Homo- and hetero-bridged mixed-valence dinuclear complexes which contain the fragment ‘Rh(C6F5)3’

The reaction of the anionic mononuclear rhodium complex [Rh(C₆F₅)₃Cl(Hpz)]^t- (Hpz = pyrazole, C₃H₄N₂) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C₆F₅)₃Rh(μ-Cl)(μ-pz)M(L₂)] [M = Rh, L₂ = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO)₂ (4); M = Ir, L₂ = COD (3)]. The complex [Rh(C₆F₅)₃(Hbim)]⁻ (5) has been prepared by treating [Rh(C₆F₅)₃(acac)]⁻ with H₂bim (acac = acetylacetonate; H₂bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C₆F₅)₃Rh(μ-bim)M(L₂)]⁻ [M = Rh, L₂ = COD (6) or TFB (7); M = Ir, L₂ = COD (8); M = Pd, L₂ = η³-C₃H₅ (9)]. With [Rh(acac)(CO)₂], complex 5 yields the tetranuclear complex [{(C₆F₅)₃Rh(μ-bim)Rh(CO)₂}₂]₂₋. Homodinuclear Rh^III derivatives [{Rh(C₆F₅)₃}₂(μ-L)₂]^·- [L₂ = OH, pz (11); OH, S^tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C₆F₅)₃(μ-OH)}₂]²⁻ by the corresponding ligands. The reaction of [Rh(C₆F₅)₃(Et₂O)_x] with [PdX₂(COD)] produces neutral heterodinuclear compounds [(C₆F₅)₃Rh(μ-X)₂Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh₃⁺) salts.     

Redox potential, ligand and structural effects in rhodium(I) complexes

The electrochemical behaviour of the set of tetracoordinate rhodium(I) complexes [Rh(O^∩O)(CO)L] [O^∩O=MeC(O)CHC(O)Me (acac), L=CO (1), P(NC₄H₄)₃ (2), PPh(NC₄H₄)₂ (3), PPh₂(NC₄H₄) (4), PPh₃ (5), PCy₃ (6), P(OPh)₃ (7) or PPh₂(C₆H₄OMe-4) (8); O^∩O=PhC(O)CHC(O)Me (bac), L=CO (9) or PPh₃ (10); O^∩O=PhC(O)CHC(O)CF₃(bta), L=CO (11) or PPh₃ (12)] and of the pentacoordinate [RhH(CO)L₃] [L=P(NC₄H₄)₃ (13), PPh₃ (14), P(OPh)₃ (15) or P(OC₆H₄Me-4)₃ (16)] and [RhHL₄] [L=PPh₃ (17) or P(OC₆H₄Me-3)₃ (18)] was studied by cyclic voltammetry and controlled potential electrolysis, in aprotic medium, at a Pt electrode. They present a single-electron oxidation wave (I) (irreversible or quasi-reversible) that can be followed, at a higher potential, by a second and irreversible one (II). The values of first oxidation potential for the tetracoordinate complexes fit the additive Lever's electrochemical parameterisation, and the ligand electrochemical Lever E_L and Pickett P_L parameters were estimated for the N-pyrrolyl phosphines PPh_n(NC₄H₄)_3−n (n=0, 1 or 2) and for the organophosphines PCy₃ and PPh₂(C₆H₄OMe-4), the former behaving as weaker net electron donors (the electron donor ability decreases with the increase of the number of N-pyrrolyl groups) than the latter phosphines. The pentacoordinate hydride complexes 13–18 fit a distinct relationship which enabled the estimate of the E_L ligand parameter for the phosphites P(OC₆H₄Me-3)₃ and P(OC₆H₄Me-4)₃. Electrochemical metal site parameters were obtained for the square planar and the pentacoordinate Rh(I)/Rh(II) couples and, for the former, the redox potential is shown to present a much higher sensitivity to a change of a ligand than the octahedral redox couples investigated so far. Linear relationships were also observed between the oxidation potential and the P_L ligand parameter (for the series [Rh(acac)(CO)L]) or the infrared ν(CO) frequency, and a generalisation of the former type of correlation is proposed for series of square-planar 16-electron complexes [M′_SL] with a common 14-electron T-shaped binding metal centre {M′_S}. Oxidation of 5 by Ag[PF₆] leads to the dimerisation of the derived Rh(II) species.     

Preparation and characterization of ruthenium(II), rhodium(III) and iridium(III) complexes of isocyanide bearing the azo group

Reactions of [(η⁶-arene)RuCl₂]₂ (1) (η⁶-arene=p-cymene (1a), 1,3,5-Me₃C₆H₃ (1b), 1,2,3-Me₃C₆H₃ (1c) 1,2,3,4-Me₄C₆H₂(1d), 1,2,3,5-Me₄C₆H₂ (1e) and C₆Me₆ (1f)) or [Cp*MCl₂]₂ (M=Rh (2), Ir (3); Cp*=C₅Me₅) with 4-isocyanoazobenzene (RNC) and 4,4′-diisocyanoazobenzene (CN–R–NC) gave mononuclear and dinuclear complexes, [(η⁶-arene)Ru(CNC₆H₄N=NC₆H₅)Cl₂] (4a–f), [Cp*M(CNC₆H₄N=NC₆H₅)Cl₂] (5: M=Rh; 6: M=Ir)_, [{(η⁶-arene)RuCl₂}₂{μ-CNC₆H₄N=NC₆H₄NC}] (8a–f) and [(Cp*MCl₂)₂(μ-CNC₆H₄N=NC₆H₄NC)}] (9: M=Rh; 10: M=Ir)_, respectively. It was confirmed by X-ray analyses of 4a and 5 that these complexes have trans-forms for the ---N=N--- moieties. Reaction of [Cp*Rh(dppf)(MeCN)](PF₆)₂ (dppf=1,1′-bis (diphenylphosphino)ferrocene) with 4-isocyanoazobenzene gave [Cp*Rh(dppf)(CNC₆H₄N=NC₆H₅)](PF₆)₂ (7), confirmed by X-ray analysis. Complex 8b reacted with Ag(CF₃SO₃), giving a rectangular tetranuclear complex 11b, [{(η⁶-1,3,5-Me₃C₆H₃)Ru(μ-Cl}₄(μ-CNC₆H₄N=NC₆H₄NC)₂](CF₃SO₃)₄ bridged by four Cl atoms and two μ-diisocyanoazobenzene ligands. Photochemical reactions of the ruthenium complexes (4 and 8) led to the decomposition of the complexes, whereas those of 5, 7, 9 and 10 underwent a trans-to-cis isomerization. In the electrochemical reactions the reductive waves about −1.50 V for 4 and −1.44 V for 8 are due to the reduction of azo group, [---N=N---]→[---N=N---]²⁻. The irreversible oxidative waves at ca. 0.87 V for the 4 and at ca. 0.85 V for 8 came from the oxidation of Ru(II)→Ru(III).     

Arylkomplexe des typs trans-[Ir(Ar)(CO)(PPh3)2]

The preparation and properties as well as some reactions of a series of arylcarbonylbis(triphenylphosphine)iridium(I) complexes [Ir(Ar)(CO)(PPh₃)₂] (Ar = C₆H₅, C₆F₅, 2-C₆H₄CH₃, 3-C₆H₄CH₃, 4-C₆H₄CH₃, 2-C₆H₄OCH₃, 2,6-C₆H₃-(OCH₃)₂, 4-C₆H₄N(CH₃)₂, 3-C₆H₄Cl, 4-C₆H₄Cl, 4-C₆H₄Cl, 3-C₆H₄CF₃, 4-C₆H₄CF₃) are described, and the most important IR data as well as the ³¹P NMR parameters of these, without exception trans-planar, compounds are given.

Some of the complexes react with molecular oxygen to form well defined dioxygen adducts [Ir(Ar)(O₂)(CO)(PPh₃)₂] (Ar = C₆H₅, 3-C₆H₄CH₃, 4-C₆H₄CH₃). Complexes with ortho-substituted aryl ligands are not oxygenated. This effect is referred to as a steric shielding of the metal center by the corresponding ortho-substituents. With SO₂ the similar irreversible addition compound [Ir(4-C₆H₄CH₃)-(SO₂)(CO)(PPh₃)₂] is obtained. Sulfur dioxide insertion into the Ir---C bond cannot be observed.

The first step of the reaction between [Ir(4-C₆H₄CH₃)(CO)(PPh₃)₂] and hydrogen chloride involves an oxidative addition of HCl to give [Ir(H)(Cl)(4-C₆-H₄CH₃)(CO)(PPh₃)₂]. Ir---C bond cleavage by reductive elimination of toluene from the primary adduct does not occur except at elevated temperature.     

新型双四面体过渡金属簇合物的合成与表征

利用Co₂(CO)₈与[Cl₃CC(O)OCH₂]₂的反应合成了以C(O)OCH₂CH₂OC(O)桥联两个Co₃C四面体骨架为特征的新型双四面体簇合物[(CO)₉Co₃(μ₃-C)C(O)OCH₂]₂(1);1与不同物质的量比的Na[M(CO)₃C₅H₄R](M=Mo,W;R=H,C(O)Me)反应,得到一步交换的产物(CO)₉Co₃(μ₃-C)C(O)OCH₂CH₂OC(O)(μ₃-C)Co₂M(CO)₈(C₅H₄R)[M=Mo,R=H(2);M=Mo,R=C(O)Me(3);M=W,R=H(4);M=W,R=C(O)Me(5)]或两步交换的产物[(C₅H₄R)(CO)₈Co₂M(μ₃-C)C(O)OCH₂]₂[M=Mo,R=H(6);M=Mo,R=C(O)Me(7);M=W,R=H(8);M=W,R=C(O)Me(9)].5或9分别与Na[Mo(CO)₃C₅H₅]以12的物质的量比反应得到含一个手性四面体骨架(CoMoWC)的(C₅H₅)(CO)₈Co₂Mo(μ₃-C)C(O)OCH₂CH₂O·C(O)(μ₃-C)CoMoW(CO)₇(C₅H₄C(O)Me)(C₅H₅)(10)或含两个手性四面体骨架(CoMoWC)的[(C₅H₅)(C₅H₄C(O)Me)(CO)₇CoMoW(μ₃-C)C(O)OCH₂]₂(11);对化合物1_11进行了CH元素分析、IR和¹HNMR等表征.结果表明,在金属交换反应中处于不同簇环境下的Co(CO)₃基团反应活性不同.对化合物1进行了晶体X射线衍射分析.化合物1的晶体属单斜晶系,P2₁/n(#14)空间群,晶胞参数a=0.933 0(2)nm,b=1.519 7(4)nm,c=1.178 3(4)nm,=91.16(2)°,Z=2,F(000)=972.分子结构呈中心对称.     

Synthesis of metallocenes of zirconium, hafnium, manganese, iron, tin, lead and half-sandwich complexes of rhodium and iridium containing the ligands (η-C5R4CR′2PMe2), where R and R′ may be H or Me

The dimethylphosphino substituted cyclopentadienyl precursor compounds [M(C₅Me₄CH₂PMe₂)], where M=Li⁺ (1), Na⁺ (2), or K⁺ (3), and [Li(C₅H₄CR′₂PMe₂)], where R′₂=Me₂ (4), or (CH₂)₅ (5), [HC₅Me₄CH₂PMe₂H]X, where X⁻=Cl⁻ (6) or PF₆⁻ (7) and [HC₅Me₄CH₂PMe₂] (8), are described. They have been used to prepare new metallocene compounds, of which representative examples are [Fe(η-C₅R₄CR′₂PMe₂)₂], where R=Me, R′=H (9); R=H and R′₂=Me₂ (10), or (CH₂)₅ (11), [Fe(η-C₅H₄CMe₂PMe₃)₂]I₂ (12), [Fe{η-C₅Me₄CH₂P(O)Me₂}₂] (13), [Zr(η-C₅R₄CR′₂PMe₂)₂Cl₂], where R=H, R′=Me (14), or R=Me, R′=H (15), [Hf(η-C₅H₄CMe₂PMe₂)₂]Cl₂] (16), [Zr(η-C₅H₄CMe₂PMe₂)₂Me₂] (17), {[Zr(η-C₅Me₄CH₂PMe₂)₂]Cl}{(C₆F₅)₃BClB(C₆F₅)₃} (18), [Zr{(η-C₅Me₄CH₂PMe₂)₂Cl₂}PtI₂] (19), [Mn(η-C₅Me₄CH₂PMe₂)₂] (20), [Mn{(η-C₅Me₄CH₂PMe₂B(C₆F₅)₃}₂] (21), [Pb(η-C₅H₄CMe₂PMe₂)₂] (23), [Sn(η-C₅H₄CMe₂PMe₂)₂] (24), [Pb{η-C₅H₄CMe₂PMe₂B(C₆F₅)₃}₂] (25), [Pb(η-C₅H₄CMe₂PMe₂)₂PtI₂] (26), [Rh(η-C₅Me₄CH₂PMe₂)(C₂H₄)] 29, [M(η,κP-C₅Me₄CH₂PMe₂)I₂], where M=Rh (30), or Ir, (31).     

新型金属-双二硫杂戊烯(M-BDT)配合物的合成、表征及X射线的指标化

合成了4个新型NiBDT配位化合物,BDT为具有9个S原子的杂戊烯.元素分析、IR谱、UV谱确定这4个新配合物的化学式分别为[(CH₃)₄N]₂[Ni(C₅S₉)₂](1),[(C₂H₅)₄N]₂·[Ni(C₅S₉)₂](2),[(C₄H₉)₄N]₂[Ni(C₅S₉)₂](3),[(C₆H₅)(CH₃)₃N]₂[Ni(C₅S₉)₂](4).采用Ito法对配合物1的X射线粉末图进行了指标化,确定该晶体属单斜晶系,简单晶格,晶胞参数:a=0.680nm,b=0.714nm,c=2.302nm,γ=111.4°,Z=2.     

Synthesis, electrochemistry and structural characterization of luminescent rhenium(I) monoynyl complexes and their homo- and hetero-metallic binuclear complexes

A series of luminescent rhenium(I) monoynyl complexes, [Re(N---N)(CO)₃(CC---R)] (N---N=bpy, ^tBu₂bpy; R=C₆H₅, C₆H₄---Cl-4, C₆H₄---OCH₃-4, C₆H₄---C₈H₁₇-4, C₆H₄---C₆H₅, C₈H₁₇, C₄H₃S, C₄H₂S---C₄H₃S, C₅H₄N), together with their homo- and hetero-metallic binuclear complexes, {Re(N---N)(CO)₃(CC---C₅H₄N)[M]} (N---N=bpy, ^tBu₂bpy; [M]=[Re{(CF₃)₂-bpy}(CO)₃]ClO₄, [Re(NO₂-phen)(CO)₃]ClO₄, W(CO)₅) have been synthesized and their electrochemical and photoluminescence behaviors determined. The structural characterization and electronic structures of selected complexes have also been studied. The luminescence origin of the rhenium(I) alkynyl complexes has been assigned as derived states of a [dπ(Re)→π*(N---N)] metal-to-ligand charge transfer (MLCT) origin mixed with a [π(CCR)→π*(N---N)] ligand-to-ligand charge transfer (LLCT) character. The assignments are further supported by extended Hückel molecular orbital (EHMO) calculations, which show that the LUMO mainly consists of π*(N---N) character while the HOMO is dominated by the antibonding character of the Re---CCR moiety resulted from the overlap of the dπ(Re) and π(CCR) orbitals.     

New organogold(I) complexes: Synthesis, structure, and dynamic behavior of the polynuclear organogold diphenylmethane and diphenylethane derivatives

Two organogold derivatives of diphenylmethane and diphenylethane, Ph₃PAu(o-C₆H₄)CH₂(C₆H₄-o)AuPPh₃ (1) and Ph₃PAu(o-C₆H₄)(CH₂)₂(C₆H₄-o)AuPPh₃ (2), have been synthesized by the reaction of ClAuPPh₃ with Li(o-C₆H₄)CH₂(C₆H₄-o)Li and Li(o-C₆H₄)(CH₂)₂(C₆H₄-o)Li respectively. The interaction of 1 with dppe results in the replacement of the two PPh₃ groups to give a macrocyclic compound (3) that includes an Au Au bond. Compounds 1 and 2 react with one or two equivalents of [Ph₃PAu]BF₄ to form new types of cationic complex [CH₂(C₆H₄-o)₂(AuPPh₃)₃]BF₄ (4), [CH₂(C₆H₄-o)₂(AuPPh₃)₄](BF₄)₂ (5), and [(CH₂)₂(C₆H₄-o)₂(AuPPh₃)₄](BF₄)₂ (6). Complexes 1–6 have been characterized by X-ray diffraction studies, FAB MS, and IR as well as by ¹H and ³¹P NMR spectroscopy. A complicated system of Au H-C agostic interactions, involving the bridging alkyl groups (—CH₂— and CH₂-CH₂—) of diphenylmethane and diphenylethane ligands, has been found to occur in complexes 1–3 and 6.     

The use of thermotropic liquid crystals in organometallic chemistry. Synthesis of new mercury, silver and gold complexes with 4,4′-disubstituted azob

Liquid crystalline 4-XC₆H₄N=NC₆H₄X-4′ [X = C₄H₉ (1a), C_1OH₂₁ (1b), OC₄H₉ (1c), OC₈H₁₇(1d)] can be easily prepared in high yields from the corresponding anilines. In order to study the influence of metals on the thermal properties of these materials, we have obtained adducts [AuCl ₃(4-C₄H₉OC₆H₄N=NC₆H₄OC₄H₉-4′)] (2) and [Ag(OC1O₃)L₂] [L = 4-XC₆H₄N=NC₆H₄X-4′; X = OC₄H, (3a), OC₈H₁₇ (3b)]. The silver adducts show themotropic behaviour. Mercuriation of dialkylazobenzenes 1a-b takes place with [Hg(OAc)₂] and LiCl to give [Hg(R)Cl] [R = C₆H₃(N=NC₆H₄X-4′)-2, X-5; X = C₄H₉ (bpap) (4a), C₁₀H₂₁ (dpap) (4b)] while dialkoxyazobenzenes 1c–d require [Hg (OOCCF₃)₂] to obtain [Hg(R)Cl] [R = C₆H₃(N---NC₆H₄X-4′)-2, X-5; X = OC₄H₉ (bxpap) (4c), OC ₈H₁₇ (4d)]. 4a-c react with NaI to give [HgR₂] [R= bpap (5a), dpap (5b), bxpap (5c), oxpap (5d)l. Both chloroaryl-, 4a and 4c, and diaryl-mercurials, 5a and 5c, act readily as transmetailating agents towards [Me₄N] [AuCl₄] in the presence of [Me₄N]Cl to give [Au(η²-R)Cl₂] [R = bpap (6a), bxpap (6b)]. After reaction of [AuCl ₃(tht)] (tht = tetrahydrothiophene) with [Me₄N]Cl and 4b (1:2:1), [Me₄N][Au(dpap)Cl₃] (7) can be isolated. C---H activati bxpap (8b)]. None of the complexes 4–8 shows mesomorphic behaviour.     

Reactions of Lewis bases with tetrakisdiphenylamide uranium(IV)

The coordinatively unsaturated uranium(IV) complex U[N(C₆H₅)₂]₄ has been prepared via the stoichiometric reaction of diphenylamine with [(Me₃Si)₂N]₂ H₂. U[N(C₆H₅)₂]₄ coordinates Lewis bases such as Et₂O, THF, pyridine or (EtO)₃PO, based on electronic absorption spectroscopy and ¹H NMR studies. Exchange between U[N(C₆H₅)₂]₄ and U[N(C₆H₅)₂]₄(L), where L is THF or pyridine, is rapid on the NMR time-scale between 307 and 323 K. Measurement of equilibrium constants for L = THF provides ΔH and ΔS values of −60 kJ mol⁻¹ and −1.8 × 10² J K⁻¹ mol⁻¹, respectively. U[N(C₆H₅)₂]₄ coordinates and binds (EtO)₃PO much more tightly (K_eq = & > 10⁴ M⁻¹) than THF or pyridine with the exchange rate between U[N(C₆H₅)₂]₄ and U[N(C₆H₅)₂]₄[OP(OEt)₃] being close to the NMR time-scale.     

Zur oxidativen spaltung von metall—metall-bindungen in metallorganischen verbindungen mittels ferriceniumkationen

The dinuclear organometallic compounds ((C₅H₅Fe(CO)₂)₂, CO₂(CO)₈ and (C₅H₅NiCO)₂) are oxidized by [(C₅H₅)₂Fe]X (X = BF₄, PF₆) in the presence of neutral ligands L to form the cationic organometallic complexes [C₅H₅Fe(CO)₂L]X, [trans-Co(CO)₃L₂]X and [C₅H₅NiL₂]X in high yield.     

Synthesis, characterization and catalytic activity in Heck-type reactions of orthometallated Pd and Pt complexes derived from (1R,2R)-1,2-diaminocyclohexane

The chiral bis-imine (1R,2R)-C₆H₁₀-[E---N=CH---C₆H₃---3,4-(OMe)₂]₂ 1 (LH) reacts with [Pd(OAc)₂] (1:1 molar ratio; OAc=acetate) giving the orthometallated [Pd(OAc)(C₆H₂---4,5-(OMe)₂---2-CH=N-(1R,2R)-C₆H₁₀---N=CH---C₆H₃-3′,4′-(OMe)₂-κ-C,N,N)] 2 (abbreviated as [Pd(OAc)(L-κ-C,N,N)]), through C---H bond activation on only one of the aryl rings and N,N-coordination of the two iminic N atoms. 2 reacts with an excess of LiCl to give [Pd(Cl)(L-κ-C,N,N)] 3. The reaction of 3 with AgClO₄ and neutral or anionic ligands L′ (1:1:1 molar ratio) affords [Pd(L-κ-C,N,N)(L′)](ClO₄) (L′=PPh₃ 4a, NCMe 5, pyridine 6, p-nitroaniline 7) or [Pd(I)(L-κ-C,N,N)] 8. Complex 4a reacts with wet CDCl₃ giving [Pd(C₆H₂---4,5-(OMe)₂---2-CH=N-(1R,2R)---C₆H₁₀---NH₂-κ-C,N,N)(PPh₃)](ClO₄) 4b as a result of the hydrolysis of the C=N bond not involved in the orthometallated ring. The molecular structure of 4b·CH₂Cl₂ has been determined by X-ray diffraction methods. Cleavage of the Pd---N bond trans to the C_aryl atom can be accomplished by coordination of strongly chelating ligands, such as acetylacetonate (acac) or bis(diphenylphosphino)ethane (dppe), forming [Pd(acac-O,O′)(L-κ-C,N)] 9 and [Pd(L-κ-C,N)(dppe-P,P′)](ClO₄) 12, while classical N,N′-chelating ligands such as 1,10-phenantroline (phen) or 2,2′-bipyridyl (bipy) behave as monodentate N-donor ligands yielding [Pd(L-κ-C,N,N)(κ¹-N-phen)](ClO₄) 10 and [Pd(L-κ-C,N,N)(κ¹-N-bipy)](ClO₄) 11. Treatment of 1 with PtCl₂(DMSO)₂ (1:1 molar ratio) in refluxing 2-methoxyethanol gives Cl₂Pt[(NH₂)₂C₆H₁₀---N,N′] 13a and [Pt(Cl)(C₆H₂---4,5-(OMe)₂---2-CH=N-(1R,2R)---C₆H₁₀---NH₂-κ-C,N,N)] 13b, while [Pt(Cl)(L-κ-C,N,N)] 14 can be obtained by reaction of [Pt(μ-Cl)(η³-2-Me---C₃H₄)]₂ with 1 in refluxing CHCl₃. Complexes 2 and 3 catalyzed the arylation of methyl acrylate giving good yields of the corresponding methyl cinnamates and TON up to 847 000. Complex 3 also catalyzes the hydroarylation of 2-norbornene, but with lower yields and without enantioselectivity.     

The reaction of cis dioxobis(2,4 pentanedionato)molybdenum (VI) and 2,2′ pyridylbenzoxazole (L), a novel route to β[Mo8O26]

MoO₂(C₅H₇O₂)₂, where C₅H₇O₂ is 2,4-pentanedione (acac), reacts with 2-2′ pyridylbenzoxazole in acetone to give a product with stoichiometry, Mo₃C₂₄H₁₆N₆O₁₂. This product dissolves readily in dimethylformamide to give a brown solution which on standing for several weeks yielded crystals. An X-ray structure determination showed these crystals to contain uncoordinated 2-2′pyridylbenzoxazole and [(CH₃)₂NH₂]₄⁺[Mo₈O₂₆]⁴⁻.     

硅桥连双(三甲硅基环戊二烯基)钛化合物的合成及脱硅基反应

硅桥连双(三甲硅基环戊二烯基)双锂盐与TiCl₄·2THF反应,生成相应的钛化合物[E(C₅H₃SiMe₃)₂]TiCl₂[E=Me₂SiSiMe₂(3),Me₂SiOSiMe₂(5)],同时还分离到了脱一个三甲硅基的产物[E(C₅H₄)(C₅H₃SiMe₃)]TiCl₂[E=Me₂SiSiMe₂(4),Me₂SiOSiMe₂(6)].其中四甲基二硅氧桥连配体更容易发生这种脱硅基反应.通过元素分析、MS和¹HNMR谱表征了化合物3-6的分子结构.     

Thermal decomposition study on mixed ligand thymine complexes of divalent nickel(II) with dianions of some dicarboxylic acids

Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA (N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C₅H₆N₂O₂)(C₄H₅NO₄)²⁻(H₂O)₂]·H₂O, [Ni(C₅H₆N₂O₂)(C₅H₇NO₄)²⁻(H₂O)₂]·H₂O and [Ni(C₅H₆N₂O₂)(C₆H₈N₂O₅)²⁻(H₂O)₂]·1.5H₂O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy (E*), enthalpy (ΔH*), entropy (ΔS*) and free energy change of decomposition (ΔG*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate.     

Ein beitrag zur darstellung und reaktivität der η-allyliridium-komplexe [Ir(η-2-RC3H4) (PPr3)2]

The η³-allyliridium complexes [Ir(η³-2-RC₃H₄)(PⁱPr₃)₂] (2, 3) have been prepared in a one-pot reaction from [IrCl(C₂H₄)₂]₂, 2-RC₃H₄Li and PⁱPr₃ in 70% yield. Compounds 2 and 3 react spontaneously with H₂ to give [IrH₅(PⁱPr₃)₂] (7) and with excess PhC=CH and MeCCH to give [Ir(CCPh)₃(PⁱPr₃)₂] (5) and [Ir(CCMe)₂(CMe=CH₂)(PⁱPr₃)₂] (6), respectively. From 2 (or 3) and two equivalents of PhCCH the complex [IrH(CCPh)₂(PⁱPr₃)₂] (4) has been obtained. Treatment of 2 or 3 with CF₃CO₂H does not lead to a cleavage of the allyl-metal bond but affords the allyl(hydrido)-iridium(III) complexes [IrH(η³-2-RC₃H₄)(η¹-P₂CCF₃)(PⁱPr₃)₂] (8, 9) in almost quantitative yield.     

Studies of N-heterocyclic compounds with triosmium clusters: Formation of the heterocyclic-linked dicluster compound [Os 6(μ-H)2(μ3-C6H4N3)2(CO)18]

The cluster [Os₃(CO)₁₀(MeCN)₂] reacts with indazole (C₇H₆N₂) to give two isomeric products [0s₃(μ-H)(μ-C₇H₅N₂)(CO)₁₀] in which the five-membered ring has been metallated with N-H cleavage to give an N,N-bonded isomer or with C-H cleavage to give a C,N-bonded isomer. These two isomers have very similar X-ray structures but can be clearly distinguished by ¹H NMR methods. They are shown to correspond to related clusters derived from pyrazole. Benzotriazole (C₆H₅N₃) also reacts (as shown earlier by others) to give two isomers: an N,N-bonded species [Os₃(μ-H)(μ-C₆H₄N₃)(CO)₁₀] coordinated only through the five-membered ring and a minor C,N-bonded isomer [Os₃(μ-H)(μ-C₆H₄N₃)(CO)₁₀], metallated at the C₆ ring and coordinated through both rings. The former isomer reacts with Me₃NO in acetonitrile to give [Os₃(μ-H)(μ-C₆H₄N₃)(CO)₉(MeCN)] which thermally looses MeCN to produce the coupled product [Os₆(μ-H)₂(μ₃-C₆H₄N₃)₂(CO)₁₈] which was shown by X-ray structure determination to have all six nitrogen atoms coordinated to osmium, a novel situation for coordinated benzotriazole. The two Os₃ units are linked together by an OsNNOsNN ring in a boat conformation with the whole cluster adopting C₂ symmetry.     

杂多三金属磷酸盐的合成与表征

早期合成的Keggin结构杂多酸均是同种齿顶原子,后来人们合成了一系列含两种齿顶原子的三元杂多酸~[1,2],我们曾制备了含3种齿顶原子的四元杂多酸~[3,4].随着齿顶原子种类的增多,杂多酸在水溶液中的稳定性降低.本文采用空缺杂多酸阴离子逐步与不同齿顶原子结合,最后用溶解度极小的(C_1H_9)_4N~+盐沉淀方法合成了未见报道的磷的四元杂多酸盐.     

Dimethylchalkogenide als liganden in kationischen cyclopentadienyleisen-bis(phosphin)-komplexen: synthese, reaktivität und kristallstruktur von [C5H5Fe(P(OCH3)3)2(S(CH3)2)]PF6

Thermal displacement of coordinated nitriles RCN (R = CH₃, C₂H₅ or n-C₃H₇) in [C₅H₅Fe(L₂)(NCR)]X complexes (L₂ = P(OCH₃)₃)₂, (P(OC₆H₅)₃)₂ or (C₆H₅)₂PC₂H₄P(C₆H₅)₂ (DPPE)) by E(CH₃)₂ affords high yields of [C₅H₅Fe(L₂)(E(CH₃)₂)]X compounds (E = S, Se and Te; X = BF₄ or PF₆). Spectroscopic data and ligand displacement reactions are presented and discussed together with related observations on [C₅H₅Fe(CO)₂(E(CH₃)₂)]BF₄ compounds. The molecular structure of [C₅H₅Fe(P(OCH₃)₃)₂(S(CH₃)₂)]PF₆ was determined by a single-crystal X-ray diffraction study: monoclinic, space group P2₁/n-C⁵_2h (No. 14) with a = 8.4064(12), b = 11.183(2), c = 50.726(8) Å, β = 90.672(13)° and Z = 8 molecules per unit cell. The coordination sphere of the iron atom is pseudo-tetrahedral with an Fe---S bond distance of 2.238 Å.