Reaktionen an komplexgebundenen liganden: XXXVI. Synthese und oxidationsverhalten von M(CO)5-komplexen (M = Cr,Mo, W) mit amin- und benzochinondiimin-liganden

The oxidation of yellow Cr(CO)₅NH₂R complexes (NH₂R = aniline, m-toluidine, 3,5-xylidine, m-anisidine) with Pbac₄ gives deep blue to deep purple coloured compounds, which have been identified as the respective [Cr(CO)₅(N-phenyl-1,4-benzochinon-diimine)] complexes. Oxidation of the p-phenylenediamine complex yields [(OC)₅CrHNC₆H₄NHCr(CO)₅], which is also deep blue. The binuclear blue complex [{Cr(CO)₅}₂HNC₆H₄NC₆H₅] is obtained by treating Cr(CO)₅THF with the free ligand in THF/hexane; it dissociates rapidly in acetone to form [Cr(CO)₅HNC₆H₄NC₆H₅] and Cr(CO)₅. Analogous Mo(CO)₅ and W(CO)₅ complexes could not be obtained. The oxidation of [W(CO)₅(m-anisidine)] by I₂ yields [W(CO)₄I]₂. All the compounds were characterized by spectroscopic methods as well as by elemental analysis.     

Carbon-13 NMR spectra of some group VIB and VIIB transition metal chalcocarbonyl complexes

The ¹³C NMR spectra of the five series of chalcocarbonyl complexes, (η⁶-C₆H₆)Cr(CO)₂(CX), (η⁶-C₆H₅CO₂Me)Cr(CO)₂(CX), (η⁵-C₅H₅)Mn(CO)₂(CX), (η⁵-C₅H₄Me)Mn(CO)₂(CX) and (η⁵-C₅H₅)Re(CO)₂(CX) (X = O, S, Se), and some of their derivatives including several ¹³C-enriched species have been investigated at ?30 to ?50°C. The chemical shift variations observed with changes in the CX ligand suggest that the π-acceptor/σ-donor capacity of these ligands increases in the order CO < CS < CSe. Changes in the nuclear charge and in the electronic density at the central metal atom affect δ(¹³CS) and δ(¹³CO) in the same manner. The increased downfield chemical shift for δ(¹³CX) in the chromium and manganese series on changing X from O to S and Se is in the direction expected from considerations of Pople's paramagnetic shielding expression.     

Carbonyl complexes of molybdenum and tungsten with sulfur donors: V. Reactions of carbonyl complexes of molybdenum(0) with uninegative (X,Y)-donor ligands (X,Y = S,N, O)

The reactions of the zerovalent carbonyl complexes Mo(CO)₆ and Mo(CO)₄(bipy) with a series of uninegative bidentate (X,Y)-donor ligands (X,Y = xanthates, dithiocarbamates, o-aminophenoxide, o-aminothiophenoxide, 2-picolinate and thioacetate) lead to new anionic tetracarbonyl complex anions [Mo⁰(X,Y)(CO)₄]^?. These anions, which can be isolated as their tetraphenylphosphonium salts, contain the (X,Y)-ligand as a bidentate group. In the case of (X,Y) = monothioacetate the decarbonylated species [PPh₄][Mo^II(TA)₃] is formed. The reacions of the new complexes with allyl bromide and methyl iodide are described.     

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).     

Metallkomplexe mit anionischen Liganden von Elementen der 4. Hauptgruppe. VIII. Pentacarbonyl-trihalogenstannido-metallat(O)-Komplexe von chrom,molybdän und wolfram mit fluor- und jodhaltigen stannidliganden

Metal Complexes with Anionic Ligands of Elements of the Main Group IV. VIII Pentacarbonyltrihalogenostannidometalate(O) Complexes of Chromium, Molybdenum, and Tungsten with Fluorine and Iodine Containing Trihalogenostannido Ligands In methylenechloride [As(C₆H₅)₄][SnF₃] readily reacts with the metalhexacarbonyls forming the arsoniumsalts of the pentacarbonyltrifluorostannidometalate(O) complexes, [M(CO)₅SnF₃]^? (M ? Cr, Mo, W). Exclusively by the reaction of the intermediately formed complex Cr(CO)₅THF only one pure triiodostannidometalate(O) Complex, [N(C₂H₅)₄][Cr(CO)₅SnJ₃], could be isolated. The trihalogenostannidometalate(O) complexes [M(CO)₅SnClX₂]^? (X ? F: M ? Cr, Mo, W; X ? J: M ? Cr) could be prepared by SnX₂-insertion reactions of the [M(CO)₅Cl]^? complexes. The bonding properties of the halogenostannide ions are discussed on the bases of the IR spectra of their metalate(O) complexes.     

Photochemical reactions of metal carbonyls [M(CO)6 (M = Cr,Mo and W), Re(CO)5Br,Mn(CO)3Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh)

Five new complexes, [M(CO)₅(apmsh)] [M = Cr; (1), Mo; (2), W; (3)], [Re(CO)₄Br(apmsh)] (4) and [Mn(CO)₃(apmsh)] (5) have been synthesized by the photochemical reaction of metal carbonyls [M(CO)₆] (M = Cr, Mo and W), [Re(CO)₅Br], and [Mn(CO)₃Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh). The complexes have been characterized by elemental analysis, mass spectrometry, f.t.-i.r. and ¹H spectroscopy. Spectroscopic studies show that apmsh behaves as a monodentate ligand coordinating via the imine N donor atom in [M(CO)₅(apmsh)] (1–4) and as a tridentate ligand in (5).     

Optisch aktive übergangsmetall-komplexe: XXXIII. Substituenteneinfluss auf die racemisierungs geschwindigkeit von (+)579und(−)579−C5H5MN(COC6H5)(NO)P(pC6H4Y)3

In the reaction of [C₅H₅Mn(CO)₂(NO)] [X] ([X] = [BF₄], [PF₆]) with p-substituted triarylphosphines P(p-C₆H₄?Y)₃ [Y = CF₃, Cl, F, C₆H₅, CH₃, OCH₃, N(CH₃)₂] the asymmetric monosubstitution products [C₅H₅Mn(CO)(NO)P(p-C₆H₄?Y)₃] [X] are formed, which can be converted into the neutral esters C₅H₅Mn(COOC₁₀H₁₉)(NO)P(p-C₆H₄?Y)₃ by natrium menthoxide. The diastereoisomers (+)₅₇₉^? and (?)₅₇₉^?C₅H₅Mn(COOC₁₀H₁₉)(NO)P(p-C₆H₄?Y)₃ are separated by fractional crystallisation and transformed into the enantiomeric salts (+)₅₇₉^? and (?)₅₇₉-[C₅H₅Mn(CO)(NO)P(p-C₆H₄?Y)₃] [X] by cleavage with HCl and precipitation with NH₄PF₆. The (+)₅₇₉^? and (?)₅₇₉^? rotating salts in the reaction with LiC₆H₅ yield the carbonyl addition products (+)₅₇₉^? and (?)₅₇₉^? C₅H₅Mn(COC₆H₅)(NO)P(p-C₆H₄?Y)₃ and the ring addition products (+)₅₇₉^? and (?)₅₇₉^?(exo-C₆H₅)C₅H₅Mn(CO)(NO)P(p-C₆H₄?Y)₃, which can be separated by chromatography.The salts (+)₅₇₉^? and (?)₅₇₉^?[C₅H₅Mn(CO)(NO)P(p-C₆H₄?Y)₃] [X] and the cyclopentadiene complexes (+)₅₇₉^? and (?)₅₇₉-(exo-C₆H₅)C₅H₅Mn(CO)(NO)P(p-C₆H₄?Y)₃ are configurationally stable, whereas the esters (+)₅₇₉^? and (?)₅₇₉^?C₅H₅Mn(COOC₁₀H₁₉)(NO)P(p-C₆H₄?Y)₃ and the benzoyl complexes (+)₅₇₉^? and (?)₅₇₉^?C₅H₅Mn(COC₆H₅)(NO)P(p-C₆H₄?Y)₃ epimerise or racemise in solution.The rate of racemisation of the benzoyl compounds (+)₅₇₉^? and (?)₅₇₉C₅H₅Mn(COC₆H₅)(NO)P(p-C₆H₄?Y)₃ was measured polarimetrically in the temperature range 0–45° C. It turned out that electron-releasingsubstituents Y in the ligand P(p-C₆H₄?Y)₃ increase the half-lives, whereas electron-attracting substituents decrease the half-lives. There is a linear correlation between the σ-constants of the substituents and the rate constants of the racemisation (reaction constant p = +2.14).     

Thermal studies of some biologically active oxovanadium(IV) complexes containing 8-hydroxyquinolinate and hydroxamate ligands

The thermal decomposition behaviours of oxovanadium(IV)hydroxamate complexes of composition [VO(Q)_2?n(HL^1,2)_n]: [VO(C₉H₆ON)(C₆H₄(OH)(CO)NHO)] (I), [VO(C₆H₄(OH)(CO)NHO)₂] (II), [VO(C₉H₆ON)(C₆H₄(OH)(5-Cl)(CO)NHO)] (III), and [VO(C₆H₄(OH)(5-Cl)(CO)NHO)₂] (IV) (where Q?=?C₉H₆NO^? 8-hydroxyquinolinate ion; HL¹?=?[C₆H₄(OH)CONHO]^? salicylhydroxamate ion; HL²?=?[C₆H₃(OH)(5-Cl)CONHO]^? 5-chlorosalicylhydroxamate ion; n?=?1 and 2), which are synthesised by the reactions of [VO(Q)₂] with predetermined molar ratios of potassium salicylhydroxamate and potassium 5-chlorosalicylhydroxamate in THF?+?MeOH solvent medium, have been studied by TG and DTA techniques. Thermograms indicate that complexes (I) and (III) undergo single-step decomposition, while complexes (II) and (IV) decompose in two steps to yield VO(HL^1,2) as the likely intermediate and VO₂ as the ultimate product of decomposition. The formation of VO₂ has been authenticated by IR and XRD studies. From the initial decomposition temperatures, the order of thermal stabilities for the complexes has been inferred as III?>?I > II?>?IV.     

Nucleophilic substitution by arenethiolates at the carbene carbon of pentacarbonyl(methoxymethylcarbene)-metal(o) complexes (metal = Cr,Mo, or W)

The phenylthiocarbene complexes, [(CO)₅MC(CH₃)(SPh)] (M = Cr, Mo, or W) have been prepared in good yield by the reaction of [(CO)₅MC(CH₃)(OCH₃)] (M = Cr, Mo, or W) with NaSPh in benzene/methanol in the presence of HCl. A series of para-substituted phenylthiocarbene complexes of tungsten. [(CO)₅WC(CH₃)SC₆H₄Y)], (Y = p-Br, p-F, p-H, p-CH₃, p-OCH₃ or p-OH) have also been prepared by the reaction of the appropriate arenethiolate ion with [(CO)₅WC(CH₃)(OCH₃)]. Poor nucleophiles such as p-nitrobenzenethiolate and pentafluorobenzenethiolate did not react with [(CO)₅WC(CH₃)(OCH₃) to form the corresponding phenylthiocarbene complex. A mechanism accounting for the formation of these phenylthiocarbene complexes is proposed. The complexes have been characterized by their infrared, electronic, mass, ¹H NMR, and ¹³C NMR spectra. These spectroscopic data have been used to establish the structure of these complexes in solution and indicate that the phenyl ring bonded to sulfur is probably not coplanar with the “carbene” plane.     

Reactions of cis-[dicarbonylbis(1,2-bis(dimethylphosphino)ethane)metal] compounds of chromium and molybdenum with organic electron acceptors; Tetracyanoethene, 1,2,4,5-tetracyanobenzene and 1,3,5-trinitrobenzene

Reaction between cis-[Mo(CO)₂(dmpe)₂] (dmpe =Me₂PCH₂CH₂PMe₂) and organic π-acids tetracyanoethene (TCNE), 1,2,4,5-tetracyanobenzene (TCNB) and 1,3,5-trinitrobenzene (TNB) proceeds via electron transfer from the metal complex, which is oxidised to the 17-electron trans-[Mo(CO)₂(dmpe)₂]⁺ ion, to the organic acceptor which is reduced to the radical anion. The final products of the reactions are characterised ascis-[Mo{C₂(CN)₃} (CO)₂(dmpe)₂] [CN], cis-[Mo{C₆H₂(CN)₄} (CO)₂(dmpe)₂] [C₆H₂(CN)₄]₈ and [Mo(CO)₂(dmpe)₂ · 2 C₆H₃(NO₂)₃] by analysis and spectroscopic (IR, NMR, ESR) measurements which are compared with those of cis-[MoX(CO)₂(dmpe)₂]X (X = Cl, Br, I) and fac, fac-[Mo₂Cl₄(CO)₄(dmpe)₃]. The reaction of cis-[Cr(CO)₂(dmpe)₂] with TCNE gives trans-[Cr(CO)₂(dmpe)₂]⁺ [TCNE]^? only.     

Alkinylphosphinhaltige substitutionsprodukte von chrom- und wolfram-hexacarbonyl

The photochemical preparation of [M(CO)₅(P(CCC₆H₅)_n(C₆H₅)_3-n], cis-[M(CO)₄(PCCC₆H₅)_n(C₆H₅)_3-n] (M = Cr, W; n = 1,2,3) and fac-[Cr(CO)₃(P(CCC₆H₅)(C₆H₅)₃] by the corresponding substitution reactions of the hexacarbonyls is described. The IR and Raman spectra of the complexes in the region of the ν(CO) and ν(CC) vibrations and the ³¹P NMR spectra are discussed.     

Reactions of tungsten(VI) and molybdenum(V) chlorides,and tungsten(VI) and molybdenum(VI) oxychlorides,with azoxybenzene

Reactions of W^VI and Mo^V chlorides with azoxybenzene yield ionic species of W^VI and Mo^VI oxychlorides in which the cation is a protonated azobenzene. The reaction between MoCl₅ or MoOCl₄ and azoxybenzene gives, after extraction with methylene chloride—ethanol mixture, the complex [trans-MoOCl₄(OC₂H₅)]^? [C₁₂H₁₀N₂H]⁺. In contrast, WOCl₄ reacts with azoxybenzene to give a stable non-ionic adduct in which the organic moiety is coordinated through its oxygen atom trans to the WO bond. Several complexes of substituted azoxybenzene having similar structures are described.     

Synthesis and cleavage reactions of thiocarbonyl-bridged Cp2Fe2(CO)3CS,and preparation of the carbene complexes CpFe(CO)C(N2C2H6)SnPh3 and [CpFe(CO)2C(OMe)2]PF6

The thiocarbonyl-bridged complex Cp₂Fe₂(CO)₃CS is obtained by the reaction of CpFe(CO)₂^? and (PhO)₂CS in THF. Infrared and NMR spectra show that the compound exists in solution in interconverting cis and trans forms, but that the isomerization occurs more slowly than for the carbonyl analog [CpFe(CO)₂]₂. Most reagents which cleave [CpFe(CO)₂]₂, such as Br₂, HgCl₂, and O₂/HBF₄, do not give simple cleavage reactions with Cp₂Fe₂(CO)₃CS. Reductive cleavage of Cp₂Fe₂(CO)₃CS with Na(Hg) gives the thiocarbonyl anion CpFe(CO)(CS)^?, which reacts with Ph₃SnCl to form CpFe(CO)(CS)SnPh₃. Methylamine reacts with CpFe(CO)(CS)SnPh₃ to give CpFe(CO)(CNMe)SnPh₃, while ethylenediamine gives the carbene complexes CpFe(CO)C(N₂C₂H₆)SnPh₃. The preparation of another new carbene complex, [CpFe(CO)₂C(OMe)₂]PF₆, is also described.     

Intermediates in associative phosphine substitution reactions of (η5-C5H5)W(CO)2(NO)

The reaction of (η⁵-C₅H₅)W(CO)₂(NO), 6W, with P(CH₃)₃ proceeds rapidly at 25°C to give (η⁵-C₅H₅)W(CO)(NO)[P(CH₃)₃], 7W. The rate of formation of 7W was found to be 4.48 × 10^?2M^?1 [6W] [P(CH₃)₃] at 25.0°c in THF. In neat P(CH₃)₃ at ?23°C, 6W is converted to (η¹-C₅H₅)W(CO)₂(NO)[P(CH₃)₃]₂, 8W. In dilute solution, 8W decomposes to initially give a 2:1 mixture of 6W and 7W. The mixture is then converted to 7W. The reaction of (η⁵-C₅H₅)Mo(CO)(NO), 6Mo, with P(CH₃)₃ is 6.1 times faster than that of the tungsten analog.     

Anionic carbonyl complexes of the group VI transition metals with sulfur containing ligands

Anionic complexes of the type [M(CO)₄(dpet)]^? (where M is Cr, Mo or W and dpet is the anion of 2-(diphenylphosphino)ethanthiol) are readily prepared by the reaction of the Tl(dpet) and [M(CO)₅X]^? anions (X = halogen). These complex anions appear to have the normal octahedral geometry with the dpet ligand coordinated through both the P and S atoms. When treated with methyl or allyl halides, neutral complexes of the type M(CO)₄(dpet—R) are formed (where R is an allyl or methyl group now bound to the sulfur atom). By treating Tl^I salts of o-aminothiophenol (atp), o-methylmercaptophenol (nmp) and methylxanthic acid (mxt), with [M(CO)₅]^? anions, the respective complexes [M(CO)₄(atp)]^?, [M(CO)₄(mmp)]^? and [M(CO)₅(mxt)]^? are formed.     

Carbonyl (η3-allyl) anions of molybdenum and tungsten

Anionic complexes of the type [M(CO)₂(diket)(η³-allyl)Cl]^? (where M is Mo or W and diket is a β-diketonate group) are readily prepared by the addition of allyl chloride to [M(CO)₄(diket)]^? anions. NMR measurements indicate an equilibrium between two conformers due to rotation of the allyl groups. [M(CO)₅(OC(=O)R)]^? anions also react with allyl chloride to form η³-allyl complex anions. Some structural aspects of both the diketonate and carboxylate derivatives are discussed.     

Reactions of RSe− (R = Me,Ph) Groups in [RSeFe(CO)4I and [RSeCr(CO)5−]

The anionic [MeSeFe(CO)₄] and [MeSeCr(CO)₅] complexes were synthesized by reaction of [PPN][HFe(CO)₄] and [PPN][HCr(CO)₅] with MeSeSeMe respectively via nucleophilic cleavage of the Se-Se bond. The ease of cleavage of the Se-Se bond follows the nucleophilic strength of metal-hydride complexes. Methylation of [RSeCr(CO)₅^?] by the soft alkylating agent MeI resulted in the formation of neutral (MeSeMe)Cr(CO)₅ in THF at 0°C. In contrast, the [ICr(CO)₅^?] was isolated at ambient temperature. Reaction of [MeSeFe(CO)₄^?] or [MeSeCr(CO)₅^?] with HBF₄ yielded (CO)₃Fc(μ-SeMe)₂Fe(CO)₃ dimer and anionic [(CO )₅Cr (μ-SeMe)Cr(CO)₅^?] respectively, and no neutral (HSeMe)Fe(CO)₄ and (HSeMe)Cr(CO)₅ were detected spectrally (IR) even at low temperature. Reaction of NOBF₄ or [Ph₃C][BF₄] and [MeSeCr(CO)₅^?] resulted in the neutral monodentate (MeSeSeMe)Cr(CO)₅ complex. Addition of 1 equiv CpFe(CO)₂I to 2 equiv [MeSeCr(CO)₅^?] gave CpFe(CO)₂(SeMe) and the anionic [(CO)₅Cr(μ-SeMe)Cr(CO)₅^?] in THF at ambient temperature.     

Gehinderte Ligandenbewegungen in Übergangsmetallkomplexen : VII. Rotation der olefinliganden L = malein- und furmarsäuredimethylester in komplexen des typs C5H5Mn(CO)2L und C5H5Cr(CO)(NO)L

The restricted rotation of the olefin ligands L = dimethyl maleate and dimethyl fumarate in complexes of the type C₅H₅Mn(CO)₂L and C₅H₅Cr(CO)-(NO)L, respectively, has been investigated on the basis of their temperature-dependent ¹H NMR spectra. The olefinic ligand is arranged preferably in a position where the CC double bond is parallel to the plane of the cyclopentadienyl ring. The possible stereoisomers are discussed using this model. The ¹H NMR spectra of C₅H₅Cr(CO)(NO)(trans-CH₃OOCCHCHCOOCH₃) provide direct evidence that the configuration (R or S) at the metal is stable up to 120°C, and that the restricted motion of the olefin is exclusively rotation around the metal—olefin bond. The activation barriers of the olefin rotation are found to be appreciably lower in the C₅H₅Mn(CO)₂L complexes (ΔG^≠(T_C) 11–12 kcal mol^?1) than in the isoelectric C₅H₅Cr(CO)(NO)L compounds (ΔG^≠(T_C) 15–20 kcal mol^?1).     

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).     

Structure of trans-W(C0)4(CNC6H11)(CS) and a correlation of ν(cs) frequencies with CS bond distances in metal thiocarbonyl complexes

An X-ray structural investigation of $\text{trans}$-W(C0)₄(CNC₆H₁₁)(CS) shows that the Wz.bnd;C bond distances to the 3 isoelectronic ligands increase in the order: WCS(1.944Å) < WCO(2.0645Å, average) < WCNC₆H₁(2.158Å). Using data from this molecule as well as results from other thiocarbonyl complexes reported in the literature, an excellent correlation of low ν(CS) frequencies with long CS bond distances is observed, a trend which supports current bonding theories for thiocarbonyl complexes.