Stibine Ligands Research Articles

Synthesis and structures of organoantimony compounds containing intramolecular Sb–N interactions

Stibines R 3 ′ Sb containing the pendant arm [2-(Me 2NCHR)C 6H 4] (where R = H or Me) were synthesized, and their reactions with CH3I and HBr have been carried out to obtain the diammonium salt {[2-(Me 2NCHR)C 6H 4] [2-(Me 3N +CHR)C 6H 4]}Sb 2[I] − (where R = H 3; Me 4) and triammonium salt {2-[(Me 2HN +CH 2)C 6H 4] 3}Sb 3[Br] − 5, respectively. A novel platinum complex 6 [PtCl 2 · 1] containing stibine 1 as a bidentate ligand has also been prepared. All these compounds show Sb–N interactions. A good conjunction was observed between semi-empirical method and 1H and 13C NMR (at different temperature) data for the diammonium salts of compounds 3 and 4. The structures of all the synthesized compounds were determined by X-ray diffraction analyses. This appears to be the second molecular structure of a Pt stibine complex containing a Pt–Cl bond trans to stibine ligand, as few Pt–Sb X-ray structures are known.

Quantifying the electronic cis effect of phosphine, arsine and stibine ligands by use of rhodium(I) Vaska-type complexes

The cis effects of phosphine, arsine and stibine ligands have been evaluated by measuring the IR stretching frequency in dichloromethane of the carbonyl ligand in a series of Rh(I) Vaska-type complexes, trans-[RhCl(CO)(L) 2]. These data were correlated with those obtained by Tolman for the electronic trans influences in the [Ni(L)(CO) 3] complexes. The electronic contribution, χ Fc, of ferrocenyl was determined as 0.8 from these plots by evaluating PPh 2Fc as ligand. In order to accommodate arsine and stibine ligands an additional correction term, to compensate for differences in the donor atom, was added to Tolman’s equation for calculation of the Tolman electronic parameter of phosphine ligands. In the resulting equation: ν(CO Ni)=2056.1+∑ i=1 3 χ i + C L values for C L of C P=0, C As=−1.5 and C Sb=−3.1 are suggested for phosphine, arsine and stibine ligands, respectively. The crystal and molecular structures of trans-[RhCl(CO)(PPh 2Fc) 2] · 2C 6H 6, trans-[RhCl(CO){P(NMe 2) 3} 2] and trans-[RhCl(CO)(AsPh 3) 2] are reported. The Tolman cone angles for PPh 2Fc and P(NMe 2) 3 were determined as 169° and 166°, while the effective cone angles for PPh 2Fc, P(NMe 2) 3 and AsPh 3 were determined as 171°, 168° and 147°, respectively.

A series of di-nuclear rhodium(i) complexes with trialkylstibines as bridging ligandsDedicated to Professor Wolfgang Malisch, a respected colleague and creative scientist, on the occasion of his 60th birthday.

Metathetical reactions of [Rh2Cl2(μ-CPh2)2(μ-SbiPr3)] 1 with NaBr and NaI afforded the corresponding di-nuclear complexes [Rh2X2(μ-CPh2)2(μ-SbiPr3)] (X = Br 2, I 3) in practically quantitative yields. Analogous displacement reactions of 1 with equimolar amounts of the sodium salts of acetylacetone (acacH), trifluoracetylacetone (acac-f3-H) and dipivaloylmethane (dpmH) led to the formation of the unsymmetrical rhodium(I) compounds [Rh2(X)Cl(μ-CPh2)2(μ-SbiPr3)] (X = acac 4, acac-f35, dpm 6). From 1 and excess of Na(acac) and Na(dpm), the symmetrical complexes [Rh2X2(μ-CPh2)2(μ-SbiPr3)] (X = acac 7, dpm 8) were formed. Treatment of 7 with acetic acid and trifluoracetic acid in the molar ratio of 1 ∶ 1 gave the unsymmetrical compounds [Rh2X(acac)(μ-CPh2)2(μ-SbiPr3)] (X = CF3CO29, CH3CO210), while with an excess of CR3CO2H the symmetrical complexes [Rh2(κ2-O2CR3)2(μ-CPh2)2(μ-SbiPr3)] (R = F 11, H 12) were obtained. The X-ray crystal structure analysis of 12 revealed that analogously to 1 the stibine ligand occupies a symmetrical bridging position. The reactions of 1, 4 and 7 with SbEt3 and Sb(CH2Ph)3 led to bridge-ligand exchange and gave the di-nuclear compounds [Rh2(acac)Cl(μ-CPh2)2(μ-SbEt3)] 13 and [Rh2X(X′)(μ-CPh2)2{μ-Sb(CH2Ph)3}] (X = X′ = Cl 14, X = Cl, X′ = acac 15, X = X′ = acac 16) without cleavage of the [Rh2(μ-CPh2)2] core fragment.

Carbene Iridium(I) and Iridium(III) Complexes Containing the Metal Center in Different Stereochemical Environments

The mixed-ligand complex [IrCl(C2H4)(SbiPr3)(PiPr3)] (2), prepared from [IrCl(C2H4)(PiPr3)]2 (1) and SbiPr3, reacts not only with CO, diphenylacetylene, and H2 by ligand substitution or oxidative addition but also with diaryldiazomethanes R2CN2 to give the four-coordinate iridium(I) carbenes [IrCl(CR2)(SbiPr3)(PiPr3)] (8−10) in 60−70% isolated yield. In contrast, treatment of 2 and of the related cyclooctene derivative trans-[IrCl(C8H14)(SbiPr3)2] (12) with C5Cl4N2 affords the diazoalkane complexes trans-[IrCl(N2C5Cl4)(SbiPr3)(EiPr3)] (11, E = P; 13, E = Sb) without elimination of N2. Displacement of the stibine ligand in 8−10 by PiPr3 leads to the corresponding bis(phosphine) compounds trans-[IrCl(CR2)(PiPr3)2] (14−16), while the reaction of 8 (R = C6H5) with NaC5H5 yields the half-sandwich-type complex [(η5-C5H5)Ir(CPh2)(PiPr3)] (17). Protonation of 17 with HCl occurs stepwise to give via the iridium(III) alkyl [(η5-C5H5)IrCl(CHPh2)(PiPr3)] (20) the ring-substituted isomer [(η5-C5H4CHPh2)IrHCl(PiPr3)] (21); however, if 17 is treated with HBF4, a cationic complex is formed which probably contains a η3-coordinated benzylic ligand. The square-planar iridium(I) carbenes 8 and 14 react with HBX4 (X = F, ArF) to afford the ionic products [IrHCl(CPh2)(PiPr3)(EiPr3)]BX4 (23, 24, E = P; 25, E = Sb) and with HCl to give the relatively labile octahedral species [IrHCl2(CPh2)(PiPr3)(EiPr3)] (26, E = P; 27, E = Sb). Treatment of 8 and 14 with ethene yields, besides [IrCl(C2H4)2(SbiPr3)2] (18) and/or trans-[IrCl(C2H4)(PiPr3)2] (28), a mixture of two isomeric olefinic products CH2CHCHPh2 (29) and CH3CHCPh2 (30), the ratio of which is independent of the ligand sphere of the iridium precursor. The molecular structures of 13, 14, 17, and 24 have been determined by X-ray crystallography.

Equilibrium, solid state behavior and reactions of four and five co-ordinate carbonyl stibine complexes of rhodium. Crystal Structures of trans-[Rh(Cl)(CO)(SbPh 3) 2], trans-[Rh(Cl)(CO)(SbPh 3) 3] and trans-[Rh(I) 2(CH 3)(CO)(SbPh 3) 2

The crystal structures of the four-coordinate trans-[Rh(Cl)(CO)(SbPh 3) 2] ( 1) and the five-coordinate trans-[Rh(Cl)(CO)(SbPh 3) 3] ( 2) are reported, as well as the unexpected oxidative addition product, trans-[Rh(I) 2(CH 3)(CO)(SbPh 3) 2] ( 3), obtained from the reaction of 2 with CH 3I. The formation constants of the five-coordinate complex were determined in dichloromethane, benzene, diethyl ether, acetone and ethyl acetate as 163±8, 363±10, 744±34, 1043±95 and 1261±96 M −1, respectively. While coordinating solvents facilitate the formation of the five-coordinate complex, the four-coordinate complex could be obtained from diethyl ether due to the favorable low crystallization energy. The tendency of stibine ligands to form five-coordinate rhodium(I) complexes is attributed mainly to electron deficient metal centers in these systems, with smaller contributions by the steric effects. The average effective cone angle for the SbPh 3 ligand in the three crystallographic studies was determined as 139° with individual values ranging from 133 to 145°.

Amidocarbonylation of cyclohexene and 1-pentene with Co2(CO)8 modified with triarylstibines in very mild conditions

Interesting results, presenting the use of different stibine ligands in amidocarbonylation of cyclohexene and 1-pentene catalyzed by Co2(CO)8, not only enhance the activity of catalyst but also increases the selectivity in comparison to classical phosphinic ligands, have been reported. The stibine and phosphine ligands used were triphenylstibine (TPS), o- and p-tritolylstibine, (o-TTS, p-TTS) 2,4,6-trimesitylstibine (TMS), p-trifluorophenylstibine (p-TFPS), triphenylphosphine (TPP), o- and p-tritolylphosphine (o-TTP, p-TTP), respectively. All the reactions were carried out in a very mild syngas pressure (25bar).

Electrospray mass spectrometric investigation of the relative ligand properties of EPh 3 ligands (E=P, As, Sb or Bi) towards Ag + and Cu +

Electrospray mass spectrometry (ESMS) has been used to investigate the relative ligand properties of the triphenylpnictogen ligands EPh 3 (E=P, As, Sb and Bi) towards silver(I) and copper(I) ions. It is found that the preferred species formed increase in coordination number from two for PPh 3 in [Ag(PPh 3) 2] + to four for SbPh 3 in [Ag(SbPh 3) 4] +, consistent with the decreasing donor ligand ability and increasing metal –E bond length in the series PPh 3–AsPh 3–SbPh 3. With BiPh 3, the spectra were complex, suggesting considerable decomposition. These studies also suggest that silver(I) and copper(I) ions will have widespread utility in the characterisation of tertiary stibine ligands, as has been described previously for phosphines and arsines. These studies demonstrate the power of the ESMS technique in determining the donor properties of a related series of ligands, and this information is of significance in coordination chemistry.

Ruthenium-(II) and -(III) complexes of a ditertiary stibine ligand. The effect of co-ordination on stibine ligand geometry †

The complexes trans-[RuX2{Ph2Sb(CH2)3SbPh2}2] (X = Cl, Br or I) have been prepared from [Ru(dmf)6][CF3SO3]3, LiX and the distibine (dmf = dimethylformamide), and characterised by chemical analysis and UV/VIS spectroscopy. They are oxidised by HNO3 in HBF4 solution to trans-[RuX2{Ph2Sb(CH2)3SbPh2}2]BF4. The latter have been characterised by similar techniques, and the RuII–RuIII redox potentials established electrochemically. The crystal structures of Ph2Sb(CH2)3SbPh2 and trans-[RuBr2{Ph2Sb(CH2)3SbPh2}2]·2CH2Cl2 [Ru–Sb 2.5758(5), 2.6043(8); Ru–Br 2.5770(7) A] have been determined. Using data from the Cambridge Crystallographic Database on transition metal SbPh3 complexes, the present complexes, and those of Ph2SbCH2SbPh2, the effect of co-ordination on the C–Sb–C angles and the Sb–C distances has been examined. A correlation of increased C–Sb–C angles with decreased Sb–C distances is observed on co-ordination.

Synthesis and Properties of the Transition Metal Complexes of a Tritertiary Stibine, 1,1,1-Tris((diphenylstibino)methyl)ethane. Structure of fac-[Mo(CO)3{MeC(CH2SbPh2)3}

The tritertiary stibine MeC(CH2SbPh2)3 (tts) reacted with [M(CO)6] (M = Cr, Mo, W) in ethanol in the presence of NaBH4 to form fac-[M(CO)3(tts)], which were characterized by analysis, IR spectroscopy, and 1H and 13C{1H} NMR spectroscopy. The crystal structure of the Mo derivative has been determined by single-crystal X-ray diffraction and shown to be the fac isomer (Sb−Mo = 2.7263(5)−2.7462(5) Å). The complexes [Pd(tts)Cl2] and [Pt(tts)Cl2] in which the tts coordinates as a bidentate ligand, and fac-[Rh(tts)Cl3] and [Cu(tts)(MeCN)]PF6 in which it is tridentate, were also prepared and characterized spectroscopically. These complexes are the first examples reported containing a tritertiary stibine ligand.

Coordination chemistry of stibine and bismuthine ligands

The synthesis of the common monodentate and bidentate stibines and bismuthines, and of multidentates containing one or more antimony or bismuth donor are briefly reviewed. The detailed coordination chemistries of SbH 3, trialkyl- and triaryl-stibines and -bismuthines are described, followed by a treatment of distibine complexes and complexes of multidentates containing antimony (and rarely bismuth) in combination with other group 15 or 16 donors. The available X-ray structural data, antimony-121 Mössbauer results, and UV-visible data on these complexes are compiled. Throughout the article comparisons are drawn with complexes of lighter group 15 donor ligands and the considerable differences between stibine ligands and the more familiar phosphines and arsines are highlighted.

Radiation induced reactions of some platinum metal nitrosyl complexes containing tertiary phosphine, arsine and stibine ligands

Photochemical reactions of complexes of the stoichiometric type M(NO)X 3(Ph 3Y) 2 for MRu, Os; YP, As, Sb; XCl, Br, I and M(NO)X 2(Ph 3Y)2 for MRh, Ir; YP, As; XCl, Br, I, have been investigated. In many of the reactions one of the organo-pnictide ligands (Ph 3Y) is oxidized and remains coordinated (through the oxygen) to the transition metal. In the case of rhodium and iridium complexes, however, different reactions occur with complete loss of NO from the metal centre. Oxidation studies of the free ligands, and mass spectrometric analysis of gaseous reaction products have been used to elucidate the nature of the oxidizing agent for the complexes. The photochemical reactions of the complexes Ru(NO)X 3(Et 2PhP) 2 for XCr, Br, I have also been studied and they differ from the others in that isomerization occurs from the trans isomer to the cis-meridional isomer.

Transition-metal fluoro compounds containing carbonyl, phosphine, arsine, and stibine ligands

Transition-metal fluoro compounds containing carbonyl, phosphine, arsine, and stibine ligands

Trans-1,3-pentadiene and cyclobutene complexes of rhodium(I) and iridium(I)

Summary The generation of “MClL2” centers in THF solution (M = Ir, L = AsPh3, SbPh3; M = Rh, L = SbPh3) leads to stable η2-MCl(C5H8)L2 complexes on the addition of an excess of trans-1,3-pentadiene. For IrCl(PPh3)2, it is only possible to recover a clean pentadiene complex if the reaction is carried out in neat diene solution. Cyclobutene also coordinates to “IrClL2” (L = AsPh3, SbPh3) to form an IrCl(C4H6)L2 product when excess cyclobutene is condensed with a starting material at −78°C, THF is added, and the solution is warmed to 25°C. These 16-electron MCl(olefin)L2 complexes are stable to disproportionation after isolation from solution. The most stable complexes are formed with the tertiary arsine and stibine ligands for M = Ir.

Trans-1,3-pentadiene and cyclobutene complexes of rhodium(I) and iridium(I)

The generation of “MClL2” centers in THF solution (M = Ir, L = AsPh3, SbPh3; M = Rh, L = SbPh3) leads to stable η2-MCl(C5H8)L2 complexes on the addition of an excess of trans-1,3-pentadiene. For IrCl(PPh3)2, it is only possible to recover a clean pentadiene complex if the reaction is carried out in neat diene solution. Cyclobutene also coordinates to “IrClL2” (L = AsPh3, SbPh3) to form an IrCl(C4H6)L2 product when excess cyclobutene is condensed with a starting material at −78°C, THF is added, and the solution is warmed to 25°C. These 16-electron MCl(olefin)L2 complexes are stable to disproportionation after isolation from solution. The most stable complexes are formed with the tertiary arsine and stibine ligands for M = Ir.

Tetracarbonylwolfram-komplexe mit zwei unterschiedlichen donorliganden : I. Darstellung und mechanismus der thermischen isomerisierung

cis- and trans-tetracarbonyltungsten complexes (R 3P)(R′ 3E)W(CO) 4 (R 3P,R′ 3E = i-Pr 3P, Ph 2-i-PrP, Ph 3P, Ph 2HP, (Me 2n) 3P, Ph(i-PrO) 2P, (i-PrO) 3P, (PhO) 3P, Ph 3As, Ph 3Sb) are obtained from the chlortetracarbonyltungstates [(R 3P)W-(CO) 4Cl] - by several different routes. a cis—trans equilibrium is attained at 20–30°C with the trans isomer being thermodynamically more stable in nearly all cases. The cis-trans isomerisation of the phosphine—arsine and phosphine—stibine complexes is shown by ligand exchange experiments to occur via dissociation of the arsine and stibine ligand, respectively. The bis(phosphine) complexes, however, isomerise intramolecularly without bond cleavage.

A carbon-13 NMR study of phosphine, phosphite, arsine and stibine ligands and their LNi(CO) 3, LCr(CO) 5 and η-(C 5H 5)Mn-(CO) 2L complexes

13C NMR chemical shift and J( 13C 31P) coupling constant data are presented for PPh 3− n Me n ( n = 0, 1 and 2, P(OPh) 3, PEt 3, AsPh 3 and SbPh 3 ligands, and some corresponding LNi(CO) 3, LCr(CO) 5 and η-(C 5H 5)Mn(CO) 2L complexes. Analysis of the 13C NMR chemical shift data for the C(4) resonance in these C 6H 5X derivatives suggests: (1) a resonance substituent parameter R = 0.005 for X = PPh 2 and R = 0.09 for X = (CO) 5CrPPh 2, (2) a decrease in the resonance interaction of the Group VA atom with the phenyl ring in EPh 3 derivatives in the order E = P > As > Sb, and (3) an increase in the electron density at the phosphorus atom in PPh 3− n Me n derivatives in the order: PPh 3 < PPh 2Me < PPhMe 2. There appears tobe an anomalous shielding of the C(1) resonance in these derivatives upon complexation, and with increasing electronegativity of the Group Va atom. The electron-withdrawing character of the metal carbonyl moiety appears to increase in the order: η-(C 5H 5)Mn(CO) 2L < LNi(CO) 3 < LCr(CO) 5. The magnitude of the 1 J( 13C 31P) and 3 J( 13C 31P) coupling in trialkyl and triaryl phosphines increases upon complexation, while the magnitude of the 2 J( 13C 31P) coupling decreases. As a result, in (Me 2PhP)Ni(CO) 3, the 3 J( 13C 31P) coupling to the C(3,5) resonance of the phenyl group is larger than the 2 J( 13C 31P) coupling to the C(2,6) resonance. In contrast, complexation of triphenyl phosphite leads to an apparent increase in the magnitude of the 2 J( 13C 31P) coupling and a decrease in the magnitude of the 3 J( 13C 31P) coupling. The signs of the one-, two- and three-bond J( 13C 31P) coupling constants in Ph 3PMo(CO) 5 have been determined to be positive.

Some cobalt carbonyl complexes of ligands containing the ECH 2E (E = Sb, As, P) moiety

Complexes of the type, Co 2(CO) 6[(R 2E) 2CH 2] (R = CH 3, C 2H 5, p-CH 3C 6H 4; E = Sb, R = C 6H 5; E = Sb, As, P) were prepared by the reaction of dicobalt octacarbonyl with the corresponding ligands in benzene at room temperature. Treatment of these complexes with a diarylacetylene in refluxing benzene displaced two bridging carbonyl groups to give complexes of the type, Co 2(CO) 4(R′ 2C 2) [(R 2E) 2CH 2] (R′ = C 6H 5, p-CH 3C 6H 4), which also were obtained from the reaction between Co 2(CO) 6(R′ 2C 2) and (R 2E) 2CH 2. The structures of these derivatives are discussed on the basis of their infrared spectra. It was found from the PMR spectra in CH 2Cl 2 at room temperature that the coordinated stibine ligand in these complexes can be easily replaced by either a free phosphine or arsine ligand, while the coordinated arsine ligand is replaced only by a free phosphine.

Trigonal-bipyramidal nickel(II) complexes of tris(3-dimethylarsinopropyl)stibine

Trigonal-bipyramidal complexes [Ni(ligand)X]B(C 6H 5) 4 (X=Cl, Br, I, NCS, NO 3, CN) of the new flexible, quadridentate stibine ligand Sb[CH 2CH 2Ch 2AS - (CH 3) 2] 3 were prepared and characterized by analyses and by spectral, magnetic, and conductivity measurements. Electronic spectra of three series of trigonal-bipyramidal complexes of the ligands D[CH 2CH 2CH 2As(CH 3) 2] 3 (D=P, As, Sb) show that the normal spectrochemical series P>As>Sb is obtained for the cyanide and chloride complexes, in constrast to the anomalous spectrochemical ord P>As>Sb that was observed by Higginson, McAuliffe, and Venanzi 8 with the rigid o-phenylene ligands ( o-Ph 2L-C 6H 4) 3L′ (L= P and As; L′=P, As, and Sb). The present study with Sb[CH 2CH 2CH 2As(CH 3) 2] 3 provides confirmatroy evidence for a compression effect in the nickel(II) complexes of the rigid ligand Sb( o-C 6H 4LPh 2) 3.

The chemistry of co-ordinated ligands. Part IV. Reactivity of cycloocta-1,5-diene and its derivatives co-ordinated to palladium and platinum

Nucleophilic addition of [CH(COMe)2]–(acac) to the co-ordinated double bond in the cyclo-octenyl complexes (C8H12acac)Pt(acac) and (C8H12OMe)Pt(acac) is induced by reaction of the complexes with tertiary phosphines, L. Transfer of the acetylacetone ligand from the metal to the co-ordinated cyclo-octenyl occurs and the complexes (C8H12acac2)PtL2 and [C8H12(acac)(OMe)]PtL2 are produced. The detailed course of this reaction is unknown but it is possible that it takes place by an intramolecular rearrangement. With the corresponding palladium complexes the reaction is different. The co-ordinated cyclo-octenyl and O-bonded acetylacetone are replaced by triphenyl-phosphine, -arsine, or -stibine ligands to give the zero-valent complexes Pd(NR3)4. From the triphenylphosphine reaction the cyclic diene C8H11acac has been isolated as the organic product.

The thermal substitution reactions of iodotricarbonyl-π-cyclopentadienylmolybdenum(II)

The reactions of π-C5H5Mo(CO)3I with a number of phosphine, phosphite, and stibine ligands in refluxing benzene solution are described. The major products are the covalent derivatives π-C5H5Mo(CO)2(L)I [L = P(OPh)3. P(OMe)3, P(OEt)3, PPh3, PEt3, P(Bun)3, and SbPh3]. These compounds could be isolated only as their cis-isomers, trans-isomers, or as a mixture of both, but in no case could both pure cis- and pure trans-isomers be isolated for a given compound. The correlation of infrared and proton n.m.r. spectra enabled compounds to be identified as either the cis- or trans-isomers.