Crystal Structure Of Fac Research Articles

The kinetic substitution reactions and structural analysis of manganese(I) acetylacetonato complexes

The methanol substitution reactions in the manganese acetylacetonato complex, fac-[Mn(CO)3(acac)(CH3OH)], was kinetically investigated with a range of entering ligands including pyridine (Py), imidazole (Im) and 4-dimethylaminopyridine (DMAP). All the complexes were characterized by NMR, UV–vis and IR spectroscopy. Moreover, crystal structures of fac-[Mn(CO)3(acac)(CH3OH)] (1), fac-[Mn(CO)3(acac)(Py)] (2) and fac-[Mn(CO)3(acac)(DMAP)] (3) are reported. The substitution of methanol in fac-[Mn(CO)3(acac)(CH3OH)] (1) by DMAP is approximately 2 times faster than Py, and 1.7 times faster when compared to Im. The results correlate well with the pKa of the entering nucleophile where pyridine (Py) < imidazole (Im) < 4-dimethylaminopyridine (DMAP). The activation parameters for complex (1) were determined as ΔH≠=73.9 ± 0.6 kJ mol−1 and the entropy of activation ΔS≠=−28 ± 2 JK−1 indicating an interchange associative mechanism.

Synthesis, crystallographic, and theoretical investigation of fac-[ReI(salen)(CO)3(S)] complexes, salen = monocharged bidentate Schiff-base and S = pyridine, CH3OH

Two rhenium(I) complexes of the form fac-[Re(L–L′)(CO)3(S)] were synthesized (L–L′ = N–O salen-type bidentate ligand, S = coordinating methanol or pyridine) and the crystal structures of fac-[tricarbonylmethanol-(2-(3-methylbutyliminomethyl)phenolato)rhenium(I)] and fac-[tricarbonyl-(2-(3-methylbutyliminomethyl)phenolato)pyridinerhenium(I)] are reported. The influence of the coordinating neutral monodentate ligand in these fac-[tricarbonyl(N,O-salen)rhenium(I)] complexes was investigated both in solid state and at theoretical level using X-ray diffraction, IR, NMR, and DFT calculations.

Synthesis, structural and spectral studies of five- and six-coordinate adducts of organotin(IV) halides containing dibenzylsulfoxide (dbso) as ligand. The crystal structures of fac-[MeSnCl3(dbso)2] and trans-[Ph2SnCl2(dbso)2

The reaction of the ambidentate ligand dibenzylsulfoxide (dbso) with Me2SnCl2 in 1:1 molar ratio leads to the formation of the five-coordinate adduct [Me2SnCl2(dbso)], whereas the same reaction conditions with Ph2SnCl2 provide the six-coordinate adduct trans-[Ph2SnCl2(dbso)2]. On the other hand, the reaction with nBu2SnCl2 forms the dimeric adduct [{nBu2SnCl2(dbso)}2], which probably possesses octahedral tin(IV) nuclei and bridging chlorides. The adducts [MeSnCl3(dbso)2] and [Ph3SnCl(dbso)] were also prepared and included in the study. All complexes were studied by microanalysis and IR, NMR (¹H, 13C and 119Sn) and Mössbauer spectroscopies to investigate their structural properties. The six-coordinate species fac-[MeSnCl3(dbso)2] and trans-[Ph2SnCl2(dbso)2] were also studied by single crystal X-ray diffractometry. These compounds crystallize in the orthorhombic, Pbcn, and monoclinic space group P2(1)/c, respectively, as discrete neutral molecules with the tin(IV) atom in a distorted octahedral geometry and the two dbso ligands in cis and trans positions, respectively.

Rhenium carbonyl compounds with (diphenyl)phosphinoalkynes and a sterically hindered phosphinoalkyne

The synthesis and characterization of two series of rhenium carbonyl complexes with P-coordinated phosphinoalkynes are reported. The anionic fac-[ReBr 2(CO) 3(Ph 2PC CR)] − and neutral fac-[ReBr(CO) 3(Ph 2PC CR) 2] (R = Ph, Tol, t Bu) complexes have been prepared and the crystal structures of fac-[ReBr 2(CO) 3(Ph 2PC CTol)] − and fac-[ReBr(CO) 3(Ph 2PC C t Bu) 2] have been determined by X-ray crystallography, evidencing the presence of the uncoordinated alkyne in all these compounds. The phosphinoalkyne ( o-Tol) 2PC CPh with bulky groups linked to the phosphorus atom was prepared in order to avoid the coordination of two phosphinoalkynes in cis-position around the rhenium metal. As a result, surprisingly the complex fac-[ReBr(CO) 3{( o-Tol) 2PC CPh} 2] was obtained. The crystal structure of this compound was determined confirming the cis-coordination of two bulky phosphinoalkynes in an octahedral rhenium atom. The electronic properties of the uncoordinated alkyne in these new rhenium complexes was analyzed, based on 13C NMR data and was compared with reported data on iron complexes. The results obtained indicate that the electronic characteristics of uncoordinated alkynes are similar in both families of complexes. Thus, the different reactivity observed between rhenium and iron complexes is related to the different nature of metallic fragments rather than to electronic features of uncoordinated alkynes.

Synthesis, characterization and antiproliferative behavior of tricarbonyl complexes of rhenium(I) with some 6-amino-5-nitrosouracil derivatives: Crystal structure of fac-[ReCl(CO) 3(DANU-N 5,O 4)] (DANU = 6-amino-1,3-dimethyl-5-nitrosouracil)

New complexes of rhenium(I) with some 5-nitrosopyrimidines with general formula [ReCl(CO) 3L] have been prepared and characterized by elemental analysis, conductivity measurements, IR and 1H, 13C and 15N NMR spectroscopic methods. The complexes appear to be monomeric and the pyrimidine ligands act in a neutral form. The structure of [ReCl(CO) 3(DANU)] · CH 3CN has been solved by X-ray diffraction. The coordination environment around the Re(I) may be described as a distorted octahedron in which the ligand behaves in a bidentate fashion through N5 and O4 atoms, making a five-membered chelate ring. The coordination sphere is completed with three carbonyl groups in fac-arrangement and one chlorine atom. The evaluation of the antiproliferative behavior against five human tumor cell lines (human breast cancer MCF-7 and EVSA-T, human neuroblastoma NB69, human glioma H4 and human bladder carcinoma cell line ECV) suggested a modulator behavior of cell growth at low concentrations due to their estrogenic-like characteristics.

Reactivity of rhodium(III) complexes containing chelating pentachlorophenyl ligands. Molecular structures of fac-[Rh(C 6Cl 5) 3(py)] and mer-[Rh(C 6Cl 5) 3( tBuNC) 3

The reactions of the octahedral rhodium(III) complexes [Rh(C 6Cl 5) 3] and [Rh(C 6Cl 5) 3Cl] − with neutral monodentate ligands have been studied. With pyridine, triethylphosphine or pyrazole, one of the rhodium o-chloro bonds of the starting materials is broken and complexes of formula [Rh(C 6Cl 5) 3L] and [Rh(C 6Cl 5) 3ClL] − are obtained. Carbonylation of [Rh(C 6Cl 5) 3] produces the insertion of CO molecules in two of the RhC aryl bonds giving the diacyl complex [Rh{C(O)C 6Cl 5} 2(C 6Cl 5)(CO)], while the reaction of [Rh(C 6Cl 5) 3] or [Rh(C 6Cl 5) 3Cl] − with the strong σ-donor ligand t BuNC breaks all the rhodium o-chloro interactions producing the compound mer-[Rh(C 6Cl 5) 3( t BuNC) 3]. All the complexes are stable to the air and moisture in the solid state and moderately stable in deoxygenated solutions. The compounds have been studied and characterised by IR, NMR and MS. The crystal structures of fac-[Rh(C 6Cl 5) 3(py)] and mer-[Rh(C 6Cl 5) 3( t BuNC) 3] have been determined by X-ray diffraction methods. They display distorted octahedral metal environments but, while the pyridine complex shows two C 6Cl 5 groups acting as chelate ligands bonded through the ipso-C atom and one of the o-Cl atoms, the isocyanide complex exhibits all the coordinated ligands acting as monodentate groups.

Amine-oxide-mediated oxidative methanolysis of metal–metal bonds in [MM′(CO) 10] (M=Mn, Re; M′=Re) and [Os 3(CO) 12]: crystal structure of fac-[Re{OC(O)OMe}(CO) 3(η 2-dppf)

The reaction of 1,1′-bis(diphenylphosphino)ferrocene (dppf) with a mixture of [MnRe(CO) 10], MeOH and Me 3NO afforded the complexes fac-[MnH(CO) 3(η 2-dppf)] and [Re 2(μ-OMe) 2(μ-dppf)(CO) 6]. In the one-pot reaction of [Re 2(CO) 10] with Me 3NO, MeOH and dppf, the major mononuclear Re species isolated was the CO 2-inserted complex fac-[Re{OC(O)OMe}(CO) 3(η 2-dppf)], the crystal structure of which was determined. The coordination sphere of the rhenium atom is roughly octahedral, consisting of an oxygen atom from the methyl carbonate ligand, two phosphorus atoms from a chelating dppf ligand, and three carbon atoms from a facial arrangement of three terminally bonded carbonyls. Analogous Me 3NO-mediated methoxylation reactions involving [Os 3(CO) 12] were also investigated. With a [Me 3NO]:[Os 3(CO) 12] ratio of 2:1, the major product is [Os 3(CO) 10(μ-H)(μ-OMe)]. With three molar equivalents of Me 3NO, significant quantities of [Os 3(CO) 10(μ-OMe) 2] are also obtained.

Coordination properties of unsymmetrical Schiff base ligands containing N 3 donor sets when restricted to bidentate chelate bonding modes. Crystal structures of fac-[PtIMe 3(PMAMP)] (PMAMP=2-{(2′-pyridylmethylene)aminomethyl}pyridine) and fac-[PtIMe 3(PMAQ)] (PMAQ=8-{(2′-pyridylmethylene)amino}quinoline)

The N 3 ligands 2-{(2′-pyridylmethylene)aminomethyl}pyridine, (PMAMP), 8-{(2′-pyridylmethylene)amino}quinoline, (PMAQ) and 2-[{(6′-methyl-2′-pyridyl)methylene}aminomethyl]pyridine (MPMAMP) are analogous to 2,2′:6′,2″-terpyridine in respect of their spatial arrangement of N donor atoms. When acting as bidentate chelates PMAMP and PMAQ bind exclusively to the Pt IV moiety PtIMe 3 such that the five-membered chelate rings incorporate the imine bond. This was deduced by detailed solution NMR studies and X-ray crystal structures. In contrast, the ligand MPMAMP, with 6-methyl substitution of the pyridyl ring attached to the carbon of the imine bond, preferentially, but not exclusively, coordinates to the nitrogen of the other pyridyl ring. The population ratio of the two complexes formed was 6:1 (303 K, CDCl 3 solution), but there was no NMR evidence of exchange between these species, in the temperature range 303–413 K, resulting from 1,4-metallotropic shifts, as occurs in analogous complexes such as fac-[PtIMe 3(2,2′:6′,2″-terpyridine)].

New complexes of lanthanide chlorides.: Reversible isomerization in octahedral [LaCl 3(HMPA) 3] and the crystal structure of fac-[SmCl 3(HMPA) 3

Complexes of [LnCl 3L] (Ln=La, Nd, Sm, Eu, and L=diethylene glycol dimethyl ether, diglyme; Ln=La, Pr, and L=dimethoxyethane, DME) were prepared from the lanthanide oxides and hydrogen chloride, which was formed in situ from chlorotrimethylsilane and water. When hexamethylphosphoramide (HMPA) was added to the suspension of the prepared DME and diglyme complexes in toluene, fac-[LnCl 3(HMPA) 3] (Ln=La, Pr, Nd, Sm, Eu, Gd) complexes, isomorphous according to the unit cell determination, were formed. The crystal structure of [SmCl 3(HMPA) 3] was determined. Each samarium atom is octahedrally coordinated by three chlorine atoms and three HMPA molecules, which are distributed in a facial mode. The exchange of coordinated and free HMPA, as well as the reversible fac– mer isomerization of [LaCl 3(HMPA) 3], was observed by variable temperature 1H NMR spectroscopy. The associative mechanism of the exchange and isomerization was proposed.

A detailed NMR study of the solution stereodynamics in tricarbonylrhenium(I) halide complexes of the non-racemic chiral ligand 2,6-bis[(4R,5R)-dimethyl-1,3-dioxan-2-yl]pyridine (L1) and the molecular structure of fac-[ReBr(CO)3(L1)] †

Tricarbonylrhenium(I) halide complexes of the non-racemic chiral ligand 2,6-bis[(4R,5R)-dimethyl-1,3-dioxan-2-yl]pyridine (L1), namely fac-[ReX(CO)3(L1)] (X = Cl, Br or I), have been prepared. In these complexes the ligand is bound in a bidentate fashion, with the N atom of the pyridine ring and an O atom of one of the acetal rings co-ordinated to the octahedral metal centre. The bidentate mode is confirmed by the crystal structure of fac-[ReBr(CO)3(L1)]. There are four possible diastereoisomers, depending on the configuration at the metal centre and at the acetal-carbon atom of the co-ordinated ring; the crystal structure of fac-[ReBr(CO)3(L1)] shows that the SR diastereoisomer is present in the solid-state. In solution, three of the four possible diastereoisomers are observed, namely SR, RR and SS; their relative populations are in the order SR > RR > SS. Above ambient temperature the complexes are stereochemically non-rigid. The fluxional kinetics have been measured by a combination of standard band shape analysis and selective inversion experiments. Two distinct processes are present: an acetal ring flip and exchange of the pendant and co-ordinated acetal rings. The latter process occurs via two independent mechanisms, namely tick-tock and rotation pathways. The activation energies for the stereodynamics are in the ranges 72–73 kJ mol–1 (tick-tock), 77–78 kJ mol–1 (acetal ring flip) and 83–90 kJ mol–1 (rotation) at 298 K.

Triphenylstibine substituted manganese and rhenium carbonyls: synthesis and multinuclear NMR spectroscopic studies. X-ray crystal structures of ax-[Mn 2(CO) 9(SbPh 3)], [Mn(CO) 5(SbPh 3)][CF 3SO 3] and fac-[Re(CO) 3Cl(SbPh 3) 2

The syntheses of [Mn 2(CO) 10− x (SbPh 3) x ] ( x=1 or 2), [Re 2(CO) 9(SbPh 3)], [Mn(CO) 5(SbPh 3)][CF 3SO 3], [M(CO) 4Cl(SbPh 3)], fac-[M(CO) 3Cl(SbPh 3) 2] (M=Mn or Re) and mer,trans-[Mn(CO) 3Cl(SbPh 3) 2] are reported. The complexes have been characterised by chemical analysis, IR and multinuclear NMR ( 1H, 13C{ 1H} and 55Mn) spectroscopies, and FAB mass spectrometry. The crystal structure of [Mn 2(CO) 9(SbPh 3)] established the axial position of the SbPh 3 ligand (Mn–Sb 2.525(1), Mn–Mn 2.909(1) Å) and that of [Mn(CO) 5(SbPh 3)][CF 3SO 3] confirmed the cation structure (Mn–Sb 2.596(3) Å). The crystal structure of fac-[Re(CO) 3Cl(SbPh 3) 2] establishes the stereochemistry (Re–Sb 2.726(1), 2.729(2) Å). Differences in the products/isomers produced in reactions of [M 2(CO) 10] and [M(CO) 5Cl] with SbPh 3 and with the corresponding PR 3 and AsR 3 ligands are identified and discussed.

Stereochemically non-rigid transition metal complexes of 2,6-bis[1-(phenylimino)ethyl]pyridine (BIP). Part 3. Dynamic NMR studies of fac-[PtXMe 3(BIP)] (X=C1, Br, or I). Crystal structure of fac-[PtIMe 3(BIP)

The complexes fac-[PtXMe 3(BIP)] (X=Cl,Br or I;BIP=2,6-bis[1-(phenylimino)ethyl]pyridine) have been synthesised and characterised as involving BIP as a bidentate chelate ligand. In solution the metal-bound ligand exists in four conformational forms, namely distal and proximal E,E and E,Z-isomers. 2D-EXSY NMR has been used to measure 1,4-metallotropic shifts of the PtXMe 3 moiety between equivalent distal E,E forms, E,Z isomerisation of the pendant imine function and restricted CC rotation of the pendant arm of the BIP ligand. Activation energies, Δ G ≠ (298.15 K), for all these processes are in the range 67–96 kJ mol −1 and are essentially halogen independent. A crystal structure of fac-[PtIMe 3(BIP)] shows that the pendant imine function is in the E-conformation and is rotated at an angle of 80.1° to the plane of the pyridine.

Stereochemically non-rigid transition metal complexes of 2,6-bis[(1-phenylimino)ethyl]pyridine (BIP) Part 2. Dynamic NMR studies of fac-[ReX(CO)3(BIP)] (X = Cl, Br, or I). Crystal structure of fac-[ReBr(CO)3(BIP)

The complexes fac-[PtXMe3(BIP)] (X Cl,Br or I;BIP 2,6-bis[1-(phenylimino)ethyl]pyridine) have been synthesised andcharacterised as involving BIP as a bidentate chelate ligand. In solution the metal-bound ligand exists in four conformationalforms, namely distal and proximal E,E and E,Z-isomers. 2D-EXSY NMR has been used to measure 1,4-metallotropic shifts ofthe PtXMe3 moiety between equivalent distal E,E forms, E,Z isomerisation of the pendant imine function and restricted C Crotation of the pendant arm of the BIP ligand. Activation energies, DG (298.15 K), for all these processes are in the range 67–96kJ mol 1 and are essentially halogen independent. A crystal structure of fac-[PtIMe3(BIP)] shows that the pendant imine functionis in the E-conformation and is rotated at an angle of 80.1° to the plane of the pyridine.

Preparation and characterisation of rhenium(I) and platinum(IV) complexes of 2,6-bis(pyrazol-1-lylmethyl)pyridine and 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine. Crystal structure of fac-[Rel(CO) 3(BMPz)

Under mild conditions [ReX(CO) 3(THF) 2] reacts with pyrazolylmethylpyridines to form the complexes fac-[ReX(CO) 3(BPz)] and fac-[ReX(CO) 3(BMPz)] (X  Cl, Br, or I; BPz = 2,6-bis(pyrazol-1-ylmethyl)pyridine ; BMPz = 2,6-bis(3,5-dimethylpyrazol-1-ylmethyl)pyridine) that involve BPz and BMPz acting as non-fluxional bidentate chelate ligands. Under more severe reaction conditions fac-[ReX(CO) 3(BPz)] is converted to fac-[Re(CO) 3(BPz)]X (X  Cl, Br, or I). Trimethylplatinum(IV)iodide reacts with BPz to form fac-[PtMe 3(BPz)]I. The crystal structure of fac-[ReI(CO) 3(BMPz)] confirms the bidentate chelate bonding of BMPz with a NReN angle of 85.8°.

Poly(2-pyridyl)phosphines, PPynPh3-n(n= 2, 3), and Their P-Substituted Derivatives as Tripodal Ligands in Molybdenum(0) Carbonyl Complexes

The final products of the reactions of either [Mo(CO)6] or [Mo(CO)4(NBD)] (NBD = norbornadiene) with PPy3 (Py = 2-pyridyl) or ZPPy3 (Z = O, S, ClAu, C6F5Au) are fac-[Mo(CO)3(Py3P-N3)] or fac-[Mo(CO)3(Py3PZ-N3)], where the ligands act as tridentate N-donors. The use of ZPPhPy2 (Z = O, S) leads to fac-[Mo(CO)3(ZPPhPy2-Z,N2)], the ligands acting as tridentate Z,N2-donors. The crystal structure of fac-[Mo(CO)3(SPPhPy2-S,N2)] was determined by area detector diffractometry and shows that the coordination at molybdenum is essentially octahedral but with trigonal elongation. Some tetracarbonyl complexes which are intermediates in the formation of the above tricarbonyl complexes have been isolated (cis-[Mo(CO)4(PPy3-P)2] and cis-[Mo(CO)4(ZPPhPy2-Z,N)] (Z = O, S)) or detected (cis-[Mo(CO)4(Py3P-N2)] and cis-[Mo(CO)4(SPPy3-S,N)]). The syntheses of the new complexes [Au(C6F5)(PRPy2-P)] (R = Py or Ph) are also described.

Dynamic nuclear magnetic resonance study of the effects of cis-chelate ligands on 1,2-metallotropic shifts in trimethylplatinum(IV) complexes of pyridazine

The complexes fac-[PtMe3(L–L)(pydz)][BF4](L–L = neutral bidentate chelate ligand; pydz = pyridazine) were readily prepared from fac-[PtlMe3(L–L)] by the action of silver(I) salts in the presence of an excess of pyridazine. Pyridazine is acting as a monodentate ligand, which undergoes a facile 1,2-metallotropic shift between the two equivalent, contiguous nitrogen donor atoms. The solutionstate stereodynamics of these complexes have been elucidated by two-dimensional exchange spectroscopy and accurate activation parameters deduced. Energy barriers [ΔG‡(298 K)] are in the range 58–78 kJ mol–1. The effects of the chelate ligand on the energetics of the fluxional shift are discussed and rationalised. The crystal structure of fac-[PtMe3(bipy)(pydz)][BF4](bipy = 2,2′-bipyridyl) was determined to confirm the fac-octahedral co-ordination geometry of the complexes.

Preparation and Characterization of Iridium(III) Complexes Containing (2-Aminoethyl)dimethylphosphine (edmp) or (2-Aminoethyl)diphenylphosphine (edpp). Structures of fac-[Ir(edmp)3]Cl3·5H2O and trans(Cl,Cl),cis(P,P)-[IrCl2(edpp)2]BF4 and Comparisons of Their Properties with Those of the Cobalt(III) and Rhodium(III) Analogs

Abstract The iridium(III) complexes containing (2-aminoethyl)dimethylphosphine (edmp) or (2-aminoethyl)diphenylphosphine (edpp) were prepared. Crystal structures of fac-[Ir(edmp)3]Cl3·5H2O (2), trans(Cl,Cl),cis(P,P)-[IrCl2(edpp)2]BF4 (3), and Δ(lel3)- and Λ(ob3)-[Ir(R,R-chxn)3](NO3)3·3H2O (4 and 5; chxn = trans-1,2-cyclohexanediamine) were determined by single-crystal X-ray diffraction. Crystal data and final R values are: for 2, FW = 703.7, triclinic, , a = 11.718(2), b = 13.199(1), c = 9.482(1) Å, α = 91.44(1), β = 105.86(1), γ = 90.53(1)°, V = 1410.0(2) Å3, Dx = 1.66 Mg m−3, and Z = 2, R = 0.039 for 5410 reflections. For 3, FW = 808.5, triclinic, , a = 11.465(1), b = 13.694(1), c = 10.049(1) Å, α = 94.764(6), β = 92.197(8), γ = 102.807(8)°, V = 1530.5(2) Å3, Dx = 1.75 Mg m−3, and Z = 2, R = 0.035 for 5978 reflections. For 4, FW = 774.9, hexagonal, P63, a = 13.005(1), c = 10.221(2) Å, V = 1497.1(3) Å3, Dm = 1.71(2), Dx = 1.72 Mg m−3, and Z = 2, R = 0.020 for 1063 reflections. For 5, hexagonal, FW = 774.9, P63, a = 13.359(1), c = 9.848(2) Å, V = 1522.0(3) Å3, Dm = 1.70(2), Dx = 1.69Mg m−3, and Z = 2, R = 0.015 for 1105 reflections. The average Ir–N bond length of 2.167(6) Å in 2 is longer by 0.077(6) Å than those in 4 and 5. The structural data of the corresponding cobalt(III) and rhodium(III) complexes show that the order of the strength of the trans influence of the –PMe2 group in edmp is CoIII &amp;lt; IrIII &amp;lt; RhIII. In 3, the elongation of the metal–nitrogen bond length by the trans influence of the –PPh2 group in edpp is smaller than that of the –PMe2 group in 2, and the elongation is nearly the same as those in the corresponding cobalt(III) and rhodium(III) complexes. The absorption spectra of the two series of complexes, fac-[M(edmp)3]3+ and trans(Cl,Cl),cis(P,P)-[MCl2(edpp)2]+ (M = CoIII, RhIII, and IrIII) are compared and Shimura’s spectrochemical parameters for iridium(III) are discussed.

Organometallic chemistry of diphosphazanes: VIII. Synthesis, spectroscopic studies and crystal structure of fac-[Mo(CO)3(MeCN){Ph2PN(iPr)P(Ph)(DMP)}], and its reactions with t

The reaction of fac-[Mo(CO)3(MeCN)3] with the unsymmetrical diphosphazane Ph2PN(iPr)P(Ph)(DMP) (L) gives the complex fac-[M

Halogenotrimethylplatinum(IV) complexes of 2,6-bis(p-tolylthiomethyl)pyridine (L1): nuclear magnetic resonance studies of their solution state stereodynamics and the crystal structure of fac-[PtBrMe3L1

Under mild conditions 2,6-bis(p-tolylthiomethyl) pyridine (L1) reacted with halogenotrimethylplatinum(IV) to afford complexes of the type fac-[PtXMe3L1](X = Cl or Br). This potentially terdentate ligand acts here in a five-membered S/N chelate bidentate fashion. Solution dynamic NMR studies revealed the presence of three fluxional processes: pyramidal inversion of the co-ordinated sulfur atom, S-S switching with correlated pyramidal inversion, and S-S switching. The mechanism for the S-S exchange process was elucidated by two-dimensional NMR exchange spectroscopy. The crystal structure of fac-[PtBrMe3L1] confirms the bidentate chelate nature of the ligand in the solid state, with a N-Pt-S(1) angle of 81.5°. IR data for the Pt-C, Pt-N and Pt-X stretching modes in these complexes are also presented.

Synthesis and reactivity of the silylated triphosphites [(R1O)2PO]3SiR2(R1= Me or Et; R2= Me, Ph or CHCH2). Crystal structure of fac-[Mo(CO)3{P,P,P-[P(OMe)2O]3SiMe}

The silylated triphosphites [(R1O)2PO]3SiR2(R1= Me or Et; R2= Me, Ph or CHCH2) have been prepared in high yield by the reactions between SiR2Cl3 and (R1O)2P(O)H in the presence of NEt3. The compound [(MeO)2PO]3SiMe reacts with [Mo(CO)4(nbd)](nbd = norbornadiene) and [Mo(CO)3(η6–C7H8)] to afford [Mo(CO)4{P,P-[P(OMe)2O]2SiMe[OP(OMe)2]}] and fac-[Mo(CO)3{P,P,P-[P(OMe)2O]3SiMe}] respectively. The crystal structure of fac-[Mo(CO)3{P,P,P-[P(OMe)2O]3SiMe}] has been determined in the space group P21/c with a= 10.1129(8), b= 14.3197(12) and c= 14.9906(11)A. The metal-co-ordinated triphosphites are significantly less electron-releasing than tertiary phosphine analogues and more closely resemble the η-arenes of [Mo(CO)3(η6–C6H6–nMen)] in their electronic character.