Yury T. Struchkov

Synthesis and characterization of the lutetium naphthalene complex, CpLuC10H8(DME)

Abstract The title compound ( 1 ) was obtained as black diamagnetic crystals by reaction of CpLuCl 2 with sodium naphthalide in DME. The naphthalene moiety in 1 is bent about the C(1)⋯C(4) plane (dihedral angle 148.5°). The LuC(C 10 H 8 ) bond lengths and redistribution of CC bond distances in the coordinated naphthalene ring suggest 2η 1 :η 2 -interaction of the Lu atom with the naphthalene moiety.

Synthesis and characterization of pentaphenyldiytterbium Ph2Yb(THF)(μ-Ph)3Yb(THF)3

Abstract The binuclear ytterbium complex Ph 2 Yb(THF)(μ-Ph) 3 Yb(THF) 3 ( 1 ) was obtained in reactions of naphthaleneytterbium C 10 H 8 Yb(THF) 2 with diphenylmercury or triphenylbismuth in THF. An X-ray crystallographic study ( a = 11.099(2), b = 19.876(4), c = 19.723(4) A, β = 103.33(3)°, Z = 2, space group P 2 1 ) showed that the molecule of 1 has two Yb atoms coupled by three bridging Ph groups, which are linked with the first Yb atom by an η 1 bond and with the second one by an unsymmetrical η 2 bond. In addition the first Yb atom has an η 1 bond with two terminal Ph groups and one coordinated THF molecule whereas the second Yb atom is linked with three THF molecules. The coordination of both Yb atoms is a distorted octahedron. In the crystal, there are two symmetrically independent molecules of 1 with a similar structure. The YbC (terminal Ph) bond length is 2.388–2.463 A. The η 1 - and η 2 -YbC (bridging Ph) bond distance varies in the ranges 2.475–2.584, 2.547–2.751 and 2.877–3.250 A. The magnetic moment μ eff (per Yb III atom) is 4.0±0.05 μ B . Reactions of 1 with water, HCl, Br 2 , MeI and CO 2 give benzene, bromobenzene, toluene and PhCOOH, respectively.

Ligand effects in the hydrogenation of methacycline to doxycycline and epi-doxycycline catalysed by rhodium complexes. Molecular structure of the key catalyst [closo-3,3-(η2,3-C7H7CH2)-3,1,2-Rh C2B9H11]

Abstract The catalytic reduction of the exocyclic methylene group of methacycline (A) leads to the formation of two diastereoisomers, doxycycline (B, the α-epimer) and 6-epi-doxycycline (C, the β-epimer), with a selectivity which markedly depends on the nature of hydrocarbon and carborane ligands of closo-(π-cyclodienyl)rhodacarborane catalysts. Neutral norbornadienyl complexes with unsubstituted carborane ligands [closo-3,3-(η2,3-C7H7CH2)-3,1,2-RhC2B9H11] (1) and [closo-2,2-(η2,3-C7H7CH2)-2,1,7-RhC2B9H11] (7) are more active and afford higher selectivity in the formation of doxycycline than those having mono- or di-substituents at the carborane cage, [closo-3,3-(cyclodienyl)-1-R-2-R′-3,1,2-RhC2B9H9] (R = H, R′ = Me, PhCH2; R = R′ = Me; cyclodienyl = η2,3-C7H7CH2 or η-C10H13) as well as those from the closely related series of η5-cyclopentadienyl complexes [(η2,3-C7H7CH2)Rh(η5-C5Rn)]+PF6− (Rn = H5, Me5, or H2-1,2,4-Ph3). Mechanistic aspects of the hydrogenation reaction of methacycline are sketched. The results of the X-ray diffraction study of the best catalyst 1 are reported.

Synthesis and structure of organotin complexes of ytterbium

Abstract Reactions of Ph 3 SnCl, PhSnCl 3 and Ph 3 SnSnPh 3 with ytterbium in THF lead to the formation of the complex (Ph 3 Sn 2 Yb(THF) 4 ( 1 * in high yields. According to X-ray data, tin atoms in complex 1 are covalently bonded with the ytterbium atom. Ionic organotin complex of ytterbium [(Ph 3 Sn 3 Sn] − 2 [Yb 2 Cl 2 (DME) 6 ] 2+ ( 2 was synthesised in 75% yield by the reaction of Ph 2 SnCl 2 with ytterbium. According to X-ray analysis, the compound consists of [(Ph 3 Sn 3 Sn] − anions and dimeric ytterbium cations with μ 2 -bridged chlorine atoms [(DME) 3 YbClYb(DME 3 ] 2+ .

NOVEL POLYNUCLEAR ORGANOTIN COMPLEXES OF SAMARIUM AND YTTERBIUM

Abstract Polynuclear complexes [(Me 3 Sn) 3 Sn] 2 Ln(THF) 4 (Ln  Sm ( 1 ), Yb ( 2 )) have been synthesized by reacting Me 3 SnCl with samarium or ytterbium in THF. The crystals of 1 and 2 are orthorhombic ( a = 21.511(2), b = 13.215(3), c = 20.640(4) A, Z = 4, space group Pca 2 1 for Ln  Sm and a = 21.534(3), b = 13.158(2), c = 20.616 A, Z = 4, space group Pca 2 1 for Ln  Yb). A similar organotin complex of ytterbium, [(Me 3 Sn) 3 Sn] 2 Yb(THF) 4 ( 3 ) having the same composition but different structure than compound 2 has been isolated from the reaction of MeSnCl 3 with Yb. The crystals of the compound 3 are tetragonal, a = 20.851(4), c = 26.311(5) A, Z = 8, space group I 4 2 d . In all cases the molecules of [(Me 3 Sn) 3 Sn] 2 Ln(THF) 4 have a distorted octahedral structure in which the central Ln (Ln  Sm, Yb) atom is bonded to four oxygen atoms of THF molecules in equatorial positions and two tin atoms of (Me 3 Sn) 3 Sn groups in axial positions. The molecule of 3 has a C 2 symmetry and an approximately eclipsed arrangement of (Me 3 Sn) 3 Sn groups. The Yb-Sn distance is 3.300(4) A. The molecules of 1 and 2 have a staggered arrangement of the (Me 3 Sn) 3 Sn groups with Ln-Sn distances of 3.402(4), and 3.386(4) A for Ln  Sm, and 3.289(5) and 3.299(4) A for Ln  Yb.

Synthesis and structure of organosilicon and organogermanium complexes of ytterbium (Ph3E)2Yb(THF)4 with YbSi and YbGe bonds

Abstract Complexes (Ph 3 Si) 2 Yb(THF) 4 ( 1 ) and (Ph 3 Ge) 2 Yb(THF) 4 ( 2 ) were synthesised by the reactions of Ph 3 SiCl or Ph 3 GeCl with ytterbium in THF and characterised by X-ray diffraction. Compounds 1 and 2 have similar centrosymmetrical octahedral structures with a central Yb atom bonded to four oxygen atoms of THF molecules in equatorial positions and two Si (or Ge) atoms of SiPh 3 (or GePh 3 ) fragments in axial positions. In the crystal of 2 there are two symmetrically independent molecules with the same structure. The YbSi and YbGe distances in 1 and 2 are 3.158(2) and 3.170(2), 3.141(2) A, respectively.

Stereoselective Free Radical Cycloaddition-macrocyclization in Facile Synthesis of trans -cyclohexano-fused 12-membered Crown Thioethers

Homolytic cycloaddition of dithiols 1,2 derived from trans- and eis-1,2-cyclohexanediols to alkynes, induced by Pr3B-O2, offers an extremely simple approach to trans- and cis-cyclohexano-fused 12-membered crown thialactones 4a-c-7a-c. The reaction of trans-1 proceeds with pronounced remote 1,6-asymmetric induction to give predominantly (IS *, 6R *, 12S *)-4a–c, while cis-2 reacts nonstereoselectively. Basing on molecular mechanics calculations the stereoselectivity is rationalized as a result of entropy favored pathway of macrocyclization.

Remote Asymmetric Induction in Free Radical Cycloaddition Leading to Trans-cyclohexano-fused 12-membered Crown Thioethers

Homolytic cycloaddition of dithiol 1, derived from trans-1,2-cyclohexanediol, to alkynes induced by Pr3BO2 occurs with 1,6-asymmetric induction to afford predominantly (1S∗, 6R∗, 12S∗)-trans-cyclohexano-fused 12-membered crown thialactones 4a-c. No pronounced diasteroselectivity was found in the corresponding reactions of dithiol 2, derived from cis-1,2-cyclohexanediol.

Reactions of cyclopentadienyl-naphthalene complexes of lutetium with C- and N-unsaturated compounds: molecular and crystal structure of [CpLu(DME)]2[1,1-μ-4,4-μ-(Ph)C(Ph)C=C(Ph)C(Ph)]☆

Abstract The naphthalene derivative of cyclopentadienyllutetium CpLuC10H8(THF)2 (1b) (THF-tetrahydrofuran) easily reacts with azobenzene in THF solution to give a dimeric diphenylhydrazido complex [CpLu(THF)]2(Ph2N2)2 (2). Interaction of CpLuC10H8(DME) (1a) (DME = 1,2-dimethoxyethane) with diphenylacetylene results in CC coupling and formation of a new type of dinuclear complex with tetracharged bridging [C4Ph4]4− ligand: [CpLu(DME)]2[1,1-μ-4,4-μ-(Ph)CC(Ph)=C(Ph)C(Ph)] (3). The structure of benzene solvate of 3 was determined by X-ray diffraction method (orthorhombic; α = 14.266(8), b = 15.625(7) and c = 21.612(10) A, space group, Pbcn, Z = 4, 2266 reflections with F > 4σ(F), R = 0.039). In the molecule of 3 there are two CpLu units joined by a C4Ph4 ligand. The shortest LuC μ2 distances 2.280(7) and 2.336(7) A are observed between Lu atoms and end C atoms of C4 fragment. The crystal of 3 contains two enantiomeric forms of molecules connected by symmetry elements. The X-ray data together with the diagmagnetism of 3 suggest in dialkylidene type of bridging ligand in this complex.

Reactions of pentafluorophenyl germanium hydrides with nickelocene

Abstract Both (C 6 F 5 ) 2 Ge(H)Ge(H)(C 6 F 5 ) 2 and (C 6 F 5 ) 2 GeH 2 react with bis-(cyclopentadienyl)nickel to form a novel germylnickel cluster [(C 6 F 5 ) 2 GeNiCp] 2 . The molecule of the complex contains a butterfly-like Ge 2 Ni 2 core with strong Ge-Ni (2.257 A) and weak NiNi (2.492 A) bonds. The tetrahedral angle between its Ni 2 Ge wings is 117.6°. Interaction of nickelocene with tris(pentafluorophenyl)germane yields 30% of the ionic complex {[(C 6 F 5 ) 3 Ge] 2 NiCp} − [CP 3 Ni 2 ] + . The X-ray diffraction analysis has shown that the structure of the [(C 6 F 5 ) 3 Ge] 2 NiCp − anion contains the 3-membered Ge-Ni-Ge chain. The NiGe bond lengths are 2.265 and 2.263 A, the Ge-Ni-Ge angle is 127.3°. The CP 3 Ni 2 cation is a triple-decker sandwich with eclipsed conformation of the Cp-rings.