The influence of substituents (R) at N atom of thiophene-2-carbaldehyde thiosemicarbazones {(C4H3S)HCN-N(H)-C(S)NHR} on bonding, nuclearity and H-bonded networks of copper(I) complexes

The nuclearity, bonding and H-bonded networks of copper(I) halide complexes with thiophene-2-carbaldehyde thiosemicarbazones {(C₄H₃S)HC²N³-N(H)-C¹(S)N¹HR} are influenced by R substituents at N¹ atom. Thiophene-2-carbaldehyde-N¹-methyl thiosemicarbazone (HttscMe) or thiophene-2-carbaldehyde-N¹-ethyl thiosemicarbazone (HttscEt) have yielded halogen-bridged dinuclear complexes, [Cu₂(μ-X)₂(η¹-S-Htsc)₂(Ph₃P)₂] (Htsc, X: HttscMe, I, 1; Br, 2; Cl, 3; HttscEt, I, 4; Br, 5; Cl, 6), while thiophene-2-carbaldehyde-N¹-phenyl thiosemicarbazone (HttscPh) has yielded mononuclear complexes, [CuX(η¹-S-HttscPh)₂] (X, I, 7a; Br 8; Cl, 9) and a sulfur bridged dinuclear complex, [Cu₂(μ-S-HttscPh)₂(η¹-S-HttscPh)₂I₂] 7b co-existing with 7a in the same unit cell. These results are in contrast to S-bridged dimers [Cu₂(μ-S-Httsc)₂(η¹-Br)₂(Ph₃P)₂] · 2H₂O and [Cu₂(μ-S-Httsc)₂(η¹-Cl)₂(Ph₃P)₂] · 2CH₃CN obtained for R = H and X = Cl, Br (Httsc = thiophene-2-carbaldehyde thiosemicarbazone) as reported earlier. The intermolecular CH_Ph?π interaction in 1-3 (2.797 Å, 1; 3.264 Å, 2; 3.257 Å, 3) have formed linear polymers, whereas the CH_Ph?X and N³?HCH interactions in 4-6 (2.791, 2.69 Å, 5; 2.776, 2.745 Å, 6, respectively) have led to the formation of H-bonded 2D polymer. The PhN¹H?π, interactions (2.547 Å, 8, 2.599 Å, 9) have formed H-bonded dimers only. The Cu?Cu separations are 3.221-3.404 Å (1-6).     

Syntheses and structures of vinyl and aryl derivatives of carbonyl halide iron complexes

cis,trans-Fe(CO)₂(PMe₃)₂(p-Y-C₆H₄)X [X=Br, Y=H (4a), MeO (4b), Cl (4c), F (4d), Me (4e); X=I, Y=H (5); X=Cl, Y=H (6)] and cis,trans-Fe(CO)₂(PMe₃)₂(σ-CHCH₂)X [X=Br (7); X=I (8); X=Cl (9)] are prepared by reacting dihalide complexes cis,trans,cis- Fe(CO)₂(PMe₃)₂X₂ [X=Br (1), X=I (2), X=Cl (3)] with Grignard reagents p-Y-C₆H₄-MgBr (Y=H, OMe, Cl, F, Me) or CH₂CH-MgBr and with lithium reagents PhLi, CH₂CH-Li. With both reagents, the reaction proceeds following two parallel pathways: one is the metallation reaction which yields alkyl derivatives, the other affords 17 electron complexes [Fe(CO)₂(PMe₃)₂X] via monoelectron reductive elimination. The influence of the halides and organometallic reagents on the yield of the metallation reaction is discussed. The solution structure of the complexes is assigned on the basis of IR and ¹H, ¹³C, ¹⁹F, ³¹P NMR spectra. The solid state structure of complexes 4a, 5 and 6 is determined by single crystal X-ray diffractometric methods.     

Main group derivatives of a cyclometallated iron carbonyl anion. Crystal structures of Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(SnPh3) and two isomers of Fe(CO)2{P(OPh)3}{(PhO)2POC6H4}(I)

The iron hydrido complex HFe(CO)₂{P(OPh)₃}{(PhO)₂POC₆H₄} (1), was rapidly deprotonated by DBU or [BzMe₃N][OH] in THF to afford the new carbonyl iron anion [Fe(CO)₂{P(OPh)₃}{(PhO)₂POC₆H₄}]⁻ ([2]⁻), containing an ortho-metallated triphenyl phosphite ligand. Complex [2]⁻ reacted with triorganostannyl and plumbyl salts and with halogens to give the octahedral Fe^II compounds Fe(CO)₂{P(OPh)₃}{(PhO)₂POC₆H₄}(X) (X=SnPh₃, 3; SnMe₃, 4; PbPh₃, 5; PbMe₃, 6; Cl, 7; Br, 8; I, 9). The Group 14 complexes 3-6 were obtained in one isomeric form in which the P^III-donor atoms are mutually cis, the carbonyl ligands are cis and the P(OPh)₃ and MR₃ (M=Sn, Pb; R=Ph, Me) groups are trans as determined by solution-state IR, ³¹P and ¹³C NMR spectroscopic data. This geometry was confirmed for 3 by a single crystal X-ray diffraction study. The halide complexes, however, were obtained as a mixture of isomers. The major isomer (7, X=Cl; 8a, X=Br; 9a, X=I) has cis P atoms, trans CO groups and the halide located trans to the phosphorus atom of the ortho-metallated phosphite ligand. The structure of 9a was confirmed by an X-ray diffraction study. Two other isomers, designated 8b (X=Br) and 9b (X=I), with cis P atoms and cis CO groups were isolated from the reactions of [2]⁻ with Br₂ and I₂, respectively. The structure of the latter was established by X-ray crystallography and is related to 9a by exchange of the P(OPh)₃ ligand and a carbonyl group such that the metal-bound C atom of the five-membered metallacycle is trans to CO. The stereo-geometry of 8b could not be unambiguously assigned from the spectroscopic data; however, two of the seven possible geometric isomers were suggested as plausible structures.     

Syntheses,structures and ligand dissociation kinetics of Vitamin B12 model compounds with exceptionally poor electron donating groups,LCo(DH)2CHX2 (X = Cl or Br)

The syntheses and ligand dissociation kinetics of vitamin B₁₂ model compounds LCo(DH)₂CHX₂ with X = Cl and Br and L = different neutral N- and P- ligands are reported together with the crystal structures of the CHCl₂ derivatives with L = py (1) and 1,5,6-trimethylbenzimidazole, Me₃Bzm (2). Compound 1 crystallizes in the space group P2₁/n with cell parameters a = 9.617(1), b = 12.601(2), c = 15.586(2) Å, β = 95.44(1)°; 2 crystallizes in the space group P1 with cell parameters a = 8.867(2), b = 10.719(2), c = 13.345(2) Å, α = 94.81(2), β = 90.89(1), γ = 105.63(2)°. The two structures were solved by Patterson and Fourier methods and refined by least-squares methods to final R values of 0.037 (1) and 0.036 (2), using 3474 (1) and 4435 (2) independent reflections.The axial NCoC fragment is characterized by CoN and CoC distances of 2.045(2) and 1.995(2) Å in 1 and 2.043(2) and 1.983(2) Å in 2, respectively. The CoC bond lengths have the smallest values so far reported in both py and Me₃Bzm alkylcobaloximes.The displacement of the L ligand followed SN1 LIM behaviour and the corresponding rate constants depend upon the nature of L and vary in CHCl₂ derivatives from 2.42 X 10⁻¹ s⁻¹ for 2-aminopyridine to 1.99 X 10⁻⁵ s⁻¹ for P(OMe)₃. For fewer CHBr₂ analogs the rate constants were smaller.Kinetic results confirm previous findings that the donating ability of CHBr₂ is less than that of CHCl₂, although the electronegativity of Cl and Br species would suggest an opposite trend. Some relationships between kinetic and structural properties are discussed.     

Syntheses of new ferrocenylphosphinecopper(I) complexes and their application to the valence isomerization of norbornadiene to quadricyclene

Copper(I) chloride and bromide reacted with an equimolar amount of ferrocenyldiphenylphosphine (PFcPh₂) in refluxing benzene, affording the new tetrameric complexes [CuX(PFcPh₂)]₄ (1, X= Cl; 2, X = Br) as yellow microcrystals. Their bipyridyl (bpy) derivatives [CuX(bpy)(PFcPh₂)] (3, X=Cl; 4, X=Br) were prepared also. When copper(I) chloride was allowed to react with abundant PFcPh₂, only the mononuclear complex [CuCl(PFcPh₂)₂] (5) was isolated. THF solutions of the copper(I) complexes and 2,5-norbornadiene (Nbd) were irradiated at 366 nm, and the valence isomerization of Nbd to quadricyclene (Q) was observed. Quantum yields with 1 and 2 were about 0.011 and 0.008, respectively, and those with other complexes were very small. ³¹P NMR studies were performed for the complexes in the presence of Nbd or norbornene, and the key photoactive species in the isomerization with 1 and 2 were determined to be their ground state copper-Nbd adducts, i.e. ‘CuX(PFcPh₂)(Nbd)’. Photoexcitation of the adducts was assumed to give rise to the valence isomerization and to release Q.     

Synthesis and reactivity of mixed pentafluorophenyl platinum(I)-palladium(I) derivatives

XPd(μ-dppm)₂Pt(C₆F₅) (X = Cl (I), Br (II)) have been prepared by reacting Pd₂(dba)₃·CHCl₃ and PtX- (C₆F₅)(η¹-dppm)₂. Reaction of complex I with SnCl₂ gives the SnCl₃⁻ derivative, whilst ligands L (PPh₃, P(OPh)₃, SbPh₃) render the cationic complexes. The species R₂N⁺, SO₂ or MeOOC)CCCOOMe insert into the PdPt bond of I to give A-frame Pd(II)- Pt(II) complexes. The reactions of CIPd(μ-dppm)₂- Pt(C6F₅) with isonitriles CNR (R = p-Tol, Cy) lead to products containing either terminal or inserted isocyanide or both.     

Synthesis of (NBu4)2[Pd2(μ-Br)2(C6X5)2Br2] (X=F,Cl), new and more versatile precursors of pentahalophenyl derivatives of palladium(II)

The title compounds (1, X=F; 2, X=Cl) were obtained in quantitative yield by refluxing together (NBu₄)₂[Pd₂(μ-Br)₂(C₆X₅)₄] and (NBu₄)₂[Pd₂(μ-Br)₂Br₄]. Treatment of 1 or 2 with AgClO₄ (Pd:Ag= 1:1) gave solutions which behaved as containing ‘Pd(C₆X₅)Br’. 1, 2 and the ‘Pd(C₆X₅)Br’ solutions were checked as precursors of mono-pentahalophenyl derivatives, yielding a variety of complexes [Pd(C₆X₅)Br(L-L)] (L-L=bipy, tmen, dpe, COD), [Pd(C₆X₅)BrL₂] (L=p-TolNH₂, py, PPh₃, AsPh₃, SbPh₃), [Pd₂(μ-Br)₂(C₆X₅)₂L₂] (X=F, L=AsPh₃; X=Cl, L=SbPh₃) and (NBu₄)[Pd(C₆X₅)Br₂L] (X=F, L= py, AsPh₃, SbPh₃; X=Cl, L=p-TolNH₂, py, PPh₃, AsPh₃, SbPh₃). The solutions of ‘Pd(C₆X₅)Br’ proved to be the best general precursors of complexes [Pd(C₆X₅)BrL₂] although complexes with OPPh₃ could not be obtained.     

Influence on reactivity of chloro ligand substitution in mononuclear cationic Pd(II) and Pt(II) triphos complexes: X-ray structure of the nitrate derivatives

The substitution of chloro ligand in [M(triphos)Cl]Cl complexes [M=Pd (1), Pt (2); triphos=Ph₂PC₂H₄P(Ph)C₂H₄PPh₂] by reaction with 1 equiv. of KX resulted in the formation of the ionic complexes [M(triphos)X]Cl [X=I, M=Pd (3), Pt (4); X=CN, M=Pd (5), Pt (6)]. Methanolic solutions of silver nitrate in excess displace the chloro ligand and counterion of 1 and 2, giving rise to the formation of the crystalline complexes [M(triphos)(ONO₂)](NO₃) [M=Pd (7), Pt (8)] suitable for X-ray diffraction studies. The complexes show a distorted square-planar environment around the metal, there being three coordination sites occupied by phosphorus atoms from the triphos and the fourth by the oxygen atom from a nitrate acting as monodentate ligand. A second NO₃ ⁻ is acting as counterion with D_3h symmetry. The use of a high excess of SnCl₂ in the presence of 1 equiv. of PPh₃ enabled the formation of complexes [M(triphos)(PPh₃)](SnCl₃)₂ [M=Pd (9), Pt (10)]. These complexes, in addition to [M(triphos)X]X [X=Br, M=Pd (1a), Pt (2a); X=I, M=Pd (1b), Pt (2b)], were synthesised and all Pt(II) complexes characterised by microanalysis. Mass spectrometry, IR spectroscopy, NMR spectroscopy and conductivity measurements were also used for characterisation. The structure and reactivity studies in solution were carried out by ³¹P{¹H} NMR. The trends in chemical shifts δ (P) and ¹J(¹⁹⁵Pt, ³¹P) coupling constants were used to establish a sequence in the X ligand exchange reactions. While [Pd(triphos)I]I (1b) undergoes a ring-opening reaction by titration with AuI, the analogous Pt(II) complex (2b) does not react. The formation of new five-coordinate Pd(II) and Pt(II) complexes was observed by titration of 5–8 with potassium cyanide.     

Synthesis and characterization of new imidorhenium(V) and imidorhenium(VI) complexes of pyridyltriazines and pyrazinyltriazine with halide coligands including rare iodide

The blue colored imido complexes [Re(NC₆H₄Cl)X₃(L)] have been synthesized by three methods: (i) reaction of [Re^VOX₃(L)] with p-ClC₆H₄NH₂, (ii) reaction of [Re^III(OPPh₃)X₃(L)] with p-ClC₆H₄NH₂ and (iii) reaction of [Re^VOX₃(PPh₃)₂] with L followed by the addition of p-ClC₆H₄NH₂ in boiling toluene. Here, X = Cl, Br, I and L are 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine (L²) and its dimethyl (L¹) and pyrazinyl (L³) analogues. The [Re(NC₆H₄Cl)Cl₃(L¹)] (1a), [Re(NC₆H₄Cl)Cl₃(L²)] (1b), [Re(NC₆H₄Cl)Br₃(L²)] (1c), [Re(NC₆H₄Cl)I₃(L²)] (1d), [Re(NC₆H₄Cl)Cl₃(L³)] (1e), [Re(NC₆H₄Cl)Br₃(L³)] (1f), [Re(NC₆H₄Cl)I₃(L³)] (1g), complexes have been characterized electrochemically and spectroscopically. The X-ray structures of [Re(NC₆H₄Cl)Cl₃(L²)] and [Re(NC₆H₄Cl)I₃(L³)] reveal that the ReCl₃ fragment is meridionally disposed and that the L ligand is N,N-coordinated such that the pyridine/pyrazine nitrogen lies trans to the imide nitrogen. The feasibility of generating the rhenium(VI) congener of the imidorhenium(V) complex is also examined with the help of six-line EPR spectra at room temperature.     

Preparation and characterization of (9-methyladenine)triammineplatinum(II) and trans-dihydroxo(9-methyladenine)triammineplatinum(IV) complexes

The preparation is reported of [(NH₃)₃Pt(9- MeA)] X₂ (9-MeA = 9-methyladenine) with XCl (1a) and XClO₄ (1b) and of trans-[(OH)₂Pt(NH₃)₃- (9-MeA)]X₂ with XCl (2a) and XClO₄ (2b), and the crystal structure of 1b. [(NH₃)₃Pt(C₆H₇N₅)](ClO₄)₂ crystallizes in space group P2₁/n with a = 20.810(7) Å, b = 7.697(3) Å, c = 10.567(4) Å, β = 91.57(6)°, Z = 4. The structure was refined to R = 0.054, R_w = 0.063. In all four compounds Pt coordination is through N7 of 9-MeA, as is evident from ³J coupling between H8 of the adenine ring and ¹⁹⁵Pt. Pt(II) and Pt(IV) complexes can be differentiated on the basis of different ³J values, larger for Pt(II) than for Pt(IV) by a factor of 1.57 (av). In Me₂SO-d₆, hydrogen bonding occurs between Cl^? and C(8)H of 9-MeA as weil as between Cl^? and the NH₃ groups in the case of the Pt(II) complex 1a. Protonation of the 9-MeA ligands was followed using ¹H NMR spectroscopy and pK_a values for the N1 protonated 9-MeA ligands were determined in D₂O. They are 1.9 for 1a and 1.8 for 2a, which compares with 4.5 for the non-platinated 9-MeA. Possible consequences for hydrogen bonding with the complementary bases thymine or uracil are discussed briefly. Protonation of the OH groups in the Pt(IV) complexes has been shown not to occur above pH 1.     

Syntheses and crystal structures of three diorganoltin(IV) macrocycles

Three novel macrocyclic diorganotin(IV) compounds of the type: {[R₁₀(SnO)₃(SnOH)₂]H_nXO_m}₂ · L (n=1, m=4, R=PhCH₂, X=P, L=0, 1; n=0, m=4, R=PhCH₂, X=S, L=4H₂O, 2; n=0, m=3, R=n-Bu, X=N, L=0, 3) were synthesized by the reaction of (PhCH₂)₂SnCl₂ with Na₂H_nXO₄ (n=1, X=P; n=0, X=S) or (n-Bu)₂SnCl₂ with NaNO₃. All the compounds 1, 2 and 3 are characterized by elemental, IR and X-ray diffraction analyses. X-ray data reveal that a macrocyclic structure with two centrosymmetric ladders of hydrolysis exists in the crystals of the three compounds. The geometry about each tin atom involved is trigonal bipyramidal.     

Manganese(III) complexes of N2O2 donor 5-bromosalicylideneimine ligands: Combined effects of electron withdrawing substituents and chelate ring size variations on electrochemical properties

A series of mononuclear manganese(III) complexes of formulae [Mn(L)(X)(H₂O)] (1-13) and [Mn(L)(X)] (14-17) (X = ClO₄, F, Cl, Br, I, NCS, N₃), derived from the Schiff bases of 5-bromosalicylaldehyde and different types of diamine (1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane and 1,4-diaminobutane), have been synthesized and characterized by the combination of IR, UV-Vis spectroscopies, cyclic voltammetry and by X-ray crystallography. The redox properties of all the manganese(III) complexes show grossly identical features consisting of a reversible or quasireversible Mn^III/Mn^II reduction. Besides Mn^III/Mn^II reduction, the complexes 4, 5, 10, 13 and 16 also show reversible or quasireversible Mn^III/Mn^IV oxidation. A linear correlation has been found for the complexes 5, 7, 11 and 13 [Mn(L²)(X)(H₂O)] (X = F, Cl, Br, I) when E_1/2 [Mn^III/Mn^II] is plotted against Mulliken electronegativities (χ_M). The effect of the flexibility of the ligand on redox potential has been studied. It has been observed that the manganese(II) state is stabilized with increasing flexibility of the ligand environment. The crystal structure of 6 shows an octahedral geometry.     

Insertion reactions of 1,4-diisocyanobenzene in binuclear Pd(I) complexes

Reactions between XPd(μ-dmp)₂PdX′ (X = X′ = Cl, Br, I, NCO, SCN, N₃ or C₆F₅; X = C₆F₅, X′ = Cl, Br, I, NCO) with 1,4-diisocyanobenzene lead to the tetranuclear complexes [(μ,μ′-CNC₆H₄NC){XPd(μ-dpm)₂PdX′}₂], where both ends of the diisocyanide are inserted in a metalmetal bond. The cationic derivatives [(μ,μ′-CNC₆H₄NC){(RNC)Pd(μ-dpm)₂(CNR)}₂](BPh₄)₄ and [(μ,μ′-CNC₆H₄NC){(RNC)Pd(μ-dpm)₂Pd(C₆F₅)}₂] (BPh₄)₂ (R = p-Tol, Cy, or ^tBu) are obtained by reacting [(μ,μ′-CNC₆H₄NC){ClPd(μ-dpm)₂PdX}₂] (X= Cl or C₆F₅) with RNC in the presence of NaBPh₄. Treatment of [(μ,μ′-CNC₆H₄NC){ClPd(μ-dpm)₂Pd(C₆F₅)}]₂ with NaBPh₄ causes the di-insertion and subsequent coordination of the isocyanide, yielding [(C₆F₅)Pd(CN-C₆H₄NC) Pd(μ-dpm)₂Pd(C₆F₅)](BPh₄)₂.     

Structure and catalytic activity of rhodium(I) carbene complexes in polymerization of phenylacetylene

Rh(I) carbene complexes of [RhX(bmim)(η⁴-1,5-cod)] type (bmim = 1-butyl-3-methyl imidazolium cation, X = Cl 2, Br 3, I 4), obtained in the reaction of [Rh(OMe)(η⁴-1,5-cod)]₂ (1) with [bmim]X ionic liquids, catalyzed polymerization of phenylacetylene (PA) to cis-polyphenylacetylene (PPA) in CH₂Cl₂ and in ionic liquids. The yield of PPA increased and molecular weight (M_w) decreased after addition of phosphorus ligands PPh₃ or P(OPh)₃. Complex 4 reacted with P(OPh)₃ giving cis-[RhI(bmim)(P(OPh)₃)₂] (5) complex which catalyzed oligomerization but not polymerization of PA.     

New molybdenum(VI) catalysts for the epoxidation of cyclohexene: synthesis, reactivity and crystal structures

Compounds 1-6 of the type MoO₂X₂L₂ (X=F, Cl, Br; L=OPMePh₂, OPPh₃) have been prepared in order to investigate the variation in catalytic activity with changes in electronic and steric properties. All six complexes catalyze the epoxidation of cyclohexene with tert-butylhydroperoxide, and the species with X=Cl and L=OPMePh₂ (2) displays the best activity with 83% conversion and 90% selectivity in one hour at ambient atmosphere. These inexpensive and easily prepared dioxo catalysts are stable to air and water. Reactions of the dioxo compounds with H₂O₂ and t-BuOOH have also been carried out. The structures of MoO₂F₂(OPMePh₂)₂ (1) and the product of its reaction with H₂O₂, MoO(O₂)₂(OPMePh₂)₂ (7) have been solved by single crystal X-ray diffraction.     

Synthesis and reactions of [M(CO)4(Ph2PSiMe3)X] complexes (M = Mn,Re; X = Halogen)

The silylphosphine ligand Ph₂PSiMe₃ reacts readily with a slurry of [Re(CO)₅X] (X  Cl, Br) in polar and in non-polar solvents to yield soluble cis-[Re(CO)₄- (Ph₂PSiMe₃)X] (Ia, X  Cl;Ib, X  Br) via CO substitution. Compound I is readily hydrolyzed by water or silica gel to cis-[Re(CO)₄(Ph₂PH)X]. Compound Ib reacts with [Re(CO)₅Br] to yield [Re₂(CO)₈(μ-PPh₂)- (μ-Br)] (II), and with [Mn(CO)₅Br] to yield [MnRe- (CO)₈(μ-PPh₂)(μ-Br)] (III).The reaction of Ph₂PSiMe₃ with [Mn(CO)₅X] (X=Cl,Br,I) is highly dependent upon reaction conditions.In polar and in non-polar solvents, an excess of ligand gives mainly cis-[Mn(CO)₄(Ph₂PSiMe₃)X] (IVa, X  Cl;IVb, X  Br;IVc, X I). With ligand: [Mn(CO)₅X] reacting ratios in the range 0.5–1.0:1, the products from the three respective halomanganese complexes in THF were: (a) mainly [Mn₂(CO)₈(μ- PPh₂)(μ-Cl) (Va); (b) both [Mn(CO)₄(Ph₂PSiMe₃)Br] and [Mn₂(CO)₈(μ-PPh₂)(μ-Br)] (Vb); and (c) exclusively [Mn(CO)₄(Ph₂PSiMe₃)I]. The compounds IVa-c are stable in solution at ambient temperatures and are readily hydrolyzed by water or methanol to [Mn(CO)₄(Ph₂PH)X]. Compound IVb reacts at room temperature with [Mn(CO)₅Cl] to yield only [Mn₂- (CO)₈(μ-PPh₂)(μ-Br)] (Vb); compound IVc reacts in hot toluene with [Mn(CO)₅Cl] to yield mainly [Mn₂(CO)₈(μ-PPh₂)(μ-I)] (Vc), together with a small amount of the chloro-bridged analog.The dinuclear species II, III and Va-c appear to be formed mainly via an intermolecular elimination of Me₃SiX from the appropriate [M(CO)₄(Ph₂PSiMe₃)X] and metalpentacarbonylhalide (chloride or bromide) complexes.     

Tertiary phosphine complexes of nickel(0) and nickel(I). New dinitrogen complexes of nickel(0)

The reduction of NiX₂(PCy₃)₂ (X = Cl, Br; PCy₃ = tricyclohexylphosphine) in toluene with sodium sand under argon affords [NiX(PCy₃)₂]₂ or Ni(PCy₃)₃. In the same way starting from NiX₂P₂ [X = Cl, Br; P = P(C₂H₅)₃, P(CH₂CH₂CH₂CH₃)₃, P(C₂H₅)₂ C₆H₅] the tetracoordinate Ni(0) complexes NiP₄ are obtained. These give NiP₃(N₂) under nitrogen. The electronic spectra of Ni(0) and Ni(I) complexes, both in the solid state and solution, are reported.     

Platinum(II) complexes with aryl tellurols and diaryl ditellurides: Syntheses and spectral investigations

Arytellurol complexes [PtCl(TeAr)(PPh₃)₂] (I) and [Pt(TeAr)₂(PPh₃)₂] (II) are readily obtained from cis-[PtCl₂(PPh)₃)₂] and NaTeAr (Ar = C₆H₅, 4-CH₃OC₆H₄ and 4-CH₃CH₂OC₆H₄) in ethanolbenzene at room temperature. ³¹P NMR spectra of (I) and (II) indicate their trans configuration in solution. Metathetical reactions between I (Ar = 4-CH₃OC₆H₄) and NaX (X = I, Br, SCN) occur in methanol to give [Pt(X)(TeC₆H₄OCH₃-4)(PPh₃)₂]. ¹H NMR shows that equimolar proportions of NaTeC₆H₅, NaTeC₆H₄OCH₂CH₃-4 and cis-[PtCl₂(PPh₃)₂] give a mixture of three complexes: II, Ar = C₆H₅; II, Ar = 4-CH₃CH₂OC₆H₄; and [Pt(TeC₆H₅)(TeC₆H₄OCH₂CH₃-4)(PPh₃)₂]. Polymeric complexes [PtCl(TeAr)]_n (III) and [Pt(TeAr)₂]_n (IV) result from reaction between K₂[PtCl₄] and NaTeAr in aqueaous ethanol. They react with excess of PPh₃ in CDCl₃ to yield monomeric complexes I and II respectively which were characterized in situ by ¹H and ³¹P NMR of the reaction mixtures. IR spectra indicate the presence of bridging chloride ligands in III. An alternating chloride and tellurol bridged chain structure for III and a tellurol bridged for IV have been proposed. Reaction between equimolar amounts of III and PPh₃ in dichloromethane yielded a tellurol bridged dimeric complex [PtCl(μ-TeAr)(PPh₃)]₂ (V) with terminal chloride ligand as suggested by IR study. Ethanolic solutions of diarylditellurides also react readily with an aqueous solution of K₂[PtCl₄] at 10 °C to give complexes for which the structure trans-[PtCl₂(ArTeTeAr)₂] (VI) is suggested from their elemental analyses, IR, Raman (in one case only), ¹H, ¹²⁵Te (in one case only), and ¹⁹⁵Pt NMR spectra and reactions with triphenylphosphine which liberated free ditellurides. At 40 °C or above the same ditellurides form polymeric complexes III with K₂[PtCl₄] in aquaeous ethanol.     

Synthesis and reactivity of osmium (VI) nitrido complexes containing pyridine-carboxylato ligands

A series of osmium(VI) nitrido complexes containing pyridine-carboxylato ligands Os^VI(N)(L)₂X (L = pyridine-2carboxylate (1), 2-quinaldinate (2) and X = Cl (a), Br (1b and 2c) or CH₃O (2b)) and [Os^VI(N)(L)X₃]⁻ (L = pyridine-2,6-dicarboxylate (3) and X = Cl (a) or Br (b)) have been synthesised. Complexes 1 and 2 are electrophilic and react readily with various nucleophiles such as phosphine, sulfide and azide. Reaction of Os^VI(N)(L)₂X (1 and 2) with triphenylphosphine produces the osmium(IV) phosphiniminato complexes Os^VI(NPPh₃)(L)₂X (4 and 5). The kinetics of nitrogen atom transfer from the complexes Os^VI(N)(L)₂Br (2c) (L = 2-quinaldinate) with triphenylphosphine have been studied in CH₃CN at 25.0 °C by stopped-flow spectrophotometric method. The following rate law is obtained: −d[Os(VI)]/dt = k₂[Os(VI)][PPh₃]. Os^VI(N)(L)₂Cl (L = 2-quinaldinate) (2a) reacts also with [PPN](N₃) to give an osmium(III) dichloro complex, trans-[PPN][Os^III(L)₂Cl₂] (6). Reaction of Os^VI(N)(L)₂Cl (L = 2-quinaldinate) (2a) with lithium sulfide produces an osmium(II) thionitrosyl complex Os^II(NS)(L)₂Cl (7). These complexes have been structurally characterised by X-ray crystallography.