The structural definition of adducts of stoichiometry MX:dppx (1:1) M = Cu, Ag, X = simple anion, dppx=Ph2P(CH2)xPPh2, x = 3-6

Single crystal X-ray structural characterizations are recorded for a wide range of adducts of the form MX:dppx (1:1)_(n), M = silver(I) (predominantly), copper(I), X = simple (pseudo-) halide or oxy-anion (the latter spanning, where accessible, perchlorate, nitrate, carboxylate - a range of increasing basicity), dppx=bis(diphenylphosphino)alkane, Ph₂P(CH₂)_xPPh₂, x = 3-6. Adducts are defined of two binuclear forms: (i) [LM(μ-X)₂L], with each ligand chelating a single metal atom, and (ii) [M(μ-X)₂(μ-(P-L-P′))₂M′] where both ligands L and halides bridge the two metal atoms; a few adducts are defined as polymers, the ligands connecting M(μ-X)₂M′ kernels, this motif persisting in all forms. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR).     

New oligo-/poly-meric forms for MX:dpex (1:1) complexes (M = Cu, Ag; X = (pseudo-)halide; dpex = Ph2E(CH2)xEPh2, E = (P), As; x = 1, 2)

Single-crystal X-ray structural characterizations of MX:dpam (1:1) (‘dpam’ = Ph₂AsCH₂AsPh₂) are reported for MX = AgCl, Br; CuI, CN/Cl (all isomorphous) and AgI, AgSCN, CuSCN arrays, all being of the novel form [(μ-X){M(μ-X)(As-dpam-As′)₂M′}]_∞, essentially the familiar M(E-dpem-E′)₂M′ binuclear array with both ‘bridging’ and (linking) ‘terminal’ (pseudo-)halides involved in the polymer. A different arrangement of bridging and linking entities is found with AgX:dpae (1:1)_2(∞|∞), X = Br, NCO, ‘dpae’ = Ph₂As(CH₂)₂AsPh₂, now comprising [M(μ-X)₂(As-dpae-As)M] kernels linked by As-dpae-As′, while in the thiocyanate analogue units are linked by the dpae ligands into a two-dimensional web. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR).     

Syntheses, spectroscopic and structural characterization of some (solvated) binuclear adducts of the form Ag(oxyanion):dpem(:S) (1:1(:x))2 (oxyanion = ClO4, F3CCO2, F3CSO3; dpem = Ph2E(CH2)EPh2 (E = P, As))

Syntheses, spectroscopic (IR, NMR and ESI MS) and single crystal X-ray structural characterizations are reported for a wide variety of adducts of Ag(oxyanion):dpem(:S) (1:1(:n))₂ (oxyanion = ClO₄, F₃CCO₂ (tfa) F₃CSO₃ (tfs); dpem = Ph₂E(CH₂)EPh₂) stoichiometry among which the basic Ag(Ph₂E(CH₂)EPh₂)₂Ag core is diversely perturbed by interactions with anions and solvent molecules. ESI MS and ³¹P NMR spectroscopy indicated that dinuclear species also exist in solution.     

Syntheses and structures of adducts of stoichiometry MX:dpex (2:1)(n), M = Cu, Ag, X = (pseudo-) halogen, dppx = Ph2E(CH2)xEPh2, E = P, As

Single crystal X-ray studies have defined the structures of a number of adducts of the form MX:dpex (2:1), M = univalent coinage metal (Cu, Ag), X = (pseudo-)halide, dpex = bis(diphenylpnicogeno)alkane, Ph₂E(CH₂)_xEPh₂, E = P, As, of diverse types, some novel. The adducts of AgCl,Br:dppm and AgNCO:dpem (x = 1) are tetranuclear as is the AgNO₃:dppp (x = 3) array, all derivative of the familiar ‘step’ structure while the combination CuCN:dppm yields a two-dimensional web of twenty-membered macro/metallacycles. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR).     

The structural definition of adducts of stoichiometry AgX:dppf (1:1)(n), X = simple anion, dppf = bis(diphenylphosphino)ferrocene

Single crystal X-ray structural characterizations are recorded for an array of adducts of the form AgX:dppf (1:1)_(n), X = simple (pseudo-)halide or oxy-anion, ‘dppf’ = bis(diphenyl phosphino)ferrocene, for adducts X = Cl (new phase), Br, I, SCN, OCN, CN, NO₃ (new phase), O₂CCH₃, n = 2, the form being dimeric [(dppf-P,P′)Ag(μ-X)₂Ag(P,P′-dppf)], for X = I, SCN, [Ag(μ-X)₂(P-dppf-P′)₂Ag′]; for X = O₂CCF₃, n = ∞, the form is an extended polymer: ?Ag(O · CO · CF₃)(P-dppf-P′)Ag′(O?. A dichloromethane solvate phase of CuI:dppf (1:1)₂ (also centrosymmetric) is also recorded. Synthetic procedures for all adducts have been reported. All compounds have been characterized both in solution (¹H, ¹³C, ³¹P NMR, ESI MS) and in the solid state (IR). The topology of the structures in the solid state was found to depend on the nature of the counterion.     

The structural definition of adducts of stoichiometry MX:dpex (2:3)(∞), M = Cu, Ag, X = simple anion, dpex = Ph2E(CH2)xEPh2, E = P, As

Single crystal X-ray structural characterizations are recorded for a number of adducts of MX:dpex (2:3) stoichiometry (MX = simple univalent copper or silver salt; dpex = Ph₂E(CH₂)_xEPh₂ (E = P, As)). CuX:dppe (2:3) (X = Cl, Br, I, CN) are binuclear [(dppe-P,P′)CuX(P-dppe-P′)CuX(P,P′-dppe)], all centrosymmetric. AgX:dpex (2:3) (dpex = ‘dpae’ (Ph₂As(CH₂)₂AsPh₂), X = Br, F₃CCO₂ (= ‘tfa’), F₃CSO₃ (≡ ‘tfs’); dpex = ‘dpape’ (Ph₂As(CH₂)₂PPh₂), X = CN, SCN, OClO₃) are one-dimensional polymers ?-E′)₁AgX(E-dpex-E′)₂-AgX(E-dpex-E′)₁AgX?, P, As sites scrambled in the latter. AgNO₃:dpam (2:3) is also a one-dimensional polymer, ?AgO·NO·OAg(As-dpam-As)AgO·NO·OAg? (‘dpam’ ≡ Ph₂As(CH₂)₂AsPh₂). AgX:dpae (2:3) (X = I, CN, ClO₄, NO₃) and AgX:dpape (2:3) (X = Br, I, NO₃) are two-dimensional polymers with large 30-membered macrocyclic rings; similar webs are found for dppx ligands in AgOH:dppb (2:3) and AgNCO, Agtfa:dpph (2:3) with 42- and 54-membered rings. Complexes AgX:dpape (1:3) (X = Cl, Br) are defined as mono-nuclear [XAg(Ph₂P(CH₂)₂AsPh₂)₃] arrays, the unidentate ligands predominantly P-bound. Synthetic procedures for the adducts are reported, selected compounds being characterized both in solution (¹H, ³¹P NMR, ESI MS) and in the solid state (IR).     

[Co{Ph2P(O)CH2P(O)Ph2}3][CoCl4] · 8CHCl3: Crystal structure and formation from [Co2(Ph2PCH2PPh2)(CO)6] in chloroform

When a solution of [Co₂(Ph₂PCH₂PPh₂)(CO)₆] in chloroform or deuterochloroform is allowed to stand in air at room temperature, it deposits dark green crystals of [Co{Ph₂P(O)CH₂P(O)Ph₂}₃][CoCl₄] · 8CHCl₃. The same product is formed more quickly and in much higher yield (80% based on Co) if the reaction is carried out in the presence of 2 equiv. of [Ph₂PCH₂PPh₂]; the Co^II appears to catalyse the air-oxidation of [Ph₂PCH₂PPh₂]. The salt was characterised by X-ray crystallography and shown to contain octahedral Co^II cations and Co^II tetrahedral anions having normal bond lengths and angles.     

Synthesis and structural characterization of adducts of silver(I) carboxylate salts AgX (X = CF3COO, CH3COO) with ER3 (E = P, As; R = Ph, cy, o-tolyl) and oligodentate aromatic bases derivative of 2,2′-bipyridyl, L, AgX:PR3:L (1:1:1)

Twenty-one adducts of the form AgX:ER₃:L (1:1:1) (X = CF₃COO (‘tfa’), CH₃COO (‘ac’), E = P, As; R = Ph, cy, o-tolyl; L = 2,2′-bipyridyl (‘bpy’)-based ligand) have been synthesized and characterized by analytical, spectroscopic (IR, far-IR, ¹H, ¹⁹F and ³¹P NMR) and single crystal X-ray diffraction studies. The resulting complexes are predominantly of the form [(R₃E)AgL]⁺X⁻, with a trigonal EAgN₂ coordination environment, the planarity of which may be perturbed by the approach of anion or solvent. The carboxylate anions have been found to be uni-, or semi-bidentate, or also completely ionic, as in the complexes [Ag(PPh₃)(bpy)(H₂O)](tfa) and [Ag(PPh₃)(dpk · H₂O)](tfa) (‘dpk · H₂O’ = bis(2-pyridyl)ketone (hydrated)). The complexes Agac:PPh₃:dpa (1:1:1) and Agac:P(o-tol)₃:dpa:MeCN (1:1:1:1) are dinuclear, with bridging unidentate acetate and terminal unidentate dpa (‘dpa’ = bis(2-pyridyl)amine).     

Synthesis and characterization of silver(I) derivatives containing acylpyrazolonate and phosphino ligands: X-ray crystal structures of monomeric [Ag(Q)(PPh3)2] and of dimeric [{Ag(Q)(PiBu3)}2] (Q = 1-phenyl-3-methyl-4-tert-butylacetylpyrazolon-5-ato)

New silver(I) acylpyrazolonate derivatives [Ag(Q)], [Ag(Q)(PR₃)]₂ and [Ag(Q)(PR₃)₂] (HQ = 1-R¹-3-methyl-4-R²(CO)pyrazol-5-one, HQ^Bn = R¹ = C₆H₅, R² = CH₂C₆H₅; HQ^CHPh2 = R¹ = C₆H₅, R² = CH(C₆H₅)₂; HQ^nPe = R¹ = C₆H₅, R² = CH₂C(CH₃)₃; HQ^tBu = R¹ = C₆H₅, R² = C(CH₃)₃; HQ^fMe = R¹ = C₆H₄-p-CF₃, R² = CF₃; HQ^fEt = R¹ = C₆H₅, R² = CF₂CF₃; R = Ph or iBu) have been synthesized and characterized in the solid state and solution. The crystal structure of 1-(4-trifluoromethylphenyl)-3-methyl-5-pyrazolone, the precursor of proligand HQ^fMe and of derivatives [Ag(Q^nPe)(PPh₃)₂] and [Ag(Q^nPe)(PiBu₃)]₂ have been investigated. [Ag(Q^nPe)(PPh₃)₂] is a mononuclear compound with a silver atom in a tetrahedrally distorted AgO₂P₂ environment, whereas [Ag(Q^nPe)(PiBu₃)]₂ is a dinuclear compound with two O₂N-exotridentate bridging acylpyrazolonate ligands connecting both silver atoms, their coordination environment being completed by a phosphine ligand.     

A new series of iodocarbonyl ruthenium (II) complexes with unsymmetrical phosphine-phosphine sulfide ligands of the type Ph2P(CH2)nP(S)Ph2, n = 1-4: Isolation and structural investigation

Hexa-coordinated chelate complex cis-[Ru(CO)₂I₂(P∩S)] (1a) {P∩S = η²-(P,S)-coordinated} and penta-coordinated non-chelate complexes cis-[Ru(CO)₂I₂(P∼S)] (1b-d) {P∼S = η¹-(P)-coordinated} are produced by the reaction of polymeric [Ru(CO)₂I₂]_n with equimolar quantity of the ligands Ph₂P(CH₂)_nP(S)Ph₂ {n = 1(a), 2(b), 3(c), 4(d)} in dichloromethane at room temperature. The bidentate nature of the ligand a in the complex 1a leads to the formation of five-membered chelate ring which confers extra stability to the complex. On the other hand, 1:2 (Ru:L) molar ratio reaction affords the hexa-coordinated non-chelate complexes cis,cis,trans-[Ru(CO)₂I₂(P∼S)₂] (2a-d) irrespective of the ligands. All the complexes show two equally intense terminal ν(CO) bands in the range 2028-2103 cm⁻¹. The ν(PS) band of complex 1a occurs 23 cm⁻¹ lower region compared to the corresponding free ligand suggesting chelation via metal-sulfur bond formation. X-ray crystallography reveals that the Ru(II) atom occupies the center of a slightly distorted octahedral geometry. The complexes have also been characterized by elemental analysis, ¹H, ¹³C and ³¹P NMR spectroscopy.     

Synthesis and structural characterization of adducts of silver(I) nitrate with ER3 (E = P, As, Sb; R = Ph, cy, o-tolyl, mes) and oligodentate aromatic bases derivative of 2,2′-bipyridyl, L, AgNO3:ER3:L (1:1:1)

Twenty-one adducts of the form AgNO₃:ER₃:L (1:1:1) (E = P, As, Sb; R = Ph, cy, o-tolyl, mes; L = 2,2′-bipyridyl (‘bpy’)-based ligand), together with AgNO₃:Pcy₃:tpy (2:2:1) and AgNO₃:PPh₃:tpy (1:2:1) (‘tpy’ ≡ (2,2′:6,2″-terpyridine)), have been synthesized and characterized by analytical, spectroscopic (IR, far-IR, ¹H and ³¹P NMR) and single crystal X-ray diffraction studies. The resulting complexes are predominantly of the form , with trigonal EAgN₂ coordination environments, the planarity of which is perturbed by the approach of the nitrate anion. The nitrate ion shows uni- or (semi-)bidentate coordination, excepting the complex AgNO₃:P(o-tol)₃:dpca (1:1:1) (dpca = bis(2-picolyl)amine) where the anion is uncoordinated, the donor dpca being a pincer-tridentate. The complex AgNO₃:Pcy₃:tpy (2:2:1), also reported, is dinuclear with a bridging unidentate nitrate and a terpyridine, the latter bridging through its central ring, with the peripheral rings forming chelates to either side, whereas the complex AgNO₃:PPh₃:tpy (1:2:1) is ionic with a five-coordinate silver, bonded to tridentate tpy and two phosphines.     

Tripodal polyphosphine ligands in silver (I) coordination chemistry: Mononuclear cf. polynuclear complex dependence vis-a-vis counterion and ligand to metal ratio

1:2, 1:1, 3:2 and 6:2 AgX:L adducts (where L is a tridentate phosphine, in detail: 1,1,1-tris(diphenylphosphinomethyl)ethane (Me-triphos) and bis(2-diphenylphosphinoethyl)phenylphosphine (Ph-triphos), X = O₃SCF₃, O₃SCH₃, BF₄ or O₂CCF₃) have been synthesized and characterized by IR, NMR (¹H, ³¹P and ¹⁹F) and ESI MS spectroscopy. The stoichiometry of the complexes is strongly dependent on the ligand to metal ratio employed and also on the nature of the counterion. ³¹P NMR (solution) data also show the complexes existing in solution, in some cases, however, disproportionating to adducts of different nuclearity. Oligonuclear species have been detected through ESI MS spectroscopy that has been demonstrated as a powerful tool for the identification of the solution species. AgBF₄:Me-triphos (1:2) has been structurally characterized as [Ag(P,P′-Me-triphos)₂](BF₄) · H₂O · 7/2 MeOH, while Ag(O₃SCF₃): Ph-triphos: H₂O (6:2:4) is a spectacular two-dimensional polymer.     

Complexes formed from 2,4,6-trimercaptotriazine (H3TMT): synthesis and structural characterization of [M(PhP(CH2CH2P(Ph)2)2(HTMT)], M=Ni(II), Pd(II), Pt(II)

Na₃TMT · 9H₂O (H₃TMT=2,4,6-trimercaptotriazine) reacts with M(PPP)Cl₂, PPP=PhP(CH₂CH₂PPh₂)₂, M=Ni, Pd, Pt, to give the compounds [M(PPP)(HTMT)]. The nickel and palladium complexes have been characterized by single-crystal X-ray diffraction analysis. PPP is tridentate in both complexes. The nickel complex has an irregular trigonal bipyramidal configuration in which the triazine is bidentate, coordinating through one sulfur and one nitrogen donor atom. The palladium complex has an approximately square planar geometry in which the triazine forms a strong Pd-S bond in the plane and also a very weak Pd-N interaction above the plane. The ³¹P NMR spectrum of the platinum complex is similar to that of the palladium complex, which is consistent with the Pt complex also having an approximately square-planar structure. Variable temperature NMR spectra show that two conformational isomers of the nickel complex are present in solution at low temperatures, though exchange is fast at room temperature. DFT calculations have confirmed the possible existence of two five-coordinate isomers of comparable stability.     

Complexes of the {ReOX2} (X = Cl, Br) core with single amino acid chelate derivatives

The reactions of 1 equiv. of the ligand 3-(ethoxycarbonylmethyl-pyridin-2-ylmethyl-amino)-propionic acid methyl ester (2) with the Re(V) starting materials [ReOX₃(PPh₃)₂] (X = Cl, Br) in refluxing chloroform yielded the Re(V)-oxo dihalide complexes [ReOX₂{(C₅H₄NCH₂)N(CH₂CO₂)(C₂H₄CO₂CH₃)}] (X = Cl, 3; X = Br, 4). The complexes were characterized by elemental analysis, NMR and IR spectroscopy, cyclic voltammetry and X-ray crystallography. Complex 3 displays distorted octahedral coordination geometry with the tridentate ligand coordinating facially to the Re(V) center. The carboxylate oxygen atom occupies an axial site trans to the ReO bond. The two chlorine atoms consequently adopt a cis configuration.     

Synthesis and X-ray structure of an octahedral platinum-silver cluster [(Ph3P)2N]2[Pt2Ag4Cl2(C2Ph)8] with disordered silver atoms

Variable-temperature X-ray structural study of the complex [(Ph₃P)₂N]₂[Pt₂Ag₄Cl₂(C₂Ph)₈] prepared by the reaction of cis-[PtCl₂(AsPh₃)₂] and [(Ph₃P)₂N][Ag(C₂Ph)₂] in 1:2 M ratio, revealed isolated (non-polymerised) [Pt₂Ag₄Cl₂(CCPh)₈]²⁻ anions with a pseudo-octahedral arrangement of metal atoms. The Pt atoms (in mutually trans vertices) are each σ-bonded to four alkynyl ligands in a square planar arrangement; these moieties are bridged by four Ag atoms; each silver atom being η²-bonded to two alkynyl groups. Chloride ligands are asymmetrically bridging two opposite Ag-Ag edges. Silver atoms show strong and unusual temperature-dependent disorder.     

Synthesis and structural characterization of dinuclear iridium hydrido complex with 3,6-bis(2-pyridyl)tetrazine, [Ir2(H)4(PPh3)4(bptz)](PF6)2 · 4CH2Cl2

Reaction of the precursor Ir complex [Ir(H)₂(PPh₃)₂(Me₂CO)₂]PF₆ with 3,6-bis(2-pyridyl)tetrazine (bptz) in CH₂Cl₂ gave a novel dinuclear Ir hydrido complex [Ir₂(H)₄(PPh₃)₄(bptz)](PF₆)₂ · 4CH₂Cl₂. Crystallographic study described an interesting coordination environment having a π-π interaction and ¹H NMR study showed unique upfield shifts of pyridyl rings that are likely induced by the ring current effect of neighboring PPh₃ ligands.     

Homoleptic platinum(II) and palladium(II) complexes of 1,5,9-trithiacyclododecane: the crystal structures of [Pt(12S3)2](PF6)2 · 2CH3NO2 and [Pd(12S3)2](BF4)2 · 0.5H2O

The synthesis, spectroscopy, electrochemistry, and crystal structures of two new mononuclear homoleptic Pt(II) and Pd(II) complexes with the crown trithioether 1,5,9-trithiacyclododecane (12S3) are reported. In contrast to behavior with analogous smaller ring trithiacrowns, both metal complexes exhibit exodentate axial sulfur donors, a consequence of the preferred conformation of the 12S3 ligand. The lack of two axial metal-sulfur interactions correlates with the observed electronic spectroscopy and oxidative electrochemistry displayed by the complexes and contrasts with properties exhibited by complexes containing smaller polythioether macrocycles. The two complexes have electronic spectra dominated by charge transfer, not d-d bands and show no M²⁺/M³⁺ couples. Both complexes show a fluxional 12S3 ligand in solution due to a 1,5-metallotropic shift, an uncommon observation of this particular type of intramolecular ligand exchange. The ¹⁹⁵Pt NMR chemical shift of −4201 ppm for [Pt(12S3)₂]²⁺ is consistent with an alternating positioning of the four sulfur lone pairs on the coordinated thioethers. Although 12S3 is poorly pre-organized for facial complexation, its flexibility to position a sulfur in an exodentate fashion enables it to form stable complexes with d⁸ metal ions such as Pt(II) and Pd(II).     

A seven-coordinate Fe compound: [Fe{O(CH2CO2)2}(H2O)2(NO3)]. Preparation, structure and magnetic properties

A seven-coordinate Fe^III complex, [Fe(oda)(H₂O)₂(NO₃)], was obtained after dissolving Fe(NO₃)₃ · 9H₂O in an aqueous solution of oxydiacetic acid (H₂oda) at room temperature. In the solid state, the Fe^III center adopts a pentagonal bipyramid geometry with an {FeO₇} core formed by a tridentate oda²⁻ and a bidentate in the equatorial plane, and two axial water molecules. Magnetic measurements and EPR spectra revealed the presence of S = 5/2 Fe^III centers with rhombic zero field splitting parameters (D = 0.81 cm⁻¹, E/D = 0.33 ). Weak antiferromagnetic interactions with J ≈ −0.06 cm⁻¹ operating between neighboring Fe ions connected through Fe-O-C-O?H-O-Fe paths are estimated using the molecular field approximation.     

Syntheses and spectroscopic and structural characterization of silver(I) complexes containing tris(isobutyl)phosphine and poly(azol-1-yl)borates

Silver(I) derivatives [Ag(L)(PⁱBu₃)] (L = H₂B(tz)₂ (dihydrobis(1H-1,2,4-triazol-1-yl)borate), HB(tz)₃ (hydrotris(1H-1,2,4-triazol-1-yl)borate), Tp (hydrotris(1H-pyrazol-1-yl)borate), Tp∗ (hydrotris(3,5-dimethyl-1H-pyrazol-1-yl)borate), Tp^Me (hydrotris(3-methyl-1H-pyrazol-1-yl)borate), Tp^CF3 (hydrotris(3-trifluoromethyl-1H-pyrazol-1-yl)borate), Tp^4Br (hydrotris(4-bromo-1H-pyrazol-1-yl)borate), HB(btz)₃ (hydrotris(1H-1,2,4-benzotriazol-1-yl)borate), Tm (hydrotris(3-methy-1-imidazolyl-2-thione)borate), pzTp (tetrakis(1H-pyrazol-1-yl)borate), pz⁰Tp^Me (tetrakis(3-methyl-1H-pyrazol-1-yl)borate) have been synthesized from the reaction of [Ag(NO₃)(PⁱBu₃)₂] with ML (M = Na or K) and characterized both in solution (¹H- and ³¹P{¹H} NMR, ESI MS spectroscopy, conductivity) and in the solid state (IR, single crystal X-ray structure analysis). These complexes are air-stable and light-sensitive and non-electrolytes in CH₂Cl₂ and acetone in which they slowly decompose, even with the strict exclusion of oxygen and light, yielding metallic silver and/or azolate (Az) species of formula [Ag(Az)(PⁱBu₃)_x] upon breaking of the bridging B-N_(azole) bond. The solid state structures of [Ag(Tp)(PⁱBu₃)], [Ag(Tp^Me)(PⁱBu₃)], [Ag(Tp^CF3)(PⁱBu₃)], [Ag{HB(btz)₃}(PⁱBu₃)], and [Ag(Tm)(PⁱBu₃)] show that the silver atom adopts a distorted tetrahedral coordination geometry. [Ag(L)(PPh₃)] can be easily obtained from the reaction of [Ag(L)(PⁱBu₃)] with excess PPh₃, whereas from the reverse reaction of [Ag(L)(PPh₃)] with PⁱBu₃a mixture of [Ag(L)(PⁱBu₃)] and [Ag(L)]₂ and [Ag(L)(PPh₃)] was recovered. ³¹P{¹H} NMR variable temperature NMR studies showed that in the pz⁰Tp^x derivatives the scorpionate ligand acts as a bidentate donor, whereas tridentate coordination is found for all tris(azolyl)borate derivatives, both in solution and in the solid state. ESI MS data suggest the existence in solution of species such as [Ag(PⁱBu₃)₂]⁺ upon dissociation of the L ligand, and also the formation of dimeric species of the form [Ag₂(L)(PⁱBu₃)₂]⁺.     

Preparation, crystal structure and magnetic property of a binuclear oxalate-bridged iron(III) compound: Fe2(C2O4)Cl4(DMF)4 (DMF = dimethylformamide)

An oxalato-bridged binuclear iron(III) compound, Fe₂(C₂O₄)Cl₄(DMF)₄ (DMF = dimethylformamide), was obtained by electrocrystallization for three weeks at 3.4 V and it displays a strong antiferromagnetic interaction of J = −6.74(4) cm⁻¹.