The designed synthesis and characterization of two novel heterometallic trinuclear incomplete cubane-like clusters [(CH3CH2)4N]{(M2CuS4)}(S2C2H4)2(PPh3) (M = Mo, W)

Two novel heterometallic trinuclear incomplete cubane-like clusters [(CH₃CH₂)₄N][{M₂CuS₄}(edt)₂(PPh₃)] (M = Mo, W) have been synthesized by reaction of [(CH₃CH₂)₄N]₂[M₂S₄(edt)₂] (M = Mo, W) with Cu(PPh₃)₂(dtp) [where edt is 1,2-ethane-dithiolato ligand, dtp is S₂P(OCH₂CH₃)₂⁻]. The two crystals are isomorphous in space group P1 (No. 1). The unit cell contains two independent molecules, but the two discrete anions have the same orientation for the PPh₃ ligands along one axis so the space group is undoubtedly non-centrosymmetric. The discrete anion contains two edt ligands and one PPh₃ ligand attached to one incomplete cubane-like cluster core {M₂CuS₄}³⁺ (M = Mo, W). The bond lengths of Mo---Mo[W---W] and the two Mo---Cu[W-Cu] are 2.852(2)[2.844(1)], 2.802(2)[2.765(3)], 2.760(2)[2.762(3)] Å, respectively. The M ₂S₄(edt)₂ (M = Mo, W) moiety remains almost unchanged, except that for the compound 1 the Mo=S double bond length elongates from av. 2.10 to av. 2.165 Å. The title clusters provide a new type of unsymmetric μ₂-bridging sulphido ligand. The incomplete cubane-like cluster core {Mo₂CuS₄}³⁺ of compound 1 is distorted because the two Cu---μ₂---S bond lengths are significantly different (2.313 Å and 2.409 Å), but the core {W₂CuS₄}³⁺ of compound 2 has approximately C_s symmetry. The IR spectra of the two title clusters and two starting materials are assigned.     

Reactions of the dichloroboryl complex of osmium, Os(BCl2)Cl(CO)(PPh3)2, with water, alcohols, and amines: Crystal structures of Os[B(OH)2]Cl(CO)(PPh3)2, Os[B(OEt)2]Cl(CO)(PPh3)2, and

We have investigated the reactivity of the unsymmetrical H-spirophosphorane (HSP) ligand HP(OCMe₂CMe₂O)(OCH₂CMe₂NH) 1 towards different palladium(II) precursors and synthesised the mononuclear complexes [PdCl₂{P(OCMe₂CMe₂O)OCH₂CMe₂NH₂}] 2 and [PdCl(C₃H₅){P(OCMe₂CMe₂O)OCH₂CMe₂NH₂}] 3. The structural features of the compounds are characterised by spectroscopic methods as well as single crystal X-ray diffraction studies. The complexes are shown to be remarkably active precatalysts for the Heck and Hiyama cross-coupling reactions. The products of the C-C bond formation reactions were obtained with high conversion and stereoselectivity. Mechanistic studies of the Heck reaction reveal that, besides homogenous precatalysts, also heterogeneous Pd(0) nanoparticles are involved in the catalytic process.     

Palladium (II) complexes with the unsymmetrical H-spirophosphorane ligand HP(OCMe2CMe2O)(OCH2CMe2NH): Synthesis, structural and catalytic studies

We have investigated the reactivity of the unsymmetrical H-spirophosphorane (HSP) ligand HP(OCMe₂CMe₂O)(OCH₂CMe₂NH) 1 towards different palladium(II) precursors and synthesised the mononuclear complexes [PdCl₂{P(OCMe₂CMe₂O)OCH₂CMe₂NH₂}] 2 and [PdCl(C₃H₅){P(OCMe₂CMe₂O)OCH₂CMe₂NH₂}] 3. The structural features of the compounds are characterised by spectroscopic methods as well as single crystal X-ray diffraction studies. The complexes are shown to be remarkably active precatalysts for the Heck and Hiyama cross-coupling reactions. The products of the C-C bond formation reactions were obtained with high conversion and stereoselectivity. Mechanistic studies of the Heck reaction reveal that, besides homogenous precatalysts, also heterogeneous Pd(0) nanoparticles are involved in the catalytic process.     

Synthesis and structure of mixed-metal thiolate complex Cp′Cr(CO)2(μ-SBu)Pt(PPh3)2: Side-on-coordination of Cr–S double bond with platinum

The reaction of [Cp′Cr(CO)₂(μ-SBu)]₂ (1) (Cp′ = MeC₅H₄) with (PPh₃)₂Pt(PhCCPh) gives Cp′Cr(CO)₂(μ-SBu)Pt(PPh₃)₂ (2) which could be regarded as a product of the substitution of acetylene ligand at platinum by a monomeric chromium–thiolate fragment. According to the X-ray diffraction analysis 2 contains single Cr–Pt (2.7538(15)) and Pt–S (2.294(2) Å) bonds while Cr–S bond (2.274(3) Å) is shortened in comparison with ordinary Cr–S bonds (2.4107(4)–2.4311(4) Å) in 1. The bonding between Cr–S fragment and platinum atom is similar to the olefine coordination in their platinum complexes.     

Chelate structures of 5-(H/Br)-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazones (H2L): Synthesis and structural characterizations of [Ni(L)(PPh3)] and [Ru(HL)2(PPh3)2]

The reactions of 5-R-2-hydroxybenzaldehyde-4-allyl-thiosemicarbazone {R: H (L¹); Br (L²)} with [M^II(PPh₃)nCl₂] (M = Ni, n = 2 and M = Ru, n = 3) in a 1:1 molar ratio have given stable solid complexes corresponding to the general formula [Ni(L)(PPh₃)] and [Ru(HL)₂(PPh₃)₂]. While the 1:1 nickel complexes are formed from an ONS donor set of the thiosemicarbazone and the P atom of triphenylphosphine in a square planar structure, the 1:2 ruthenium complexes consist of a couple from each of N, S and P donor atoms in a distorted octahedral geometry. These mixed-ligand complexes have been characterized by elemental analysis, IR, UV–Vis, APCI-MS, ¹H and ³¹P NMR spectroscopies. The structures of [Ni(L²)(PPh₃)] (II) and [Ru(L¹H)₂(PPh₃)₂] (III) were determined by single crystal X-ray diffraction.     

Coordination chemistry of di-2-pyridylketone. Synthesis, spectroscopic investigations, X-ray studies and DFT calculations of Re(III) and Re(V) complexes

The paper presents a combined experimental and computational study of Re(III) and Re(V) complexes containing di-2-pyridylketone and its gem-diol form – [ReCl₃(dpk-N,O)(PPh₃)] (1), [ReCl₃(dpk-N,N′)(OPPh₃)] (2) and [ReOBr₃(dpk-OH)]·2(dpkH⁺Br⁻) (3). All the complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 2 has been additionally studied by magnetic measurement. The magnetic behavior of 2 is characteristic of mononuclear octahedral Re(III) complex with d⁴ low-spin (³T_1g ground state) and arise because of the large spin–orbit coupling (ζ = 2500 cm⁻¹), which gives diamagnetic ground state. DFT and time-dependent (TD)DFT calculations have been carried out for [ReCl₃(dpk-N,N′)(OPPh₃)] and [ReOBr₃(dpk-OH), and their UV–vis spectra have been discussed on this basis.     

Vinyliden-Übergangsmetallkomplexe XXVI. Synthese und struktur kationischer Carbonyl-, Alken-, Vinyliden-, Alkinyl- und Alkin-Rhodiumkomplexe mit der Baueinheit trans-[Rh(PPr3)2]

The complex trans-[Rh(CO)(NH₃)(PiPr₃)₂]PF₆ (2) was prepared from [(η³-C₃H₅)Rh(PⁱPr₃)₂] (1), NH₄PF₆ and CO or from 1 and NH₄PF₆ in presence of an excess of methanol. With an excess of CO, the dicarbonyl and tricarbonyl compounds trans-[Rh(CO)₂(PⁱPr₃)₂]PF₆ (3) and [Rh(CO)₃(PⁱPr₃)₂]PF₆ (4) were obtained. Displacement of one CO ligand in 3 by pyridine and acetone led to the formation of trans-[Rh(CO)(py)PⁱPr₃)₂]PF₆ (5a) and trans-[Rh(CO) (O=CMe₂(PⁱPr₃)₂]PF₆ (6), respectively. Treatment of 1 with [pyH]BF₄ and pyridine gave trans-[Rh(py)₂(PⁱPr₃)₂]BF₄ (7); in presence of H₂ the dihydrido complex [RhH₂(py)₂(PⁱPr₃)₂]BF₄ (8) was formed. The reaction of 1 with NH₄PF₆ and ethylene produced trans [Rh(C₂H₄(NH₃(PⁱPr₃)₂]PF₆(9) whereas with methylvinylketone and acetophenone the octahedral hydridorhodium(III) complexes [RhH(η²-CH=CHC(=O)CH₃ (NH₃(PⁱPr₃)₂]PF₆(11) and [RhH(η2-C₆H₄C(=O)CH₃(NH₃(Pⁱpr₃)₂]PF₆ (13) were obtained. The synthesis of the cationic vinylidenerhodium(I) compounds trans-[Rh(=C=CHR)(py)(PⁱPr₃)₂]BF₄ (14–16) and trans-[Rh(=C=CHR)(NH₃)(PⁱPr₃) ₂]PF6 (17–19) was achieved either on treatment of 1 with [pyH]BF₄ or NH₄PF₆ in presence of 1-alkynes or by ethylene displacement from 9 by HCCR. With tert-butylacetylene as substrate, the alkinyl(hydrido)rhodium(III) complex [RhH(CC^tBu)(NH₃)(O=CMe₂)(PⁱPr₃) ₂]PF₆ (20) was isolated which in CH₂Cl₂ solution smoothly reacted to give 19 (R =^tBu). The cationic but-2-yne compound trans-[Rh(MeCCMe)(NH₃)(Pⁱ Pr₃)₂]PF₆ (21) was prepared from 1, NH₄PF₆ and C₂Me₂. The molecular structures of 3 and 14 were determined by X-ray crystallography; in both cases the square-planar coordination around the metal and the trans disposition of the phosphine ligands was confirmed.

Abstract

Der Komplex trans-[Rh(CO)(NH₃)(PⁱPr₃)₂]PF₆ (2) wurde aus [(η³-C₃H₅)Rh(PⁱPr₃)₂] (1), NH₄PF₆ und CO oder aus 1, NH₄PF₆ und Methanol hergestellt. In Gegenwart von überschüssigem CO wurden die Dicarbonyl- und Tricarbonyl-Verbindungen trans-[Rh(CO)₂(PⁱPr₃)₂]PF₆ (3) und [Rh(CO)₃(PⁱPr₃)₂]PF₆ (4) erhalten. Die Verdrängung eines CO-Liganden in 3 durch Pyridin oder Aceton führte zur Bildung von trans-[Rh(CO)(py)(PⁱPr₃)₂]PF₆ (5a) bzw. trans-[Rh(CO)(O=CMe₂)(PⁱPr₃)₂]PF₆ (6). Bei Einwirkung von [pyH]BF₄ und Pyridin auf 1 entstand trans-[Rh(py)₂(PⁱPr₃)₂]BF₄ (7); in Gegenwart von H₂ bildete sich der Dihydrido-Komplex [RhH₂(py)₂(PⁱPr₃) ₂]BF₄ (8). Die Reaktion von 1 mit NH₄PF₆ und Ethen lieferte trans-[Rh(C₂H₄)(NH₃)(PⁱPr₃)₂] PF₆ (9) während mit Methylvinylketon und Acetophenon die oktaedrischen Hydridorhodium(III)-Komplexe [RhH(η²-CH=CHC(=O)CH₃ (NH₃)-(PⁱPr₃)₂]PF₆ (11) und [RhH(η-²-C₆H₄C(=O)CH₃(NH₃)(PⁱPr₃)₂)₂]PF₆ (13) erhalten wurden. Die Synthese der kationischen Vinyli-denrhodium(I)-Verbindungen trans-[Rh(=C=CHR(py)(PⁱPr₃)₂]BF₄ (14–16) und trans-[Rh(=C=CHR)(NH₃)(PⁱPr₃)₂]PF₆ (17–19) gelang durch Einwirkung von [pyH]BF₄ bzw. NH₄PF₆ auf 1 in Gegenwart von 1-Alkinen oder durch Ethen-Verdrängung aus 9 mit HCCR. Mit tert-Butylacetylen als Reaktionspartner wurde der Alkinyl(hydrido)rhodium(III)-Komplex [RhH(CC^tBu)(NH₃(O=CMe₂)(PⁱPr₃)₂]PF₆ (20) isoliert, der in CH₂Cl₂-Lösung sofort zu 19 (R =^tBu) reagiert. Die kationische 2-Butin-Verbindung trans -[Rh(MeCCMe)(NH₃)PⁱPr₃)₂]PF₆ (21) wurde aus 1, NH₄PF₆ und C₂Me₂ hergestellt. Die Strukturen von 3 und 14 wurden kristallographisch bestimmt; in beiden Fa len ließ sich die quadratisch-planare Koordination des Metalls und die trans-Anordnung der Phosphanliganden bestätigen.     

Organo-imido alkoxides of tungsten(VI). The crystal and molecular structures of [W(NPh)(μ-OMe)(OMe)3]2 and [W(NPh)(OCMe3)3Cl(NH2CMe3)]

Reaction of phenylimido tungsten tetrachloride with MeOH and t-butylamine gave the dimeric complexes [W(NPh)(μ-OMe)(OMe)₃]₂ and [W(NPh)(μ-OMe)(OMe)₂Cl]₂. With ethanol [W(NPh)(μ-OEt)(OEt)₂Cl]₂ was formed whereas isopropyl and neopentyl alcohols gave the monomeric complexes [W(NPh)(OR)₄(NH₂CMe₃)](R = CHMe₂, CH₂CMe₃); t-butanol gave [W(NPh)(OCMe₃)3Cl(NH₂CMe₃)] which could not be converted to [W(NPh) (OCMe₃)₄]. Further reaction of [W(NPh)(μ-OMe)(OMe)₃]₂ with o-HOC₆H₄CH = NC₆H₃Me₂(salim-H) gave the salicylaldimine complex [W(NPh)(OMC)₃(salim)]. The products were characterised by analytical data, IR, ¹H NMR, ¹³C NMR and mass spectroscopy. The crystal and molecular structures of the title complexes have been determined from single crystal X-ray diffractometer data. Crystals of [W(NPh)(μ-OMe)(OMe)₃]₂are triclinic with a = 8.473(7), b = 10.776(5), c = 7.683(Å, α = 102.26(3), β = 102.68(4), γ = 71.13(6)°, space group P$\text{1}$ Crystals of 3) [W(NPh)(OCMe₃)₃Cl(NH₂CMe₃) are monoclinic with a = 9.341(2), b = 29.608(7), c = 10.257(2) Å, β = 106.28(2)°, space group, P2₁/c. Both structures were solved by Patterson and Fourier methods and refined to R = 0.075 for the 1022 observed data of [W(NPh) (μ-OMe)(OMe)₃]₂ and to R = 0.074. For the 2033 observed data of [W(NPh)(OCMe₃)₃Cl(NH₂CMe₃). The former molecule is shown to be a dimer, the two halves of the molecule being related by a centre of symmetry. Both W atoms adopt a distorted octahedral coordination geometry and they are linked by two methoxy bridges. Trans to one of the bridging donors is the phenyl imido group with a WN bond length of 1.61(4) Å; the remaining coordination sites are filled with methoxy groups. The structure of W(NPh)(OCMe₃)₃ Cl(NH₂CMe₃) is monomeric with the phenylimido group trans to the NH₂CMe₃ ligand in a distorted octahedral coordination geometry. Remaining sites are filled with the chloride and 3 OCMe₃ ligands. The WN (imido) bond length is 1.71(2) Å, whilst WN(amine) is 2.40(2) Å     

Diamine incorporated compounds derived from polymeric nickel(II) fumarates and oxalates: Crystal structure, spectral and thermal properties of [Ni(en)3](O2CCHCHCO2)·3H2O and [Ni(en)3](O2CCO2)

Lewis-base mediated fragmentation of polymeric nickel(II) fumarate and oxalate are attempted using chelating σ-donor diamines like ethylenediamine (en) and 1,3-diaminopropane (dap) in various conditions which yielded [Ni(en)₃](fum)·3H₂O (1), [Ni(en)₃](ox) (2), [Ni(dap)₂(fum)] (3) and [Ni(dap)(ox)]·2H₂O (4). While 1 and 2 are molecular products each containing octahedral [Ni(en)₃]²⁺ moieties and the anionic dicarboxylate species, 3 and 4 are dap-incorporated polymeric products. The fumarate derivative 1 containing [Ni(en)₃]²⁺ moieties crystallizes in the monoclinic space group C2/c with a = 17.899(4) Å, b = 11.747(2) Å, c = 10.748(2) Å, β = 125.59(3)°, V = 1837.7(6) ų, Z = 4, while the oxalate analogue 2 is seen to be in the trigonal space group P−31c with a = 8.8770(13) Å, b = 8.8770(13) Å, c = 10.482(2) Å, γ = 120°, V = 715.3(2) ų, Z = 2. The octahedral [Ni(en)₃] units in both 1 and 2 are seen to be strongly H-bonded to the dicarboxylate moieties through the coordinated en units leading to a three-dimensional network. However, in 1 the water molecules also take part in the H-bonding and contribute to the overall 3D structure. In both 1 and 2 the crystal packing is done with the [Ni(en)₃]²⁺ units with absolute configuration Λ(δδδ) and its mirror conformer with Δ configuration in exactly equal numbers. Spectral (IR and UV–Visible) and magnetic measurements were carried out and some of the ligand-field parameters like D_q, B and β were evaluated for all the four compounds. These values suggest the presence of octahedrally coordinated nickel(II) in all the four complexes. Spectral data suggest that 3 has the two chelating dap moieties and the fumarate coordinated in η¹ form through both its carboxylate moieties while 4 has one chelating dap and the oxalate moiety coordinated in η⁴-bis-chelating form. Though both 1 and 2 are made of the same type of [Ni(en)₃]²⁺ units their thermograms give entirely different thermal features; 1 showing three clearly successive and step-wise dissociation of each en unit while 2 having a combined loss of two en units in the first thermal step. The relevant thermodynamic and kinetic parameters like E_a and ΔS also could be evaluated for various thermal steps for the compounds 1–4 using Coats–Redfern equation.     

Novel rhenium(III) complexes with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-trazine: X-ray structures and DFT calculations for [ReCl3(OPPh3)(dppt)] and [ReCl3(PPh3)(dppt)] complexes

The reaction of [ReOCl₃(PPh₃)₂] with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-trazine (dppt) has been examined and [ReCl₃(OPPh₃)(dppt)] has been obtained. The triphenylphosphine oxide can be easily replaced by PPh₃ in the reaction of [ReCl₃(OPPh₃)(dppt)] with an excess of triphenylphosphine. The [ReCl₃(OPPh₃)(dppt)] and [ReCl₃(PPh₃)(dppt)] complexes have been structurally and spectroscopically characterized. Their molecular orbital diagrams have been calculated with the density functional theory (DFT) method, and their electronic spectra have been discussed on the basis of time-dependent DFT calculations. The compound [ReCl₃(OPPh₃)(dppt)] has been studied additionally by magnetic measurement. The magnetic behavior is characteristic of mononuclear complexes with d⁴ low-spin octahedral Re(III) complexes (³T_1g ground state) and arise because of the large spin–orbit coupling (ζ = 2500 cm⁻¹), which gives diamagnetic ground state.     

Vanadium(II) alkyls. Synthesis and X-ray crystal structures of trans-VMe2(dmpe)2 and cis-V(CH2SiMe3) 2(dmpe)2

Treatment of the vanadium(II) tetrahydroborate complex trans-V(η¹-BH₄)₂(dmpe)₂ with (trimethylsilyl) methyllithium gives the new vanadium(II) alkyl cis-V(CH₂SiMe₃)₂(dmpe)₂, where dmpe is the chelating diphosphine 1,2-bis(dimethylphosphino)ethane. Interestingly, this complex could not be prepared from the chloride starting material VCl₂(dmpe)₂. The CH₂SiMe₃ complex has a magnetic moment of 3.8 μ_B, and has been characterized by ¹H NMR and EPR spectroscopy. The cis geometry of the CH₂SiMe₃ complex is somewhat unexpected, but in fact the structure can be rationalized on steric grounds. The X-ray crystal structure of cis-V(CH₂SiMe₃)₂(dmpe)₂ is described along with that of the related vanadium(II) alkyl complex trans-VMe₂(dmpe)₂. Comparisons of the bond distances and angles for VMe₂(dmpe) ₂, V---C = 2.310(5) Å, V---P = 2.455(5) Å, and P---V---P = 83.5(2)° with those of V(CH₂SiMe₃)₂(dmpe)₂, V---C = 2.253(3) Å, V---P = 2.551(1) Å, and P ---V---P = 79.37(3)° show differences due to the differing trans influences of alkyl and phosphine ligands, and due to steric crowding in latter molecule. The V---P bond distances also suggest that metal-phosphorus π-back bonding is important in these early transition metal systems. Crystal data for VMe₂(dmpe)₂ at 25°C: space group P2₁/n, with a = 9.041(1) Å, b = 12.815(2) Å, c = 9.905(2) Å, β = 93.20(1)°, V = 1145.8(5) ų, Z = 2, R_F = 0.106, and R_wF =0.127 for 74 variables and 728 data for which I 2.58 σ(I); crystal data for V(CH₂SiMe₃)₂(dmpe)₂ at −75°C: space group C2/c, with a = 9.652(4) Å, b = 17.958(5) Å, c = 18.524(4) Å, β = 102.07(3)°, V= 3140(3) ų, Z = 4, R_F = 0.033, and R_wF = 0.032 for 231 variables and 1946 data for which I 2.58 σ(I).     

(C6H16N2)Zn3(HPO3)4H2O: a new layered zinc phosphite templated by diprotonated trans-1,4-diaminocyclohexane

Employing trans-1,4-diaminocyclohexane (trans-1,4-DACH) as a template, a new two-dimensional layered zinc phosphite (C₆H₁₆N₂)Zn₃(HPO₃)₄H₂O (1) has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group P2₁/n with a=10.458(2) Å, b=14.720(3) Å, c=13.079(3) Å, β=97.93(3)°, V=1994.1(7) ų, Z=4, R₁=0.0349 (I>2σ(I)) and wR₂=0.0605 (all data). The inorganic layer is built up by alternation of ZnO₄ tetrahedra and HPO₃ pseudo pyramids forming a 4.6.8-net. The sheet is featured by a series of capped six-membered rings. The diprotonated trans-1,4-DACH molecules reside in the interlayer region and interact with the inorganic network through H-bonds.     

Chiral chelate phosphanes: XI. Application of cyclopentane-based C2 chiral bis(phosphane) ligands C5H8(PR2)2 to Pt---Sn-catalyzed styrene hydroformylation

Treatment of [(1,5-C₈H₁₂)PtCl(X)] (X=Cl, CH₃, CH₂CMe₃) with C₂ chiral cyclopentane-1,2-diyl-bis(phosphanes) C₅H₈(PR₂)₂, either as racemic mixtures or as resolved enantiomers, afforded the chelate complexes [C₅H₈(PR₂)₂Pt(Cl)(X)] (X=Cl: R=Ph (1), N-pip (2), OPh (3); X=CH₃: R=Ph (4), N-pip (5), OPh (6); X=CH₂CMe₃: R=Ph (7), N-pip (8), OPh (9); ‘N-pip’=N(CH₂)₅), (+)-[(1R,2R)-C₅H₈{P(OPh)₂}₂PtCl₂] [(R,R)-3], (−)-[(1S,2S)-C₅H₈{P(OPh)₂}₂PtCl₂] [(S,S)-3], (−)-[(1R,2R)-C₅H₈(PPh₂)₂Pt(Cl)(X)], and (+)-[(1S,2S)-C₅H₈(PPh₂)₂Pt(Cl)(X)] (X=CH₃: (R,R)-4, (S,S)-4; X=CH₂CMe₃: (R,R)-7, (S,S)-7). Reacting 4, 6, and 7 with AgO₃SCF₃ led to triflate derivatives [C₅H₈(PR₂)₂Pt(X)(OSO₂CF₃)] [X=CH₃: R=Ph (11), OPh (12); X=CH₂CMe₃: R=Ph (13)] with covalently bonded OSO₂CF₃ ligands. The unusual Pt₂ complex [μ-Cl{C₅H₈(PPh₂)₂PtCH₃}₂]O₃SCF₃ (14) containing an unsupported single Pt---Cl---Pt bridge was also isolated. In the presence of SnCl₂, complexes 1, 3, 4, 6, 7, and 9 are catalysts for the hydroformylation of styrene forming 2- and 3-phenylpropanal together with ethylbenzene. Except for 1, they also catalyze the consecutive hydrogenation of the primary propanals to alcohols. High regioselectivities towards 2-phenylpropanal (branched-to-normal ratios ≥91:9) were obtained in hydroformylations catalyzed by 3 and 4, for which the influence of varied CO/H₂ partial pressures, catalyst-to-substrate ratios and different reaction temperatures and times on the outcome of the catalytic reaction was also studied. When tin-modified complexes (R,R)-3, (S,S)-3, and (S,S)-4 were used as optically active Pt(II) catalysts, an only low stereoselectivity for asymmetric hydroformylation (e.e.<18%) was observed. The Pt---Sn complexes [C₅H₈(PR₂)₂Pt(CH₃)(SnCl₃)] [R=Ph (15), OPh (17)], resulting from SnCl₂ insertion into the Pt---Cl bonds of 4 or 6, undergo rapid degradation in solution, forming mixtures composed of [C₅H₈(PR₂)₂Pt(X)(Y)] with R=Ph or OPh and X/Y=Cl/SnCl₃ (16, 18), Cl/Cl (1, 3), and SnCl₃/SnCl₃ (19, 20), respectively. In the presence of SnCl₂, triflate complex 11 also becomes a catalyst for styrene hydroformylation and consecutive hydrogenation of the aldehydes to alcohols. The crystal structures of 11 complexes — 2, 5, 7, 8, 9, 10 (the previously prepared [C₅H₈{P(N-pip)₂}₂Pt(CH₂CMe₃)₂]), 13, 14, 16, (R,R)-3, and (S,S)-3 — were determined by X-ray diffraction.     

Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pr2C6H3)

The compounds [MoCl(NAr)₂R] (R=CH₂CMe₂Ph (1) or CH₂CMe₃(2); Ar=2,6-Prⁱ₂C₆H₃) have been prepared from [MoCl₂(NAr)₂(dme)] (dme=1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether. Similarly, the mixed-imido complex [MoCl₂(NAr)(NBu^t)(dme)] affords [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)] (3). Chloride substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)₂(CH₂CMe₂Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)₂(CH₂CMe₂Ph)] (5) (Ind=Indenyl), [Mo(OBu^t)(NAr)₂(CH₂CMe ₂Ph)] (6), [MoMe(NAr)₂(CH₂CMe₂Ph)] (7), [MoMe(PMe₃)(NAr)₂(CH₂CMe ₂Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂CMe₂P h)](9). In the latter case, a by-product {[Mo(NAr)₂(CH₂CMe₂Ph) ]₂(μ-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for which the evidence is unclear) there are α-agostic interactions present.     

Fe–Hg Interactions and P Chemical Shifts in [Fe(CO)3 (PPh2R)2(HgCl2)] (R=pym, fur, py, thi)

In order to study the effects of R group on Fe–Hg interactions and 31P chemical shifts, the structures of mononuclear complexes Fe(CO)₃(PPh₂R)₂ (R=pym:1, fur: 2, py: 3,thi: 4; pym=pyrimidine, fur=furyl, py=pyridine, thi=thiazole) and binuclear complexes [Fe(CO)₃(PPh₂R)₂(HgCl₂)] (R=pym: 5, fur: 6, py: 7, thi: 8) were studied using the density functional theory (DFT) PBE0 method. The 31P chemical shifts were calculated by PBE0-GIAO method. Nature bond orbital (NBO) analyses were also performed to explain the nature of the Fe–Hg interactions. The conclusions can be drawn as follows: (1) The complexes with nitrogen donor atoms are more stable than those with O or S atoms. The more N atoms there are, the higher is the stabilility of the complex. (2) The Fe–Hg interactions play a dominant role in the stabilities of the complexes. In 5 or 6, thereisa σ-bond between Fe and Hg atoms. However, in 7 and 8, the Fe–Hg interactions act as σ_P–Fe→n_Hg and σ_C–Fe→n_Hg delocalization. (3) Through Fe→Hg interactions, there is charge transfer from R groups towards the P, Fe, and Hg atoms, which increases the electron density on P nucleus in binuclear complexes. As a result, compared with their mononuclear complexes, the 31P chemical shifts in binuclear complexes show some reduction.     

Novel M(II)–Hg(II) coordination polymers generated from metal-containing building blocks M(2-pyrazinecarboxylate)2 · (H2O)2 (M=Cu, Ni, Co) and HgCl2

A new class of M(II)–Hg(II) (M=Cu(II), Co(II), Ni(II)) mixed-metal coordination polymers, Cu(2-pyrazinecarboxylate)₂HgCl₂ (4), [Co(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.61H₂O (5) and [Ni(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.77H₂O (6), have been prepared by self assembly of metal-containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂(M=Cu(II), Co(II), Ni(II)), with HgCl₂. Compounds 4–6 were characterized fully by IR, elemental analysis and single crystal X-ray diffraction. Compound 4 crystallized in the monoclinic space group C2/c, with a=17.916(5) Å, b=7.223(2) Å, c=13.335(4) Å, β=128.726(3)°, V=1346.2(6) ų, Z=4. It contains alternating Hg(II) and Cu(II) metal centers that are cross-linked by 2-pyrazinecarboxylate spacers and chlorine co-ligands to generate a unique three-dimensional Hg(II)–Cu(II) mixed metal framework. Compound 5 crystallized in the triclinic space group P , with a=6.3879(7) Å, b=6.6626(8) Å, c=13.2286(15) Å, α=96.339(2)°, β=91.590(2)°, γ=113.462(2)°, V=511.71(10) ų, Z=1. Compound 6 also crystallized in the triclinic space group P , with a=6.3543(8) Å, b=6.6194(8) Å, c=13.2801(16) Å, α=96.449(2)°, β=92.263(2)°, γ=113.541(2)°, V=506.67(11) ų, Z=1. Compounds 5 and 6 are isostructural and in the solid state the Hg(II)M(II)Hg(II) units are connected by Hg₂Cl₂ linkages to produce a novel M(II)–Hg(II) (M=Co(II), Ni(II)) zigzag mixed-metal chain, in which a new type of M–M′–M′–M array was observed. The metal containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂ (M=Cu(II), Co(II), Ni(II)), exhibit different connectivities to HgCl₂ depending on the metal cation contained within them.     

Cyclopentadienyl-ruthenium and -osmium chemistry : XXXIX. Syntheses of novel alkynyl-ruthenium complexes. X-Ray structures of two forms of {Ru(PPh3)2(η-C5H5)}2(μ-C4) and of Ru{CCC(O)Me}(PPh3)2(η-C5H5)

Reactions between [Ru(thf)(PPh₃)₂(η-C₅H₅)]⁺ and lithium acetylides have given further examples of substituted ethynylruthenium complexes that are useful precursors of allenylidene and cumulenylidene derivatives. From Li₂C₄, mono- and bi-nuclear ruthenium complexes were obtained: single-crystal X-ray studies have characterised two rotamers of {Ru(PPh₃)₂(η-C₅H₅)}₂(μ-C₄), which differ in the relative cis and trans orientations of the RuL_n groups. Protonation of Ru(CCCCH)(PPh₃)₂(η-C₅H₅) afforded the butatrienylidene cation [Ru(C=C=C=CH₂)(PPh₃)₂(η-C₅H₅)]⁺, which reacted readily with atmospheric moisture to give the acetylethynyl complex Ru{CCC(O)Me}(PPh₃)₂(η-C₅H₅), also fully characterised by an X-ray structural study.     

Hydrothermal Syntheses, Structures, and Properties of Two New Potassium Vanadium Phosphates: K3(VO) (V2O3) (PO4)2(HPO4) and K3 (VO) (HV2O3) (PO4)2(HPO4)

Two new potassium vanadium phosphates have been prepared and their structures have been determined from analysis of single crystal X-ray data. The two compounds, K₃(VO)(V₂O₃) (PO₄)₂(HPO₄) and K₃(VO)(HV₂O₃)(PO₄)₂(HPO₄), are isostructural, except for the incorporation of an extra hydrogen atom into the nearly identical frameworks. The structures consist of a three-dimensional network of [VO]_n chains connected through phosphate groups to a [V₂O₃] moiety. Magnetic susceptibility experiments indicate that in the case of the di-hydrogen compound, there are no significant magnetic interactions between the three independent vanadium (IV) centers. Crystal data: for K₃(VO)(V₂O₃)(PO₄)₂ (HPO₄), M_r = 620.02, orthorhombic space group Pnma (No. 62), a = 7.023(4) Å, b = 13.309(7) Å, c = 14.294(7) Å, V = 1336(2) ų, Z = 4, R = 5.02%, and R_w = 5.24% for 1238 observed reflections [I > 3σ(I)]; for K₃(VO)(HV₂O₃)(PO₄)₂(HPO₄), M_r = 621.04, orthorhombic space group Pnma (No. 62), a = 6.975(3) Å, b = 13.559(7) Å, c = 14.130(7) Å, V = 1336(1) ų, Z = 4, R = 6.02%, and R_w = 6.34% for 1465 observed reflections [I > 3σ(I)].     

Structural and energetic aspects of hydrogen bonding and proton transfer to ReH2(CO)(NO)(PR3)2 and ReHCl(CO)(NO)(PMe3)2 by IR and X-ray studies

The interaction of rhenium hydrides ReHX(CO)(NO)(PR₃)₂ 1 (X=H, R=Me (a), Et (b), iPr (c); X=Cl, R=Me (d)) with a series of proton donors (indole, phenols, fluorinated alcohols, trifluoroacetic acid) was studied by variable temperature IR spectroscopy. The conditions governing the hydrogen bonding ReHHX in solution and in the solid state (IR, X-ray) were elucidated. Spectroscopic and thermodynamic characteristics (−ΔH=2.3–6.1 kcal mol⁻¹) of these hydrogen bonded complexes were obtained. IR spectral evidence that hydrogen bonding with hydride atom precedes proton transfer and the dihydrogen complex formation was found. Hydrogen bonded complex of ReH₂(CO)(NO)(PMe₃)₂ with indole (2a–indole) and organyloxy-complex ReH(OC₆H₄NO₂)(CO)(NO)(PMe₃)₂ (5a) were characterized by single-crystal X-ray diffraction. A short NHHRe (1.79(5) Å) distance was found in the 2a–indole complex, where the indole molecule lies in the plane of the Re(NO)(CO) fragment (with dihedral angle between the planes 0.01°).     

Transition metal chemistry of phosphorus based ligands. Ruthenium(II) chemistry of bis(phosphino)amines, X2PN(R)PX2 (R=H or Ph, X=Ph; R=Ph, X2=O2C6H4)

Reactions of CpRuCl(PPh₃)₂ with bis(phosphino)amines, X₂PN(R)PX₂ (1 R=H, X=Ph; 2 R=X=Ph; 3 R=Ph, X₂=O₂C₆H₄) give neutral or cationic mononuclear complexes depending on the reaction conditions. Reaction of 1 with CpRuCl(PPh₃)₂ gives one neutral complex, [CpRu(Cl)(η²-Ph₂PN(H)PPh₂)] (4) and two cationic complexes, [CpRu(η²-Ph₂PN(H)PPh₂)(η¹-Ph₂PN(H)PPh₂)]Cl (5) and [CpRu(PPh₃)(η²-Ph₂PN(H)PPh₂)]Cl (6), whereas the reaction of 2 with CpRuCl(PPh₃)₂ leads only to the isolation of cationic complex, [CpRu(PPh₃)(η²-Ph₂PN(Ph)PPh₂)]Cl (7). The catechol derivative 3, in a similar reaction, affords an interesting mononuclear complex [CpRu(PPh₃){η¹-(C₆H₄O₂)PN(Ph)P(O₂H₄C₆)}₂]Cl (8) containing two monodentate bis(phosphino)amine ligands. The structural elucidation of the complexes was carried out by elemental analyses, IR and NMR spectroscopic data.