Peter MacKinnon

Organolanthanoids V. The crystal and molecular structure of DI-η5-cyclopentadienyl-1,2-dimethoxyethaneytterbium(II)

Abstract Crystals of di-η5-cyclopentadienyl-1,2-dimethoxyethaneytterbium(II) are mono-clinic, space group Cc, with a 9.25(2), b 23.49(5), c 8.23(2) A, β 123.59(4)° and Z  4. The ytterbium ion is pseudo-tetrahedrally coordinated by two cyclopentadienyl groups and a bidentate 1,2-dimethoxyethane ligand, and there is no inter-molecular association. The sites of the cyclopentadienyl ligands are disordered.

Four-and five-co-ordinate lanthanide (II) aryloxides: X-ray structures of the bis(2,6-di-t-butyl-4-methylphenoxo)ytterbium(II) complexes [Yb(OAr)2(L)2] and [Yb(OAr)2(L′)3][ArC6H2But2-2,6-Me-4, L = tetrahydrofuran (thf) or OEt2, L′= thf]

General methods for the preparation of hydrocarbon-soluble, monomeric ytterbium (II) aryloxides are described {Yb+2TIOAr, or [Yb(NR2)2(OEt2)2]+2ArOH;RSiMe3, ArC6H2But2-2,6-Me-4; crystalline [Yb(OAr)2(thf)3](thf = tetrahydrofuran)(1) has the unprecedented square-pyramidal YbII stereochemistry (one thf apical), whereas the complexes [Yb(Oar)2(L)2][L = thf (2) or OEt2(3)] are tetrahedral, with 2.207 (12)(1), 2.137(10)(2), or 2.154(28)A(3); complex (3) with thf readily yields (1) or (2)}.

Oxarhodaborane chemistry: the formation of [µ-9,9′-O-{5-(η5-C5Me5)-nido-5-RhB9H12}2] and [7-(η5-C5Me5)-10-(NEt3)-nido-7, 12-RhOB10H10] from [nido-(η5-C5Me5)RhB10H13Cl]

Chromatography in air on silica of the nido eleven-vertex metallaborane [(η5-C5Me5)RhB10H13Cl]2, yields the µ-9,9′-oxo-bridged bis(nido-5-rhodadecaboranyl) species [{(η5-C5Me5)RhB9H12}2O]3, whereas treatment with NEt3 before exposure to air and chromatography on silica results in the novel contiguous nido twelve-vertex oxarhodadecaborane [7-(η5-C5Me5)10-(NEt3)-nido-7,12-RhOB10H10]4.

Preparations, structures and thermal decomposition of some bis(pentafluorobenzoato)dioxouranium(VI) complexes

Abstract Reaction Of UO2(O2CCH3)2 with pentafluorobenzoic acid yields UO2(O2CC6F5)2, which has been converted into the solvated complexes UO2(O2CC6F5)2L2·S [L2 = 2,2′-bipyridyl (bpy), S = 0.33 (PhH) or 0.07 (t-BuOH); L = Ph3PO, S = t-BuOH; L = Ph3AsO, S = 0.40 (t-BuOH)] and the solvent free UO2(O2CC6F5)2L2 [L2 = bpy; L = Ph3PO]. The crystal structure of UO2(O2CC6F5)2bpy (orthorhombic, space group P212121; a = 18.45(2), b = 18.94(2), c = 7.069(8) A, Z = 4] reveals distorted hexagonal bipyramidal stereochemistry with a trans UO2 group, chelating pentafluorobenzoate ligands, and chelating 2,2′-bipyridyl, which is significantly displaced from the hexagonal plane. The structure of UO2(O2CC6F5)2(OPPh3)2·t-BuOH [rhombohedral, space group R3; a = 21.51(3) A, α = 117.28(5)°, Z = 3] shows trans UO2, pseudo trans Ph3PO ligands, and one unidentate and one disordered chelating pentafluorobenzoate ligand, whilst t-BuOH could not be located because it is highly disordered. Relationships between ν (CO2) frequencies and the carboxylate coordination are discussed, and UO2(O2CC6F5)2(OAsPh3)2.0.40 (t-BuOH) is considered to have stereochemistry similar to that of the phosphine oxide complex. The complexes undergo decarboxylation in dimethyl sulphoxide yielding pentafluorobenzene and carbonatodioxouranium(VI) species not UO2(C6F5)2 derivatives.

Syntheses of organoytterbium(III) compounds by oxidation of dicyclopentadienylytterbium(II). Crystal structure of [(η-C5H5)2Yb(O2CC6F5)]2

Abstract Organoytterbium(III) complexes [(η-C 5 H 5 ) 2 )YbX] (X = O 2 CMe, O 2 CC 6 F 5 , O 2 CC 5 H 4 N, Cl, Br, I, CCPh, C 6 F 5 , (MeCO) 2 CH, (PhCO) 2 CH) have been synthesized in high yield from [η-C 5 H 5 ) 2 ]Yb(MeOCH 2 ) 2 ] and the corresponding HgX 2 , TlX, AgX 2 or CuX species. An X-ray diffraction study of the pentafluorobenzoate has shown it to be dimeric, with a somewhat unsymmetrical bridging carboxylate.

CRYSTALLIZATION AND X-RAY STRUCTURES OF NAYB(C5H5)3 AND YB(C5H5)2

The complex [NaYb(C 5 H 5 ) 3 ] (C 5 H 5 = cyclopentadienyl), prepared from Yb(C 5 H 5 ) 3 and sodium naphthalenide in tetrahydrofuran (thf) or from Yb(C 5 H 5 ) 2 and Na(C 5 H 5 ) in tetrahydrofuran and crystallized at ca. 400 °C (<10 - 4 mm Hg), is a three-dimensional polymer in which µ-η 5 :η 5 -C 5 H 5 groups link sodium and ytterbium (each metal having a pseudo-triangular arrangement of C 5 H 5 ligands); Yb(C 5 H 5 ) 2 , similarly crystallized, has a polymeric chain structure with one terminal and two bridging C 5 H 5 ligands per ytterbium, and there is η 1 -bonding between adjacent chains.