Post-synthetic modification of divalent nickel acetate cubanes with carboxylates

Starting from nickel(II) cubane [Ni^II₄(HL)₄(OAc)₄] (2a), five different tetranuclear cubic complexes [Ni^II₄(HL)₄(O₂CR)₄] (3) were generated simply by applying a post-synthetic cubane modification strategy via a complete acetate-to-carboxylate co-ligand exchange. This was achieved by stirring the parent complex 2a with a large excess of the corresponding sodium carboxylate salt 4 for three days in THF. Single-crystal X-ray structure analyses of Ni^II cubanes 3a·2 Et₂O and 3b·0.5 CH₂Cl₂·0.5 Et₂O reveal unequivocally that both are isostructural in terms of the [Ni₄(μ₃-O₄]⁴⁺ core and crystallize in the triclinic space group P-1 with two molecules in the unit cell. In the solid state, the cubic centers of 3a,b differ only slightly in bond lengths and angles mainly due to the different substituents in the carboxylate co-ligand and packing in the unit cell. The orientation of 3a,b and the formation of supramolecular aggregates in the crystal packing were controlled by π–π interactions as well as intra- and intermolecular O–H?O hydrogen bonds. Variable-temperature magnetic susceptibility measurements reveal that 3a–c show a ferrimagnetic coupling scheme that leads to a diamagnetic ground state for all investigated complexes.     

Reactions of group 13 metal trialkyls with oxamides

Alkyl aluminum-, gallium-, and indium oxamidates Me₄Al₂(dpoa) (1), Me₄Al₂(dboa) (2), Me₄Ga₂(dpoa) (3), Me₄Ga₂(dboa) (4), ^tBu₄Ga₂(dpoa) (5) and Me₄In₂(dboa) (6) (dpoa-H₂ = N,N′-diphenyloxamide, dboa-H₂ = N,N′-di-tert-butyloxamide) have been prepared and characterized. Compounds 1-3, 5 and 6 exist in the form of isomers a only, with a skeleton framework of the molecules consisting of two almost flat, coplanar and fused MNOC₂ (M = Al, Ga, In) heterocyclic rings. Depending on the reaction conditions, the compound 4 was obtained as the isomer 4a or as the mixture of two isomers 4a and 4b. Molecular structures of the compounds 1a-6a have been determined by X-ray crystallography. A structure of the isomer 4b was proposed on the basis of NMR spectroscopy. A skeleton framework of the 4b molecule consists of two fused different cycles, GaO₂C₂ and GaN₂C₂.     

Reaction of CF3 radicals with group IV tetramethyls

Arrhenius parameters have been measured for the abstraction of hydrogen from the C Si, Ge, and Sn tetramethyls: The rate constants correlate with the proton chemical shift, which is related to a polar effect. In all cases except carbon, a hot-molecule β-fluorine rearrangement-elimination reaction occurs following radical combination: We suggest the occurrence of a radical exchange reaction for the Si, Sn, and Ge systems, with k_exchange (CF₃ + Sn(Me)₄) ～ 10⁷ ml m^?1 s^?1.     

Magnetic properties of a novel family of ferrous cubanes

A novel family of paramagnetic tetranuclear ferrous cubanes is reported. Two complexes from this family are described and their magnetic properties are discussed in relation to their structures.     

A mechanistic study of the hydrogenation of cyclohexene catalyzed by dimethylzirconocene

A kinetic study of the hydrogenation of cyclohexene in the presence of phenylsilane and catalytic amounts of dimethylzirconocene has been carried out. The rate law for the reaction was deduced to be of the form of rate =k[catalyst][silane]^3/2 [olefin]⁰, showing that the catalytically active species would be a hydridosilylzirconium complex formed by the reaction of dimethylzirconocene with phenylsilane     

Synthesis and reactivity of sulfido ruthenium carbonyl clusters

A survey of the structures and reactivity of ruthenium carbonyl cluster complexes containing sulfido ligands is presented and discussed.     

立方烷和高立方烷类衍生物的合成及应用

以立方烷和高立方烷的发展过程为线索,详细地叙述了其合成过程,并阐述了相应的合成方法,针对立方烷及高立方烷的特殊结构特点,叙述了其目前作为含能材料和药物的主要应用状况,以及其可观的发展前景。     

Reaction of vinyl chloride with group 4 metal olefin polymerization catalysts

The reactions of three types of group 4 metal olefin polymerization catalysts, (C(5)R(5))(2)ZrX(2)/activator, (C(5)Me(5))TiX(3)/MAO (MAO = methylalumoxane), and (C(5)Me(4)SiMe(2)N(t)Bu)MX(2)/activator (M = Ti, Zr), with vinyl chloride (VC) and VC/propylene mixtures have been investigated. Two general pathways are observed: (i) radical polymerization of VC initiated by radicals derived from the catalyst and (ii) net 1,2 VC insertion into L(n)MR(+) species followed by beta-Cl elimination. rac-(EBI)ZrMe(mu-Me)B(C(6)F(5))(3) (EBI = 1,2-ethylenebis(indenyl)) reacts with 2 equiv of VC to yield oligopropylene, rac-(EBI)ZrCl(2), and B(C(6)F(5))(3). This reaction proceeds by net 1,2 VC insertion into rac-(EBI)ZrMe(+) followed by fast beta-Cl elimination to yield [rac-(EBI)ZrCl][MeB(C(6)F(5))(3)] and propylene. Methylation of rac-(EBI)ZrCl(+) by MeB(C(6)F(5))(3)(-) enables a second VC insertion/beta-Cl elimination to occur. The evolved propylene is oligomerized by rac-(EBI)ZrR(+) as it is formed. At high Al/Zr ratios, rac-(EBI)ZrMe(2)/MAO catalytically converts VC to oligopropylene by 1,2 VC insertion into rac-(EBI)ZrMe(+), beta-Cl elimination, and realkylation of rac-(EBI)ZrCl(+) by MAO; this process is stoichiometric in Al-Me groups. The evolved propylene is oligomerized by rac-(EBI)ZrR(+). Oligopropylene end group analysis shows that the predominant chain transfer mechanism is VC insertion/beta-Cl elimination/realkylation. In the presence of trace levels of O(2), rac-(EBI)ZrMe(2)/MAO polymerizes VC to poly(vinyl chloride) (PVC) by a radical mechanism initiated by radicals generated by autoxidation of Zr-R and/or Al-R species. CpTiX(3)/MAO (Cp = C(5)Me(5); X = OMe, Cl) initiates radical polymerization of VC in CH(2)Cl(2) solvent at low Al/Ti ratios under anaerobic conditions; in this case, the source of initiating radicals is unknown. Radical VC polymerization can be identified by the presence of terminal and internal allylic chloride units and other "radical defects" in the PVC which arise from the characteristic chemistry of PCH(2)CHCl(*) macroradicals. However, this test must be used with caution, since the defect units can be consumed by postpolymerization reactions with MAO. (C(5)Me(4)SiMe(2)N(t)Bu)MMe(2)/[Ph(3)C]][B(C(6)F(5))(4)] catalysts (M = Ti, Zr) react with VC by net 1,2 insertion/beta-Cl elimination, yielding [(C(5)Me(4)SiMe(2)N(t)Bu)MCl][B(C(6)F(5))(4)] species which can be trapped as (C(5)Me(4)SiMe(2)N(t)Bu)MCl(2) by addition of a chloride source. The reaction of rac-(EBI)ZrMe(2)/MAO or [(C(5)Me(4)SiMe(2)N(t)Bu)ZrMe][B(C(6)F(5))(4)] with propylene/VC mixtures yields polypropylene containing both allylic and vinylidene unsaturated chain ends rather than strictly vinylidene chain ends, as observed in propylene homopolymerization. These results show that the VC insertion of L(n)M(CH(2)CHMe)(n)R(+) species is also followed by beta-Cl elimination, which terminates chain growth and precludes propylene/VC copolymerization. Termination of chain growth by beta-Cl elimination is the most significant obstacle to metal-catalyzed insertion polymerization/copolymerization of VC.     

Reaction of chlorodithiophosphoric acid pyridiniumbetaine with adamantane derivatives containing amino group

Reactions of chlorodithiophosphoric acid pyridiniumbetaine, py.PS₂Cl (I) with 1-aminoadamantane (amantadine, Am) and 1-amino-3,5-dimethyladamantane (memantine, Mem), 1-(adamant-1-yl)ethylamine (rimantadine, Rim), and 1-aminomethyladamantane (amAd) were studied. New compounds – N,N′,N′′,N′′′-tetrakis(adamant-1-yl)trithiophosphoric acic tetraamide (II), N,N′,N′′,N′′′-tetrakis(3,5-dimethyladamant-1-yl)trithiophosphoric acid tetraamide (III), chlorodithiophosphoric acid 1-(adamant-1-yl)ethylamide pyridiniumbetaine (IV), pyridinium salt of 1,3-bis(adamant-1-yl)ethane-2,4-mercapto-2,4-dithioxo-1,3-diaza-2λ⁵,4λ⁵-diphosphetidine (V), N,N′,N′′,N′′′-tetrakis(adamant-1-ylmethyl)trithiophosphoric acid tetraamide (VI), and pyridinium salt of 1,2-bis(adamant-1-ylmethane)-4-mercapto-2,4-dithioxo-1-aza-3-thia-2λ⁵,4λ⁵-diphosphetidine (VII) – were prepared and characterized either/or by ³¹P NMR and infrared spectroscopy, the substances II a IV by X-ray diffraction analysis, III, V, VI, VII by MALDI TOF MS.     

Participation of an enimine methyl group in cyclization with PC13

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 490–491, February, 1989.     

From group 13-group 13 donor-acceptor bonds to triple-decker cations

Donor-acceptor bonding between group 13 elements seems counter-intuitive because one normally thinks of e.g. boron and aluminium compounds as classical Lewis acids. Indeed, many such compounds have achieved industrial prominence in this regard. Recently, however, it has become possible to stabilize these and other group 13 elements in the +1 oxidation state as opposed to the archetypical +3 oxidation state. Moreover, it turns out that in the +1 oxidation state these species are excellent donors--hence the formation of these unprecedented donor-acceptor bonds. The discovery of such bonds has led, albeit indirectly, to the development of triple-decker main group cations. This aspect is also covered in the review.     

Reaction of RF-palmitic acid-F13 with dicyclohexylcarbodiimide

The 1,3-dicyclohexylcarbodiimide (DCC) adduct of R_F-palmitic acid-F₁₃1 has been synthesized and characterized. The X-ray crystal structure shows that the product arises from an O- to N-acyl migration of an initially formed N,N′-dicyclohexyl-O-R_F-palmitoyl-F₁₃-isourea 2 to give 1-R_F-palmitoyl-F₁₃-1,3-dicyclohexylurea 3. X-ray data for an R_F-palmitic acid-F₁₃ unit are reported for the first time. The product of the reaction of DCC with palmitic acid is also the urea derivative which has been characterized by IR and NMR methods.     

Fluorine functionalized compounds of group 13 elements

The review gives a short survey of some developments in the synthetic chemistry of organoaluminum fluorides. Into the focus is brought the Janus-faced Lewis base-Lewis acid Al compound, group 13 difluorodiorganometalates, fluorine functionalized carbaalane derivatives, fluorination of aluminum imide clusters, diamidoaluminum fluoride, and some group 13 β-diketiminate mono- and difluorides.     

Sterically crowded diolates of group 13 metals

The dependence of the structure of complexes of sterically crowded 2,4-dimethylpentane-2,4-diol with group 13 metals trialkyls on the kind of metal, as well as steric bulk of the substituents on the metal atoms is reported. The reaction of ^tBu₃Ga with 2,4-dimethylpentane-2,4-diol leads to the formation of an unstable dimeric product {^tBu₂Ga[(OC(CH₃)₂CH₂C(CH₃)₂OH]}₂ (1) possessing a four-membered Ga₂O₂ core and two unreacted hydroxyl groups. Compound 1 undergoes further intramolecular reaction to yield the unusual (monoalkyl)gallane O,O^′-chelate complex {^tBuGa[OC(CH₃)₂CH₂C(CH₃)₂O]}₂ (2). In contrast to ^tBu₃Ga, ^tBu₃In reacts with 2,4-dimethylpentane-2,4-diol to give the stable dimeric complex ^tBu₄In₂[OC(CH₃)₂CH₂C(CH₃)₂OH]₂ (4) stabilised by two intramolecular O-H?O bonds. At higher temperature compound 4 reacts with an excess of ^tBu₃In to form the trinuclear complex ^tBu₅In₃[OC(CH₃)₂CH₂C(CH₃)₂O]₂ (5). The reactions of 2,4-dimethylpentane-2,4-diol with trialkylmetallane with small alkyl groups, i.e. Me₃Ga and Me₃In allow for the isolation of the trinuclear diolates {Me₅M₃[OC(CH₃)₂CH₂C(CH₃)₂O]₂} [M=Ga (3), M=In (6)]. The crystal structures of 2, 3 and 4 have been determined by single crystal X-ray diffraction. The reactions of tert-butylmetallane diolates with trimethyl metallanes have been studied. The interaction of the allane complex {^tBuAl[OC(CH₃)₂CH₂C(CH₃)₂O]}₂ with Me₃Al results in the formation of the trialuminium mixed-ligand product {Me₃(^tBu)₂Al₃[OC(CH₃)₂CH₂C(CH₃)₂O]₂} (7). Compounds 2 and 4 undergo a total transmetallation reaction in the presence of Me₃M to yield [Me₅M₃(diol-(2H))₂] [M=Al, Ga] products.