gives [(dppp)(2)Pt(2)(mu-OH)(mu-NHNHPh)](OTf)(2) 3. Two equivalents of phenylhydrazine with [(dppp)Pt(mu-OH)](2)(X)(2) gives [(dppp)Pt(mu-NHNHPh)](2)(X)(2) 4 (X = BF(4), OTf). Crystals of 3.ClCH(2)CH(2)Cl from ClCH(2)CH(2)Cl/(i)()Pr(2)O are monoclinic (P2(1)/n) with a = 20.990(2), b = 13.098(1), c = 25.773 (2) A, and beta = 112.944(2) degrees. Crystals of 4(X = BF(4)).ClCH(2)CH(2)Cl(.)()2((t)()BuOMe) from ClCH(2)CH(2)Cl/(t)()BuOMe are monoclinic (C2/m) with a = 30.508(1), b = 15.203(1), c = 19.049 (1) A, and beta = 118.505(2) degrees.     

Synthesis and Reactivity of (Pentafluorophenyl)platinate(II) Complexes with Bridging 1,8-Naphthyridine (napy) and X Ligands (X = C(6)F(5), OH, Cl, Br, I, SPh). Crystal Structure of [NBu(4)][Pt(2)(&mgr;-napy)(&mgr;-OH)(C(6)F(5))(4)].CHCl(3)

By reaction of [NBu(4)](2)[Pt(2)(&mgr;-C(6)F(5))(2)(C(6)F(5))(4)] with 1,8-naphthyridine (napy), [NBu(4)][Pt(C(6)F(5))(3)(napy)] (1) is obtained. This compound reacts with cis-[Pt(C(6)F(5))(2)(THF)(2)] to give the dinuclear derivative [NBu(4)][Pt(2)(&mgr;-napy)(&mgr;-C(6)F(5))(C(6)F(5))(4)] (2). The reaction of several HX species with 2 results in the substitution of the bridging C(6)F(5) by other ligands (X) such as OH (3), Cl (4), Br (5), I (6), and SPh (7), maintaining in all cases the naphthyridine bridging ligand. The structure of 3 was determined by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic system, space group P2(1)/n, with a = 12.022(2) ?, b = 16.677(3) ?, c = 27.154(5) ?, beta = 98.58(3) degrees, V = 5383.2(16) ?(3), and Z = 4. The structure was refined to residuals of R = 0.0488 and R(w) = 0.0547. The complex consists of two square-planar platinum(II) fragments sharing a naphthyridine and OH bridging ligands, which are in cis positions. The short Pt-Pt distance [3.008(1) ?] seems to be a consequence of the bridging ligands.     

Syntheses and Structures of the Complexes cis-[M(C(6)F(5))(2)(N&arcraise;X)] (M = Pd, Pt; N&arcraise;X = 2-Iodoaniline, 2-Benzoylpyridine) Containing N&arcraise;X Acting as a Didentate Chelating Ligand and Displaying I-->M or O-->M Interactions

Complexes cis-[M(C(6)F(5))(2)(THF)(2)] (M = Pd, Pt) are weak Lewis acids and react with the halocarbon ligand 2-iodoaniline (R-I) yielding the corresponding cis-[M(C(6)F(5))(2)(R-I)] [M = Pd (1), Pt (2)]. In these complexes a (C-)I-M bond is present. The use of other 2-haloanilines (halogen = F, Cl, Br) does not yield the analogous complexes because of the lesser nucleophilic character of the halogen involved. The presence of the (C-)I-Pt bond in 2 has been confirmed by an X-ray structure determination, which also reveals an N-H.M hydrogen bond between two neutral molecules. Complex 2 crystallizes in the space group P&onemacr;: Z = 4; a = 11.797(4) ?; b = 13.735(4) ?; c = 14.107(4) ?; alpha = 97.24(2) degrees; beta = 90.91(2) degrees; gamma = 99.44(2) degrees; V = 2235(2) ?(3). Similarly, complexes cis-[M(C(6)X(5))(2)(THF)(2)] (M = Pd, Pt; X = F, Cl) react with the ligand 2-benzoylpyridine {R-C(O)Ph}, in which the oxygen atom of the ketonic group can behave as a nucleophilic center, yielding the complexes cis-[M(C(6)X(5))(2){R-C(O)Ph}] [M = Pd, X = F (3); M = Pt, X = F (4), Cl (5)]. Complex 3 crystallizes in the space group C2/c: Z = 16; a = 26.284(3) ?; b = 10.623(1) ?; c = 31.423(4) ?; beta = 93.15(1) degrees; V = 8760(2) ?(3). The I-M or O-M bonds in complexes 1-5 are weak and can be easily broken by the addition of neutral (CO, PPh(3), and CH(3)CN) or anionic (Br(-)) ligands.     

Anisotropic Exchange Effects in Temperature and Pressure Dependences of EPR Zero-Field Splitting in [(C(6)H(5))(3)(n-propyl)P](2)Cu(2)Cl(6)

X-band single-crystal and powder EPR data were collected in the temperature range 4.2-300 K and under hydrostatic pressure up to 500 MPa for [(C(6)H(5))(3)(n-propyl)P](2)Cu(2)Cl(6) (C(42)H(44)P(2)Cu(2)Cl(6)). The crystal and molecular structure have been determined from X-ray diffraction. The compound crystallizes in the monoclinic space group P2(1)/n (Z = 2) and have unit cell dimensions of a = 9.556(5) ?, b= 17.113(3) ?, c = 13.523(7) ?, and beta = 96.10(4) degrees. The structure consists of two controsymmetric Cu(2)Cl(6)(2)(-) dimers well separated by complex anions. EPR spectra are typical for the triplet S = 1 state of Cu(2)Cl(6)(2)(-) dimer with parameters g(x)() = 2.114(8), g(y)() = 2.095(8), g(z)() = 2.300(8), and D(x)() = 0.025(1) cm(-)(1), D(y)() = 0.057(1) cm(-)(1), and D(z)() = -0.082(1) cm(-)(1) at room temperature. The D tensor is dominated by a contribution from anisotropic exchange but the dipole-dipole Cu-Cu coupling is not much less. The anisotropic exchange integrals were estimated to be as follows: J(xy,x)()()2(-)(y)()()2(an) = -45 cm(-)(1), J(xy,xy)()(an) = +17 cm(-)(1), J(xy,yz)()(an) = +62 cm(-)(1). The D tensor components are strongly temperature dependent and linearly increase on cooling with an anomalous nonlinear behavior below 100 K. The D values increase linearly with pressure, but the effect is much smaller than the temperature effect. This suggests that the D vs T dependence is dynamical in origin. EPR data, a possible mechanism, and contributions to the observed dependences are discussed and compared to EPR results for similar compounds.     

Synthesis and reactivity of bridging and terminal hydrosulfido palladium and platinum complexes. Crystal structures of [NBu4]2[(Pt(c6F5)2(mu-SH)]2], [Pt(C6F5)2(PPh3)[S(H)AgPPh3]], and [Pt(C6F5)2(PPh3)[S(AuPPh3)2]

The reactions of the hydroxo complexes [M(2)R(4)(mu-OH)(2)](2)(-) (M = Pd, R = C(6)F(5), C(6)Cl(5); M = Pt, R = C(6)F(5)), [[PdR(PPh(3))(mu-OH)](2)] (R = C(6)F(5), C(6)Cl(5)), and [[Pt(C(6)F(5))(2)](2)(mu-OH)(mu-pz)](2-) (pz = pyrazolate) with H(2)S yield the corresponding hydrosulfido complexes [M(2)(C(6)F(5))(4)(mu-SH)(2)](2-), [[PdR(PPh(3))(mu-SH)](2)], and [[Pt(C(6)F(5))(2)](2)(mu-SH)(mu-pz)](2-), respectively. The monomeric hydrosulfido complexes [M(C(6)F(5))(2)(SH)(PPh(3))](-) (M = Pd, Pt) have been prepared by reactions of the corresponding binuclear hydrosulfido complexes [M(2)(C(6)F(5))(4)(mu-SH)(2)](2-) with PPh(3) in the molar ratio 1:2, and they can be used as metalloligands toward Ag(PPh(3))(+) to form the heterodinuclear complex [(C(6)F(5))(2)(PPh(3))[S(H)AgPPh(3)]], and toward Au(PPh(3))(+) yielding the heterotrinuclear complexes [M(C(6)F(5))(2)(PPh(3))[S(AuPPh(3))(2)]]. The crystal structures of [NBu(4)](2)[[Pt(C(6)F(5))(2)(mu-SH)](2)], [Pt(C(6)F(5))(2)(PPh(3))[S(H)AgPPh(3)]], and [Pt(C(6)F(5))(2)(PPh(3))[S(AuPPh(3))(2)]] have been established by X-ray diffraction and show no short metal-metal interactions between the metallic centers.     

Solid state and solution studies of lanthanide(III) complexes of cyclohexanetriols, models of the coordination sites found in sugars

This report covers studies in trivalent lanthanide complexation by two simple cyclohexanetriols that are models of the two coordination sites found in sugars and derivatives. Several complexes of trivalent lanthanide ions with cis,cis-1,3,5-trihydroxycyclohexane (L(1)()) and cis,cis-1,2,3-trihydroxycyclohexane (L(2)()) have been characterized in the solid state, and some of them have been studied in organic solutions. With L(1)(), Ln(L)(2) complexes are obtained when crystallization is performed from acetonitrile solutions whatever the nature of the salt (nitrate or triflate) [Ln(L(1)())(2)(NO(3))(2)](NO(3)) (Ln = Pr, Nd); [Ln(L(1)())(2)(NO(3))H(2)O](NO(3))(2) (Ln = Eu, Ho, Yb); [Ln(L(1)())(2)(OTf)(2)(H(2)O)](OTf) (Ln = Nd, Eu). Lanthanum nitrate itself gives a mixed complex [La(L(1)())(2)(NO(3))(2)][LaL(1)()(NO(3))(4)] from acetonitrile solution while [La(L(1)())(2)(NO(3))(2)](NO(3)) is obtained using dimethoxyethane as reaction solvent and crystallization medium. With L(2)(), Ln(L)(2) complexes have also been crystallized from methanol solution [Ln(L(2)())(2)(NO(3))(2)]NO(3), (Ln = Pr, Nd, Eu). Single-crystal X-ray diffraction analyses are reported for these complexes. Complex formation in solution has been studied for several triflate salts (La, Pr, Nd, Eu, and Yb) with L(1 )()and L(2)(), respectively in acetonitrile and in methanol. In contrast to the solid state, both structures Ln(L) and Ln(L)(2) equilibrate in solution, as was demonstrated by low-temperature (1)H NMR and electrospray ionization mass spectrometry experiments. Competing experiments in complexing abilities of L(1)() and L(2)() with trivalent lanthanide cations have shown that only L(2)() exhibits a small selectivity (Nd > Pr > Yb > La > Eu) in methanol.     

Sulfur-rich zinc chemistry: new tris(thioimidazolyl)hydroborate ligands and their zinc complex chemistry related to the structure and function of alcohol dehydrogenase

The 1-substituted tris(2-thioimidazolyl)hydroborate ligands Tt(R) were prepared as the potassium salts from KBH(4) and the corresponding 1-R-2-thioimidazole for R = t-Bu and C(6)H(4)-p-CH(CH(3))(2) (Cum). Their reactions with zinc salts yielded the tetrahedral complexes Tt(R)Zn-X with X = F, Cl, ONO(2) and (Tt(t)()(-)(Bu))(2)Zn. With zinc perchlorate the labile perchlorate complexes Tt(R)Zn-OClO(3) were obtained. They served as starting materials for the incorporation of substrates which are relevant for the chemistry of horse liver alcohol dehydrogenase: Ethanol led to [Tt(t)()(-Bu)Zn.EtOH] ClO(4).EtOH, p-nitrophenol (NitOH) yielded Tt(Cum)Zn-ONit. Pyridine-2-carbaldehyde and salicylic aldehyde were incorporated as N(pyridine) and O(phenolate) coligands with possible additional O(aldehyde) coordination. Substituted pyridyl methanols (R-PyCH(2)OH) yielded the trinuclear complexes [(Tt(t)()(-Bu))(2)Zn(3)(R-PyCH(2)O)(2)] (ClO(4))(2) with bridging Tt and pyridylmethoxide ligands. Preliminary experiments on the functional modeling of alcohol dehydrogenase have shown that TtZn complexes promote both the dehydrogenation of 2-propanol and the hydrogenation of pentafluorobenzaldehyde.     

Self-Assembly of Ribbons and Frameworks Containing Large Channels Based upon Methylene-Bridged Dithio-, Diseleno-, and Ditelluroethers

Homoleptic copper(I) and silver(I) complexes [M(n)(L-L)(2)(n)()](BF(4))(n)() (M = Cu or Ag; L-L = MeECH(2)EMe; E = S, Se or Te) have been prepared and characterized by analysis, FAB mass spectrometry, and IR and multinuclear NMR spectroscopy ((1)H, (77)Se, (125)Te, (63)Cu and (109)Ag). The single-crystal X-ray structures of [Cu(n)()(MeSeCH(2)SeMe)(2)(n)()](PF(6))(n)() (orthorhombic, P2(1)2(1)2(1), a = 10.879(7) ?, b = 16.073(7) ?, c = 9.19(1) ?, Z = 4) and [Ag(n)()(MeSeCH(2)SeMe)(2)(n)()](BF(4))(n)() (monoclinic, P2(1)/c, a = 14.546(9) ?, b = 14.65(1) ?, c = 30.203(9) ?, Z = 4) reveal extended three-dimensional cationic frameworks in the solid state which contain large cylindrical or rectangular channels accommodating the PF(6)(-) or BF(4)(-) counterions. In contrast, a single-crystal X-ray structure of [Cu(n)()(MeSCH(2)SMe)(2)(n)()](PF(6))(n)().nMeNO(2) (orthorhombic, Pbcn, a = 15.506(3) ?, b = 8.934(2) ?, c = 25.859(3) ?, Z = 8) shows tetrahedral Cu(I) ions coordinated to bridging dithioethers forming an cationic ribbon-like arrangement of 8-membered rings. Adjacent rings are linked by the Cu atoms. Variable temperature NMR studies have been used to probe various exchange processes occurring in solution in these systems.     

New mercury vanadium phosphate hydrate Hg(4)(-)(x)()O(1-)(y)()((VO)(PO(4))(2).H(2)O with unprecedented tetrahedral oxo-cluster [Hg( approximately )(4)O( approximately )(5)

The new mercury vanadium phosphate hydrate Hg(4)(-)(x)()O(1)(-)(y)()(VO)(PO(4))(2).H(2)O has been synthesized under hydrothermal conditions. X-ray investigations led to orthorhombic symmetry, space group P2(1)2(1)2(1) (No. 19), a = 6.3632(2) A, b = 12.4155(5) A, c = 14.2292(6) A, Z = 4. The crystal structure was solved and refined from single-crystal diffractometer data to residuals R[F(2) > 2sigmaF(2)] = 0.039, R(w)(F(2)) = 0.055. The VPO framework consists of infinite one-dimensional [VO(PO(4))(2)]( infinity ) chains with corner-connected VO(6) octahedra and PO(4) tetrahedra. The chains run along the [100] direction and are held together by the unprecedented tetrahedral cationic units [Hg(4)(-)(x)()O(1)(-)(y)()](4+). Presence of Hg-Hg bonding contacts is proved from theoretical calculations.     

Group 5 imido complexes derived from diamido-pyridine ligands

Reaction of the vanadium(V) imide [V(NAr)Cl(3)(THF)] (Ar = 2,6-C(6)H(3)(i)()Pr(2)) with the diamino-pyridine derivative MeC(2-C(5)H(4)N)(CH(2)NHSiMe(2)(t)()Bu)(2) (abbreviated as H(2)N'(2)N(py)) gave modest yields of the vanadium(IV) species [V(NAr)(H(3)N'N' 'N(py))Cl(2)] (1 where H(3)N'N' 'N(py) = MeC(2- C(5)H(4)N)(CH(2)NH(2))(CH(2)NHSiMe(2)(t)()Bu) in which the original H(2)N'(2)N(py) has effectively lost SiMe(2)(t)()Bu (as ClSiMe(2)(t)()Bu) and gained an H atom. Better behaved reactions were found between the heavier Group 5 metal complexes [M(NR)Cl(3)(py)(2)] (M = Nb or Ta, R = (t)()Bu or Ar) and the dilithium salt Li(2)[N(2)N(py)] (where H(2)N(2)N(py) = MeC(2-C(5)H(4)N)(CH(2)NHSiMe(3))(2)), and these yielded the six-coordinate M(V) complexes [M(NR)Cl(N(2)N(py))(py)] (M = Nb, R = (t)()Bu 2; M = Ta, R = (t)()Bu 3 or Ar 4). The compounds 2-4 are fluxional in solution and undergo dynamic exchange processes via the corresponding five-coordinate homologues [M(NR)Cl(N(2)N(py))]. Activation parameters are reported for the complexes 2 and 3. In the case of 2, high vacuum tube sublimation afforded modest quantities of [Nb(N(t)()Bu)Cl(N(2)N(py))] (5). The X-ray crystal structures of the four compounds 1, 2, 3, and 4 are reported.     

Lanthanide-transition-metal carbonyl complexes: new [Co4(CO)11]2- clusters and lanthanide(II) isocarbonyl polymeric arrays

Two types of Ln(II)-Co(4) isocarbonyl polymeric arrays, [(Et(2)O)(3)(-)(x)()(THF)(x)()Ln[Co(4)(CO)(11)]]( infinity ) (1-3; x = 0, 1) and [(THF)(5)Eu[Co(4)(CO)(11)]]( infinity ) (4), were prepared and structurally characterized. Transmetalation involving Ln(0) and Hg[Co(CO)(4)](2) in Et(2)O yields [(Et(2)O)(3)Ln[Co(4)(CO)(11)]]( infinity ) (1, Ln = Yb; 2, Ln = Eu). Dissolution of the solvent-separated ion pairs [Ln(THF)(x)()][Co(CO)(4)](2) (Ln = Yb, x = 6; Ln = Eu) in Et(2)O affords [(Et(2)O)(2)(THF)Yb[Co(4)(CO)(11)]]( infinity ) (3) and [(THF)(5)Eu[Co(4)(CO)(11)]]( infinity ) (4). In these reactions, oxidation and condensation of the [Co(CO)(4)](-) anions result in formation of the new tetrahedral cluster [Co(4)(CO)(11)](2)(-). The two types of Ln(II)-Co(4) compounds contain different isomers of [Co(4)(CO)(11)](2)(-), and, consequently, the structures of the infinite isocarbonyl networks are distinct. The cluster in [(Et(2)O)(3)(-)(x)()(THF)(x)()Ln[Co(4)(CO)(11)]]( infinity ) (1-3) possesses pseudo C(3)(v)() symmetry (an apical Co, three basal Co atoms; one face-bridging, three edge-bridging, seven terminal carbonyls) and connects to Ln(II) centers through eta(2),micro(4)- and eta(2),micro(3)-carbonyls to generate a 2-D puckered sheet. In contrast, [(THF)(5)Eu[Co(4)(CO)(11)]]( infinity ) (4) incorporates a C(2)(v)() symmetric cluster (two unique Co environments; two face-bridging, one edge-bridging, eight terminal carbonyls), and isocarbonyl linkages (eta(2),micro(4)-carbonyls) to Eu(II) atoms create a 1-D zigzag chain. Complexes 1-4 contain the first reported eta(2),micro(4)-CO bridges between a Ln and a transition-metal carbonyl cluster. Infrared spectroscopic studies revealed that the isocarbonyl associations to Ln(II) persist in solution. The solution structure and dynamic behavior of the [Co(4)(CO)(11)](2)(-) cluster in 1 was investigated by variable-temperature (59)Co and (13)C NMR spectroscopies.     

New homoleptic organometallic derivatives of vanadium(III) and vanadium(IV): synthesis, characterization, and study of their electrochemical behaviour

The arylation of [VCl3(thf)3] with LiR(Cl), where R(Cl) is a polychlorinated phenyl group [C6Cl5, 2,4,6-trichlorophenyl(tcp), or 2,6-dichlorophenyl (dcp)] gives four-coordinate, homoleptic organovanadium(III) derivatives with the formula [Li(thf)(4)][V(III)(R(Cl))(4)] (R(Cl) = C(6)Cl(5) (1), tcp (2), dcp (3)). The anion [V(III)(C6Cl5)4]- has an almost tetrahedral geometry, as observed in the solid-state structure of [NBu4][V(C6Cl5)4] (1') (X-ray diffraction). Compounds 1-3 are electrochemically related to the neutral organovanadium(IV) species [V(IV)(R(Cl))4] (R(Cl) = C6Cl5 (4), tcp (5), dcp (6)). The redox potentials of the V(IV)/V(III) semisystems in CH2Cl2 decrease with decreasing chlorination of the phenyl ring (E(1/2) = 0.84 (4/1), 0.42 (5/2), 0.25 V (6/3)). All the [V(IV)(R(Cl))4] derivatives involved in these redox couples could also be prepared and isolated by chemical methods. The arylation of [VCl(3)(thf)(3)] with LiC6F5 also gives a homoleptic organovanadium(III) compound, but with a different stoichiometry: [NBu4]2[V(III)(C6F5)5] (7). In this five-coordinate species, the C6F5 groups define a trigonal bipyramidal environment for the vanadium atom (X-ray diffraction). EPR spectra for the new organovanadium compounds 1-6 are also given and analysed in terms of an elongated tetrahedral structure with C(2v) local symmetry. It is suggested that the R(Cl) groups exert a protective effect towards the vanadium centre.     

Halide and nitrite recognizing hexanuclear metallacycle copper(II) pyrazolates

Halide-centered hexanuclear, anionic copper(II) pyrazolate complexes [trans-Cu(6)((3,5-CF(3))(2)pz)(6)(OH)(6)X](-), X = Cl, Br, I are isolated in a good yield from the redox reaction of the trinuclear copper(I) pyrazolate complex [μ-Cu(3)((3,5-CF(3))(2)pz)(3)] with a halide source such as PPh(3)AuCl or [Bu(4)N]X, X = Cl, Br, or I, in air. X-ray structures of the anion-centered hexanuclear complexes show that the six copper atoms are bridged by bis(3,5-trifluoromethyl)pyrazolate and hydroxyl ligands above and below the six copper atom plane. The anions are located at the center of the cavity and weakly bound to the six copper atoms in a μ(6)-arrangement, Cu-X = ~3.1 ?. A nitrite-centered hexanuclear copper(II) pyrazolate complex [trans-Cu(6)((3,5-CF(3))(2)pz)(6)(OH)(6)(NO(2))](-) was obtained when a solution of [PPN]NO(2) in CH(3)CN was added dropwise to the trinuclear copper(I) pyrazolate complex [μ-Cu(3)((3,5-CF(3))(2)pz)(3)] dissolved in CH(3)CN, in air. Blue crystals are produced by slow evaporation of the acetonitrile solvent. The X-ray structure of [PPN][trans-Cu(6)((3,5-CF(3))(2)pz)(6)(OH)(6)(NO(2))] complex shows the nitrite anion sits in the hexanuclear cavity and is perpendicular to the copper plane with a O-N-O angle of 118.3(7)°. The (19)F and (1)H NMR of the pyrazolate ring atoms are sensitive to the anion present in the ring. Anion exchange of the NO(2)(-) by Cl(-) can be observed easily by (1)H NMR.