Distorted-octahedral Coordination Research Articles

Ancillary-Ligand-Assisted Variation in Nuclearities Leading to the Formation of Di-, Tri-, and Tetranuclear Copper(II) Complexes with Multifaceted Carboxylate Coordination Chemistry

The self-assembly of a carboxylate-based dinucleating ligand, N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H3cpdp), and copper(II) ions in the presence of various exogenous ancillary ligands results in the formation of the new dinuclear complex [Cu2(cpdp)(μ-Hisophth)]4·2H2isophth·21H2O (1), trinuclear complex [Cu3(Hcpdp)(Cl)4] (2), and tetranuclear complex [Cu4(cpdp)(μ-Hphth)(μ4-phth)(piconol)(Cl)2]·3H2O (3) (H2phth = phthalic acid; H2isophth = isophthalic acid; piconol = 2-pyridinemethanol; Cl- = chloride). In methanol-water, the reaction of H3cpdp with CuCl2·2H2O at room temperature leads to the formation of 2. On the other hand, 1 and 3 have been obtained by carrying out the reaction of H3cpdp with CuCl2·2H2O/m-C6H4(CO2Na)2 and CuCl2·2H2O/o-C6H4(CO2Na)2/piconol, respectively, in methanol-water in the presence of NaOH at ambient temperature. All three complexes have been characterized by elemental analysis, molar electrical conductivity and magnetic moment measurements, FTIR, UV-vis spectroscopy, and PXRD, including single-crystal X-ray structural analyses. The molecular structure of 1 is based on a μ-alkoxide and μ-isophthalate-bridged dimeric [Cu2] core; the structure of 2 represents a trimeric [Cu3] core in which a μ-alcohol-bridged dinuclear [Cu2] unit is exclusively coupled with a [CuCl2] species by two μ:η1:η1-syn-anti carboxylate groups forming a triangular motif; the structure of 3 embodies a tetrameric [Cu4] core, with two copper(II) ions in a distorted-octahedral coordination environment, one copper(II) ion in a distorted-trigonal-bipyramidal coordination environment, and the other copper(II) ion in a square-planar coordination environment. In fact, 2 and 3 represent rare examples of copper(II)-based multinuclear complexes showing outstanding features of rich coordination chemistry: (i) using a symmetrical dinucleating ligand, trinuclear complex 2 is generated with four- and five-coordination environments around copper(II) ions; (ii) the unsymmetrical tetranuclear complex 3 is obtained by using the same ligand with four-, five- and six-coordination environments around copper(II) ions; (iii) tetracopper(II) complex 3 shows four different bridging modes of carboxylate groups simultaneously such as μ:η2, μ:η1:η1, μ3:η2:η1:η1, and μ4:η1:η1:η1:η1, the μ4:η1:η1:η1:η1 mode of phthalate being unprecedented. The formation of these [Cu2], [Cu3], and [Cu4] complexes can be controlled by changing the exogenous ancillary ligands and pH of the reaction solutions, thus allowing an effective tuning of the self-assembly. The magnetic susceptibility measurements suggest that the copper centers in all three complexes are antiferromagnetically coupled. The thermal properties of 1-3 have been investigated by thermogravimetric and differential thermal analytical (TGA and DTA) techniques, indicating that the decomposition of all three complexes proceeds via multistep processes.

Structure of a luminescent 3D coordination polymer constructed with a trinuclear core of cadmium-trimesate and isoquinoline

A new photoluminescent 3-D coordination polymer 1 containing a trinuclear Cd(II) cluster [Cd3(TMA)2] (TMA = trimesate) has been synthesized under solvothermal conditions, reacting Cd(II) ions with trimesic acid in the presence of isoquinoline and DMF. Compound 1 contains three crystallographically different Cd(II) ions interconnected by two trimesate ligands. The Cd(1) and Cd(2) ions are six-coordinated with a distorted-octahedral coordination sphere, {Cd(1)O6} and {Cd(2)NO5} respectively. The Cd(3) ion is seven-coordinated having a distorted-monocapped trigonal prismatic geometry {Cd(3)N2O5}. Crystallographic studies shows that 1 has two-dimensional sheets interlock each other, giving rise to a twofold interpenetrating network consisting of trinuclear cores [Cd3(TMA)2] as nodes bridged by trimesate anions. Compound 1 exhibits a strong blue emission in solid-state (λem = 430 nm) and suspensions in different organic solvents (λem = 405–440 nm) at room temperature with lifetimes in the nanosecond range. Structure-related photoluminescence is attributed to presence of the rigid trinuclear core involving coordinated isoquinoline molecules. The crystalline material of 1 possess thermal stability up to 200 °C.

Diiminopyrrolide Copper Complexes: Synthesis, Structures, and rac-Lactide Polymerization Activity

2,5-Diiminopyrrole ligands with N-xylyl (L3), N-naphthyl (L4), N-cyclohexyl (L5), N-diphenylmethyl (L6), and N-p-bromobenzyl (L7), as well as the 5-R-2-iminopyrroles with N-S-methylbenzyl (L8, R = H; L10, R = Me; L11, R = Cl) and N-benzyl (L9, R = H) were reacted with Cu(OMe)2 and pyridylmethanol (R1OH) or dimethylaminoethanol (R2OH) to yield the corresponding dinuclear complexes L2Cu2(μ-OR)2. Reactions in the absence of chelating R1OH or R2OH only yielded homoleptic L2Cu or L2Cu2. Complexes with R2OH were obtained with all ligands but L4, complexes with R1OH for all ligands but L3, L4, and L6. All complexes but those with L7 displayed dinuclear crystal structures with pentacoordinated copper centers and bridging alkoxy groups. The alkoxy group and the pyrrolide ligand were consistently found in equatorial positions. Imine, pyridine, or amine occupied the axial position. L7 coordinated both imino groups to copper, yielding a distorted-octahedral coordination geometry. All complexes containing R1OH, with t...

Synthesis, Crystal Structure and Luminescence Property on Cabazoly-Based Zinc Metal Organic Frameworks

A novel zinc metal organic frameworks, named ZnL(2,2′-bpy), has been successfully synthesized, serving 3,6-dicarboxylic-9-ethylcarbazole acid (H2L) as ligand. This kind of ZnMOFs was characterized by FI-IR, elemental analysis, SEM, powder X-ray diffraction and single crystal X-ray diffraction to illustrate the structures. TG analysis was applied to investigate the thermostability. Structural analysis demonstrates that ZnMOFs possess triclinic crystal structure which is a 1D chain that occurs distorted-octahedral coordination geometry. Furthermore, the luminescent performance of ZnMOFs is performed and discussed in detail. The results show that ZnMOFs can emit blue luminescence originating, which is assigned to the ligand-to-metal charge transfer (LMCT).

Rare-Earth-Metal Complexes Supported by New Chiral Tetra-Azane Chelating Ligands: Synthesis, Characterization, and Catalytic Properties for Intramolecular Asymmetric Hydroamination

A number of new chiral tetra-azane proligands (1R,2R)-N,N′-bis(o-arylamino-benzylidene)-1,2-diaminocyclohexane ((1R,2R)-[(ArHN)C6H4CH═N]2C6H10, Ar = 2,6-Me2C6H3 (L1H2), 2,6-Et2C6H3 (L2H2), 2,6-iPr2C6H3 (L3H2)) have been synthesized via a nucleophilic displacement of the two fluorine atoms in (o-C6H4FCH═N)2C6H10 with the lithium salt of the corresponding aniline derivative. Their rare-earth-metal complexes L1ScCl2Li(THF)3 (1), L1YCl2Li(THF)3 (2), L2YCl2Li(THF)3 (3), and L3YCl2Li(THF)2 (4) were synthesized in good yields via the salt metathesis of MCl3 (M = Sc, Y) with the dilithium salts of the ligands L1Li2(THF)4, L2Li2(THF),4, and L3Li2(THF)4, respectively. Further more, the two diethylamido complexes L1Y(NEt2)ClLi(THF)3 (5) and L3Y(NEt2)ClLi(THF)2 (6) were also synthesized from reactions of the corresponding chloride complexes 2 and 4 with diethylamidolithium. The new proligands L1H2–L3H2 and their rare-earth-metal complexes 1–6 have been characterized by elemental analyses and 1H and 13C NMR spectroscopy. The structures of complexes 1, 2, and 4 have been further confirmed by single-crystal X-ray diffraction analysis. The molecular structural analysis reveals that the metal centers in complexes 1, 2, and 4 acquire a distorted-octahedral coordination environment in their solid-state structures by sharing the chloride with a LiCl(THF)n moiety. After in situ treatment with nBuLi or Me3SiCH2Li, complexes 1–4 show reasonable catalytic activity and good enantioselectivity (up to 90%) for intramolecular asymmetric hydroamination reactions of terminal aminoalkenes. The amido complexes 5 and 6 can catalyze the intramolecular hydroamination reaction directly and show catalytic activities and enantioselectivities similar to those of the in situ formed alkyl complexes.

Exploring the exchange interaction in a mixed valence {Co II4Co III2} hexanuclear cluster with novel topology

Reaction between [Co 2(μ-OH 2)(μ-Piv) 2(Piv) 2(HPiv) 4] and a (salicylidene)ethanolamine ligand under ambient reaction conditions, affords hexanuclear complexes [Co III 2Co II 4(Piv) 8(HPiv) 2(L) 2(OH) 2] ( 1– 2). Both products have been characterized crystallographically and found to be mixed-valent, containing divalent and trivalent Co centers. Down to 30 K, the variable-temperature magnetic susceptibility data are dominated by the single-ion properties of high spin Co(II) centers with distorted-octahedral coordination geometries. Below this temperature, the effect of intramolecular ferromagnetic exchange interactions becomes apparent. Magnetic data has been analyzed in terms of ground isolated effective S ˜ = 1 / 2 Kramers doublets where low temperature magnetization data suggests an anisotropic behavior. We have also employed DFT-broken symmetry calculations to evaluate in an isotropic approach the exchange interaction pathways.

Catalytic Properties of Cobalt(III)−Oxo Cubanes in the TBHP Oxidation of Benzylic Alcohols

Two series of oxo-bridged Co(III) complexes of the type Co(4)O(4)(O(2)CC(6)H(4)-X)(4)(py)(4) (1) and Co(4)O(4)(O(2)CC(6)H(4)-X)(4)(4-Mepy)(4) (2), where X = H (a), Me (b), MeO (c), Cl (d), NO(2) (e), have been synthesized and characterized in detail. The molecular structures of the complexes consist of a cubelike Co(4)(mu(3)-O)(4) core having Co and O atoms at alternate vertices with carboxylato ligands bridging the Co(3+) ions along four face diagonals of the approximate cube. Nitrogen atoms from pyridyl ligands complete the distorted-octahedral coordination around each Co(III). These neutral Co(III) complexes undergo a nearly reversible one-electron oxidation involving the redox couple [Co(4)(III)(mu(3)-O)(4)](4+) <--> [Co(3)(III)Co(IV)(mu(3)-O)(4)](5+) at potentials (approximately 0.7-1.0 V) that linearly depend on the electronic influence of X. The cobalt(III) clusters of types 1 and 2 have been found to effectively promote the TBHP oxidation of benzylic alcohols under homogeneous conditions to produce the corresponding carbonyl compounds.

Manganese(II) Complexes in Ethene Polymerization

A series of manganese(II) dichloro complexes made in situ and bearing mainly various nitrogen ligands was studied with a parallel screening method in order to identify catalytically active complexes for ethene polymerization using methylaluminoxane (MAO) as a cocatalyst. From the series two of the most active octahedral manganese(II) complexes, those bearing tetradentate nitrogen ligands with chiral bridges, [N,N‘-bis(quinoline-2-methylene)diiminocyclohexane]MnCl2 (1) and {N,N‘-(6,6‘-dimethylbiphenyl-2,2‘-diyl)bis[(2-pyridyl)methyl]diimine}MnCl2 (2), were selected for more detailed studies. According to their solid-state structures, it is common for these C2-symmetric manganese complexes to have a distorted-octahedral coordination geometry where chlorides occupy cis positions with wide Cl−Mn−Cl angles (132−135°). The highest activity in ethene polymerization (67 kg of PE/((mol of Mn) h)) was obtained with 1/MAO at 80 °C. Furthermore, the alkylation of 1 and 2 with MeMgBr and (benzyl)MgBr was investigated,...

Mixed-Valent Cobalt Spin Clusters: a Hexanuclear Complex and a One-Dimensional Coordination Polymer Comprised of Alternating Hepta- and Mononuclear Fragments

Reactions between Co(OAc)2 and 2-amino-2-methyl-1,3-propanediol (ampdH2) afford a hexanuclear complex [Co6(H2O)(MeOH)(OAc)6(ampd)4] (1) and a one-dimensional coordination polymer comprised of discrete heptanuclear complexes covalently bound to mononuclear Co centers [Co8(H2O)2(OAc)7(ampd)6]n (2). While 1 is obtained under ambient reaction conditions, the formation of 2 requires solvothermal methods. Both products have been characterized crystallographically and found to be mixed-valent, containing divalent and trivalent Co centers. Down to 30 K, the variable-temperature magnetic susceptibility data of 1 and 2 are dominated by the single-ion properties of high-spin Co(II) centers with distorted-octahedral coordination geometries. Below this temperature, the effect of intramolecular ferromagnetic exchange interactions becomes apparent. The ferromagnetic coupling in 1 has been analyzed in terms of an anisotropic exchange model, and inelastic neutron scattering data are consistent with the proposed model. Although the structure of 2 precludes a quantitative interpretation, the magnetic data suggest ferromagnetic exchange within the heptanuclear unit and negligible interactions along the chain between the hepta- and mononuclear fragments.

Neutral and Dianionic Organoantimony(III) Dithiolene Complexes: Syntheses, X-ray Crystal Structures, and Unexpected Reactivity

The new neutral PhSb(dmid) (dmid2- = 4,5-dithiolato-1,3-dithiol-2-one) complex has been synthesized upon reaction of deprotected 1,3,4,6-tetrathiapentalene-2,5-dione with dichlorophenylstibine. Single-crystal X-ray structure determination shows an original three-dimensional network in the solid state, via Sb- - -O and Sb- - -S secondary interactions, based on an octagonal “Sb4S4” motif. Not only PhSb(dmid) but also PhSb(dmit) (dmit2- = 4,5-dithiolato-1,3-dithiole-2-thione) reacts with a second 1 equiv of dithiolate to give a series of highly reactive dianionic complexes, unknown so far. One of these complexes, [Me4N]2[PhSb(dmid)2], was structurally characterized by single-crystal X-ray measurements. Both dithiolene ligands, lying in the equatorial plane of a distorted octahedron, are unsymmetrically coordinated, with two Sb−S distances much longer than the other two. These dianionic species reacted with 1 equiv of PhSbCl2 to give, unexpectedly, a series of Sb(V) [Ph2Sb(dithiolene)2]- complexes. The same compounds were obtained directly upon slow addition of 1 equiv of PhSbCl2 on the corresponding dithiolate suspensions. This demonstrates that dianionic [PhSbIII(dithiolene)2]2- species are key intermediates in the synthesis of [Ph2SbV(dithiolene)2]- salts. The single-crystal X-ray structure determination of the tetraethylammonium salts of [Ph2Sb(dmid)2]-, [Ph2Sb(dmit)2]-, and [Ph2Sb(dmid)(dmit)]- show a distorted-octahedral coordination geometry for the Sb center with a cis configuration of the phenyl groups. This is preserved also in solution, as established by 13C NMR. Using the same technique, combined with 1H NMR, in a scrambling experiment, a fast dithiolene exchange has been emphasized. In the case of the [Ph2Sb(dmid)2]- salt, two polymorphs, with different folding angles along the S- - -S hinge, were crystallized.

A periodic walk: a series of first-row transition metal complexes with the pentadentate ligand PY5.

A series of transition metal complexes derived from the pentadentate ligand PY5, 2,6-(bis-(bis-2-pyridyl)methoxymethane)pyridine, illustrates the intrinsic propensity of this ligand to complex metal ions. X-ray structural data are provided for six complexes (1-6) with cations of the general formula [M(II)(PY5)(Cl)](+), where M = Mn, Fe, Co, Ni, Cu, Zn. In complexes 1-4 and 6, the metal ions are coordinated in a distorted-octahedral fashion; the four terminal pyridines of PY5 occupy the equatorial sites while the axial positions are occupied by the bridging pyridine of PY5 and a chloride anion. Major distortions from an ideal octahedral geometry arise from displacement of the metal atom from the equatorial plane toward the chloride ligand and from differences in pyridine-metal-pyridine bond angles. The series of complexes shows that M(II) ions are consistently accommodated in the ligand by displacement of the metal ion from the PY5 pocket, a tilting of the axial pyridine subunit, and nonsymmetrical pyridine subunit ligation in the equatorial plane. The displacement from the ligand pocket increases with the ionic radius of M(II). The axial pyridine tilt, however, is approximately the same for all complexes and appears to be independent of the electronic ground state of M(II). In complex 5, the Cu(II) ion is coordinated by only four of the five pyridine subunits of the ligand, resulting in a square-pyramidal complex. The overall structural similarity of 5 with the other complexes reflects the strong tendency of PY5 to enforce a distorted-octahedral coordination geometry. Complexes 1-6 are further characterized in terms of solution magnetic susceptibility, electrochemical behavior, and optical properties. These show the high-spin nature of the complexes and the anticipated stabilization of the divalent oxidation state.

Reaction of trimethylene–bisadenine with d 10 divalent cations

The synthesis, spectroscopic characterisation and X-ray structure determination of Ade 2(CH 2) 3 1, [(H-Ade) 2(CH 2) 3]Cl 2⋅H 2O 2 and the outer sphere complex [(H-Ade) 2(CH 2) 3] 2[Cd 2Cl 8(H 2O) 2]⋅4H 2O 3 are reported (Ade=adenine). An important change of conformation appears when trimethylene–bisadenine is protonated. The eclipsed and anti conformation between the two adenine moieties of 1 varies to a gauche and syn conformation for the corresponding Cl − 2 and [Cd 2Cl 8(H 2O) 2] 4− 3 salts. Compound 3 presents a new dimeric [Cd 2Cl 8(H 2O) 2] 4− anion in which cadmium(II) has a distorted-octahedral co-ordination with two cis chlorine atoms bridging two cadmium atoms. The corresponding Zn(II) and Hg(II) salts have been obtained by similar procedures.

A new tetraazamacrocycle functionalized with four pendant pyridyl groups: synthesis and crystal structure of the nickel(II) complex of 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane(L), [NiL] 2+

The title complex, [NiL](ClO 4) 2 was synthesized by the reaction of Nickel(II) perchlorate and the new macrocycle ligand, 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane (L) in ethanol solution. The crystal and molecular structure of this complex has been determined by single-crystal X-ray diffraction. The complex consists of [NiL] 2+ cation and two perchlorate anions. Within the [NiL] 2+ cation, the potential octadentate ligand is using its 4 nitrogen atoms of the macrocycle and 2 pyridine nitrogens to coordinate with the central nickel(II), while the other two pyridine nitrogens remained uncoordinated. The central nickel(II) ion is in a distorted-octahedral coordination environment and in high-spin state.

Structure and Chemical Properties of Chlorohydrido(diarylsilyl)rhodium(III) Complexes,mer-RhCl(H)(SiHAr2)(PMe3)3. Thermally Induced Chloro Transfer from Rhodium to Silicon in the Complexes and Silane Exchange

Reactions of the diarylsilanes H2SiPh2, H2Si(C6H4Me-p)2, H2Si(C6H4OMe-p)2, H2Si(C6H4F-p)2, and H2Si(C6H4CF3-p)2 with [Rh(PMe3)4]Cl involve oxidative addition of an Si−H bond of the substrates to give mer-RhCl(H)[SiH(C6H4X-p)2](PMe3)3 (1, X = H; 2, X = Me; 3, X = OMe; 4, X = F; 5, X = CF3). X-ray crystallography of 1, 3, 4, and 5 shows a distorted-octahedral coordination around the Rh center with three meridional PMe3 ligands and with the chloro and diarylsilyl ligands at mutually trans positions. The Rh−Si bond distances of the complexes are in the range 2.311−2.319 Å. Addition of H2Si(C6H4Me-p)2 to a toluene solution of 1 results in partial conversion of the complex into 2 accompanied by liberation of H2SiPh2. The exchange of the diphenylsilyl ligand of 1 on addition of the other diarylsilanes proceeds reversibly at 10−50 °C with the thermodynamic parameters of the reactions 1 + H2Si(C6H4X-p)2 = mer-RhCl(H)[SiH(C6H4X-p)2](PMe3)3 + H2SiPh2 as ΔH° = 4.16 kJ mol-1 and ΔS° = 8.2 J mol-1 K-1 for X = Me, ΔH° = 6.51 kJ mol-1 and ΔS° = 11.7 J mol-1 K-1 for X = OMe, and ΔH° = −2.33 kJ mol-1 and ΔS° = −5.3 J mol-1 K-1 for X = F, respectively. Enthalpy of the reactions of 1 with H2Si(C6H4X-p)2 (X = Me, OMe, and F) decreases with increase in the σp value of X. Heating a toluene solution of 1 at 50 °C and at 110 °C gives mixtures of fac-Rh(H)2(SiClPh2)(PMe3)3 (6) and RhCl(H)(SiClPh2)(PMe3)3 (7). The structure of 6 has been determined by X-ray crystallography, while 7 was characterized by comparison of the NMR (1H, 31P{1H}, 13C{1H}, and 29Si{1H}) peaks with those of the complex prepared independently from the reaction of HSiClPh2 with [Rh(PMe3)4]Cl.

Syntheses and characterisation of mono- and di-nuclear iron(III) complexes of 1,4,7-triazacyclononane-N-acetate (L). Crystal structures of [FeCl2L] and [Fe2(μ-O)(μ-O2CMe)L2]ClO 4· NaClO4·2H2O

B. Graham, B. Moubaraki, K. S. Murray, L. Spiccia, J. D. Cashion and D. C. R. Hockless, J. Chem. Soc., Dalton Trans., 1997, 887 DOI: 10.1039/A606651H

Thiobenzamidato and thiobenzoato complexes of ruthenium, osmium and iridium

S. D. Robinson, A. Sahajpal and D. A. Tocher, J. Chem. Soc., Dalton Trans., 1997, 757 DOI: 10.1039/A607011F

Technetium(V) and rhenium(V) nitrido complexes with bis(diphenyl-thiophosphoryl)amide, N(SPPh2)2−

Technetium(V) and rhenium(V) nitrido complexes of the compositions [MNL 2 ] and [MN(Cl)(PPhMe 2 )L] have been synthesized by reaction of Na[N(SPPh 2 ) 2 ] and [MNCl 2 (PPh 3 ) 2 ] or [MNCl 2 (PPhMe 2 ) 3 ] complexes, respectively [M = Re or Tc; L = N(SPPh 2 ) 2 - ]. The amide anion acts in all isolated complexes as a chelating ligand co-ordinated via the sulfur atoms. The complexes [TcN{N(SPPh 2 ) 2 } 2 ], [ReN{N(SPPh 2 ) 2 } 2 ] and [TcN(Cl)(PPhMe 2 ) 2 {N(SPPh 2 ) 2 }] have been studied by X-ray crystallography. The bis-chelates are five-co-ordinate with the nitrogen atoms at the apexes of square pyramids. The Tc atom in [TcN(Cl)(PPhMe 2 ) 2 {N(SPPh 2 ) 2 }] has a distorted-octahedral co-ordination sphere with Cl bonded trans to the nitrido function. The complex [ReN{N(SPPh 2 ) 2 } 2 ] is the first five-co-cordinate nitride which reacts with BCl 3 to form a nitrido bridge between rhenium and boron; [Re(NBCl 3 ){N(SPPh 2 ) 2 } 2 ] is characterized by a covalent N–B bond of 1.539(5) A. The Re–N multiple bond distance is only slightly influenced by addition of the Lewis acid. The complex [ReN(Cl)(PPhMe 2 ) 2 {N(SPPh 2 ) 2 }] reacts with BCl 3 with substitution of N(SPPh 2 ) 2 - and formation of the well known [Re(NBCl 3 )Cl 2 (PPhMe 2 ) 3 ]. The corresponding technetium complexes do not form Tc–N–B bridges upon reactions with BCl 3 . The [MN(Cl)(PPhMe 2 ) 2 {N(SPPh 2 ) 2 }] (M = Tc or Re) complexes reacted with S 2 Cl 2 to give thionitrosyl compounds with the metals in lower oxidation states; [Re(NS)Cl 2 (PPhMe 2 ) 3 ] and [Re(NS)Cl 3 (PPhMe 2 ) 2 ] have been characterized spectroscopically, [Tc(NS)Cl 3 (PPhMe 2 ) 2 ] was studied by X-ray diffraction and EPR spectroscopy. The phosphine ligands are trans to each other.

Asymmetric functionalisation of aza macrocycles. Syntheses, crystal structures and electrochemistry of [Ni(Bz[9]aneN3)2][PF6]2and [Pd(Bz[9]aneN3)2][PF6]2·2MeCN (Bz[9]aneN3= 1-benzyl-1,4,7-triazacyclononane)

1-Benzyl-1,4,7-triazacyclononane (Bz[9]aneN3) has been prepared and its co-ordination chemistry with NiII and PdII investigated. The crystal structure of the complex [Ni(Bz[9]aneN3)2][PF6]2 revealed six independent Ni–N distances, affording a distorted-octahedral co-ordination geometry. Four lie in the range 2.089(4)–2.123(4)Å, while the distances to the benzyl amine N-donors are significantly longer at 2.262(4) and 2.251(4)Å. The benzyl amine N-donors occupy adjacent sites at the metal centre affording a syn geometry. Cyclic voltammetry of [Ni(Bz[9]aneN3)2][PF6]2 in MeCN at a platinum electrode showed a reversible NiII–NiIII oxidation at E½=+0.76 V vs. ferrocene–ferrocenium at 235 K. This process was irreversible at higher temperatures. The ESR spectrum of [Ni(Bz[9]aneN3)2]3+ exhibits an axial signal, with g‖= 2.03 and g⊥= 2.15, consistent with a tetragonally elongated octahedral co-ordination geometry at NiIII. The crystal structure of [Pd(Bz[9]aneN3)2][PF6]2·2MeCN revealed the Pd atom on an inversion centre with the ligands bound via two N-donors from each, Pd–N 2.0588(19) and 2.0605(19)Å. The benzyl amine N-donors do not interact with the metal centre, Pd ⋯ N 3.402(4)Å. Cyclic voltammetry of [Pd(Bz[9]aneN3)2][PF6]2 in MeCN showed a reversible PdII–PdIII couple at E½=+0.36 V at 298 K. The ESR spectrum of [Pd(Bz[9]aneN3)2]3+ exhibits an axial signal, with g‖= 2.007 and g⊥= 2.117. Superhyperfine coupling (A‖= 26.9 G) is observed to two N-donors in the axial component consistent with a tetragonally elongated octahedral co-ordination geometry at the PdIII.

Isolation, structure and spectroscopic properties of [Re2(C3S5)5]2? complexes and electrical conductivities of their oxidized species

Salts of the dianion [Re2(C3S5)5]2–[C3S52–= 4,5-disulfanyl-1,3-dithiole-2-thionate(2–)] with PPh4+1, NEt4+2 and NBun4+3 were prepared. A single-crystal X-ray analysis of 1 revealed that the dinuclear anion containing a Re–Re single bond and two Re–S–Re bridges involving the C3S5 ligands contains distorted-octahedral co-ordination geometries around both metal atoms and that the anions are associated into a dimeric form through sulfur–sulfur contacts, being further arranged into a chain through other such contacts. Redox potentials of the [Re2(C3S5)5]2– anion were determined by cyclic voltammetry. Complexes 1 and 2 were oxidized by iodine, [Fe(C5H5)2][PF6], and [ttf]3[BF4]2(ttf˙+= the tetrathiafulvalenium radical cation) or current-controlled electrolysis to yield species [ttf][Re2(C3S5)5], [PPh4]x- and [NEt4]y-[Re2(C3S5)5](x,y= 0.1–0.65). They behave as semiconductors with electrical conductivities of 2.0 × 10–3–4.9 × 10–2 S cm–1 for compacted pellets at room temperature. The electronic states of the oxidized complexes are discussed on the basis of electronic absorption, IR, ESR as well as X-ray photoelectron spectra.

Reaction of methanol with diphenylantimony(V) trihalides: crystal structure of [SbPh2Br2(OMe)·MeOH]2

A re-examination of the reaction between diphenylantimony trichloride and methanol showed that the initial product is a methanol adduct of the monomethoxide, SbPh2Cl2(OMe), rather than the oxide (SbPh2Cl2)2O, which is a hydrolysis product formed during recrystallisation. The corresponding tribromide, and the mixed halides, SbPh2Br3–nCln where n= 1 or 2, react similarly with methanol, losing a bromine atom to give solvated monomethoxy products. X-Ray diffraction analysis revealed that SbPh2Br2(OMe) crystallises as a centrosymmetric dimer, incorporating two molecules of methanol, which are attached via strong hydrogen bonds to the oxygen atoms of the methoxy groups. Co-ordination of the methanol oxygen to a symmetry-related antimony atom completes the distorted-octahedral co-ordination about antimony and forms a central eight-atom ring system in the chair conformation. Two unusual features are the similarity of the two Sb–O distances [2.101(4) and 2.121(4)Å], even though the former is formally a normal σ bond and the latter a donor linkage, and the presence of a weak π-arene ⋯ H–C hydrogen bond, which probably accounts for the orthogonality of the phenyl groups at antimony.