Variable-energy photoelectron spectroscopy of substituted rhenium and manganese pentacarbonyls: molecular orbital assignments and the interatomic resonant effect

High-resolution variable-energy photoelectron spectra of M(CO)5X [M = Re, X = Re(CO)5, Cl, Br, and I; and M = Mn, X = Mn(CO)5 and Br] are reported. Tunable synchrotron radiation is used to distinguish the Re 5d and Br 4p orbital based peaks for the controversial Re(CO)5Br. Our results provide firm molecular orbital assignments for all of these molecules. The valence orbital in the ordering of ionization energies for M(CO)5Cl (M = Mn and Re) and Mn(CO)5Br is a 1(M-X) > e(X) > b2(M) > e(M); but for M(CO)5I (M = Mn and Re) and Re(CO)5Br the ordering is a1(M-X) > e(M) > b2(M) > e(X). The crossover of the HOMO in the Re molecules due to the change in the halogen electronegativities occurs at Re(CO)5Br. The metal np-->nd resonance is observed for all of these molecules. For molecules like M2(CO)10 (M = Re and Mn) and Mn(CO)5Br, the observation of this np-->nd resonance is useful in assigning the metal nd based orbitals in their valence level spectra. However, for molecules like Re(CO)5X (X = Br and Cl), a np-->nd type resonance is observed on bands arising from both Re 5d and halogen mp based orbitals. This new resonant effect on the ligand-based orbitals is shown to be mainly due to the interatomic resonant effect. The core and valence level chemical shifts of these compounds are treated using Jolly's approach to confirm the assignments for the valence level spectra of some of these molecules. The high-resolution inner valence and core level spectra of these compounds are reported. Broadening of Re 4f, Br 3d, and I 4d core level spectra is discussed. The Auger peaks are observed in the high-resolution, high-intensity Br 3d of Re(CO)5Br and I 4d of Re(CO)5I spectra.     

Reactions of the Dirhenium(II) Complexes Re(2)X(4)(dppm)(2) (X = Cl, Br; dppm = Ph(2)PCH(2)PPh(2)) with Isocyanides. 10.(1) Synthesis and Characterization of the Complex [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3) and Several Isomeric Forms of [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)]Y (Y = PF(6), O(3)SCF(3))

The reactions of the unsymmetrical, coordinatively unsaturated dirhenium(II) complexes [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)]Y (XylNC = 2,6-dimethylphenyl isocyanide; Y = O(3)SCF(3) (3a), PF(6) (3b)) with XylNC afford at least three isomeric forms of the complex cation [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](+). Two forms have very similar bis(&mgr;-halo)-bridged edge-sharing bioctahedral structures of the type [(CO)BrRe(&mgr;-Br)(2)(&mgr;-dppm)(2)Re(CNXyl)(2)]Y (Y = O(3)SCF(3) (4a/4a'), PF(6) (4b/4b')), while the third is an open bioctahedron [(XylNC)(2)BrRe(&mgr;-dppm)(2)ReBr(2)(CO)]Y (Y = O(3)SCF(3) (5a), PF(6) (5b)). While the analogous chloro complex cation [Re(2)Cl(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](+) was previously shown to exist in three isomeric forms, only one of these has been found to be structurally similar to the bromo complexes (i.e. the isomer analogous to 5a and 5b). The reaction of 3a with CO gives the salt [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3) (7), in which the edge-sharing bioctahedral cation [(XylNC)BrRe(&mgr;-Br)(&mgr;-CO)(&mgr;-dppm)(2)ReBr(CO)](+) has an all-cis arrangement of pi-acceptor ligands. The Re-Re distances in the structures of 4b', 5a, and 7 are 3.0456(8), 2.3792(7), and 2.5853(13) ?, respectively, and accord with formal Re-Re bond orders of 1, 3, and 2, respectively. Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](PF(6))(0.78)(ReO(4))(0.22).CH(2)Cl(2) (4b') at 295 K: monoclinic space group P2(1)/n (No. 14) with a = 19.845(4) ?, b = 16.945(5) ?, c = 21.759(3) ?, beta = 105.856(13) degrees, V = 7038(5) ?(3), and Z = 4. The structure was refined to R = 0.060 (R(w) = 0.145) for 14 245 data (F(o)(2) > 2sigma(F(o)(2))). Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)]O(3)SCF(3).C(6)H(6) (5a) at 173 K: monoclinic space group P2(1)/n (No. 14) with a = 14.785(3) ?, b = 15.289(4) ?, c = 32.067(5) ?, beta = 100.87(2) degrees, V=7118(5) ?(3), and Z = 4. The structure was refined to R = 0.046 (R(w) = 0.055) for 6962 data (I > 3.0sigma(I)). Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3).Me(2)CHC(O)Me (7) at 295 K: monoclinic space group P2(1)/n (No. 14) with a = 14.951(2) ?, b = 12.4180(19) ?, c = 40.600(5) ?, beta = 89.993(11) degrees, V = 7537(3) ?(3), and Z = 4. The structure was refined to R = 0.074 (R(w) = 0.088) for 6595 data (I > 3.0sigma(I)).     

PX4+, P2X5+, and P5X2+ (X=Br,I) salts of the superweak Al(OR)4- anion [R=C(CF3)3

PX(4) (+)[Al(OR)(4)](-) (X=I: 1 a, X=Br: 1 b) was prepared from X(2), PX(3), and Ag[Al(OR)(4)] [R=C(CF(3))(3)] in CH(2)Cl(2) at -30 degrees C in 69-86 % yield. P(2)X(5) (+) salts were prepared from 2 PX(3) and Ag[Al(OR)(4)] in CH(2)Cl(2) at -30 degrees C yielding almost quantitatively P(2)X(5) (+)[Al(OR)(4)](-) (X=I: 3 a, X=Br: 3 b). The phosphorus-rich P(5)X(2) (+) salts arose from the reaction of cold (-78 degrees C) mixtures of PX(3), P(4), and Ag[Al(OR)(4)] giving P(5)X(2) (+)[Al(OR)(4)](-) (X=I: 4 a, X=Br: 4 b) with a C(2v)-symmetric P(5) cage. Silver salt metathesis presumably generated unstable PX(2) (+) cations from PX(3) and Ag[Al(OR)(4)] (X=Br, I) that acted as electrophilic carbene analogues and inserted into the Xbond;X (Pbond;X/Pbond;P) bond of X(2) (PX(3)/P(4)) leading to the highly electrophilic and CH(2)Cl(2)-soluble PX(4) (+) (P(2)X(5) (+)/P(5)X(2) (+)) salts. Reactions that aimed to synthesize P(2)I(3) (+) from P(2)I(4) and Ag[Al(OR)(4)] instead led to anion decomposition and the formation of P(2)I(5)(CS(2))(+)[(RO)(3)Al-F-Al(OR)(3)](-) (5). All salts were characterized by variable-temperature solution NMR studies (3 b also by (31)P MAS NMR), Raman and/or IR spectroscopy as well as X-ray crystallography (with the exception of 4 a). The thermochemical volumes of the Pbond;X cations are 121 (PBr(4) (+)), 161 (PI(4) (+)), 194 (P(2)Br(5) (+)), 271 (P(2)I(5) (+)), and 180 A(3) (P(5)Br(2) (+)). The observed reactions were fully accounted for by thermochemical calculations based on (RI-)MP2/TZVPP ab initio results and COSMO solvation enthalpy calculations (CH(2)Cl(2) solution). The enthalpies of formation of the gaseous Pbond;X cations were derived as +764 (PI(4) (+)), +617 (PBr(4) (+)), +749 (P(2)I(5) (+)), +579 (P(2)Br(5) (+)), +762 (P(5)I(2) (+)), and +705 kJ mol(-1) (P(5)Br(2) (+)). The insertion of the intermediately prepared carbene analogue PX(2) (+) cations into the respective bonds were calculated, at the (RI-)MP2/TZVPP level, to be exergonic at 298 K in CH(2)Cl(2) by Delta(r)G(CH(2)Cl(2))=-133.5 (PI(4) (+)), -183.9 (PBr(4) (+)), -106.5 (P(2)I(5) (+)), -81.5 (P(2)Br(5) (+)), -113.2 (P(5)I(2) (+)), and -114.5 kJ mol(-1) (P(5)Br(2) (+)).     

Anionic Halomolybdate(III) Chemistry. Tetrahydrofuran Loss from [MoX(3)Y(THF)(2)](-) (X, Y = Cl, Br, I), Preparation and Properties of [Mo(3)X(12)](3)(-) (X = Br, I), and Crystal Structure of the Edge-Sharing Trioctahedral [PPh(4)](3)[Mo(3)I(12)

By interaction of MoX(3)(THF)(3) with [Cat]X in THF, the salts [Cat][MoX(4)(THF)(2)] have been synthesized [X = I, Cat = PPh(4), NBu(4), NPr(4), (Ph(3)P)(2)N; X = Br, Cat = NBu(4), PPh(4) (Ph(3)P)(2)N]. Mixed-halide species [MoX(3)Y(THF)(2)](-) (X, Y = Cl, Br, I) have also been generated in solution and investigated by (1)H-NMR. When the tetraiodo, tetrabromo, and mixed bromoiodo salts are dissolved in CH(2)Cl(2), clean loss of all coordinated THF is observed by (1)H-NMR. On the other hand, [MoCl(4)(THF)(2)](-) loses only 1.5 THF/Mo. The salts [Cat](3)[Mo(3)X(12)] (X = Br, I) have been isolated from [Cat][MoX(4)(THF)(2)] or by running the reaction between MoX(3)(THF)(3) and [Cat]X directly in CH(2)Cl(2). The crystal structure of [PPh(4)](3)[Mo(3)I(12)] exhibits a linear face-sharing trioctahedron for the trianion: triclinic, space group P&onemacr;; a = 11.385(2), b = 12.697(3), c = 16.849(2) ?; alpha = 76.65(2), beta = 71.967(12), gamma = 84.56(2) degrees; Z = 1; 431 parameters and 3957 data with I > 2sigma(I). The metal-metal distance is 3.258(2) ?. Structural and magnetic data are consistent with the presence of a metal-metal sigma bond order of (1)/(2) and with the remaining 7 electrons being located in 7 substantially nonbonding orbitals. The ground state of the molecule is predicted to be subject to a Jahn-Teller distortion, which is experimentally apparent from the nature of the thermal ellipsoid of the central Mo atom. The [Mo(3)X(12)](3)(-) ions reacts with phosphines (PMe(3), dppe) to form products of lower nuclearity by rupture of the bridging Mo-X bonds.     

Einkristall-RöntgenStrukturanalysen von Verbindungen mit einer kovalenten Metall-Metall-Bindung. VII. Die Kristall- und Molekülstruktur von dimeren Halogenobis- (pentacarbonylrhenium)indium(III), [(Re(CO)5)2In(μ-X)]2 (X = Cl,Br, I)

Single-Crystal X-Ray Analysis of Compounds with a Covalent Metal-Metal Bond. VII. Crystal and Molecular Structure of the Halogeno-Bridged Dimers of Halogenobis(pentacarbonylrhenium)indium(III), [(Re(CO)₅)₂In(μ-X)]₂ (X = Cl, Br, I) [(Re(CO)₅)₂In(μ-X)]₂ crystallizes if X = Cl and X = Br in the monoclinic system, space group P2₁/c (No. 14), with the lattice constants X = Cl: a = 10.540(6), b = 12.961(7), c = 26.071(12) Å, β = 106.3(1) Å, Z = 4, X = Br: a = 10.548(9), b = 13.108(7), c = 26.192(15) Å, β = 106.0(2)°, Z = 4 and if X = I in the triclinic system, space group P1 (No. 2), with the lattice constants a = 10.739(2), b = 7.160(1), c = 13.647(1) Å, α = 68.65(9), β = 71.89(9), γ = 65.52(9)°, Z = 1. The central molecular fragment consists of a plane In₂X₂ ring with the mean In—X distances: X = Cl: 2.624(6) Å, X = Br: 2.764(3) Å and X = I: 2.986(2) Å and the angles In—X—In/X—In—X, X = Cl: 97.2(2)°/ 82.8(2)°, X = Br: 94.8(1)°/85.2(1)° and X = I: 96.47(5)°/83.53(5)°. Two Re(CO)₅ groups are bonded to each of these In atoms to form a distorted tetrahedral coordination. The mean In—Re bond-distances are: X = Cl: 2.797(2), X = Br: 2.796(2) and X = I:2.811 (2) Å. There is a octahedral coordination around the Re atoms.     

Ring-opening reactions induced by gold(I) of five- and four-coordinate palladium(II) and platinum(II) complexes containing tripodal or linear polyphosphines

The tripodal ligands NP(3)(tris[2-(diphenylphosphino)ethyl]amine) and PP(3)(tris[2-(diphenylphosphino)ethyl]phosphine), form five-coordinate [Pd(NP(3))X]X [X = Cl (1), Br (2)], [M(PP(3))X]X [M = Pd: X = Cl (4), Br (5), I (6); M = Pt, X = Cl (7), Br (8), I (9)] and four-coordinate[Pd(NP(3))I]I (3) complexes containing three fused rings around the metal. The interaction between Au(tdg)X (tdg = thiodiglycol; X = Cl, Br) or AuI and the respective ionic halo complexes 1-9 in a 1:1 stoichiometric ratio occurs via a ring-opening reaction with formation of the heterobimetallic systems PdAu(NP(3))X(3)[X = Cl (11), Br (12), I (13)], [MAu(PP(3))X(2)]X [M = Pd: X = Cl (14), Br (15), I (16); M = Pt: X = Cl (17), Br (18), I (19)]. The cations of complexes 17 and 18 were shown, by X-ray diffraction, to contain a distorted square-planar Pt(II) arrangement (Pt(P(2)P)X) where PP(3) is acting as tridentate chelating ligand and an almost linear PAuX moiety bearing the dangling phosphorus formed in the ring-opening process. PPh(3) coordinates to Au(I) and not to M(II) when added in excess to 14 and 17. Complexes 14-17 and [Pt(P(4))](BPh(4))(2) (10) (P4=linear tetraphosphine) also react with A(I), via chelate ring-openings to give MAu(2)(PP(3))X(4) [M = Pd: X = Cl (20), Br (21), I (22); M = Pt: X = Cl (23)] and [Pt(2)Au(2)(mu-Cl)(2)(mu-P(4))(2)](BPh(4))(4) (24), respectively.     

Electron-Transfer Reactions of Re(CO)(5): Atom-Transfer-Concerted Mechanism vs Bimetallic Intermediate Formation

Flash photochemically generated Re(CO)(5) reacts with halide complexes, Cu(Me(4)[14]-1,3,8,10-tetraeneN(4))X(+), Cu(Me(2)pyo[14]trieneN(4))X(+), and Ni(Me(2)pyo[14]trieneN(4))X(+) (X = Cl, Br, I) and ion pairs, [Co(bipy)(3)(3+), X(-)]. The rate constants for the electron transfers have values, k approximately 10(9) M(-1) s(-1), close to expectations for processes with diffusion-controlled rates. Reaction intermediates, probably bimetallic species, were detected in electron-transfer reactions of Re(CO)(5) with Cu(Me(6)[14]dieneN(4))X(+), (X = Cl, Br, I). In the absence of the halides X(-), the electron-transfer reactions between Re(CO)(5) and these complexes are slow, k < 10(6) M(-1) s(-1). The results are discussed in terms of inner-sphere pathways, namely an atom-transfer-concerted mechanism. The mediation of bimetallic intermediates in the electron transfer is also considered.     

Synthesis and Liquid-Crystalline Properties of Diazabutadiene Complexes of Rhenium(I)

New N,N '-bis(4-((4-alkoxybenzoyl)oxy)phenyl)-1,4-diaza-1,3-butadiene (L) ligands, obtained by condensation of 4-((alkoxybenzoyl)oxy)anilines and glyoxal, were complexed to different [ReX(CO)(3)] fragments to give the complexes [ReX(L)(CO)(3)] (X = Cl, Br, I) and [Re(CF(3)SO(3))(L)(CO)(3)].THF. The chloro and bromo complexes were obtained by direct reaction of the ligands with [ReX(CO)(5)] (X = Cl, Br), while the iodo and triflato derivatives were obtained via metathesis of the chloro or bromo precursors with potassium iodide or silver triflate respectively. The liquid-crystalline behavior of the ligands and the related rhenium complexes has been studied by means of optical microscopy, differential scanning calorimetry, and small angle X-ray diffraction. Nematic and smectic C phases were observed when the coordinated counteranions were Cl, Br, and I, respectively; the triflato derivatives were not mesomorphic.     

Rhenium(I) carbonyl complexes of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPT). Rhenium(I)-promoted methoxylation of the triazine ring carbon atom in dinuclear rhenium complexes

2,4,6-Tris(2-pyridyl)-1,3,5-triazine (TPT) bridged dinuclear rhenium(I) tricarbonyl halide complexes with the composition (mu-TPT)[ReX(CO)(3)](2) (3, X = Cl; 4, X = Br) can be made either by one-pot reaction of TPT with 2 equiv of [ReX(CO)(5)] (X = Cl and Br) in chloroform or by reacting mononuclear [ReX(CO)(3)(TPT)] (2) (1, X = Cl; 2, X = Br) with an excess amount of [ReX(CO)(5)]. Crystal data are as follows. 1: monoclinic, P2(1)/c, a = 11.751(1) A, b = 11.376(1) A, c = 15.562(2) A, beta = 103.584(2) degrees, V = 2022.0(4) A(3), Z = 4. 2: monoclinic, P2(1)/c, a = 11.896(1) A, b = 11.396(1) A, c = 15.655(1) A, beta = 104.474(2) degrees, V = 2054.9(3) A(3), Z = 4. 3: triclinic, P1, a = 11.541(2) A, b = 12.119(2) A, c = 13.199(2) A, alpha = 80.377(2) degrees, beta = 76.204(3) degrees, gamma = 66.826(2) degrees, V = 1642.5(4) A(3), Z = 2. Crystals of 4 crystallized from acetone: triclinic, P1, a = 11.586(5) A, b = 12.144(5) A, c = 13.364(6) A, alpha = 80.599(7) degrees, beta = 76.271(8) degrees, gamma = 67.158(8) degrees, V = 1678.0(12) A(3), Z = 2. Crystals of 4' are obtained from CH(2)Cl(2)-pentane solution: monoclinic, C2/c, a = 17.555(4) A, b = 15.277(3) A, c = 13.093(3) A, beta = 111.179(3) degrees, V = 3274.0(12) A(3), Z = 4. By contrast, similar reactions in the presence of methanol yielded complexes with the composition [mu-C(3)N(3)(OMe)(py)(2)(pyH)][ReX(CO)(3)](2) (5, X = Cl; 6, X = Br). Crystal data for 5: monoclinic, C2/c, a = 26.952(2) A, b = 16.602(1) A, c = 14.641(1) A, beta = 116.147(1) degrees, V = 5880.5(8) A(3), Z = 8. 6: monoclinic, C2/c, a = 27.513(3) A, b = 16.740(2) A, c = 14.837(2) A, beta = 116.925(2) degrees, V = 6092.8(10) A(3), Z = 8. An unusual metal-induced methoxylation at the carbon atom of the triazine ring of the bridging TPT ligand was observed. The nucleophilic attack of MeO(-) on C(3) results in a tetrahedral geometry around the carbon atom. Concomitantly, the uncoordinated pyridyl ring is protonated and rotated into a perpendicular orientation relative to the central C(3)N(3) ring. Reaction of TPT with [NEt(4)](2)[ReBr(3)(CO)(3)] in benzene-methanol resulted in an unexpected dinuclear complex 7, with formulation [mu-C(3)N(3)(OMe)(py)(3)][Re(CO)(3)][ReBr(CO)(3)]. The methoxylated TPT ligand functions simultaneously as a tridentate and bidentate ligand with two fac-Re(CO)(3)(+) cores. Crystal data for 7: monoclinic, P2(1)/n, a = 12.114(1) A, b = 14.878(1) A, c = 15.807(1) A, beta = 104.601(1) degrees, V = 2756.9(3) A(3), Z = 4.     

Highly luminescent complexes [Mo6X8(n-C3F7COO)6]2- (X=Br, I)

New complexes (Bu(4)N)(2)[Mo(6)X(8)(n-C(3)F(7)COO)(6)] (X = Br, I) display extraordinarily bright long-lived red phosphorescence both in solution and solid phases, with the highest emission quantum yields and the longest emission lifetimes among hexanuclear metal cluster complexes of Mo, W and Re, hitherto reported.     

Unprecedented eta(1)-P(basal) coordination of P(4)X(3) molecules (X = S, Se). An experimental and theoretical study of the apical vs basal complexation dichotomy

Reaction of [(triphos)Re(CO)(2)(OTf)] (1) [triphos = MeC(CH(2)PPh(2))(3); OTf = OSO(2)CF(3)] with P(4)S(3) and P(4)Se(3) yields pairs of coordination isomers, namely, [(triphos)Re(CO)(2)[eta(1)-P(apical)-P(4)X(3)]](+) (X = S, 2; Se, 5) and [(triphos)Re(CO)(2)[eta(1)-P(basal)-P(4)X(3)]](+) (X = S, 3; Se, 6). The latter represent the first examples of the eta(1)-P(basal) coordination achieved by the P(4)X(3) molecular cage. Further reaction of 2/3 and 5/6 mixtures with 1 affords the dinuclear species [[(triphos)Re(CO)(2)](2)[mu,eta(1:1)-P(apical,)P(basal)-P(4)X(3)]](2+) (X = S, 4; Se, 7) in which the unprecedented M-eta(1)-P(basal)/eta(1)-P(apical)-M' bridging coordination of the P(4)X(3) molecule is accomplished. A theoretical analysis of the bonding properties of the two coordination isomers is also presented. The directionality of apical vs basal phosphorus lone pairs is also discussed in terms of MO arguments.     

Ultrafast photochemical dissociation of an equatorial CO ligand from trans(X,X)-[Ru(X)2(CO)2(bpy)] (X = Cl, Br, I): a picosecond time-resolved infrared spectroscopic and DFT computational study

Ultrafast photochemistry of the complexes trans(X,X)-[Ru(X)(2)(CO)(2)(bpy)] (X = Cl, Br, I) was studied in order to understand excited-state reactivity of equatorial CO ligands, coordinated trans to the 2,2'-bipyridine ligand (bpy). TD-DFT calculations have identified the lowest electronic transitions and singlet excited states as mixed X -->bpy/Ru --> bpy ligand to ligand/metal to ligand charge transfer (LLCT/MLCT). Picosecond time-resolved IR spectroscopy in the region of nu(CO) vibrations has revealed that, for X = Cl and Br, subpicosecond CO dissociation is accompanied by bending of the X-Ru-X moiety, producing a pentacoordinated intermediate trans(X,X)-[Ru(X)(2)(CO)(bpy)]. Final movement of an axial halide ligand to the vacant equatorial position and solvent (CH(3)CN) coordination follows with a time constant of 13-15 ps, forming the photoproduct cis(X,X)-[Ru(X)(2)(CO)(CH(3)CN)(bpy)]. For X = I, the optically populated (1)LLCT/MLCT excited state undergoes a simultaneous subpicosecond CO dissociation and relaxation to a triplet IRuI-localized excited state which involves population of an orbital that is sigma-antibonding with respect to the axial I-Ru-I bonds. Vibrationally relaxed photoproduct cis(I,I)-[Ru(I)(2)(CO)(CH(3)CN)(bpy)] is formed with a time constant of ca. 55 ps. The triplet excited state is unreactive, decaying to the ground state with a 155 ps lifetime. The experimentally observed photochemical intermediates and excited states were assigned by comparing calculated (DFT) and experimental IR spectra. The different behavior of the chloro and bromo complexes from that of the iodo complex is caused by different characters of the lowest triplet excited states.     

Mixed-metal assemblies containing multiply bonded dirhenium species linked through thiocyanate- and cyanide-containing bridging units

The lability of the terminal Re-Cl bond that is cis to the bridging CO ligand in the edge-sharing bioctahedral complexes Re(2)(mu-Cl)(mu-CO)(mu-PP)(2)Cl(3)(L), where PP = Ph(2)PC(=CH(2))PPh(2) (dppE) when L = CO (1) and PP = Ph(2)PCH(2)PPh(2) (dppm) when L = CO (2) or XyINC (3), has been exploited in the preparation of mixed-metal Re(4)Pd(2), Re(2)Ag, Re(2)W, Re(2)Pt, and Re(2)Rh assemblies, in which the dirhenium units are bound to the other metals through NCS or CN bridges. These complexes, which retain the Re=Re bonds of the parent dirhenium complexes, comprise the novel centrosymmetric complex [Re(2)Cl(3)(mu-dppE)(2)(CO)(2)(mu-NCS)](2)Pd(2)(mu-SCN)(mu-NCS)Cl(2) (9), and the trimetallic complexes Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-NC)Ag(CN)] (10), Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-NC)W(CO)(5)] (11), [Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-NC)Pt(CN)(CN-t-Bu)(2)]]PF(6) (12), [Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-N(CN)(2))Rh(CO)(PPh(3))(2)]]O(3)SCF(3) (13), and Re(2)Cl(3)(mu-dppm)(2)(CO)(2)[(mu-NC)W(CO)(5)] (16). The identities of 9 and 16 have been established by X-ray crystallography, and all complexes characterized by IR and NMR spectroscopy and cyclic voltammetry. The reactions of the dicarbonyl complex 1, and the isomeric pair of complexes Re(2)Cl(4)(mu-dppm)(2)(CO)(CNXyl), which have edge-sharing bioctahedral (ESBO) (3) and open bioctahedral (OBO) (4) geometries, with Na[N(CN)(2)] and K[C(CN)(3)] have been used to prepare complexes in which the uncoordinated CN groups have the potential to coordinate other mono- or dimetal units to form extended arrays. The complexes which have been prepared and characterized are the monosubstituted species Re(2)Cl(3)(X)(mu-dppE)(2)(CO)(2) (X = N(CN)(2) (14) or C(CN)(3) (15)) and Re(2)Cl(3)(X)(mu-dppm)(2)(CO)(CNXyl) (X = N(CN)(2) (17) or C(CN)(3) (18) with ESBO structures; X = N(CN)(2) (19) or C(CN)(3) (20) with OBO structures), of which 15, 18, and 20 have been characterized by single-crystal X-ray structure determinations. The substitutional labilities of the Re-Cl bonds in the complexes Re(2)Cl(4)(mu-dppm)(2)(CO) (5), Re(2)Cl(4)(mu-dppm)(2)(CNXyl) (6), and Re(2)Cl(4)(mu-dppm)(2) (7) toward Na[N(CN)(2)] and K[C(CN)(3)] have also been explored and the complexes Re(2)Cl(3)(X)(mu-dppm)(2)(CO) (X = N(CN)(2) (21) or C(CN)(3) (22)), Re(2)Cl(3)(X)(mu-dppm)(2)(CNXyl) (X = N(CN)(2) (23) or C(CN)(3) (24)), Re(2)Cl(2)(X)(2)(mu-dppm)(2)(CNXyl) (X = N(CN)(2) (25) or C(CN)(3) (26)), Re(2)[N(CN)(2)](4)(mu-dppm)(2) (27), and Re(2)[C(CN)(3)](4)(mu-dppm)(2) (28) isolated in good yield. Single-crystal X-ray structure determinations of 24, 26, and 27 have shown that the Re-Re triple bonds present in the starting materials 5-7 are retained in these products.     

(Ph)3PBr][Br7], [(Bz)(Ph)3P]2[Br8], [(n-Bu)3MeN]2[Br20], [C4MPyr]2[Br20], and [(Ph)3PCl]2[Cl2I14]: extending the horizon of polyhalides via synthesis in ionic liquids

The five polyhalides [(Ph)(3)PBr][Br(7)], [(Bz)(Ph)(3)P](2)[Br(8)], [(n-Bu)(3)MeN](2)[Br(20)], [C(4)MPyr](2)[Br(20)] ([C(4)MPyr] = N-butyl-N-methylpyrrolidinium), and [(Ph)(3)PCl](2)[Cl(2)I(14)] were prepared by the reaction of dibromine and iodine monochloride in ionic liquids. The compounds [(Ph)(3)PBr][Br(7)] and [(Bz)(Ph)(3)P](2)[Br(8)] contain discrete pyramidal [Br(7)](-) and Z-shaped [Br(8)](2-) polybromide anions. [(n-Bu)(3)MeN](2)[Br(20)] and [C(4)MPyr](2)[Br(20)] exhibit new infinite two- and three-dimensional polybromide networks and contain the highest percentage of dibromine ever observed in a compound. [(Ph)(3)PCl](2)[Cl(2)I(14)] also consists of a three-dimensional network and is the first example of an infinite polyiodine chloride. All compounds were obtained from ionic liquids as the solvent that, on the one hand, guarantees for a high stability against strongly oxidizing Br(2) and ICl and that, on the other hand, reduces the high volatility of the molecular halogens.     

Copper halide-bridged ruthenium telluride carbonyl complexes: discovery of the semiconducting cluster chain polymer {[PPh4]2[Te2Ru4(CO)10Cu4Br2Cl2].THF}infinity

A new series of Te-Ru-Cu carbonyl complexes was prepared by the reaction of K(2)TeO(3) with [Ru(3)(CO)(12)] in MeOH followed by treatment with PPh(4)X (X=Br, Cl) and [Cu(MeCN)(4)]BF(4) or CuX (X=Br, Cl) in MeCN. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was first treated with PPh(4)X followed by the addition of [Cu(MeCN)(4)]BF(4), doubly CuX-bridged Te(2)Ru(4)-based octahedral clusters [PPh(4)](2)[Te(2)Ru(4)(CO)(10)Cu(2)X(2)] (X=Br, [PPh(4)](2)[1]; X=Cl, [PPh(4)](2)[2]) were obtained. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)X (X=Br, Cl) followed by the addition of CuX (X=Br, Cl), three different types of CuX-bridged Te-Ru carbonyl clusters were obtained. While the addition of PPh(4)Br or PPh(4)Cl followed by CuBr produced the doubly CuBr-bridged cluster 1, the addition of PPh(4)Cl followed by CuCl led to the formation of the Cu(4)Cl(2)-bridged bis-TeRu(5)-based octahedral cluster compound [PPh(4)](2)[{TeRu(5)(CO)(14)}(2)Cu(4)Cl(2)] ([PPh(4)](2)[3]). On the other hand, when the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)Br followed by the addition of CuCl, the Cu(Br)CuCl-bridged Te(2)Ru(4)-based octahedral cluster chain polymer {[PPh(4)](2)(Te(2)Ru(4)(CO)(10)Cu(4)Br(2)Cl(2)).THF}(infinity) ({[PPh(4)](2)[4].THF}(infinity)) was produced. The chain polymer {[PPh(4)](2)[4].THF}(infinity) is the first ternary Te-Ru-Cu cluster and shows semiconducting behavior with a small energy gap of about 0.37 eV. It can be rationalized as resulting from aggregation of doubly CuX-bridged clusters 1 and 2 with two equivalents of CuCl or CuBr, respectively. The nature of clusters 1-4 and the formation and semiconducting properties of the polymer of 4 were further examined by molecular orbital calculations at the B3LYP level of density functional theory.     

(S)-(2-(2'-Pyridyl)ethyl)cysteamine and (S)-(2-(2'-pyridyl)ethyl)-d,l-homocysteine as ligands for the "fac-[M(CO)(3)](+)" (M = Re, (99m)Tc) core

The reaction of fac-[NEt(4)](2)[Re(CO)(3)Br(3)] with (S)-(2-(2'-pyridyl)ethyl)cysteamine, L(1), in methanol leads to the formation of the cationic fac-[Re(CO)(3)(NSN)][Br] complex, 1, with coordination of the nitrogen of the pyridine, the sulfur of the thioether, and the nitrogen of the primary amine. When fac-[NEt(4)](2)[Re(CO)(3)Br(3)] reacts with the homocysteine derivative (S)-(2-(2'-pyridyl)ethyl)-d,l-homocysteine, L(2), the neutral fac-Re(CO)(3)(NSO) complex, 2, is produced with coordination of the nitrogen of the primary amine, the sulfur of the thioether, and the oxygen of the carboxylate group, while the pyridine ring remains uncoordinated. The analogous technetium-99m complexes, 1' and 2', were also prepared quantitatively by the reaction of L(1) and L(2) with the fac-[(99m)Tc(CO)(3)(H(2)O)(3)](+) precursor at 70 degrees C in water. Given that both (S)-(2-(2'-pyridyl)ethyl)cysteamine and homocysteine can be easily N- or S-derivatized by a bioactive molecule of interest, both the NSN or NSO ligand systems could be used to develop target-specific radiopharmaceuticals for diagnosis and therapy.     

Synthesis, Characterization, and Comparative Properties of [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] and [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)

The reaction of [PPN](2)[Re(6)C(CO)(19)] with Mo(CO)(6) and Ru(3)(CO)(12) under sunlamp irradiation provided the new mixed-metal clusters [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] and [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)], which were isolated in yields of 85% and 61%, respectively. The compound [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] crystallizes in the monoclinic space group P2(1)/c with a = 20.190 (7) ?, b = 16.489 (7) ?, c = 27.778 (7) ?, beta = 101.48 (2) degrees, and Z = 4 (at T = -75 degrees C). The cluster anion is composed of a Re(6)C octahedral core with a face capped by a Mo(CO)(4) fragment. There are three terminal carbonyl ligands coordinated to each rhenium atom. The four carbonyl ligands on the molybdenum center are essentially terminal, with one pair of carbonyl ligands (C72-O72 and C74-O74) subtending a relatively large angle at molybdenum (C72-Mo-C74 = 147.2(9) degrees ), whereas the remaining pair of carbonyl ligands (C71-O71 and C73-O73) subtend a much smaller angle (C71-Mo-C73 = 100.5(9) degrees ). The (13)C NMR spectrum of (13)CO-enriched [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] shows signals for four sets of carbonyl ligands at -40 degrees C, consistent with the solid state structure, but the carbonyl ligands undergo complete scrambling at ambient temperature. The (13)C NMR spectrum of (13)CO-enriched [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)] at 20 degrees C is consistent with the expected structure of an octahedral Re(6)C(CO)(18) core capped by a Ru(CO)(3) fragment. The visible spectrum of [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)] shows a broad, strong band at 670 nm (epsilon = 8100), whereas all of the absorptions of [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)] are at higher energy. An irreversible oxidation wave with E(p) at 0.34 V is observed for [PPN](2)[Re(6)C(CO)(18)Mo(CO)(4)], whereas two quasi-reversible oxidation waves with E(1/2) values of 0.21 and 0.61 V (vs Ag/AgCl) are observed for [PPN](2)[Re(6)C(CO)(18)Ru(CO)(3)]. The molybdenum cap in [Re(6)C(CO)(18)Mo(CO(4))](2-) is cleaved by heating in donor solvents, and by treatment with H(2), to give largely [H(2)Re(6)C(CO)(18)](2-). In contrast, [Re(6)C(CO)(18)Ru(CO)(3)](2-) shows no tendency to react under similar conditions.     

First row wheels, [((t)Bu(3)SiS)MX](12)(M = Co, X = Cl; M = Ni, X = Br), are common amongst both simpler and more complex aggregates

[((t)Bu(3)SiS)MX[(12) are wheels for first row transition metals (M = Co, X = Cl; M = Ni, X = Br), but for nickel, simpler [e.g. [((t)Bu(3)SiS)Ni](2)(mu-SSi(t)Bu(3))(2)[ and more complicated [e.g. [(mu-SSi(t)Bu(3))Ni](5)(mu(5)-S)] structures are by-products.     

Synthesis and characterization of a new family of square-planar nickel(II) carbonyl derivatives

The reaction of [NBu(4)](2)[Ni(C(6)F(5))(4)] (1) with solutions of dry HCl(g) in Et(2)O results in the protonolysis of two Nibond;C(6)F(5) bonds giving [NBu(4)](2)[[Ni(C(6)F(5))(2)](2)(mu-Cl)(2)] (2 a) together with the stoichiometrically required amount of C(6)F(5)H. Compound 2 a reacts with AgClO(4) in THF to give cis-[Ni(C(6)F(5))(2)(thf)(2)] (3). Reacting 3 with phosphonium halides, [PPh(3)Me]X, gives dinuclear compounds [PPh(3)Me](2)[[Ni(C(6)F(5))(2)](2)(mu-X)(2)] (X=Br (2 b) or I (2 c)). Solutions of compounds 2 in CH(2)Cl(2) at 0 degrees C do not react with excess CNtBu, but do react with CO (1 atm) to split the bridges and form a series of terminal Ni(II) carbonyl derivatives with general formula Qcis-[Ni(C(6)F(5))(2)X(CO)] (4). The nu(CO) stretching frequencies of 4 in CH(2)Cl(2) solution decrease in the order Cl (2090 cm(-1))>Br (2084 cm(-1))>I (2073 cm(-1)). Compounds 4 revert to the parent dinuclear species 2 on increasing the temperature or under reduced CO pressure. [NBu(4)]cis-[Ni(C(6)F(5))(2)Cl(CO)] (4 a) reacts with AgC(6)F(5) to give [NBu(4)][Ni(C(6)F(5))(3)(CO)] (5, nu(CO)(CH(2)Cl(2))=2070 cm(-1)). Compound 5 is also quantitatively formed ((19)F NMR spectroscopy) by 1:1 reaction of 1 with HCl(Et(2)O) in CO atmosphere. Complex 3 reacts with CO at -78 degrees C to give cis-[Ni(C(6)F(5))(2)(CO)(2)] (6, nu(CO)(CH(2)Cl(2))=2156, 2130 cm(-1)), which easily decomposes by reductive elimination of C(6)F(5)bond;C(6)F(5). Compounds 3 and 6 both react with CNtBu to give trans-[Ni(C(6)F(5))(2)(CNtBu)(2)] (7). The solid-state structures of compounds 3, 4 b, 6, and 7 have been established by X-ray diffraction methods. Complexes 4-6 are rare examples of square-planar Ni(II) carbonyl derivatives.     

New halide-centered discrete Ag(I)(8) cubic clusters containing diselenophosphate ligands, [Ag(8)(X)[Se(2)P(OR)(2)](6)](PF(6)) (X = Cl, Br; R = Et, Pr, (i)Pr): syntheses, structures, and DFT calculations

Six clusters Ag(8)(micro(8)-X)[Se(2)P(OR)(2)](6)(PF(6)) (R = Et, X = Cl, 1a, X = Br, 1b; R = Pr, X = Cl, 2a, X = Br, 2b; R = (i)Pr, X = Cl, 3a, X = Br, 3b) were isolated from the reaction of [Ag(CH(3)CN)(4)](PF(6)), NH(4)[Se(2)P(OR)(2)], and Bu(4)NX in a molar ratio of 4:3:1 in CH(2)X(2). Positive FAB mass spectra show m/z peaks at 2573.2 for 1a, 2617.3 for 1b, 2740.9 for 2a, 2786.9 for 2b, 2742.3 for 3a, and 2787.0 for 3b due to respective molecular cation, (M - PF(6))(+). (31)P NMR spectra of 1a-3b display a singlet at delta 82.3, 81.5, 82.9, 81.7, 76.3, and 75.8 ppm with a set of satellites (J(PSe) = 661, 664, 652, 652, 656, and 656 Hz, respectively). The X-ray structure (1a-2b) consists of a discrete cationic cluster in which eight silver ions are linked by six diselenophosphate ligands and a central micro(8)-Cl or micro(8)-Br ion with a noncoordinating PF(6)(-) anion. The shape of the molecule is a halide-centered distorted Ag(8) cubic cluster. The dsep ligand exhibits a tetrametallic tetraconnective (micro(2), micro(2)) coordination pattern, and each caps on a square face of the cube. Each silver atom of the cube is coordinated by three selenium atoms and the central chloride or bromide ion. Additionally, molecular orbital calculations at the B3LYP level of the density functional theory have been carried out to study the Ag-micro(8)-X (X = Cl, Br) interactions for cluster cations [Ag(8)(micro(8)-X)[Se(2)P(OR)(2)](6)](+). Calculations show very weak bonding interactions exist between micro(8)-X and Ag atoms of the cube.