Electrochemical Dissociative Oxidation of the Unsaturated Pd3(dppm)3(CO)2+ Cluster; An Astonishing Resemblance with the Photo-Oxidative Analogue

Cyclic voltammetry (CV), rotating disk electrode voltammetry (RDE) and bulk electrolysis were used to investigate the electrochemical oxidation of the title cluster in acetonitrile (CH₃CN). Two irreversible 2-electron oxidation processes occur at +0.95 V and +1.15 V vs. SCE. Bulk electrolysis demonstrates that the d⁹–d⁹ Pd₂(dppm)₂(NCCH₃) ₂ ²⁺ 4 complex is generated among the first intermediates, and the d⁸ Pd(dppm)(NCCH₃) ₂ ²⁺ 3 is formed as the final product. The intermediacy of “Pd₃(dppm)₃(CO)⁴⁺” and “Pd₃(dppm) ₃ ⁴⁺ ” is suspected but not confirmed. This oxidation process exhibits a close resemblance to the photo oxidative reactivity of the title cluster in the presence of chlorocarbons (R–Cl) for which the sole observed product is Pd(dppm)Cl₂.This paper is dedicated to Professor Brian Johnson on the occasion of his retirement.     

Characterization of a New Tetranuclear Cluster of Palladium, [Pd4(dppm)4(H)]—

The recently discovered and characterized [Pd₄(dppm)₄(H)]²⁺ cluster catalyst ( 1 ; dppm = Ph₂PCH₂PPh₂), slowly evolves in the presence of the reducing tetraphenylborate anion, to generate a new diamagnetic cluster [Pd₄(dppm)₄(H)]⁺ ( 2 ). The evolution of this starting material 1 , has been monitored using NMR (¹H and ³¹P), UV‐vis and ESR spectroscopy. This new 56‐electron Pd cluster has been characterized from X‐ray crystallography, and consists of a cyclic species exhibiting an approximate puckered square structure. The Pd₂ bond distances are 2.7367(10) and 2.7495(11)Å and indicate the presence of weak bonding. The diagonal Pd···Pd separations are 3.646(10) and 3.590(10)Å indicating that the square is relatively symmetric. Such a structure is unprecedented for “Pd_x(dppm)_x” species. Although not formally observed from the X‐ray data, the hydride is assumed to be fluxional as found in 1 . The cyclic voltammogram for 2 exhibits an irreversible reduction wave at —1.65V vs SCE which is greater than that found for 1 , and corroborates the lower oxidation state for Pd (+1/2). The Pd‐H bonding scheme and MO symmetry for a model cluster where the hydride has been placed at the center of the Pd₄ frame, have been addressed qualitatively using the EHMO model. These calculations demonstrate clearly that the Pd‐H bonding is strong.     

Deoxygenation of Nitrosobenzene by the Electrogenerated Pd<Subscript>3</Subscript>(dppm)<Subscript>3</Subscript>(μ<Subscript>3</Subscript>-CO) Cluster

The 2-electron reduction of the unsaturated Pd₃(dppm)₃(CO)²⁺ cluster ([Pd₃]²⁺) affords the highly reactive neutral cluster [Pd₃]⁰, which reacts with nitrosobenzene (PhNO) yielding the organic azoxybenzene product (PhN(O)NPh) via the formation of “triplet” nitrene “PhN”. The formation of [Pd₃(μ₃-O)] as a possible (relatively unstable) intermediate is also postulated based on MALDI-TOF findings, but not formally demonstrated. Concurrently, no reaction between [Pd₃]⁰ and OPPh₃ occurs. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. This paper is dedicated to Professor Dieter Fenske.     

Das erste Erdalkalimetall-Mercurato(II)-Palladat(II,IV): Ba2Hg3Pd52+ Pd24+ O14

On the First Alkaline Earth Mercurato(II)-Palladate(II, IV): Ba₂Hg₃Pd₅²⁺Pd₂⁴⁺O₁₄ Single crystals of Ba₂Hg₃Pd₇O₁₄ were prepared by oxygen high-pressure technique (3900 bar) and investigated by X-ray technique. It crystallizes with monoclinic symmetry, space group C–C2/m; Z = 2 (a = 10.583; b = 6,207; c = 10.919 Å, β = 90.56°). The Hg²⁺ ions show partially dumb-bell like and one sided 3 fold coordination respectively. Pd⁴⁺ /Pd²⁺ show an octahedric or square planar surrounding.     

Synthese,Kristallstruktur und spektroskopische Charakterisierung von [Au12(PPh)2(P2Ph2)2(dppm)4Cl2]Cl2

Synthesis, Crystal Structure and Spectroscopic Characterization of [Au₁₂(PPh)₂(P₂Ph₂)₂(dppm)₄Cl₂]Cl₂ The reaction of [(AuCl)₂dppm] (dppm = Ph₂PCH₂PPh₂) with P(Ph)(SiMe₃)₂ in CHCl₃ results in the formation of [Au₁₂(PPh)₂(P₂Ph₂)₂(dppm)₄Cl₂]Cl₂ ( 1 ), the crystal structure of which was determined by single crystal X‐ray analysis (space group P2₁/c, a = 1425.3(3) pm, b = 2803.7(6) pm, c = 2255.0(5) pm, β = 95.00(3)°, V = 8977(3)·10⁶ pm³, Z = 2). The dication in 1 consists of two Au₆P₃ units built by highly distorted Au₃P and Au₂P₂ heterotetrahedra, connected via four bidentate phosphine ligands. Additionally, the compound was characterized by IR‐, UV‐ and NMR spectroscopy. The ³¹P{¹H} NMR spectrum is discussed in detail.     

Synthesis,X-ray structure and properties of the trinuclear copper(I) complex [Cu3(dppm)3(NO3)(OH)](NO3)

The novel trinuclear Cu^I complex [Cu₃(dppm)₃(NO₃)(OH)](NO₃) obtained by reacting dppm with Cu(NO₃)₂ · 3H₂O in the presence of NaBPh₄ was characterized by a single-crystal X-ray analysis as well as by physico-chemical and spectroscopic methods. The [Cu₃(dppm)₃(NO₃)(OH)]⁺ cation consists of a triangular array of copper atoms, (with dppm ligands bridging each edge of the triangle), a triply bridging OH group and NO^– ₃ anion bound to two faces of the Cu₃ unit, respectively.     

Synthesis,structure and characterization of the trinuclear copper (I) complex [Cu3(μ3-Br)2(dppm)3]Br

The novel trinuclear copper(I) complex [Cu₃(μ₃,-Br)₂(dppm)₃]Br has been obtained by reaction of bis(diphenyl-phosphino)methane (dppm) with cupric bromide. The title complex was characterized by single-crystal X-ray analysis, elemental analysis, molecular weight determination, ³¹P NMR and its conductivity was also measured. The [ Cu₃ (dppm)₃ Br₂ ]⁺ cation consists of a triangular array of copper atoms, with dppm ligands (Ph₂ PCH₂ PPh₂) bridging each edge of the triangle and two triply bridging Br groups bound to the two faces of the Cu₃ unit. Crystallographic data: monoclinic, space group P2₁/c, a = 1.4739(4), b = l.7708(5), c = 2.8395(8) nm, β= 97.16(3)°, V = 7.353nm³, Z = 4, F(000)= 3296, D_calc, = 1.472 g/cm³, μ = 26.478 cm^?1, R=0.06, R_W = 0.08, 4654 reflections observed with I3≥(I).     

Halide Abstraction from Organic Solvents in Reactions of a Copper(I) Alkoxide: Synthesis and Crystal Structures of [Cu5(dppm)(dppm−)2(OtBu)Cl2] and [Cu3(dppm)3Br2][CuBr2]

The synthesis and structures of the two Cu^I halide complexes [Cu₅(dppm)(dppm^?)₂(O^tBu)Cl₂] and [Cu₃(dppm)₃Br₂][CuBr₂] (dppm = Ph₂PCH₂PPh₂, dppm^? = [Ph₂PCHPPh₂]^?) are reported. The compounds were obtained by treating reaction mixtures of [CuO^tBu] and dppm with dichloromethane or dibromomethane.     

Synthese und Strukturen von [Cu8As3(AsSiMe3)2(dppb)4]+‐[Cu{As2(SiMe3)2}{As4(SiMe3)4}]‐, [Cu8As3(AsSiMe3)2(dppb)4]+‐[Cu{As(SiMe3)2}2]‐ und [Cu10(Sb3)2(SbSiMe3)2(dppm)6]

The reaction of CuCl, LiAs(SiMe₃)₂ and dppb (Bis(diphenylphosphino)butane) leads to the formation of ionic cluster complexes. Depending on the reaction conditions one can isolate [Cu₈As₃(AsSiMe₃)₂(dppb)₄]⁺[Cu{As₂(SiMe₃)₂}{As₄(SiMe₃)₄}]^‐ ( 1 ) and [Cu₈As₃(AsSiMe₃)₂(dppb)₄]⁺[Cu{As(SiMe₃)₂}₂]^‐ ( 2 ). The same reaction of CuCl, dppm (Bis(diphenylphosphino)methane) and LiSb(SiMe₃)₂ leads to the neutral cluster complex [Cu₁₀(Sb₃)₂(SbSiMe₃)₂(dppm)₆] ( 3 ). The structures of 1‐3 have been solved by X‐ray single crystal analyses.     

Synthesis of palladium-tin carbonylphosphine clusters and X-ray study of the Pd3Sn2(acac)4(CO)2(PPh3)3 cluster

It has been shown for the first time that the reaction of bi-valent tin acetyl-acetonate with palladium carbonylphosphine clusters, Pd₄(CO)₅(PPh₃)₄ (I), Pd₄(CO)₅(PEt₃)₄ (II) and Pd₃(CO)₃(PPh₃)₄ (III), results in the formation of heterometal pentanuclear clusters of general formula Pd₃Sn₂(acac)₄(CO)₂(PR₃)₃; R  Ph (IV), Et (V). X-ray analysis of Pd₃Sn₂(acac)₄(CO)₂(PPh₃)₃ at 20°C (λ(Mo), 4396 reflections, space group P2₁/n, Z = 4, R = 0.037) shows that IV in the form of the crystalline hydrate, Pd₃Sn₂(acac)₄(CO)₂(PPh₃)₃ · χH₂O (χ ∼ 1), contains a distorted “propeller”-shaped Pd₃Sn₂ metal frame with PdSn distances of 2.679–2.721(1) Å; two short PdPd bonds, 2.708 and 2.720(1) Å, bridged by μ₂-CO ligands, and an elongated central Pd(1)Pd(2) bond of 2.798 Å. Sn atoms have distorted octahedral coordination, the dihedral angles formed by Pd₃ moieties and two Pd₂Sn triangles are 127.6 and 106.5°; and the angle between Pd₂Sn moieties is 126.0°.     

Synthèse rationelle de clusters mixtes à trois au quatre métaux differents et contenant le ligand Ph2PCH2PPh2 (dppm)

Reaction of PdPtCl₂(dppm)₂ with Co(CO)₄^? or Mn(CO)₅^? affords the tetrametallic clusters PdPtCo₂(CO)₇(dppm)₂ and PdPtMn₂(CO)₉(dppm)₂. The cobalt cluster reacts with iodide to give PdPtCoI(CO)₃(dppm)₂ which upon reaction with Fe(CO)₃NO^? or Mn(CO)₅^? yields PdPtFeCo(CO)₆NO(dppm)₂ and PdPtMnCo(CO)₈(dppm)₂, respectively.     

A diplatinum complex containing one bridging and two chelating dppm ligands. The X-ray structure analysis of [Pt2 (dppm)3] [PF6]2 (dppm = Ph2CH2PPh2)

The dinuclear platinum(I) complex [Pt₂(dppm)₃][PF₆]₂ unexpectedly contains a PtPt bond, one bridging and two chelating dppm ligands, in marked contrast to the related zerovalent platinum compound [Pt₂(dppm)₃].     

Crystal Structures of (PPh3)2Pd(N3)2, (AsPh3)2Pd(N3)2, (2‐Chloropyridine)2Pd(N3)2, [(AsPh4)2][Pd2(N3)4Cl2], [(PNP)2][Pd(N3)4], [(AsPh4)2][Pt(N3)4] · 2 H2O,and [(AsPh4)2][Pt(N3)6]

The crystal structures of the monomeric palladium(II) azide complexes of the type L₂Pd(N₃)₂ (L = PPh₃ ( 1 ), AsPh₃ ( 2 ), and 2‐chloropyridine ( 3 )), the dimeric [(AsPh₄)₂][Pd₂(N₃)₄Cl₂] ( 4 ), the homoleptic azido palladate [(PNP)₂][Pd(N₃)₄] ( 5 ) and the homoleptic azido platinates [(AsPh₄)₂][Pt(N₃)₄] · 2 H₂O ( 6 ) and [(AsPh₄)₂][Pt(N₃)₆] ( 7 ) were determined by X‐ray diffraction at single crystals. 1 and 2 are isotypic and crystallize in the triclinic space group P1. 1 , 2 and 3 show terminal azide ligands in trans position. In 4 the [Pd₂(N₃)₄Cl₂]^2– anions show end‐on bridging azide groups as well as terminal chlorine atoms and azide ligands. The anions in 5 and 6 show azide ligands in equal positions with almost local C_4h symmetry at the platinum and palladium atom respectively. The metal atoms show a planar surrounding. The [Pt(N₃)₆]^2– anions in 7 are centrosymmetric (idealized S₆ symmetry) with an octahedral surrounding of six nitrogen atoms at the platinum centers.     

Electrospray Mass Spectrometry Study on Polynuclear Pd(II) and Ni (II) Complexes of 3, 6, 9, 16, 19, 22‐Hexaazatricyclo [22. 2.2.211,14] triaconta‐11, 13, 24, 26 (1), 27, 29‐Hexaene

Polynuclear Pd(II) and Ni(II) complexes of macrocyclic polyamine 3,6,9,16,19,22‐hexaazatricyclo[22.2.2.2^11,14]‐triaconta 11,13,24,26(l),27,29‐hexaene (L) in solution were investigated by electrospray ionization mass spectrometry (ESIMS). For methanol solution of complexes M₂LX₄ (M = Pd(II) and Ni(II), X= Cl and I), two main clusters of peaks were observed which can be assigned to [M₂LX₃]⁺ and [M₂LX₂]²⁺. When Pd₂LCl₄ was treated with 2 or 4 mol of AgNO₃, it gave rise formation of Pd₂LCl₂ (NO₃)₂ · H₂O and [Pd₂L(H₂O)_m(NO₃)_n]^(4‐n)+, respectively. ESMS spectra show that the dissociation of the former in the ionization process gave peaks of [Pd₂LCl₂]²⁺ and [(Pd₂LCl₂)NO₃]⁺, while dissociation of the later gave the peaks of [Pd₂L(CH₃CO₂)₂]²⁺ and [Pd₂L(CH₃CO₂)₂](NO₃) ⁺ in the presence of acetic acid. Similar species were observed for Pd₂LI₄ when treated with 4 mol of AgNO₃. When [Pd₂L · (H₂O)_m(NO₃)_n]^(4‐n)+ reacted with 2 mol of oxalate anions at 40°C, [Pd₄L₂(C₂O₄)₂(NO₃)₂]²⁺ and [Pd₄L₂(C₂O₄)₂ (NO₃)]³⁺ were detected. This implies the formation of square‐planar molecular box Pd₄L₂(C₂O₄)₂(NO₃)₄ in which C₂O₄^? may act as bridging ligands as confirmed by crystal structure analysis. The dissociation form and the stability of complex cations in gaseous state are also discussed. This work provides an excellent example of the usefulness of ESIMS in the identification of metal complexes in solution.     

Crystal Structure and Electrical Conductivity of Palladium Sulfide BronzesMP3S4(M=La,Nd, and Eu)

Palladium sulfide bronzesMPd₃S₄(M=La, Nd, and Eu) were prepared in single phase. The bronzes are cubic with twoMatoms in (0,0,0; 1/2,1/2,1/2) and six palladium atoms in (1/4,0,1/2⥀) positions. The sulfur positions (x,x,x⥀) were determined with a guide of theRfactors. Thexvalues were 1/4 for La and Nd compounds (i.e., space groupPm3n), while a plot of theRfactors of EuPd₃S₄gave a very broad curve showing thexvalue rather displaced from 1/4. This result is considered to be associated with the mixed valency of europium (Eu²⁺and Eu³⁺) in this compound.MPd₃S₄(M=La, Nd, and Eu) exhibited metallic conductions with the electrical conductivities decreasing with increasing temperature in the experimental range from ∼15 K to room temperature. At 300 K, σ were 2.77, 2.42, and 2.28 S m⁻¹forMPd₃S₄(M=La, Nd, and Eu), respectively. From the Hall coefficient measurements, the carriers were found to be the electrons with their numbers 1.71, 1.68, and 0.82 per unit cell of the crystals ofM=La, Nd, and Eu compounds, respectively. These values suggest the formulas to beM³⁺(Pd²⁺₃e⁻)S²⁻₄for La and Nd compounds, and to be Eu²⁺_0.5Eu³⁺_0.5(Pd²⁺₃e⁻_0.5)S²⁻₄for Eu compound.     

Synthesis and spectroscopy of cis-configured mononuclear palladium(II) and platinum(II) complexes of chalcogeno o-carboranes and structures of [Pt(SCboPh)2(dppm)], [Pt(SeCboPh)2(dppm)], [Pt(SCboS)(PMe2Ph)2] and [Pt(SCboS)(PMePh2)2]

The reactions of [MCl₂(P^∩P)] and [MCl₂(PR₃)₂)] with 1-mercapto-2-phenyl-o-carborane/NaSeCb^oPh and 1,2-dimercapto-o-carborane yield mononuclear complexes of composition, [M(SCb^oPh)₂(P^∩P)], [M(SeCb^oPh)₂(P^∩P)] (M = Pd or Pt; P^∩P = dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane) or dppp (1,3-bis(diphenylphosphino)propane)) and [M(SCb^oS)(PR₃)₂] (2PR₃ = dppm, dppe, 2PEt₃, 2PMe₂Ph, 2PMePh₂ or 2PPh₃). These complexes have been characterized by elemental analysis and NMR (¹H, ³¹P, ⁷⁷Se and ¹⁹⁵Pt) spectroscopy. The ¹J(Pt–P) values and ¹⁹⁵Pt NMR chemical shifts are influenced by the nature of phosphine as well as thiolate ligand. Molecular structures of [Pt(SCb^oPh)₂(dppm)], [Pt(SeCb^oPh)₂(dppm)], [Pt(SCb^oS)(PMe₂Ph)₂] and [Pt(SCb^oS)(PMePh₂)₂] have been established by single crystal X-ray structural analyses. The platinum atom in all these complexes acquires a distorted square planar configuration defined by two cis-bound phosphine ligands and two chalcogenolate groups. The carborane rings are mutually anti in [Pt(SCb^oPh)₂(dppm)] and [Pt(SeCb^oPh)₂(dppm)].     

Synthesis and spectroscopy of cis-configured mononuclear palladium(II) and platinum(II) complexes of chalcogeno o-carboranes and structures of [Pt(SCboPh)2(dppm)], [Pt(SeCboPh)2(dppm)], [Pt(SCboS)(PMe2Ph)2] and [Pt(SCboS)(PMePh2)2]

The reactions of [MCl₂(P^∩P)] and [MCl₂(PR₃)₂)] with 1-mercapto-2-phenyl-o-carborane/NaSeCb^oPh and 1,2-dimercapto-o-carborane yield mononuclear complexes of composition, [M(SCb^oPh)₂(P^∩P)], [M(SeCb^oPh)₂(P^∩P)] (M = Pd or Pt; P^∩P = dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane) or dppp (1,3-bis(diphenylphosphino)propane)) and [M(SCb^oS)(PR₃)₂] (2PR₃ = dppm, dppe, 2PEt₃, 2PMe₂Ph, 2PMePh₂ or 2PPh₃). These complexes have been characterized by elemental analysis and NMR (¹H, ³¹P, ⁷⁷Se and ¹⁹⁵Pt) spectroscopy. The ¹J(Pt–P) values and ¹⁹⁵Pt NMR chemical shifts are influenced by the nature of phosphine as well as thiolate ligand. Molecular structures of [Pt(SCb^oPh)₂(dppm)], [Pt(SeCb^oPh)₂(dppm)], [Pt(SCb^oS)(PMe₂Ph)₂] and [Pt(SCb^oS)(PMePh₂)₂] have been established by single crystal X-ray structural analyses. The platinum atom in all these complexes acquires a distorted square planar configuration defined by two cis-bound phosphine ligands and two chalcogenolate groups. The carborane rings are mutually anti in [Pt(SCb^oPh)₂(dppm)] and [Pt(SeCb^oPh)₂(dppm)].     

Substitution reactions of trans-[PdXPh(SbPh3)2J (X=Cl or Br) with nitrogen,phosphines and arsenic donor ligands. Crystal structures of trans-[PdClPh(PPh3)2], [PdClPh(bipy)], [PdClPh(dppm)]2, and [PdBrPh(dppm)]2

Exchange reactions of trans-[PdXPh(SbPh₃)₂] (1) (X=Cl or Br) with ligands L in refluxing dichloromethane give the palladium phenyl complexes [PdXPhL₂] (X=Cl, L=PPh₃, AsPh₃, L₂=2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (dmbipy), 1,10-phenanthroline (phen); X=Br, L=PPh₃, L₂=bipy). Treatment of the complexes with bis(diphenylphosphino)methane (dppm) in refluxing dichloromethane gives [PdXPh(dppm]₂. These complexes have been characterised by microanalysis, IR and ¹H NMR spectroscopic data together with single crystal X-ray determinations of the phenyl palladium complexes, trans-[PdClPh(PPh₃)₂], [PdClPh(bipy)], [PdClPh(dppm)]₂, and [PdBrPh(dppm)]₂.     

The structure of [Pd3(η3-2-methylallyl)2Cl4]

An X-ray crystal structure determination of [Pd₃(2-methylallyl)₂Cl₄] shows it to be centrosymmetric with a rippled near-planar arrangement of PdCl₂PdCl₂Pd, the terminal Pd atoms being η³-bonded to the 2-methylallyl ligand.     

Koordinativ ungesättigte Dirutheniumkomplexe: Synthese und Kristallstrukturen von [Ru2(CO)4(μ‐H)(μ‐S)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] und [Ru2(CO)4(μ‐X)(μ‐PtBu2)(μ‐Ph2PCH2PPh2)] (X = Cl,S2CH)

Coordinatively Unsaturated Diruthenium Complexes: Synthesis and X‐Ray Crystal Structures of [Ru₂(CO)₄(μ‐H)(μ‐S)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)], [Ru₂(CO)₄(μ‐X)(μ‐P^tBu₂)(μ‐Ph₂PCH₂PPh₂)] (X = Cl, S₂CH) [Ru₂(CO)₄(μ‐H)(μ‐P^tBu₂)(μ‐dppm)] ( 1 ) reacts in benzene with elemental sulfur to the addition product [Ru₂(CO)₄(μ‐H)(μ‐S)(μ‐P^tBu₂)(μ‐dppm)] ( 2 ) (dppm = Ph₂PCH₂PPh₂). 2 is also obtained by reaction of 1 with ethylene sulfide. The reaction of 1 with carbon disulfide yields with insertion of the CS₂ into the Ru₂(μ‐H) bridge the dithioformato complex [Ru₂(CO)₄(μ‐S₂CH)(μ‐P^tBu₂)(μ‐dppm)] ( 3 ). Furthermore, 1 reacts with [NO][BF₄] to the complex salt [Ru₂(CO)₄(μ‐NO)(μ‐H)(μ‐P^tBu₂)(μ‐dppm)][BF₄] ( 4 ), and reaction of 1 with CCl₄ or CHCl₃ affords spontaneously [Ru₂(CO)₄(μ‐Cl)(μ‐P^tBu₂)(μ‐dppm)] ( 5 ) in nearly quantitative yield. The molecular structures of 2 , 3 and 5 were confirmed by crystal structure analyses.