Chuen Her Ueng

[(TeMe2)Mn(CO)4(μ5-Te)(μ4-Te)Mn4(CO)12]-: A pentacoordinate bridging tellurido ligand in a square-pyramidal geometry

The first Te-Mn-CO clusters were obtained by the thermal reaction of K2 TeO3 with [Mn2 (CO)10 ] in MeOH. The basicity of the μ4 -Te ligand in the octahedral cluster anion [(μ4 -Te)2 Mn4 (CO)12 ]2- is demonstrated by its binding to the fragment [(TeMe2 )Mn(CO)4 ]+ in an axial fashion to afford the novel cluster 1.

Synthesis of pyrrole derivatives mediated by dicobalthexacarbonyl

Addition of or- and ~-annno acid derivatives to the cobalt stabilized propargylic cation 2 gives dicobalthexacarbonyl complexes with an amino acid derivative at the propargyl position. Oxidation of the resulting complexes with Fe(III) produces propargyl amines 4. Intramolecular cyclization of 4 with LDA followed by oxidation of the crude product with DDQ affords pyrrole derivatives as the major products.

Tellurium-Bridged Manganese Carbonyl Clusters: Synthesis and Structural Transformations of [Te4Mn3(CO)10]−, [Te2Mn3(CO)9]2−, [Te2Mn3(CO)9]−, and [Te2Mn4(CO)12]2−

The reactions of appropriate ratios of K2TeO3 and [Mn2(CO)10)] in superheated methanol solutions lead to a series of novel cluster anions [Te4Mn3(CO)10] (1), [Te2Mn3(CO)9]2- (2), [Te2Mn3(CO)9]- (3), and [Te2Mn4(CO)12]2- (4). When cluster 1 is treated with [Mn2(CO)10]/KOH in methanol, paramagnetic cluster 2 is formed in moderate yield. Cluster 2 is oxidized by [Cu(MeCN)4]BF4 to give the closo-cluster [Te2Mn3(CO)9]- (3), while treatment of 2 with [Mn2(CO)10]/KOH affords the closo-cluster 4. IR spectroscopy showed that cluster 1 reacted with [Mn2(CO)10] to give cluster 4 via cluster 2. Clusters 1-4 were structurally characterized by spectroscopic methods or/and X-ray analyses. The core structure of 1 can be described as two [Mn(CO)3] groups doubly bridged by two Te2 fragments in a mu2-eta2 fashion. Both [Mn(CO)3] groups are further coordinated to one [Mn(CO)4] moiety. Cluster 2 is a 49 e- species with a square-pyramidal core geometry. While cluster 3 displays a trigonal-bipyramidal metal core, cluster 4 possesses an octahedral core geometry.

Carbonylchromium Derivatives of Bismuth: New Syntheses and Relevance to CO Activation

We have discovered a series of novel pentacarbonylchromium derivatives of bismuth from the reactions of NaBiO(3) with [Cr(CO)(6)] in KOH/MeOH solutions. When the reaction was carried out at room temperature, the highly charged [Bi[Cr(CO)(5)](4)](3-) (1) was obtained, whose structure was shown by X-ray analysis to possess a central bismuth atom tetrahedrally coordinated to four [Cr(CO)(5)] groups. As the reaction was heated at 80 degrees C, the methyl-substituted complex [MeBi[Cr(CO)(5)](3)](2-)(2) was obtained, presumably via the CbondO activation of MeOH. Further reactions of 1 with CH(2)Cl(2) or CHtbondCCH(2)Br form the halo-substituted complexes [XBi[Cr(CO)(5)](3)](2-)(X=Cl, 3; Br, 4), respectively. On the other hand, the reactions of 1 with RI (R=Me, Et) led to the formation of the alkyl-substituted complexes [RBi[Cr(CO)(5)](3)](2-)(R=Me, 2; Et). The formation of complexes 1-4 is discussed, presumably via the intermediate bismuthinidene [Bi[Cr(CO)(5)](3)](-) or the trianion [Bi[Cr(CO)(5)](3)](3-).

Reactivity of [Et4N]2[MeSb{Fe(CO)4}3] toward HOAc and [Cu(MeCN)4]BF4: Formation of [Et4N][Me(OAc)Sb{Fe(CO)4}2] and [MeSb{Fe(CO)4}{Fe2(CO)8}]

Abstract Reactions of the tetrahedral methylantimony complex [Et4N]2[MeSb{Fe(CO)4}3] with HOAc and [Cu(MeCN)4][BF4] were investigated. While the reaction of [Et4N]2[MeSb{Fe(CO)4}3] with HOAc forms the substituted complex [Et4N][Me(OAc)Sb{Fe(CO)4}2] ([Et4N][I]), the treatment with [Cu(MeCN)4][BF4] forms the oxidized product [MeSb{Fe(CO)4}{Fe2(CO)8}] (II). The structures of [Et4N][I] and II are determined by single-crystal X-ray diffraction. [Et4N][I] crystallizes in the orthorhombic space group Pna21 with a=16.627(4), b=9.411(3), c=17.347(4) A, V=2714(1) A3, and Z=4. The crystals of II are triclinic, space group P1 with a=9.335(1), b=10.313(3), c=10.372(1) A, α=97.46(1), β=93.63(1), γ=94.65(1)°, V=984.0 (3) A3, and Z=2. Cluster I is an OAc group substituted product which displays a tetrahedral metal core with the central antimony atom bonded to two Fe(CO)4 fragments, one Me group, and one OAc moiety. Compound II is the two-electron oxidized product of [Et4N]2[MeSb{Fe(CO)4}3] where one FeFe bond is formed upon the addition of [Cu(MeCN)4][BF4]. The results are compared with those of the analogous bismuth system and the role of the main group elements is discussed as well.

1,3-Diphenyl-2-tricyclo[3.3.1.13,7]dec-2-ylidenepropane-1,3-diimine, and its -1-imino-3-one and -1,3-dione Derivatives

1,3-Diphenyl-2-tricyclo[3.3.1.1 3,7 ]dec-2-ylidenepropane-1,3-diimine, C 25 H 26 N 2 , (1), 1-imino-1,3-diphenyl-2-tri-cyclo[3.3.1.1 3.7 ]dec-2-ylidenepropan-3-one, C 25 H 25 NO, (2) and 1,3-diphenyl-2-tricyclo[3.3.1.1 3,7 ]dec-2-yl-idenepropane-1,3-dione, C25H2402, (3), were prepared from the reactions of 2-(dicyanomethylene)adamantane with phenylmagnesium bromide upon workup with dry methanol or dilute acid aqueous solution, and their crystal structures were determined by X-ray diffraction. Compounds (1) and (2) have similar molecular structures with the two imino groups in (1) and the imino and ketone groups in (2) being on the same side of the C1, C2, C12, C13 plane, compared with the two O atoms in compound (3), which are on opposite sides.