Cäcilia M. Mössmer

Bis(arene)vanadium(O) complexes as a source of vanadium(II) derivatives by both disproportionation of the [V(η6-arene)2]+ cations and oxidation. of [V(η6-arene)2]

Abstract The [V(η 6 -arene) 2 ] + cation (arene = benzene, toluene or mesitylene) is disproportionate to [V(η 6 -arene) 2 ] and V II compounds in ether solvents such as THF or 1,2-dimethoxyethane (DME). The extent of disproportionation depends on the nature of both the counteranion and the arene ligand. Addition of the filtered crude reaction mixtures, presumably containing the [V(η 6 -arene) 2 ][Al 2 X 7 ] derivatives, to THF gave [V 2 (μ-X) 3 (THF) 6 [AlX 4 ] (arene = benzene or toluene; X = Cl or Br). For X = Cl and arene = toluene, addition to a THF solution of LiI yielded [V 2 (μ-Cl) 3 (THF) 6 ]I. The atom connectivity was established for [V 2 (μ-Cl) 3 (THF) 6 ][AlC 4 ], while [V 2 (μ-Cl) 3 (THF) 6 ]I was fully characterized by X-ray diffraction methods. Crystal data: [V 2 (μ-Cl) 3 (THF) 6 ]I: monoclinic, space group C 2/ c (no. 15), a 25.199(8), b 13.865(6), c 9.879(4) A, β 103.98(2)°, V 3349.3 A 3 , Z = 4, D c 1.523 g cm ]t-3 , μ 17.256 cm −1 , F (000) = 1560. The vanadium(II) derivative VI 2 (THF) 0.7 was obtained, together with [V(η 6 -mesitylene) 2 ] in the reaction of [V(η 6 -mesitylene) 2 ][AlI 4 ] with THF. By reaction of [V(η 6 -mesitylene) 2 ] with CPh 3 X (X = Br or I) in 1,2-dimethoxyethane (DME), the dihalides of vanadium(II), [VX 2 (DME) 2 ] have been isolated in good yields. The crystal and molecular structure of the monomeric cis -[VI 2 (DME) 2 ] of pseudo-octahedral geometry has been studied by X-ray diffraction methods. Crystal data: [VI 2 (DME) 2 ]: monoclinic, space group P 2 1 / n (non-standard No. 14), a 7.819(4), b 13.150(4), c 15.535(5) A, β 90.23(3)°, V 1597.3(1) A 3 , Z = 4, D c 2.017 g cm −3 , μ 44.231 cm −1 , F(000) = 916.

1,3-Bis(2,4-dibromophenyl)triazene.

The crystal structure of the title compound, C(12)H(7)Br(4)N(3), shows that the stereochemistry about the N[double bond]N double bond of the N[double bond]N-N(H) moiety is trans. The whole molecule deviates slightly from planarity (r.m.s. deviation 0.164 A). While one of the aryl substituents is almost coplanar with the triazene chain, weak intermolecular Br...C contacts cause the second aryl substituent to deviate by an angle of 9.1 (8) from the plane defined by the N[double bond]N-N group. Weak intermolecular N-H...Br interactions between molecules related by the diagonal glide plane give rise to chains, which are stacked along the [100] crystallographic direction. An unequal distribution of double-bond character between the N atoms suggests a delocalization of pi electrons over the diazoamino group and the adjacent aryl groups.

3-(4-Acetylphenyl)-1-(4-nitrophenyl)triazene.

The crystal structure of the title compound, C(14)H(12)N(4)O(3), shows that the stereochemistry about the N=N double bond of the N=N-N(H) moiety is trans. The whole molecule is almost planar (r.m.s. deviation = 0.0654 A), the interplanar angle between the phenyl rings being 0.7 (1) degrees and the largest interplanar angle being that between the phenyl ring and the nitro group of the 4-nitrophenyl substituent [11.5 (2) degrees ]. Intermolecular N-H.O interactions between molecules related by translation give rise to chains along the [110] and [1-10] directions, and these chains are held together by N.O pi-pi interactions. An unequal distribution of the double-bond character among the N atoms suggests a delocalization of pi electrons over the diazoamine group and the adjacent aryl substituents.

Transition Metal Complexes of Derivatized Chiral Dihydro-1,2,4-triazin-6-ones, Part IV [1]. Synthesis and Structural Characterization of a Copper(II) Complex of (L)-3-Acetyl-5-benzyl-1-phenyl-4,5-dihydro-1,2,4-triazin-6-one Oxime

Reaction of (L)-3-acetyl-5-benzyl-1-phenyl-4,5,-dihydro-1,2,4-triazine-6-one oxime (1) with copper acetate afforded the complex 5 in high yield. Single crystal X-ray structural analysis of 5 revealed a square-pyramidal geometry around the copper ion where the two oxime ligands are coordinated symmetrically to the Cu atom. The apex of the square-pyramid is occupied by a chloride ligand with the copper atom roofed above the center of the plane of the four coordinating nitrogens by about 0.22 Å . MS-FAB, magnetic and other analytical data are in accord with this solid-state structure.

Bischler-Napieralski synthesis of some new pyrazole-fused β-carbolines

3-(4-Acylaminopyrazol-5-yl)-4-methylindoles (13a,b), under Bischler-Napieralski reaction conditions, undergo cyclization at the pyrrolic carbon-2 with ultimate formation of the corresponding pyrazolo[3,4:5′,6′]pyrido[3,4-b]indoles (14a,b) as evidenced by crystal structure analysis of 14a.