The evaluation of singlet-triplet separations for [W2(μ-H)(μ-Cl)Cl4(μ-dppm)2] and [W2(μ-H)2 (μ-O2CC6H5)2(P(C6H5)3)2] based on P NMR and crystallographic data

The singlet-triplet separations for the edge-sharing bioctahedral (ESBO) complex W₂(μ-H)(μ-Cl)(Cl₄(μ-dppm)₂ · (THF)₃ (II) has been studied by ³¹P NMR spectroscopy. The structural characterization of [W₂(μ-H)₂(μ-O₂CC₆H₅)₂Cl₂(P(C₆H₅)₃)₂] (I) by single-crystal X-ray crystallography has allowed the comparison of the energy of the HOMOLUMO separation determined using the Fenske-Hall method for a series of ESBO complexes with two hydride bridging atoms, two chloride bridging atoms and the mixed case with a chloride and hydride bridging atom. The complex representing the mixed case, [W₂(μ-H)(μ-Cl)Cl₄(μ-dppm)₂ · (THF)₃] (II), has been synthesized and the value of −2J determined from variable-temperature ³¹P NMR spectroscopy.     

Strong antiferromagnetism in the dinuclear 2-pyridone complex with N–C–O bridges: A paddle-wheel analogue of the dinuclear tetracarboxylates

A novel dinuclear complex [Cu₂(μ-L)₄(HL)₂] (1) was isolated from starting 2-pyridone (HL) via a resonance and a tautomeric transformation. Each copper centre is in a square-pyramidal coordination sphere, defined by two oxygen atoms (Cu–O4 1.978(5), Cu–O11 1.964(4) Å) and two nitrogen atoms (Cu–N2 2.003(5), Cu–N3 2.007(5) Å) of four bridging deprotonated pyridin-2-olates and an oxygen atom on the top from a neutral 2-pyridone (Cu–O2 2.227(5) Å), analogous to tetracarboxylate paddle-wheel complexes. Compound 1 was compared with mixed pyridin-2-olato/methanoato analogues [Cu₂(μ-HCO₂)₂(μ-L)₂(HL)₂] · 2CH₃CN (2) and [Cu₂(μ-HCO₂)₂(μ-L)₂(HL)₂] (2a) (2a is an air stable form obtained from 2 outside mother-liquid). The EPR spectra of air stable 1 and 2a show three signals H_z1, H₂ and H_z2, typical for the binuclear systems with spin S = 1, both revealing strong antiferromagnetism 2J = −334 (1) and −324 cm⁻¹ (2a). Interestingly, only for 1 additional H₁ signal at 100 mT is noticed (D(1) = 0.293 cm⁻¹ < hν = 0.320 cm⁻¹ < D(2a) = 0.347 cm⁻¹). On the other hand, several broad signals in the 100–450 mT region, only in the high temperature spectrum for 2a are observed. These results are in agreement with the magnetic susceptibility analysis.     

N,N′-bis(substituted-phenyl)oxamides and their dinuclear pentacoordinate nickel(II) complexes

The preparation, spectroscopic characterization and magnetic study of N,N′-bis(substituted-phenyl)oxamidate-bridged nickel(II) dinuclear complexes of formula {[Ni(N₃-mc)]₂(μ-CONC₆H₄-X)}(PF₆)₂ (N₃-mc = 2,4,4-trimethyl-1,5,9-triazacyclo-dodec-1-ene (Me₃-N₃-mc) or 2,4,4,9-tetramethyl-1,5,9-triazacyclododec-1-ene (Me₄-N₃-mc), X = 2-Cl, 4-Cl, 2-OCH₃, 4-OCH₃) are reported. These paramagnetic nickel(II) complexes have been characterized by both one- and two-dimensional (COSY) ¹H NMR techniques. The COSY spectrum of 5 has allowed to achieve the assignment of the phenyl protons of the N,N′-diphenyloxamidate. The crystal structures of [Ni(Me₃-N₃-mc)(μ-CONC₆H₄-4-Cl)]₂(PF₆)₂ (6), [Ni(Me₃-N₃-mc)(μ-CONC₆H₄-4-OMe)]₂(PF₆)₂ (8) and [Ni(Me₄-N₃-mc)(μ-CONC₆H₄-2-Cl)]₂(PF₆)₂ (9) have been determined and their magnetic properties have been studied. The value of magnetic coupling between the two nickel(II) ions across the oxamidate bridge [J = − 37.6 (6), −39.9 (8) and −39.7 cm⁻¹ (9)] is sensitive to the distortion of the coordination sphere of the metal ions and the topology of the molecular bridge.     

Syntheses, crystal structures and magnetic properties of a new nitronyl nitroxide NIT2-bithph and its manganese(II) compound [Mn(hfac)2(IMHBithph)]2·(NIT2-bithph)(C6H14)

A new nitronyl nitroxide NIT2-bithph (1) and its manganese(II) compound [Mn(hfac)₂(IMHBithph)]₂·(NIT2-bithph)(C₆H₁₄) (2) (hfac = hexafluoroacetylacetonate; NIT2-bithph = 4,4,5,5-tetramethyl-2-(bithiophenal-2-yl)imidazoline-1-oxyl-3-oxide; IMHBithph = 1-hydroxy-2-bithiophenal-4,4,5,5-tetramethyl-4,5-dihydro- 1H-imidazole) have been synthesized and structurally characterized by X-ray diffraction methods. The units of compound 1 were connected as one-dimensional chain by the intermolecular hydrogen bonds which afford an intermolecular antiferromagnetic interaction between nitronyl nitroxide radicals within the chain (J = −1.89 cm⁻¹). Compound 2 resulting from the reaction of Mn(hfac)₂·2H₂O and NIT2-bithph is dinuclear and includes the reduced amidino-oxide form of NIT2-bithph, it is made up of three parts: a [Mn(hfac)₂(IMHBithph)]₂ dimer unit, an uncoordinated NIT2-bithph radical and a noncoordinated solvent molecule of hexane, the molecule of radical is hydrogen bonded to its reduced form. Two reduced IMHBithph ligands bridge the two manganese(II) ions through their amidino-oxide oxygen atoms resulting in a small intramolecular antiferromagnetic interaction between the manganese ions (J = −1.55 cm⁻¹).     

Dinuclear molybdenum complexes derived from diphenols: electrochemical interactions and reduced species

The new diphenolato complexes [{Mo(NO){HB(dmpz)₃}Cl}₂Q] where dmpz = 3,5-dimethylpyrazolyl and Q = OC₆H₄(C₆H₄O (n = 1 or 2), OC₆H₄CR=CRC₆H₄O (R = H or Et), and OC₆H₄CH=CHC₆H₄CH=CHC₆H₄O have been prepared and their electrochemical properties (cyclic and differential pulse voltammetry) compared with previously reported analogues where Q = OC₆H₄O, OC₆H₄EC₆H₄O (E = SO₂, CO and S), OC₆H₄ (CO)C₆H₄ C₆H₄(CO)C₆H₄O and 1,5- and 2,7-O₂C₁₀H₆. The electrochemical interaction between the redox centres in the new complexes is very weak, in contrast to that in the 1,4-benzenediolato and naphthalendiolato species. The EPR spectra of the reduced mixed-valence species [{Mo(NO){HB(dmpz)₃}Cl}₂Q]⁻ where Q = 1,3- and 1,4-OC₆H₄O and OC₆H₄SC₆H₄O shows that they are valence-trapped at room temperature, whereas those of the dianions [{Mo(NO){HB(dmpz)₃}Cl}₂Q]²⁻ where Q = 1,4-OC₆H₄O, OC₆H₄EC₆H₄O (E = CO or S) and OC₆H₄CH=CHC₆H₄CH=CHC₆H₄O shows that the unpaired spins on each molybdenum centre are strongly correlated (J, the spin exchange integral A_Mo, the metal-hyperfine coupling constant). The electrochemical properties and the comproportionation constants for the reaction [{Mo(NO){HB(dmpz)₃} Cl}₂Q] + [{Mo(NO){HB(dmpz)₃}Cl}O]₂]²⁻2[{Mo(NO) {HB(dmpz)₃}Cl}₂Q]⁻ where Q = diphenolato bridge, are compared with related compounds containing benzenediamido and dianilido bridges.     

Thiocyanato adducts of chromium(II) carboxylates and the molecular structure of tetraethyl-ammonium tetra-μ-propionatodiisothio-cyanatodichromate(II)

X-Ray crystallographic studies on [NEt₄]₂[Cr₂[(O₂CC₂H₅)₄(NCS)₂] show that the Cr–Cr separation (2.467Å) in the dinuclear anion is one of the longest known. The thiocyanato groups are N-bonded, and the results emphasize the known sensitivity of the quadruple Cr–Cr bond to the nature of the axial ligands. The compound crystallises in the tetragonal space group P4/mnc with two molecules per unit cell, the dimensions of which are a = b = 9.785(1), c = 21.186(2) Å. Magnetic investigations from room to liquid nitrogen temperature on the tetra-μ-propionato complex and on [NMe₄]₂ [Cr₂(O₂CCH₃)₄(NCS)₂] show that both complexes have been obtained free from paramagnetic chromium(III) impurities. Their weak paramagnetic susceptibilities (X_cr is approx. 200 x 10⁻⁶ cm³ mol⁻¹ at 295 K and 50 x 10⁻⁶cm³mol⁻¹ at 90 K) are inherent, and are ascribed to temperature independent paramagnetism at low temperature plus para-magnetism arising from slight population of the triplet state (2J 700 cm⁻¹, g = 2, N = 50 x 10⁻⁶cm³mol⁻¹) at higher temperatures.     

Tetra(μ3-hydroxo)hexa(μ2-carboxylato-O,O′)-bridged tetranuclear terbium(III) cubane complex

A novel tetranuclear terbium(III) complex [Tb₄(OH)₄(pybet)₆(H₂O)₈][Tb₄(OH)₄(pybet)₆(H₂O)₇ (NO₃)](ClO₄)₁₄·6H₂O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb₄(μ₃-OH)₄(μ₂-carboxylato-O,O′)₆ core. The ligand pybet is pyridinoacetate, C₅H₅⁺N-CH₂CO₂⁻. Magnetic susceptibility data were measured for this Tb₄ complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction (J = −0.015 cm⁻¹) or there is a small crystal-field splitting of the ⁷F₆ Tb^III ground state.     

Copper(II)-activated transformation of azomethine to imidate: synthetic and structural studies

The Schiff base 2-pyridine–carboxaldehyde 4-dimethylaminobenzoylhydrazone (HL, 1) was prepared by reacting 2-pyridine–carboxaldehyde and 4-dimethylaminobenzoylhydrazine in a 1:1 molar ratio in methanol. Reaction of HL (1) with Cu(O₂CCH₃)₂·H₂O (in a 1:1 molar ratio) in methanol afforded a dinuclear copper(II) complex, [Cu₂(μ-O₂CCH₃)₂L′₂]·2H₂O (2). The azomethine functionality (---CH=N---) of 1 is converted to imidate (---C(OMe)=N---) in the complexed ligand L′⁻. Molecular structures of both 1 and 2 were determined by X-ray crystallographic studies. The dinuclear molecule of 2 is centrosymmetric and contains two monoatomic bridging acetate groups. Each copper(II) centre is in a square-pyramidal N₂O₃ coordination sphere. The ligand, L′⁻ coordinates the metal ion via the pyridine-N, the imidate-N, and the deprotonated amide-O atoms. One of the acetate oxygen atoms completes the N₂O₂ square-plane. The oxygen of the symmetry-related acetate fills the apical coordination site. Structural parameters are consistent with both copper ions being in a +2 oxidation state. The room temperature magnetic moment is 1.89 μ_B (per Cu). In powder phase the complex displays an axial EPR spectrum at 298 K. The complex is nonconducting in methanol solution. The electronic spectrum shows a ligand field absorption at 680 nm and charge transfer bands in the range 426–215 nm.     

Preparation and X-ray characterization of two-coordinate Cu(I) complex of aliphatic thiolato ligand: Effect of steric bulk on coordination features

We have synthesized in a single-step procedure from available copper(I) precursor at RT two Cu(I) thiolato clusters of the formula [Cu₄(μ-SCH(CH₃)₂)₆]²⁻ and [Cu₅(μ-SC(CH₃)₃)₆]⁻ as revealed by X-ray crystallography, where increased steric bulk leads to a bigger cage with some two-coordinate metal centers. In addition, we identified a mononuclear two coordinate thiolato complex with the bulkier ligand, of the formula NEt₄[Cu(SC(CH₃)₃)₂]. This is only the second example of such a complex of an aliphatic ligand that is structurally characterized. The X-ray structure reveals an S–Cu–S angle of 176.7–179.5°, with Cu–S distances of 2.14 Å.     

Synthesis and properties of some diruthenium acetate compounds

The compound [Ru₂(μ-O₂CCH₃)₄(THF)₂]BF₄ (I) containing the Ru₂⁵⁺ unit was prepared by reaction of Ru₂Cl(μ-O₂CCH₃)₄ with AgBF₄ in THF. This compound, in contrast with Ru₂Cl(μ-O₂CCH₃)₄, is soluble in several polar organic solvents and reacts in THF with OPPh₃ and PPh₃ giving [Ru₂(μ-O₂CCH₃)₄(OPPh₃)₂]BF₄·CH₂Cl₂ (II) and [Ru(μ-O₂CCH₃)(O₂CCH₃)(PPh₃)]_n (III), respectively. The complex II has been also obtained as hexafluorophosphate [Ru₂(μ-O₂CCH₃)₄(OPPh₃₂]PF₆·CH₂Cl₂ (IV) by treatment of Ru₂Cl(μ-O₂CCH₃)₄ with an excess of NOPF₆ and PPh₃ in methanol. In this reaction the triphenylphosphine oxide is generated by oxidation of the triphenylphosphine.     

Synthesis and spectroscopic, magnetic and EPR studies of di-μ-hydroxo-bis[(NN)(N-phenyl-2-pyridinamine)copper(II)]hexaflourophosphate, with NN=2,2′-bipyridine or 1,10-phenanthroline.: X-ray crystal structure of the 2,2′-bipyridine complex

Binuclear complexes [{Cu(NN)(PhNHpy)}₂(μ-OH)₂](PF₆)₂, where NN=2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen), have been synthesized and characterized by chemical analysis, conductance measurements and IR and electronic spectroscopy. The X-ray crystal structure of [{Cu(bipy)(PhNHpy)}₂(μ-OH)₂](PF₆)₂ shows a distorted square-planar pyramidal coordination for Cu(II), defined by two nitrogen atoms of bipy, two bridging oxygen atoms and the pyridinic nitrogen atom of the ligand. Magnetic susceptibility measurements (in the 4.8–290 K range) reveal coupling which is antiferromagnetic for the bipy complex (2J=−24.2 cm⁻¹) and slightly ferromagnetic for the phen complex (2J=3.3 cm⁻¹). The EPR spectra show the expected triplet signals.     

Preparation and characterization of ruthenium(II), rhodium(III) and iridium(III) complexes of isocyanide bearing the azo group

Reactions of [(η⁶-arene)RuCl₂]₂ (1) (η⁶-arene=p-cymene (1a), 1,3,5-Me₃C₆H₃ (1b), 1,2,3-Me₃C₆H₃ (1c) 1,2,3,4-Me₄C₆H₂(1d), 1,2,3,5-Me₄C₆H₂ (1e) and C₆Me₆ (1f)) or [Cp*MCl₂]₂ (M=Rh (2), Ir (3); Cp*=C₅Me₅) with 4-isocyanoazobenzene (RNC) and 4,4′-diisocyanoazobenzene (CN–R–NC) gave mononuclear and dinuclear complexes, [(η⁶-arene)Ru(CNC₆H₄N=NC₆H₅)Cl₂] (4a–f), [Cp*M(CNC₆H₄N=NC₆H₅)Cl₂] (5: M=Rh; 6: M=Ir)_, [{(η⁶-arene)RuCl₂}₂{μ-CNC₆H₄N=NC₆H₄NC}] (8a–f) and [(Cp*MCl₂)₂(μ-CNC₆H₄N=NC₆H₄NC)}] (9: M=Rh; 10: M=Ir)_, respectively. It was confirmed by X-ray analyses of 4a and 5 that these complexes have trans-forms for the ---N=N--- moieties. Reaction of [Cp*Rh(dppf)(MeCN)](PF₆)₂ (dppf=1,1′-bis (diphenylphosphino)ferrocene) with 4-isocyanoazobenzene gave [Cp*Rh(dppf)(CNC₆H₄N=NC₆H₅)](PF₆)₂ (7), confirmed by X-ray analysis. Complex 8b reacted with Ag(CF₃SO₃), giving a rectangular tetranuclear complex 11b, [{(η⁶-1,3,5-Me₃C₆H₃)Ru(μ-Cl}₄(μ-CNC₆H₄N=NC₆H₄NC)₂](CF₃SO₃)₄ bridged by four Cl atoms and two μ-diisocyanoazobenzene ligands. Photochemical reactions of the ruthenium complexes (4 and 8) led to the decomposition of the complexes, whereas those of 5, 7, 9 and 10 underwent a trans-to-cis isomerization. In the electrochemical reactions the reductive waves about −1.50 V for 4 and −1.44 V for 8 are due to the reduction of azo group, [---N=N---]→[---N=N---]²⁻. The irreversible oxidative waves at ca. 0.87 V for the 4 and at ca. 0.85 V for 8 came from the oxidation of Ru(II)→Ru(III).     

Syntheses, X-ray structures, and reactions of ruthenium carbonyl complexes containing 1,1-dithiolates

Treatment of [Ru₂(CO)₄(MeCN)₆][BF₄]₂ or [Ru₂(CO)₄(μ-O₂CMe)₂(MeCN)₂] with uni-negative 1,1-dithiolate anions via potassium dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium tert-butylthioxanthate, and ammonium O,O′-diethylthiophosphate gives both monomeric and dimeric products of cis-[Ru(CO)₂(η²-(SS))₂] ((SS)⁻=Me₂NCS₂⁻ (1), Et₂NCS₂⁻ (2), ^tBuSCS₂⁻ (3), (EtO)₂PS₂⁻ (4)) and [Ru(CO)(η²-(Me₂NCS₂))(μ,η²-Me₂NCS₂)]₂ (5). The lightly stabilized MeCN ligands of [Ru₂(CO)₄(MeCN)₆][BF₄]₂ are replaced more readily than the bound acetate ligands of [Ru₂(CO)₄(μ-O₂CMe)₂(MeCN)₂] by thiolates to produce cis-[Ru(CO)₂(η²-(SS))₂] with less selectivity. Structures 1 and 5 were determined by X-ray crystallography. Although the two chelating dithiolates are cis to each other in 1, the dithiolates are trans to each other in each of the {Ru(CO)(η²-Me₂NCS₂)₂} fragment of 5. The dimeric product 5 can be prepared alternatively from the decarbonylation reaction of 1 with a suitable amount of Me₃NO in MeCN. However, the dimer [Ru(CO)(η²-Et₂NCS₂)(μ,η²-Et₂NCS₂)]₂ (6), prepared from the reaction of 2 with Me₃NO, has a structure different from 5. The spectral data of 6 probably indicate that the two chelating dithiolates are cis to each other in one {Ru(CO)(η²-Et₂NCS₂)₂}fragment but trans in the other. Both 5 and 6 react readily at ambient temperature with benzyl isocyanide to yield cis-[Ru(CO)(CNCH₂Ph)(η²-(SS))₂] ((SS)=Me₂NCS₂⁻ (7) and Et₂NCS₂⁻ (8)). A dimerization pathway for cis-[Ru(CO)₂(η²-(SS))₂] via decabonylation and isomerization is proposed.     

Synthesis and magnetism of the first tetranuclear copper(II)–iron(III) complexes of macrocyclic oxamides

Four novel tetranuclear macrocyclic complexes of the formula [(CuLⁱ)₃Fe](ClO₄)₃·3H₂O (i=1–4, Lⁱ are the dianions of the [14]N₄ and [15]N₄ macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene] have been prepared and characterized. These complexes are the first examples of oxamido-bridged Cu(II)–Fe(III) heterometallic species. Cryomagnetic studies on [(CuL¹)₃Fe](ClO₄)₃·3H₂O (1) and [(CuL³)₃Fe](ClO₄)₃·3H₂O (3) (77–300 K) revealed that the Cu(II) and Fe(III) ions interact antiferromagnetically through the oxamido bridge, with the exchange integral J=−30.8 cm⁻¹ for 1 and J=−28.7 cm⁻¹ for 3 based on . The interaction parameters have been compared with that of the related [Cu₃Mn] compound.     

Structure and properties of the dinuclear complex [Co2(μ-OAc)2(OAc)2(μ-H2O)(phen)2]

The dinuclear complex [Co₂(μ-OAc)₂(OAc)₂(μ-H₂O)(phen)₂] has been prepared and its structure was determined. The compound crystallizes in the monoclinic space group P2(1)/c. The Co–Co distance is 3.574 Å and is similar to the Fe–Fe distance in the reduced methane monooxygenase hydroxylase. The electronic and IR spectra of the complex confirm octahedral coordination of the cobalt atoms and formation of strong O–HO hydrogen bonds in the solid state. The dependence of the magnetic susceptibility of the complex on temperature indicates an antiferromagnetic interaction, the value of the isotropic exchange parameter J was estimated to be −2.1 cm⁻¹. The ¹H NMR spectra show that in organic solvents the structure of compound is the same as in the solid state, however, in water solution the complex dissociates giving compounds with different Co:phen ratios.     

Homo- and hetero-bridged mixed-valence dinuclear complexes which contain the fragment ‘Rh(C6F5)3’

The reaction of the anionic mononuclear rhodium complex [Rh(C₆F₅)₃Cl(Hpz)]^t- (Hpz = pyrazole, C₃H₄N₂) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C₆F₅)₃Rh(μ-Cl)(μ-pz)M(L₂)] [M = Rh, L₂ = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO)₂ (4); M = Ir, L₂ = COD (3)]. The complex [Rh(C₆F₅)₃(Hbim)]⁻ (5) has been prepared by treating [Rh(C₆F₅)₃(acac)]⁻ with H₂bim (acac = acetylacetonate; H₂bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C₆F₅)₃Rh(μ-bim)M(L₂)]⁻ [M = Rh, L₂ = COD (6) or TFB (7); M = Ir, L₂ = COD (8); M = Pd, L₂ = η³-C₃H₅ (9)]. With [Rh(acac)(CO)₂], complex 5 yields the tetranuclear complex [{(C₆F₅)₃Rh(μ-bim)Rh(CO)₂}₂]₂₋. Homodinuclear Rh^III derivatives [{Rh(C₆F₅)₃}₂(μ-L)₂]^·- [L₂ = OH, pz (11); OH, S^tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C₆F₅)₃(μ-OH)}₂]²⁻ by the corresponding ligands. The reaction of [Rh(C₆F₅)₃(Et₂O)_x] with [PdX₂(COD)] produces neutral heterodinuclear compounds [(C₆F₅)₃Rh(μ-X)₂Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh₃⁺) salts.     

A homodinuclear complex of manganese containing novel ligand, Mn2(CO)6(μ-H){μ-S(SC3H5)C=C(PPr3)S}

The title complex Mn₂(CO)₆(μ-H){μ-S(SC₃H₅)C=C(PPr₃ⁱ)S} was synthesized by allyation of the homobinuclear anion [Mn₂(CO)₆(μ-H){μ-S(SC₃H₅)C=C(PPr₃ⁱ)S}]⁻¹, and characterized by elemental analysis, IR, ¹H NMR and ³¹P NMR spectra. The molecular structure shows that it contains a novel fairly planar ligand S(S)C=C(PPr₃ⁱ)S, and the two Mn(CO)₃ fragments are symmetrically placed at both sides of the plane of the ligand.     

A tetra-nuclear copper(II) complex stabilizes an extended structure of a water nonamer: Synthesis and characterization of [Cu4(C54H46N4O14)(OH)2] · 10H2O

A tetra-nuclear copper(II) complex [Cu₄(C₅₄H₄₆N₄O₁₄)(OH)₂] · 10H₂O (1) has been synthesized starting from l-tyrosine, NaOH, 2,6-diformyl-4-methylphenol (dfp) and CuSO₄ · 5H₂O. Compound 1 crystallizes from an ethanol–water mixture in triclinic space group. In the crystal of 1, two binuclear copper units, related by a center of symmetry, are bridged by two hydroxo bridges and results in the formation of a tetra-nuclear {Cu₄} structure. Five lattice water molecules, located in the asymmetric unit, interact among themselves and form an unusual form of a water nonamer. In the crystal, the water nonamer is again hydrogen bonded to the next nonamer forming a chainlike polymer. Each {Cu₄} complex unit attaches four such water nonamer chains. Variable temperature magnetic data fit to the Bleaney–Bower’s equation with a Curie type of impurity of S = 0.5. The best fit of the magnetic data to this equation yielded 2J = −217, g = 2.019 and a TIP value of 60 × 10⁻⁶ cm³ mol⁻¹.     

Synthesis and structural characterization of sulfonates, phosphinates and carboxylates of organometallic Group 4 metal fluorides

Reaction of [Cp^*TiF₃] (Cp^* = (ν⁵-C₅Me₅)) with Me₃SiOSO₂- p-C₆H₄CH₃, Me₃SiOPOPh₂ and 1,2-(Me₃SiOCO)₂C₆H₄ yields the dinuclear complexes [{Cp^*TiF(μ-F)(μ-OSO₂-p-C₆H₄CH₄)}₂] (1), [{Cp^*TiF(μ-F)(μ-OPOPh₂)}₂] (2) and [{Cp^*TiF(μ-F)(μ-OCO-o-C₆H₄CO₂SiMe₃)}₂] (3). The molecular structures of 1 and 2 have been determined by single-crystal X-ray analysis. In complexes 1-3, the two titanium atoms are connected by bridging fluorine atoms as well as bridging sulfonate, phosphinate and carboxylate groups respectively. Each titanium atom is also bonded to a terminal fluorine atom. Reaction of [Cp₂^*ZrF₂] with 1,2-(Me₃SiOCO)₂C₆H₄ leads to the mononuclear pentacoordinate 18-electron species [Cp₂^*ZrF(μ-OCO-o-C₆H₄CO₂SiMe₃)] (4) and its structure was determined by X-ray crystallographic methods.     

Synthesis and crystal structure of the novel trimanganese tetrathiolate incomplete cubane: [Mo(η-C5H5)2(H)CO][Mn3(CO)9(μ-SC6H5)4]

An unexpected trimanganese(I) tetrathiolate-bridged complex, [Mn₃(CO)₉(μ-SC₆H₅)₄]⁻, with an incomplete cubane structure, was obtained by thermal reaction of [Mn₂(CO)₁₀] with [Mo(η⁵-C₅H₅)₂(SC₆H₅)₂]. The structure, established by single-crystal X-ray diffraction studies, shows the cation, [Mo(η⁵-C₅H₅)₂(H)CO]⁺, directed towards the vacant site of the cubane structure. Possible routes by which the anion and the cation could be formed are discussed.