First X‐Ray Structure Analyses of Rhodium(III) η1‐Allyl Complexes and a Mechanism for Allylic Isomerization Reactions

Metal‐to‐metal allyl transfer : Using the first structurally characterized rhodium η¹‐allyl complexes it is shown that the σ‐bound allyl substituent can be transferred from the Rh^III complex to a Rh^I complex in a fast equilibrium. This process may account for the decrease in regioselectivity observed in allylic alkylation reactions in which complex 1 is used as a catalyst.

     

Sulfur‐assisted Chloride and Triphenylphosphine Dissociation of Palladium(II) Complex with Phenyloxythiocarbonyl,PhOC(S), Containing Ligand: X‐Ray Structure of [Pd(PPh3)2{η1‐C(S)OPh}(Cl)]

Treatment of Pd(PPh₃)₄ with phenylchlorothionoformate, PhOC(S)Cl, in dichloromethane at ?20 °C produces the phenyloxythiocarbonyl complex [Pd(PPh₃)₂{η¹‐C(S)OPh}(Cl)], 1 . The ³¹P{¹H} NMR spectrum of 1 shows the dissociation of either the chloride or the triphenylphosphine ligand to form complex [Pd(PPh₃)₂(η²‐SCOPh)][Cl], 2 or the dipalladium complex [Pd(PPh₃)Cl]₂(μ,η²‐SCOPh)₂, 3 . Continuous stirring of the dichloromethane solution of 1 at room temperature for 4 h forms the dipalladinum complex [Pd(PPh₃)Cl]₂(μ,η²‐SCOPh)₂, 3 as the final product. Respective reactions of 1 and Et₂NCS₂Na or dppa {bis(diphenylphosphino)amine} gives complex [Pd(PPh₃){η¹‐C(S)OPh}(η²‐S₂CNEt₂)], 4 or [Pd(PPh₃){η¹‐C(S)OPh}(η²‐dppa)][Cl], 5 . Complex 1 is determined by single‐crystal X‐ray diffraction and crystallized in the monoclinic space group P2₁ with Z = 4. The cell dimensions of 1 are as follows: a = 9.5613(1) Å, b = 33.6732(3) Å, c = 12.2979(1) Å.     

Manganese(II) Complexes with Bridging Selenidoarsenate(III) Anions [AsSe2(Se2)]3− and [(AsSe2)2(μ‐Se2)]4−

Solvothermal reaction of [MnCl₂(terpy)] with elemental As and Se at a 1:1:2 molar ratio in H₂O/trien (10:1) at 150 °C affords the linear trimanganese(II) complex [{Mn(terpy)}₃(μ‐AsSe₄)₂] ( 1 ). The tridentate [AsSe₂(Se₂)]^3? anions of 1 chelate the terminal {Mn(terpy)}²⁺ fragments and bridge these through their remaining Se atom to the central {Mn(terpy)}²⁺ moiety. Weak interactions of Mn1···Se and Mn3···Se bonds with length 2.914(7) and 3.000(7) Å link the molecules of 1 into infinite chains. Treatment of [MnCl₂(cyclam)]Cl with As and Se at a 1:1:2 molar ratio in superheated H₂O/CH₃OH (1:1) at 150 °C yields the dinuclear complex [{Mn(cyclam)}₂ (μ‐As₂Se₆)] ( 2 ), whose novel [(AsSe₂)₂(μ‐Se₂)]^4? ligands bridge the Mn^II atoms in a μ‐1κ²Se¹, Se²: 2κ²Se⁵,Se⁶ manner.     

Synthesis and Characterization of New Copper(I) Complexes Containing Thione Derivatives of 1, 2, 4‐Triazine. Crystal Structure of [Cu(PPh3)2(ATTO)]NO3 (ATTO = 4‐amino‐1, 2, 4‐triazin‐3(2H)‐thione‐5‐one)

The reaction of 4‐amino‐1, 2, 4‐triazin‐3(2H)‐thione‐5‐one (ATTO, 1 ) with [Cu(PPh₃)₂]NO₃ in ethanol led to the complex [Cu(PPh₃)₂(ATTO)]NO₃ ( 2 ). 2 was characterized by elemental analyses, IR, ¹H NMR and Raman spectroscopy. A single‐crystal X‐ray diffraction of compound 2 revealed that ATTO acts as a bidentate ligand via its nitrogen and sulfur atoms. Crystal data for 2 at 20 °C: space group P2₁/n with a = 975.7(1), b = 1533.5(2), c = 2504.2(3) pm, β = 92.25(1)°, Z = 4, R₁ = 0.0632.     

Origin and Location of Electrons and Protons during the Formation of Intermetalloid Clusters [Sm@Ga3−xH3−2xBi10+x]3− (x=0, 1)

Reaction of [GaBi₃]^2? with [Sm(C₅Me₄H)₃] yielded the first protonated ternary intermetalloid clusters [Sm@Ga_3?xH_3?2xBi_10+x]^3? ( 1 ; x=0,1). The presence of the Ga? H bonds and the transfer of electrons and protons during the formation of 1 were elucidated by a combination of experimental and quantum chemical methods, thereby rationalizing the role of the solvent ethane‐1,2‐diamine as a Brønsted acid. As an organic by‐product, we observed the previously unknown octamethylfulvene ( 2 ) upon C? C coupling of (C₅Me₄H)^?.     

Metal Complexes of New Mixed Oxaaza‐Macrocyclic Ligands. X‐Ray Crystal Structure of L1, L2, [SrL2(H2O)2](ClO4)2 and [BaL2(NCS)2(CH3CN)]·CH3CN

A new mixed oxaaza‐macrocyclic ligand, L¹, has been obtained by direct synthesis between 1,4‐bis‐(2′‐formylphenyl)‐1,4‐dioxabutane and the diamine 2,2′‐ethylenedioxydiethylamine. The dialkylated ligand L², bearing two nitrobenzyl pendant groups, has been prepared and transitional, post‐transitional and Ca²⁺, Sr²⁺, and Ba²⁺ metal complexes have been synthesized in order to elucidate the coordination preferences. The crystal structures of the ligands L¹ and L² and the complexes [SrL²(H₂O)₂](ClO₄)₂ and [BaL²(NCS)₂(CH₃CN)]·CH₃CN have been determined by single crystal X‐ray diffraction. The structures reveal the presence of mononuclear endomacrocyclic complexes where the pendant arms radiate away from the ligand.     

Zinc(II) and Cadmium(II) Complexes of the 3‐(2‐Pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine (PDPT) Ligand,Structural Studies of [Zn(PDPT)2Cl(ClO4)] and [Cd(PDPT)2(NO3)(ClO4)]

Two new mixed‐anion zinc(II) and cadmium(II) complexes of 3‐(2‐pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine (PDPT) ligand, [Zn(PDPT)₂Cl(ClO₄)] and [Cd(PDPT)₂(NO₃)(ClO₄)], have been synthesized and characterized by elemental analysis, IR‐ and ¹H NMR spectroscopy. The single crystal X‐ray analyses show that the coordination number in these complexes is six with four N‐donor atoms from two “PDPT” ligand and two of the anionic ligands, ZnN₄ClO_perchlorate, CdN₄O_nitrateO_perchlorate. Self‐assembly of these compounds in the solid state via π–π‐stacking interactions is discussed.     

Oxovanadium(IV,V) Complexes with 2‐Acetylpyridine‐2‐furanoylhydrazone (Hapf) as Ligand. X‐Ray Crystal Structures of [VO2(apf)] and [V2O2(μ‐O)2(apf)2]

The preparation of oxovanadium(IV, V) coordination compounds with 2‐acetylpyridine‐2‐furanoylhydrazone (Hapf) is described. [VO(apf)(acac)] was prepared from oxovanadium(IV) diacetylacetonate [VO(acac)₂] by reaction with Hapf in methanol or dichloromethane. The complex is paramagnetic and its EPR spectrum is consistent with an octahedral coordination for the vanadium(IV) atom. Voltammetry studies of [VO(apf)(acac)] indicate an irreversible oxidation, in agreement with the chemical behavior of the compound in solution. The vanadium(IV) complex undergoes slow oxidation in alcoholic solution, losing the acetylacetonate ligand to form [VO₂(apf)] and [V₂O₂(μ‐O)₂(apf)₂]. The crystal structures of these last compounds were determined by X‐ray diffraction methods. [V₂O₂(μ‐O)₂(apf)₂] crystallizes monoclinic [P2₁/c, Z = 2, a = 817.400(10), b = 1650.90(3), c = 984.70(2) pm, β = 112.7190(10)°]. The crystal structure consists of dimeric units, in which two μ‐oxo ligands subtend asymmetric bridges between the vanadium atoms in a very distorted octahedral coordination. In the crystal of [VO₂(apf)], orthorhombic [Pnma, Z = 4, a = 1630.000(10), b = 675.10(4), c = 1136.40(2) pm], the vanadium(V) atom is pentacoordinated.     

New Rhenium(V) Nitrofuryl Semicarbazone Complexes.Crystal Structure of [ReOCl2(PPh3)(3‐(5‐Nitrofuryl)acroleine semicarbazone)]

The synthesis and characterization of the first two Re complexes with semicarbazone ligands is presented. Selected ligands are 5‐Nitro‐2‐furaldehyde semicarbazone (Nitrofurazone) ( L1 ) and its derivative 3‐(5‐Nitrofuryl)acroleine semicarbazone ( L2 ). Complexes of general formula [Re^VOCl₂(PPh₃) L ], where L = L1 and L2 , were prepared in good yields and high purity by reaction of [Re^VOCl₃(PPh₃)₂] with L in ethanol or methanol solutions. The complexes formula and molecular structures were supported by elemental analyses and electronic, FTIR, ¹H, ¹³C and ³¹P NMR spectroscopies. In addition, the crystal and molecular structure of [Re^VOCl₂(PPh₃) L2 ] was determined by X‐ray diffraction methods. [ReOCl₂(PPh₃)(3‐(5‐Nitrofuryl)acroleine semicarbazone)] crystallizes in the space group P‐1 with a = 11.2334(2), b = 11.3040(2), c = 12.5040(2) Å, α = 81.861(1), β = 63.555(1), γ = 83.626(1)°, and Z = 2. The Re(V) ion is in a distorted octahedral environment, equatorially coordinated to a deprotonated semicarbazone molecule acting as a bidentate ligand through its carbonylic oxygen and azomethynic nitrogen atoms, to an oxo ligand and a chlorine atom. The six‐fold coordination is completed by another chlorine atom and a triphenylphosphine ligand at the axial positions.     

Synthesis and Crystal Structures of the Molybdenum(II) Complexes with the N,N‐dimethylthiocarbamoyl Containing Ligand: Crystal Structures of β [Mo(CO)2{η2‐S2P(OEt)2}(η2‐SCNMe2)(PPh3)] and [Mo(CO)2(η3‐Tp)(η2‐SCNMe2)(PPh3)]

Reactions of the thiocarbamoyl‐molybdenum complex [Mo(CO)₂(η²‐SCNMe₂)(PPh₃)₂Cl] 1 , and ammonium diethyldithiophosphate, NH₄S₂P(OEt)₂, and potassium tris(pyrazoyl‐1‐yl)borate, KTp, in dichloromethane at room temperature yielded the seven coordinated diethyldithiophosphate thiocarbamoyl‐molybdenum complexe [Mo(CO)₂{η²‐S₂P(OEt)₂}(η²‐SCNMe₂)(PPh₃)] β‐3 , and tris(pyrazoyl‐1‐yl)borate thiocabamoyl‐molybdenum complex [Mo(CO)₂(η³‐Tp)(η²‐SCNMe₂)(PPh₃)] 4 , respectively. The geometry around the metal atom of compounds β‐3 and 4 are capped octahedrons. The α‐ and β‐isomers are defined to the dithio‐ligand and one of the carbonyl ligands in the trans position in former and two carbonyl ligands in the trans position in later. The thiocabamoyl and diethyldithiophosphate or tris(pyrazoyl‐1‐yl)borate ligands coordinate to the molybdenum metal center through the carbon and sulfur and two sulfur atoms, or three nitrogen atoms, respectively. Complexes β‐3 and 4 are characterized by X‐ray diffraction analyses.     

[Pb2(AMP)2(μ‐X)2X2], X = Br− and I−, AMP = 2‐aminomethylpyridine,Two New Dimeric Lead(II) Complexes Extended in One‐dimensional Helical Chain Polymers by Noncovalent π–π‐stacking

The two lead(II) complexes [Pb₂(AMP)₂(μ‐X)₂X₂], X = Br^?, I^? and AMP = 2‐aminomethylpyridine, have been synthesized and characterized. Self‐assembly of these compounds in the solid state via π–π‐stacking interactions is discussed.     

Synthesis,Characterization and X‐ray Crystal Structures of [Cu(ncaen)2]ClO4 and [Cu(nca2en)(PPh3)2]BPh4 Complexes

A novel ligand, N,N′‐Bis‐[3‐(2‐nitrophenyl)‐allylidene]‐ethane‐1,2‐diamine (nca₂en), and their corresponding copper(I) complexes, [Cu(ncaen)₂]ClO₄ ( 1 ), and [Cu(nca₂en)(PPh₃)₂]BPh₄ ( 2 ), have been synthesized and characterized by CHN analyses, ¹H and ¹³C‐NMR, IR, and UV‐Vis spectroscopy. The crystal and molecular structures of [Cu(ncaen)₂]ClO₄ ( 1 ), and [Cu(nca₂en)(PPh₃)₂]BPh₄ ( 2 ), were determined by X‐ray crystallography from single‐crystal data. The coordination polyhedron about the copper(I) atom in the two complexes is best described as a distorted tetrahedron. A quasireversible redox behavior is observed for complex 1 and 2 (E_1/2 = 0.55 and 0.95 V, respectively).     

Syntheses and Characterization of New Copper Complexes with the Heterocyclic Thione,AMTTO. X‐Ray Structures of [Cu(AMTTO)Cl2], [Cu(AMTTO)2]Cl,and [Cu(AMTTO)(PPh3)2Cl] (AMTTO = 4‐Amino‐6‐methyl‐1, 2, 4‐triazine‐3‐thione‐5‐one)

The complexes [Cu(AMTTO)Cl₂] ( 2 ), [Cu(AMTTO)₂]Cl ( 3 ), and [Cu(AMTTO)(PPh₃)₂Cl] ( 4 ) have been prepared and characterized by IR spectroscopy and elemental analyses. Also single‐crystal X‐ray diffraction studies on compound 2 , 3 and 4 revealed that AMTTO acts in 2 as a bidentate ligand via nitrogen and sulfur atoms, in 3 and 4 as a monodentate via sulfur atoms. Complex 3 was already mentioned in literature, but the structure was not described in detail. The molecules in 2 form infinite chains through additional weak Cu—S interactions along [010] indicating the Jahn‐Teller distortion of the d⁹ ion Cu²⁺. The infinite chains are connected by hydrogen bonding along [100]. Crystal data for 2 at —80°C: monoclinic, space group P2₁/m, a = 666.7(1), b = 609.4(1), c = 1132.6(2) pm, b = 95.46(2)°, Z = 2, R₁ = 0.0365; for 3 at —80°C: orthorhombic, space group Pbcn, a = 1291.2(2), b = 1146.5(1), c = 1000.5(1) pm, Z = 4, R₁ = 0.0315; for 4 at —80°C: monoclinic, space group, P2₁/n, a = 879.4(1), b = 1849.3(2), c = 2293.8(3) pm, β = 92.38(1)°, Z = 4, R₁ = 0.0688.     

Bis(μ‐acetato‐κ3O,O′:O′)bis[bis(acetato‐κ2O,O′)diaquadysprosium(III)] tetrahydrate

The title compound, [Dy₂(C₂H₃O₂)₆(H₂O)₄]·4H₂O, crystallizes in the form of dimeric units related by an inversion centre. Each cation is nine‐coordinate, binding to two water mol­ecules and three acetate groups, two of which are bidentate and the third tridentate. This last acetate group acts as a bridge between neighbouring metal atoms, leading to an intradimer Dy?Dy separation of 4.170 (1) Å.