Improved syntheses of Ru(CO)2 (O3SCF3)2 (bidentate) complexes and their conversion into new [Ru(CO)2 (bidentate)2]2+ complexes

Reaction of the complexes Ru(CO)₂Cl₂L [L = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen)] with trifluoromethanesulphonic acid under carefully controlled conditions yields Ru[cis-(CO)₂] [cis-(O₃SCF₃)₂] (bidentate complexes. From reactions of the trifluoromethanesulphonates with the appropriate bidentate ligands, the new complexes [cis-Ru(CO)₂-L(L′)]²⁺ (L as above; L′ = 4,4′-dimethyl-2,2′-bipyridyl or 4,4′-diisopropyl-2,2′-bipyridyl) as well as the known [_cis-Ru(CO)₂L₂]²⁺ and [cis-Ru(CO)₂bpy(phen)]²⁺ have been prepared.     

Diazene ligand geometry effects on the formation and properties of metal carbonyl complexes. Group vib pentacarbonyl complexes of cis- and trans-1,2-diisopropyldiazene and 1,2-diisopropylhydrazine

The Group VIB complexes M(CO)₅L have been synthesized for the cases L= cis-1,2-diisopropyldiazene (c-DIPD) with M = Cr, Mo, W, L = trans-1,2-diisopropyldiazene (t-DIPD) with M = Or, W, and L, = 1,2-diisopropylhydrazine (DIPH) with M = Cr, W. Failure to obtain any bimetallic complexes is discussed in terms of steric interactions of these and related complexes. The significance of diazene ligand geometry is demonstrated by the differences in properties of the c-DIPD and t-DIPD complexes. The available evidence indicates that cis diazenes are better ligands than their trans isomers. Complex stability decreases in the order W > Cr > Mo and c-DIPD > t-DIPD. Infrared, visible, and NMR spectra are interpreted in terms of bonding in the complexes. A 30–60 cm^?1 reduction of v(NN) of the diazenes upon coordination is attributed to metal-ligand π-bonding with c-DIPD being a better π-acceptor than t-DIPD. The NMR spectra of the c-DIPD complexes are temperature dependent and show that the M(CO)₅ moiety undergoes coordination site exchange between the two nitrogen atoms. No exchange occurs in the t-DIPD complexes. Coalescence temperatures of 10, ?48, and 60°C were recorded for the Cr, Mo, and W complexes of c-DIPD respectively, with the Gibbs free energy barriers of 15.0, 11.5 and 15.0 kcal/ mol. A comparison with exchange in other M(CO)₅(cis-diazene) complexes is made and the role of the diazene structure on the reaction rate is discussed. The M(CO)₅(DIPH) (M = Cr, W) complexes have been oxidized by H₂O₂/Cu²⁺ and by activated MnO₂ to DIPD complexes in low yield. The tungsten DIPH complex gives only W(CO)₅(t-DIPD) but the chromium system gives predominantly Cr(CO)₅(c-DIPD).     

Crystal field aspects of vibrational spectra: VII. Derivation of a spectrochemical series of ligands from infrared spectra

The infrared spectra (700-200 cm^?1) of 52 complexes of general formula Na[ML₃] or [ML₂B] (where M = a divalent metal ion of the first transition series; L = α-thenoyltrifluoroacetonate or benzoyltrifluoroacetonate anion; B = 2H₂O, 2NH₃, 2pyridine, 2,2'-bipyridine or 1,10-phenanthroline) are discussed. Within each series of complexes with common L and B, the IR band near 400 cm^?1 which exhibits maximum sensitivity to the coordinated metal ion (the sensitivity being in the sequence of crystal field stabilization energies) and which generally occurs in a region free from ligand absorption, is assigned to the metal—oxygen stretching frequency (v(M—O)). For each series of complexes with common M and L, the magnitude of v(M—O) decreases progressively with increasing ligand field strength of B. This relationship enables the coordinated bases, B, to be arranged in a spectrochemical series which is practically identical with that obtained from electronic spectra.     

Übergangsmetallcarbin-komplexe: LXXXV. Strukturuntersuchungen der reaktionsprodukte von trans-Br(CO)2L2LCNEt2 (L2 = 2,2′-bipyridyl, 1,10-phenanthrolin) mit den organylanionen [(CO)5MEPh2]− (M = Cr,Mo, W; E = P,As, Sb)

The reaction of trans-Br(CO)₂L₂WCNEt₂ (L₂ = 2,2′-bipyridyl (2,2′-bipy), 1,10-phenanthroline (ophen)) with organyl anions of Main Group V elements coordinated to a pentacarbonylmetal fragment of the general formula [(CO)₅MEPh₂]⁻ (M = Cr, Mo, W; E = P, As, Sb) leads, by substitution of the bromine ligand, to new neutral diethylaminocarbyne complexes of the type (CO)₅MEPh₂(CO)₂L₂-WCNEt₂ (M = Cr, Mo, W; E = P, As, Sb; L₂ = 2,2′-bipy, ophen) which contain a heavier element of Main Group V in a bridging position between two transition metals. Spectroscopic investigations at low temperatures show that the bridged complexes exist as a mixture of cis and trans isomers, with the thermodynamic equilibrium favouring the cis complexes. Temperature dependent NMR spectra indicate a dynamic process in which the chelating ligand L₂ (L₂ = 2,2′-bipy, ophen) switches between two cis and two cis / trans positions, relative to the carbyne ligand, and causes a rapid interconversion of the two stereoisomers at room temperature.     

A carbon-13 NMR study of some metal carbonyl compounds containing one-electron ligands

Carbon-13 NMR spectral data for complexes having the general formula CpM(CO)_nX (Cp = η⁵-C₅H₅; M = Mo or W, n = 3; M = Fe, n = 2; X = halogen, methyl or acetyl) and their phosphine and isocyanide substitution products are reported. For CpM(CO)₃X complexes two carbonyl resonances (1 : 2 ratio) are observed in all cases, consistent with the retention of the “piano-stool” geometries observed in the solid state. Substituted complexes CpM(CO)₂(L)X (M = Mo or W; L = PR₃ or cyclohexyl isocyanide) are unequivocally assigned cis or trans geometries on the basis of the number of observed carbonyl resonances and values of ²J(PC) for the phosphine substituted derivatives. Spectral data for [M(CO)₅X]^? (M = Cr, Mo or W; X = Cl, Br or I) and η⁷-C₇H₇Mo(CO)₂X and the halide derivatives above generally show an increase in the shielding for carbonyls adjacent to the halide ligand in the order Cl < Br < I. Carbonyl resonances are more shielded in isostructural complexes in the order Cr < Mo < W (triad effect).     

Synthesis,characterization and photochemistry of some monometallic and bimetallic 2,2′-bipyrimidine complexes of chromium and tungsten carbonyls

Synthesis, electronic absorption spectra, ¹³C NMR and photochemistry are reported for the complexes M(CO)₄bpym (M = Cr or W) and [W(CO)₄]₂bpym. The electronic absorption spectra indicate, for these complexes, that the lowest lying metal-to-ligand (L) charge transfer (MLCT) excited state is lower in energy than the ligand field (LF) excited states. The ¹³C NMR spectra showed that the chemical shifts of C(5) and C(6) for the M-bpym complexes move downfield with respect to that of the free ligand, bpym, while C(4) moves upfield upon complexation. Small, wavelength-dependent quantum yields for loss of CO were obtained upon irradiation. These quantum yields were an order of magnitude larger for the Cr-bpym complex than for the W complexes (Φ = 2.4 x 10^?2 quanta/min for Cr-bpym, 2.5 x 10^?3 quanta/min for W-bpym and 1.1 x 10^?3 quanta/min for W-bpym-W, λ_irr = 366 nm).     

Reactions of tricarbonylpyridine complexes (NN)(py)M(CO)3 (M = Mo, W; NN = 2,2′-bipyridine, 1,10-phenanthroline) with mercuric derivatives HgX2 (X = Cl, CN, SCN)

Treatment of mercury(II) halides and pseudohalides with complexes (NN)(L)M(CO)₃ (L = py; NN = 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen); M = Mo, W) gives new tricarbonyl complexes. In all cases elimination of the pyridine ligand occurs and in some cases there is partial displacement of halogen from the mercuric halide. Treatment of bipy(py)W(CO)₃ with mercuric chloride gives only an adduct. Conductivity, IR and electronic absorption are given, and possible formulations suggested.     

Anionic tricarbonyl derivatives of molybdenum and tungsten and their reactions with allyl halides

A series of carbonylmetallate anions $\text{fac}$-[MX(CO)₃L₂]^?, where M = Mo or W, X = Cl, Br or I and L₂ = 1,10-phenanthroline(phen) or 2,2′-bipyridine(bipy) have been prepared from the corresponding $\text{cis}$-M(CO)₄L₂ complexes. No evidence of $\text{fac}$-to $\text{mer}$-isomerisation was evident on dissolution, although in MeCN solvolysis occurred with the formation of $\text{fac}$-M(CO)₃L₂(MeCN). Reaction of the anions with various allyl halides resulted in high yields of η³-allyl complexes [MX(CO)₂(η³-RC₃H₄)L₂]. The significance of these observations for the mechanism of the allyl oxidative-addition reaction are discussed.     

Synthesis and characterisation of [AgL(μ-PR2)M(CO)5], L= 1,10-phenanthroline or tricyclohexylphosphine; M = Cr,Mo, W

The new heterobimetallic phosphide-bridged compounds [AgL(μ-PR₂)M(CO)₅], (L = 1,10-phenanthroline or tricyclohexylphosphine: M = Cr, M, W) have been prepared from AgO₃SCF₃, M(CO)₅PR₂H and the ligand L in the presence of Et₂NH or MeO⁻ as base, and characterized by ³¹P NMR spectroscopy.     

Substituierte halogenocarbonylmetallate des chroms,molybdäns und wolframs : III. Ligandensubstitution an halogenocarbonylmetallaten der VI. Nebengruppe

The halopentacarbonylmetal compounds of molybdenum and tungsten react with phosphines in polar aprotic solvents with CO substitution to give the ionic derivatives [LM(CO)₄X]^? (X = Cl, Br; M = Mo, W; L = i-Pr_nPh_3?nP, (Me₂N)_nPh_3?nP, (i-PrO)_nPh_3?nP, Ph₂MeP, Et₃P, (PhO)₃P, n = 0, 1, 2, 3). The substitution of the halide ligand, which is catalysed by protic solvents, provides a convenient route to the neutral complexes LM(CO)₅ and LL′M(CO)₄ (L = phosphines; L′ = ammonia, acetonitrile, pyridine, piperidine). cis-(NH₃)(i-Pr₃P)W(CO)₄ in solution is slowly deuterated by D₂O. In this reaction all three hydrogen atoms appear to be exchanged simultaneously.     

Rhodium and iridium complexes containing the anion of 1-phenyl-3-methyl-4-benzoyl- pyrazolone-5, a sophisticated analogue of β-diketones

Several (diolefin)M(A) complexes (M = Rh, Ir) were prepared, where AH is 1-phenyl-3-methyl- 4-benzoylpyrazolone-5, a very stable asymmetric analogue of acetylacetone. In these complexes the diolefin could be replaced by one mole of (Ph₂PCH₂CH₂)₂, two of CO or of PPh₃, or three of CNBu^t, while 1,10-phenanthroline displaced the chelating ligand to yield [(cyclooctadiene)Rh(phen)]⁺ (A)^?. Some compounds X?Y (X?Y = iodine or MeI) added oxidatively yielding the corresponding trivalent species. Using ³¹P NMR spectra the presence of the expected steric isomers was detected in (Ph₃P)(CO)Rh(A) and in (Ph₃P) (CO)Rh(A)(X)(Y).     

Substitution reactions of [MBr(π allyl)(CO)2(LL)] complexes (M = Mo,W; L-L = 2,2 -bipyridine 1,2-bis(diphenylphosphine)ethane) with xanthates and dithiocarbamates

The complexes [MBr(π-allyl)(CO)₂(bipy)] (M = Mo, W, bipy = 2,2′-bipyridine) react with alkylxanthates (M^IRxant), and N-alkyldithiocarbamates (M^IRHdtc) (M^I = Na or K), yielding complexes of general formula [M(S,S)- (π-allyl)(CO)₂(bipy)] (M = Mo, (S,S) = Rxant (R = Me, Et, t-Bu, Bz), RHdtc (R = Me, Et); M = W, (S,S) = Extant). A monodentate coordentate coordination of the (S,S) ligand was deduced from spectral data. The reaction of [MoBr(π-allyl)(CO)₂(bipy)] with MeHdtc and Mexant gives the same complexes whether pyridine is present or not. The complexes [Mo(S,S)(π-allyl)(CO)₂(bipy)] ((S,S) = MeHdtc, Mexant) do not react with an excess of (S,S) ligand and pyridine.No reaction products were isolated from reaction of [MoBr(π-allyl)(CO)₂(dppe)] with xanthates or N-alkyldithiocarbamates.     

The thermochemistry of carbonyl complexes of Cr,Mo and W with pyridine and acetonitrile

Microcalorimetric measurements at elevated temperatures of the heats of thermal decomposition and of iodination of a number of [M(CO)_nL_6-n] complexes (M = Cr, Mo, W; n = 3, 4; L = py, MeCN) have led to values for the standard enthalpies of formation of the following crystalline compounds (values given in kJ mol^?) at 25°C: fac-[Mo(CO)₃py₃](275 ± 12), fac-[Mo(CO)₃(NCCH₃)₃]  (410 ± 12), fac-[W(CO)₃py₃](250 ± 12), fac-[W(CO)₃(NCCH₃)₃](405 ± 12) and cis-[Cr(CO)₄py₂](505 ± 20). From these and other data, including estimated heats of sublimation, the bond enthalpy contributions of the various metalligand bonds in the gaseous metal complexes were evaluated as follows (values in kJ mol^?): D(Crpy) 102, D(Mopy) 146, DWPy) 173, D(Mo7z.sbnd;NCMe) 135 and D(WNCMe) 169. For a given metal the bond enthalpy contribution decreased in the order D(MCO) > D(Mpy) > D(Mz.sbnd;NCMe). This order is related to the σ- and π-bonding character of the ligand.     

Rhodium and platinum complexes as catalysts for the polymerization of phenylacetylene

In polymerization reactions of phenylacetylene three different types of polyphenylacetylene (PPA) were prepared by using Rh and Pt complexes as catalysts in different reaction conditions. Type I PPA is obtained with [Rh (COD) Chel] PF₆ complexes (COD = cis,cis-cycloocta 1,5-diene; chel = 2,2′-bipyridine, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline) in bulk, benzene methanol, while type II PPA is obtained with the same catalysts in p-dioxane and type III PPA in the presence of [Pt (? C?CPh)₂(PPh₃)₂] in bulk. Type I, II, and III PPA exhibit different IR and ¹H-NMR spectra, which have been compared with literature data. Correlations proposed by different Authors between spectral properties of PPA and chain structures are also discussed.     

Steric influences on sulphur inversion barriers in group 6a tetracarbonyl complexes of dithioethers

The complexes cis-[M(CO)₄(RSCH₂CH₂SR)] (M = Cr, Mo, W, R =^t Bu; M = W, R = Me, Et, ⁱPr, ^tBu) and cis-[M(CO)₄(cis-RSCHCHSR)] (M = Cr, Mo, W; R = Me, ^tBu) have been synthesised, and sulphur inversion studied using variable temperature ¹H and ¹³C {¹H} NMR techniques. For complexes of the saturated ligands, signals due to both DL and meso invertomers were observed at −90°C, with the relative populations of these invertomers being dependent on the steric bulk of the alkyl groups attached to sulphur. Sulphur inversion barriers, which have been calculated via total bandshape analysis of the variable temperature NMR spectra of these complexes, show a marked dependence on the steric requirements of the dithioether ligand. For the complexes of the unsaturated ligands, only the meso-invertomers were observed at limiting low temperatures (ca. −90°C), and sulphur inversion barriers were therefore not able to be calculated in these cases.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

Kinetics of the aquation of cis-chlorocyanobis(2,2′-bipyridine)cobalt(III) and cis-chlorocyanobis(1,10-phenanthroline)cobalt(III) cations

We have studied the kinetics of aquation of cis-chlorocyanobis(2,2′-bipyridine)Co(III), and cis-chlorocyanobis(1,10-phenanthroline)Co(III) cations, and determined activation parameters, in order to compare the labilities of these cations with the lability of the analogous compounds containing ethylenediamine and other non-participating ligands such as Cl^? and NO₂^?.     

Solvent-controlled formation of η-butadienyl or η-allyl group 6 transition metal complexes in water or alcohols

Preparation of acyl chloride, ester, amide or thioester-substituted η³-butadienyl complexes of the type [MCl(CO)₂(η³-CH₂C(COXR)CCH₂)(L₂)] (M=Mo,W; XR=Cl, OR, NHR, SR; L₂=1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline) from 1,4-dichloro-2-butyne and Ph₄P[MCl(CO)₃(L₂)] in water resulted in improved yields (M=Mo) and recycling of reagents. Whilst analogous reactions in anhydrous methanol to yield either substituted η³-butadienyl (XR=OR) or η³-allyl [MoCl(CO)₂(η³-CH₂C(CO₂R)C(OR)Me)(phen)] were dependent upon the presence of organic bases or ethers, reactions in propanol or butanol gave the η³-butadienyl complexes only. Possible mechanisms are discussed. Halide extraction from ester or amide butadienyl complexes in hydroxylic solvents gave highly reactive cations of the type [Mo(CO)₂(η³-butadienyl)(phen)(solvent]⁺, and carboxylate products were obtained by displacement of metal-bound solvent by glucuronate or hydroxybutyrate ions.     

Tetracoordinate cobalt(II) complexes with neocuproine: single-molecule magnets with potential biological activity

Interaction of two mononuclear tetracoordinate complexes [Co(dmphen)Br₂] and [Co(dmphen)I₂] (dmphen = 2,9-dimethyl-1,10-phenanthroline), which have been recently reported to behave as single-molecule magnets (SMMs) in an applied external field, with calf thymus (CT) DNA in solution was studied by spectral methods (UV–Vis, fluorescence, and circular dichroism). Results indicate that both complexes along with their chlorido analogue [Co(dmphen)Cl₂] are able to bind with the CT DNA via intercalation, with the values of Stern–Volmer constants obtained from the linear quenching plot in range of 1.86 × 10⁴–2.11 × 10⁴ M^?1. Furthermore, Topoisomerase I inhibition studies suggest that all three complexes exhibit inhibition activity at concentrations of 45 μM.     

Ligand isotope studies of Zeise's salt derivatives (and their CO analogues)with some aza-heterocycles and their N-oxides. I: Full infrared spectral assignments (4000-50 cm−1)

Detailed infrared assignments (4000-50 cm⁻¹) are made of 41 π-acid complexes of the type cis-[Pt(bipyO₂H)(A)X₂]X and trans-[PtL(A)X₂] (A = C₂H₄, CO; X = Cl, Br; L = pyridazine {pdz}, pyrazine N-oxide {pzO}, quinoline {quin}, quinoline N-oxide {quinO}, 2,2′-bipyridine {bipy}, 1,10-phenanthroline {phen}) and their deuterated L and C₂D₄ analogues. Slight coupling between νPt-C₂ or νPt-CO and νPt-L is observed for some complexes. The question of the uncertainty in the assignments of νPt-O (aromatic N-oxides) is raised, and strong coupling between νPt-N (aza-nitrogen) and νPt-Br is demonstrated.