Guanidinate derivatives of rare-earth metals. The synthesis, properties, and molecular structures of the complexes {(Me3Si)2NC(NPri)2}3Nd, {(Me3Si)2NC(NCy)2}3Lu, and {(Me3Si)2NC(NPri)2}2HC(NPri)2}Nd

The reactions of anhydrous LnCl₃ (Ln = Nd or Lu) with three equivalents of {(Me₃Si)₂NC(NR)₂}Li (R = Prⁱ or Cy; Cy is cyclohexyl) in THF afforded the corresponding tris(guanidinate) derivatives of lanthanides {(Me₃Si)₂NC(NR)₂}₃Ln (Ln = Nd, R = Prⁱ, (1); Ln = Lu, R = Cy (2)), which were isolated after the recrystallization from hexane in 82 and 88% yields, respectively. The complex {(Me₃Si)₂NC(NCy)₂}₂{HC(NCy)₂}Nd (3) containing two guanidinate ligands and one formamidinate ligand was isolated in attempting to synthesize the bis(guanidinate) borohydride derivative by the reaction of {(Me₃Si)₂NC(N-Cy)₂}Na with Nd(BH₄)₃(THF)₂ (in a molar ratio of 2: 1) in THF. This complex is apparently formed as a result of the fragmentation and redistribution of the guanidinate ligands. The X-ray diffraction study showed that in the crystalline state compounds 1–3 are mononuclear complexes containing no coordinated Lewis bases.     

Bridging mu-eta(5):eta(4)-coordination of an indenyl ligand and reductive coupling of diazabutadienes in the assembly of di- and tetranuclear mixed-valent ytterbium indenyldiazabutadiene complexes

The redox reaction of [Yb(C(9)H(7))(2)(thf)(2)] with the diazabutadiene PhN==C(Me)--C(Me)==NPh (DAD) has been found to depend on the molar ratio of the reactants. Reaction in a 1:2 molar ratio affords the dinuclear mixed-valent complex [Yb(2)(mu-eta(5):eta(4)-C(9)H(7))(eta(5)-C(9)H(7))(2){mu-eta(4):eta(4)-PhNC(Me)==C(Me)NPh}] containing an indenyl ligand with an unusual mu-eta(5):eta(4) bridging coordination. Reaction of equimolar amounts of these compounds results in an organolanthanide-mediated reductive coupling of the DAD ligands and formation of the tetranuclear mixed-valent complex [Yb(2)(mu-eta(5):eta(4)-C(9)H(7))(eta(5)-C(9)H(7))(2){mu-eta(4):eta(4)-PhNC(CH(2))==C(Me)NPh}](2) with a novel tetradentate tetraimine ligand.     

Free radical fixation by tin(IV) diphenylcatecholate complexes

The reactions of sodium and thallium catecholates CatM₂ (Cat is the 3,6-di-tert-butylpyrocatechol dianion; M = Na, T1) with tin diphenyl dichloride afford new tin catecholate complexes Ph₂SnCat · THF (I) and Ph₂SnCat (II). The molecular structure of pentacoordinated complex I is determined by X-ray diffraction analysis. The synthesized complexes are capable of fixating both short-lived (PhC(O)O^., (CH₃)₂NC(S)S^., and NC(CH₃)₂C^.) and stable free radicals (aroxyl, nitroxyl, triphenylmethyl, and phenoxazinyl) to form stable o-semiquinone tin derivatives.     

Mixed-ligand guanidinate derivatives of rare-earth metals. Molecular structures of { (Me3Si)2NC(N-cyclo-Hex)2}Y[N(SiMe3)2]2, [{ (Me3Si)2NC(N-cyclo-Hex)2}YbI(THF)2]2, and [{(Me3Si)2N} Y(THF)(µ-Cl)]2 complexes

The insertion of N,N′-dicyclohexylcarbodiimide at one of the Y-N bonds of the [(Me₃Si)₂N]₃Y complex in toluene at 70 °C afforded the monoguanidinate diamide derivative { (Me₃Si)₂NC(N-cyclo-Hex)₂}Y[N(SiMe)₃]₂ (1) (cyclo-Hex is cyclohexyl) in 72% yield. The reaction of equimolar amounts of sodium N,N′-dicyclohexyl-N″-bis(trimethylsilyl)guanidinate, which was prepared in situ from {(Me₃Si)₂N}Na and N,N′-dicyclohexylcarbodiimide, and YbI₂(THF)₂ in THF gave the [{(Me₃Si)₂NC(N-cyclo-Hex)₂}YbI(THF)₂]₂ complex (2). An attempt to use this procedure for the synthesis of the yttrium compound { (Me₃Si)₂NC(NSiMe₃)₂}₂YCl containing the sterically more hindered guanidinate ligand unexpectedly led to the formation of the diamide chloride complex [{(Me₃Si)₂N}₂Y(THF)(µ-Cl)]₂ (3). The structures of complexes 1–3 were established by X-ray diffraction. Compound 1 is mononuclear. Complexes 2 and 3 are dinuclear and contain two µ²-bridging halide ligands.     

Crystal structure and nonlinear optical properties of the K2UO2(SO4)2 · 2H2O compound at 293 K

Single crystals of potassium uranyl sulfate are grown, and their atomic structure is determined using X-ray diffraction analysis. The compound crystallizes in the orthorhombic crystal system with space group Pna2₁ [a = 13.773(4) Å, b = 7.288(2) Å, c = 11.556(4) Å, R ₁ = 0.033, wR ₂ = 0.0892 for 2630 reflections with I > 2σ(I)]. The crystal structure of the K₂UO₂(SO₄)₂ · 2H₂O compound is built up of two-dimensional infinite, negatively charged layers of the composition [UO₂(SO₄)₂·H₂O] _2∞ ^δ? ], which are linked together through the K⁺ ions. The specific features of the atomic arrangement in the structure of this compound are analyzed, and the second harmonic generation of laser radiation is investigated.     

Experimental study of X-ray charge density and the selection of reference points for a source function in η6-(2-methyl-1,4-dihydro-2H-3,1-benzoxazine)tricarbonylchromium(0)

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Synthesis and Structure of Tetraphenylstibonium and Tetraphenylphosphonium Hydrogen Sulfates

Reactions of pentaphenylantimony and pentaphenylphosphorane with sulfuric acid yielded tetraphenylstibonium and tetraphenylphosphonium hydrogen sulfates, respectively; their crystal and molecular structure was determined.     

Synthesis and Structure of Triarylantimony Bis(arenesulfonates)

Triarylantimony bis(arenesulfonates) were prepared by reaction of triarylantimonies with hydrogen peroxide in the presence of arenesulfonic acids. The steric structure of the products was assessed. Triarylantimony bis(arenesulfonates) were reacted with sodium salts to obtain sodium arenesulfonates and the corresponding triarylantimony derivatives.     

Synthesis,structure, and thermal destruction of aroxytetraphenylstiboranes

A series of aroxytetraphenylstiboranes, Ph₄SbOAr, were obtained by the reaction of pentaphenylstiborane with phenols at 20 °C. The thermolysis of these compounds givesO- or o-C-phenylation products. The thermolysis of stiboranes, which incorporate aryl groups containing electron-withdrawing substituents (Ar=2,4-Br₂, 2,4-Cl₂, 2-NO₂, 4-OPh) produces predominantly simple diaryl ethers of asymmetric structure in 58 %, 90 %, 32 %, and 60 % yields, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 958–963, May, 1995.     

Reactions of Vinyl Type Carbocations Generated in Fluorosulfonic Acid with Benzene Derivatives. New Synthesis of Alkyl 3,3-Diarylpropenoates

Vinyl type carbocations ArC⁺=CHX [X = CO₂H, CO₂Alk, C≡N, P(O)(OAlk)₂] generated from alkyl 3-arylpropynoates and related compounds in fluorosulfonic acid at ?75 to ?20°C react with various benzene derivatives, following the mechanism of electrophilic substitution of hydrogen. A new procedure for the synthesis of alkyl 3,3-diarylpropenoates having various substituents in the aryl fragments has been developed on the basis of protonation of the triple bond in alkyl 3-arylpropynoates.