Cationic rhodium(I) and iridium(I,III) complexes of cinnamonitrile and their catalytic activities

Summary Reactions of cinnamonitrile (trans-PhCH=CHCN) with [M(ClO₄)(CO)(PPh₃)₂] (M=Rh or Ir) produce hydrogenation oftrans-PhCH=CHCN to PhCH₂CH₂CN at 100°C under 3 atm of hydrogen.     

Darstellung und Kristallstrukturen von Ag[N(CN)2](PPh3)2, Cu[N(CN)2](PPh3)2 und Ag[N(CN)2](PPh3)3

Preparation and Crystal Structures of Ag[N(CN)₂](PPh₃)₂, Cu[N(CN)₂](PPh₃)₂, and Ag[N(CN)₂](PPh₃)₃ The coordination compounds Ag[N(CN)₂](PPh₃)₂ ( 1 ), Cu[N(CN)₂](PPh₃)₂ ( 2 ), and Ag[N(CN)₂](PPh₃)₃ ( 3 ) are obtained by the reaction of AgN(CN)₂ or CuN(CN)₂ with triphenylphosphane in CH₂Cl₂. X‐ray structure determinations were performed on single crystals of 1 , 2 , and 3 · C₆H₅Cl. The three compounds crystallize monoclinic in the space group P2₁/n with the following unit cell parameters. 1 : a = 1216.07(9), b = 1299.5(2), c = 2148.4(3) pm, β = 99.689(13)°, Z = 4; 2 : a = 1369.22(10), b = 1257.29(5), c = 1888.04(15) pm, β = 94.395(7)°, Z = 4; 3 · C₆H₅Cl: a = 1276.6(4), b = 1971.7(3), c = 2141.3(5) pm, β = 98.50(3)°, Z = 4. In all structures the metal atoms have a distorted tetrahedral coordination. The crystal structure of 3 · C₆H₅Cl shows monomeric molecular units with terminal coordinated dicyanamide. The crystal structure of 1 is built up by dinuclear units, which are bridged by dicyanamide ligands. However, the crystal structure of 2 corresponds to a onedimensional coordination polymer, bridged by dicyanamide anions.     

Palladium(II) and Platinum(II) Complexes with Bisphosphanes, [S2C=C(CN)2]2– and [Se2C=C(CN)2]2– as Chelating Ligands

The palladium(II) and platin(II) 1, 1‐dicyanoethylene‐2, 2‐dithiolates [(L–L)M{S₂C=C(CN)₂}] (M = Pd: L–L = dppm, dppe, dcpe, dpmb; M = Pt: dppe, dcpe, dpmb) were prepared either from[(L–L)MCl₂] and K₂[S₂C=C(CN)₂] or from [(PPh₃)₂M{S₂C=C(CN)₂}] and the bisphosphane. Moreover, [(dppe)Pt{S₂C=C(CN)₂}]was obtained from [(1, 5‐C₈H₁₂)Pt{S₂C=C(CN)₂}] and dppeby ligand exchange. The 1, 1‐dicyanoethylene‐2, 2‐diselenolates[(dppe)M{Se₂C=C(CN)₂}] (M = Pd, Pt) were prepared from[(dppe)MCl₂] and K₂[Se₂C=C(CN)₂]. The oxidation potentials of the square‐planar palladium and platinum complexes were determined by cyclic voltammetry. The reaction of [(dcpe)Pd(S₂C=O)] with TCNE led to a ligand fragment exchange and gave the 1, 1‐dicyanoethylene‐2, 2‐dithiolate [(dcpe)Pd{S₂C=C(CN)₂}] in good yield.     

Dinuclear Au(I), Au(II) and Au(III) Complexes with (CF2)n Chains: Insights into The Role of Aurophilic Interactions in the Au(I) Oxidation

New dinuclear Au(I), Au(II) and Au(III) complexes containing (CF₂)_n bridging chains were obtained. Metallomacrocycles [Au₂{μ-(CF₂)₄}{μ-diphosphine}] show an uncommon figure-eight structure, the helicity inversion barrier of which is influenced by aurophilic interactions and steric constraints imposed by the diphosphine. Halogenation of LAu(CF₂)₄AuL (L=PPh₃, PMe₃, (dppf)_1/2, (binap)_1/2) gave [Au(II)]₂ species, some of which display unprecedented folded structures with Au−Au bonds. Aurophilic interactions facilitate this oxidation process by preorganizing the starting [Au(I)]₂ complexes and lowering its redox potential. The obtained [Au(II)]₂ complexes undergo thermal or photochemical elimination of R₃PAuX to give Au(III) perfluorinated auracycles. Evidence of a radical mechanism for these decomposition reactions was obtained.     

Synthese und Kristallstrukturen von (PPh4)2[TeS3] · 2 CH3CN und (PPh4)2[Te(S5)2]

Synthesis and Crystal Structures of (PPh₄)₂[TeS₃] · 2 CH₃CN and (PPh₄)₂[Te(S₅)₂] (PPh₄)₂[TeS₃] · 2 CH₃CN was obtained by the reaction of PPh₄Cl, Na₂S₄ and Te in acetonitrile. With sulfur it reacts yielding (PPh₄)₂[Te(S₅)₂]. The crystal structures of both products were determined by X-ray diffraction. (PPh₄)₂[TeS₃] · 2 CH₃CN: triclinic, space group P1 , Z = 2, R = 0.041 for 4 629 reflexions; it contains trigonal-pyramidal [TeS₃]^2? ions with an average Te? S bond length of 233 pm. (PPh₃)₂[Te(S₅)₂]: monoclinic, P2₁/n, Z = 2, R = 0.037 for 2 341 reflexions. In the [Te(S₅)₂]^2? ion the tellurium atom has a nearly square coordination by four S atoms. Along with the Te atoms each of the two S₅ groups forms a ring with chair conformation.     

Kronenthioetherkomplexe des Blei(II), Zink(II) und Cadmium (II) und Cadmium(II). Die Kristallstrukturen von [PbL2(ClO4)2] und [ZnL2](ClO4)2 · CH3CN (L = 1,4,7 - Trithiacyclononan)

Crown Thioether Complexes of Lead (II), Zinc(II), and Cadmium (II). Crystal Structures of [PbL₂(ClO₄)₂] and [ZnL₂](ClO₄)₂ · CH₃CN (L = 1,4,7 - Trithiacyclononane) The reaction of 1,4,7-trithiacyclononane (L) with the perchlorate salts of lead(II) and zinc(II) in CH₃CN (2:1) affords colorless crystals of [PbL₂(ClO₄)₂] and [ZnL₂](ClO₄)₂ · CH₃CN, respectively, The crystal structures have been determined. The Pb^II centre is coordinated to six sulfur atoms (the average distance Pb? S is 3.076 Å) and two oxygen atoms, one of each ClO₄^? anion (monodentate ClO₄^?). A distorted square antiprismatic polyhedron is thus generated. In [ZnL₂](ClO₄)₂ · CH₃CN the zinc(II) centre is octahedrally surrounded by six sulphur atoms (average distance Zn? S = 2.494 Å); the ClO₄^? anions are not coordinated. For[CdL₂](ClO₄)₂ · H₂O an analogous structure is proposed.     

Heterometallic Complexes with Gold(I) Metalloligands: Self‐Assembly of Helical Dimers Stabilized by Weak Intermolecular Interactions and Solvophobic Effects

New gold(I) alkynyl metalloligands bpylC?CAuL, bpyl′C?CAuPPh₃, and PPN[Au(C?Cbpyl′)₂] (bpyl or bpyl′=2,2′‐bipyridin‐5‐yl or ?4‐yl, respectively; L=PMe_xPh_3?x (x=1–3), P(C₆H₃Me₂‐3,5)₃, PCy₃, XyNC) have been synthesized. Ligands bpylC?CH and metalloligands bpylC?CAuL (L=PPh₃, PMePh₂, PCy₃, CNXy) react with MX₂ (M=Fe, Zn, X=ClO₄; M=Co, X=BF₄) to give complexes [M(bpylC?CZ)₃]X₂ (Z=H or AuL). In most cases, these complexes are mixtures of fac and mer isomers in a statistical distribution, in both CH₂Cl₂ and MeCN. However, for L=PPh₃, the fac isomer is dominant in MeCN. NMR and ESI‐MS studies, together with the crystal structure of [Co(bpylC?CAuPPh₃)₃](BF₄)₂, suggest that this solvent dependence is originated by the formation of helical dimers between two fac complexes in MeCN. These dimers are stabilized by solvophobic effects and multiple intermolecular interactions. Complex [Fe(Ph₃PAuC?CbpdiylC?CAuPPh₃)₃](ClO₄)₂ (bpdiyl=2,2′‐bipyridin‐5,5′‐diyl) was obtained by reaction of three diauro diethynylbipyridines and Fe(ClO₄)₂.     

Cationic dihydridoiridium(III) complexes of nitriles

The reaction of [IrL(CO)(PPh₃)₂]ClO₄ (PPh₃ = triphenylphosphine) with H₂ produces new cationic dihydridoiridium(III) complexes of nitriles (L), [Ir(H)₂L(CO)(PPh₃)₂]ClO₄ [L = CH₃CN (1), CH₃CH₂CN (2), CH₃CH₂CH₂CN (3) and C₆H₅CN (4)], where nitriles are coordinated through the nitrogen atom. Proton NMR spectral data for complexes 1–4 suggest that the two hydrides in each complex are cis to each other and trans to CO and nitrogen (nitrile), and the two PPh₃ are trans to each other.     

Pentafluorophenyl(dithiocarbamate)gold(III) complexes. Crystal and molecular structure of (C6F5)2Au{S2CN(CH2Ph)2}

Addition of dialkyldithiocarbamate ligands to solutions of Au(C₆F₅)₃(tht) gives either monomeric Q[Au(C₆F₅)₃(η¹-S₂CNR₂)] (Q = N(PPh₃)₂ or NBu₄; R = Me, Et, CH₂Ph) or binuclear dithiocarbamate-bridged complexes. NBu₄(μ-S₂CNR₂){Au(C₆F₅)₃}₂]. When binuclear [Au(μ-Cl)(C₆F₅)₂]₂ is used as gold source, neutral mononuclear complexes [Au(C₆F₅) ₂(η²-S₂CNR₂)] are obtained. The structure of [Au(C₆F₅)₂{η²-S₂CN(CH₂Ph)₂}] has been determined by X-ray diffraction.     

Bi- and tetranuclear polyfluorophenyl-bridged gold(I) complexes

The reaction of RAuL (R = 2,4,6-C₆F₃H₂, 3,6-C₆F₂H₃, 4-C₆FH₄ or 3-CF₃C₆H₄; L = PPh₃ or AsPh₃) or RAudpeAuR with inorganic acids HA (A = ClO₄, BF₄ or PF₆) leads to binuclear complexes of the types [R(AuL)₂]A or [R(Au₂dpe)]BF₄. Similarly, reaction of NBu₄[Au(2,4,6-C₆F₃H₂)₂] with HPF₆ yields the tetranuclear complex Au₄(2,4,6-C₆F₃H₂)₄. Addition of RAuL to solutions obtained by treating ClAuL with AgA also gives compounds of the type [R(AuL)₂]A.     

Neutral and cationic orthopalladated ( ) complexes ( = phenylazophenyl, dimethylbenzylamine, 8-methylquinoline, 2-methoxy-3-N,N-dimetrylaminopropyl)

By reacting [Pd( )(μ-Cl)]₂ with AgClO₄ in NCMe, the corresponding cationic complexes [Pd( )(NCMe)₂]ClO₄ ( = phenylazophenyl-C²,N¹; dimethylbenzylamine-C²,N; 8-methylquinoline-C⁸,N) can be obtained. Solutions containing the cations [Pd( )(S)₂]⁺ are obtained when the reaction is carried out in tetrahydrofuran or acetone (S). The treatment of these solutions with bidentate ligands (L—L) (Ph₂PCH₂PPh₂,Ph₂PNHPPh₂ or Ph₂PCH₂PPh₂CHC(O)Ph) gives the mononuclear [Pd( )(L3l)]ClO₄ complexes, with L3l acting as a chelate ligand. On the other hand [Pd( (μ-Cl)]₂ reacts with L3l (Ph₂PCH₂PPh₂, Ph₂PNHPPh₂) yielding [Pd( )Cl(L3l)] with L3l acting as monodentate. The reactions between [Pd( )(NCMe)₂]ClO₄ and 2,2′-bipyrimidyl give rise to the formation of the mononuclear [Pd( ) (bipym)]ClO₄ or binuclear [Pd₂( )₂(μ-bipym)](ClO₄)₂, [( )Pd(μ-bipym)Pd( )](ClO₄)₂ derivatives. Finally [Pd( )Cldppm] (dppm = Ph₂PCH₂PPh₂) react with NaH producing the neutral complexes [Pd( )(ddppm)] (ddppm = Ph₂PCHPPh₂) which by reaction with HCl lead again to the starting materials [Pd( )Cl(dppm)].     

Synthesis,formation constants and reactions of cationic rhodium(I) complexes of nitriles

Reactions of Rh(ClO₄)(CO)(PPh₃)₂ with nitriles produce new cationic rhodium(I) complexes, [RhL(CO)(PPh₃)₂]ClO₄ [L = CH₃CN (1), CH₃CH₂CH₂CN (2) or C₆H₅CN (3)], whose spectral data suggest that the nitriles are coordinated through the nitrogen atom. Formation constants for the reaction Rh(ClO₄)(CO)(PPh₃)₂ + L ⇋ [RhL(CO)(PPh₃)₂]ClO₄, have been measured to be 1.01 × 10⁵ M⁻¹ (CH₃CN), 1.07 × 10⁵ M⁻¹ (CH₃CH₂CH₂CN) and 2.59 × 10⁴ M⁻¹ (C₆H₅CN) at 25°C in monochlorobenzene. The differences in the formation constants for the different nitriles seem to be predominantly due to differences in ΔH (not to differences in ΔS). The nitriles in 1–3 are readily replaced with nitrogen base ligands (unsaturated nitriles and pyridine) and PPh₃.     

Synthesis and 197Au-Mössbauer spectroscopic studies of dihalo(pentafluorophenyl)(bidentate ligand)gold(III) complexes

Addition of a bidentate ligand (LL = 1,10-phenanthroline, o-phenylenebis(dimethylarsine)) to solutions of Au(C₆F₅)X₂(tht) (X = Cl, Br; tht = tetrahydrothiophene) leads to potentially five-coordinate gold(III) derivatives. ¹⁹⁷Au Mössbauer spectroscopy points, however, to four-coordinate square-planar complexes with a weak penta-coordination in the phen-containing derivatives. The complexes react with AgClO₄ to give four-coordinate cationic complexes of the types [Au(C₅F₅)X(LL)]ClO₄ or [Au(C₆F₅)(PPh₃)(LL)](ClO₄)₂.     

Preparation and Reactivity of Mixed‐Ligands Hydride Complexes [RuHCl(CO)(PPh3)2{P(OR)3}]

Mixed‐ligands hydride complexes [RuHCl(CO)(PPh₃)₂{P(OR)₃}] ( 2 ) (R = Me, Et) were prepared by allowing [RuHCl(CO)(PPh₃)₃] ( 1 ) to react with an excess of phosphites P(OR)₃ in refluxing benzene. Treatment of hydrides 2 first with triflic acid and next with an excess of hydrazine afforded hydrazine complexes [RuCl(CO)(κ¹‐NH₂NHR1)(PPh₃)₂{P(OR)₃}]BPh₄ ( 3 , 4 ) (R1 = H, CH₃). Diethylcyanamide derivatives [RuCl(CO)(N≡CNEt₂)(PPh₃)₂{P(OR)₃}]BPh₄ ( 5 ) were also prepared by reacting 2 first with HOTf and then with N≡CNEt₂. The complexes were characterized spectroscopically and by X‐ray crystal structure determination of [RuHCl(CO)(PPh₃)₂{P(OEt)₃}] ( 2b ).     

Characterising lone-pair activity of lead(II) by 207Pb solid-state NMR spectroscopy: coordination polymers of [N(CN)2]- and [Au(CN)2]- with terpyridine ancillary ligands

A series of lead(II) coordination polymers containing [N(CN)₂]^? (DCA) or [Au(CN)₂]^? bridging ligands and substituted terpyridine (terpy) ancillary ligands ([Pb(DCA)₂] ( 1 ), [Pb(terpy)(DCA)₂] ( 2 ), [Pb(terpy){Au(CN)₂}₂] ( 3 ), [Pb(4′‐chloro‐terpy){Au(CN)₂}₂] ( 4 ) and [Pb(4′‐bromo‐terpy)(μ‐OH₂)_0.5{Au(CN)₂}₂] ( 5 )) was spectroscopically examined by solid‐state ²⁰⁷Pb MAS NMR spectroscopy in order to characterise the structural and electronic changes associated with lead(II) lone‐pair activity. Two new compounds, 2 and [Pb(4′‐hydroxy‐terpy){Au(CN)₂}₂] ( 6 ), were prepared and structurally characterised. The series displays contrasting coordination environments, bridging ligands with differing basicities and structural and electronic effects that occur with various substitutions on the terpyridine ligand (for the [Au(CN)₂]^? polymers). ²⁰⁷Pb NMR spectra show an increase in both isotropic chemical shift and span (Ω) with increasing ligand basicity (from δ_iso=?3090 ppm and Ω=389 ppm for 1 (the least basic) to δ_iso=?1553 ppm and Ω=2238 ppm for 3 (the most basic)). The trends observed in ²⁰⁷Pb NMR data correlate with the coordination sphere anisotropy through comparison and quantification of the Pb? N bond lengths about the lead centre. Density functional theory calculations confirm that the more basic ligands result in greater p‐orbital character and show a strong correlation to the ²⁰⁷Pb NMR chemical shift parameters. Preliminary trends suggest that ²⁰⁷Pb NMR chemical shift anisotropy relates to the measured birefringence, given the established correlations with structure and lone‐pair activity.     

[RhCl(CO)(PPh3)]2. A precursor for the synthesis of cationic rhodium complexes with nitrogen donor ligands

Summary The use of [RhCl(CO)(PPh₃)]₂ as a precursor for the synthesis of complexes of the types [Rh(CO)L₂(PPh₃)]A (A = [ClO₄]^– or [BPh₄]^–; L = pyridine type ligand) and [Rh(CO)(L-L)(PPh₃)]A (A = [ClO₄]^– or [BPh₄]^–; L-L = bidentate nitrogen donor) and the preparation of several complexes of the types [Rh(CO)L(PPh₃){P(p-RC₆H₄)₃}]BPh₄ and [Rh(CO)(phen)(PPh₃){P(p-RC₆H₄)₃}]A (A = [ClO₄]^– or [BPh₄]^–; R = H or Me) is described.Author to whom all correspondence should be directed.     

Die Reaktionen von M[BF4] (M = Li,K) und (C2H5)2O·BF3 mit (CH3)3SiCN. Bildung von M[BFx>(CN)4—x] (M = Li,K; x = 1, 2) und (CH3)3SiNCBFx(CN)3—x, (x = 0, 1)

The Reactions of M[BF₄] (M = Li, K) and (C₂H₅)₂O·BF₃ with (CH₃)₃SiCN. Formation of M[BF_x(CN)_4—x] (M = Li, K; x = 1, 2) and (CH₃)₃SiNCBF_x(CN)_3—x, (x = 0, 1) The reaction of M[BF₄] (M = Li, K) with (CH₃)₃SiCN leads selectively, depending on the reaction time and temperature, to the mixed cyanofluoroborates M[BF_x(CN)_4—x] (x = 1, 2; M = Li, K). By using (C₂H₅)₂O·BF₃ the synthesis yields the compounds (CH₃)₃SiNCBF_x(CN)_3—x x = 0, 1. The products are characterized by vibrational and NMR‐spectroscopy, as well as by X‐ray diffraction of single‐crystals: Li[BF₂(CN)₂]·2Me₃SiCN Cmc2₁, a = 24.0851(5), b = 12.8829(3), c = 18.9139(5) Å V = 5868.7(2) ų, Z = 12, R₁ = 4.7%; K[BF₂(CN)₂] P4₁2₁2, a = 13.1596(3), c = 38.4183(8) Å, V = 6653.1(3) ų, Z = 48, R₁ = 2.5%; K[BF(CN)₃] P1¯, a = 6.519(1), b = 7.319(1), c = 7.633(2) Å, α = 68.02(3), β = 74.70(3), γ = 89.09(3)°, V = 324.3(1) ų, Z = 2, R₁ = 3.6%; Me₃SiNCBF(CN)₂ Pbca, a = 9.1838(6), b = 13.3094(8), c = 16.840(1) Å, V = 2058.4(2) ų, Z = 8, R₁ = 4.4%     

Synthesis of S,N-chelating heterocyclic thionates of palladium(II). Crystal structure of cis-[Pd(pym2S)(PPh3)2] (pym2S = pyrimidine-2-thionate)

The synthesis of mononuclear palladium(II) complexes containing chelating heterocyclic thionates is described. The new compounds of general formula cis-[Pd(RS-N)(L) _x ](ClO₄) [x = 2, L = PPh₃, RS-N = pyridine-2-thionate (py2S) (1), pyrimidine-2-thionate (pym2S) (2), imidazolidine-2-thionate (imzdS) (3), 1-methylimidazoline-2 thionate (mimzS) (4), 1,3-thiazoline-2-thionate (tzdS) (5); x = 1, L = dppe, RS-N = pyridine-2-thionate (py2S) (6), pyrimidine-2-thionate (pym2S) (7), imidazolidine-2-thionate (imzdS) (8), 1-methylimidazole-2 thionate (mimzS) (9) and 1,3-thiazoline-2-thionate (tzdS) (10)] were prepared by directly reacting the hydroxo-complexes [{Pd(PPh₃)₂(-OH) }₂](ClO₄)₂ and [ {Pd(dppe)(-OH) }₂](ClO₄)₂ with the corresponding heterocyclic thiones (RS-N)H. The complexes have been characterized by partial elemental analyses, conductance measurements and spectroscopic methods (I.r., FAB, ¹H- and ³¹P-n.m.r.). No evidence for monomer-dimer equilibrium was found in solution. The crystal structure of (2) has been determined by X-ray diffraction analysis.     

Preparation and catalytic activity of cationic rhodium(I) and iridium(I) complexes with phosphine sulphide ligands

The preparation and properties of cationic rhodium and iridium complexes of types [M(diolefin)L₂](ClO₄) and [M(diolefin)L(PPh₃)](ClO₄) [M = Rh, diolefin = 1,5-cyclooctadiene (COD) or 2,5-norbornadiene; M = Ir, diolefin = COD; L = phosphine sulphide] are described. The complexes have been characterized by IR, ¹H NMR and ³¹P NMR spectroscopy. The use of [M(diolefin)L₂](ClO₄) as catalyst precursors in homogeneous hydrogenation of olefins has been studied.     

Sterically Tuned P‐Phosphanylamino Phosphaalkenes (Me3Si)2C=PN(R)PPh2 and (iPrMe2Si)2C=PN(R)PPh2

Deprotonation of the aminophosphanes Ph₂PN(H)R 1a – 1h [R = tBu ( 1a ), 1‐adamantyl ( 1b ), iPr ( 1c ), CPh₃ ( 1d ), Ph ( 1e ), 2,4,6‐Me₃C₆H₂ (Mes) ( 1f ), 2,4,6‐tBu₃C₆H₂ (Mes*) ( 1g ), 2,6‐iPr₂C₆H₃ (DIPP) ( 1h )], followed by reactions of the phosphanylamide salts Li[Ph₂PNR] 2a , 2b , 2g , and 2h with the P‐chlorophosphaalkene (Me₃Si)₂C=PCl, and of 2a – 2g with (iPrMe₂Si)₂C=PCl, gave the isolable P‐phosphanylamino phosphaalkenes (Me₃Si)₂C=PN(R)PPh₂ 3a , 3b , 3g , and (iPrMe₂Si)₂C=PN(R)PPh₂ 4a – 4g . ³¹P NMR spectra, supported by X‐ray structure determinations, reveal that in compounds 2a , 2b , 3a , and 3b , with bulky N‐alkyl groups the Si₂C=P–N–P skeleton is non‐planar (orthogonal conformation), whereas 3g , 3h , and 4g with bulky N‐aryl groups exhibit planar conformations of the Si₂C=P–N–P skeleton. Solid 3g and 4g exhibit cisoid orientation of the planar C=P–N–C units (planar I) but in solid 3h the transoid rotamer is present (planar II). From 3g , 4d , and 4g mixtures of rotamers were detected in solution by pairs of ³¹P NMR patterns ( 3h : line broadening).