| The synthesis and properties of dicarba-closo-dode-caborane derivatives were first reported at the end of 1963 in both the United States and the USSR. Their chemistry is one of the most complete in the field of boranes and heteroboranes. One of the most striking features of the carborane is the capability of the 2 carbon atom and 10 boron atoms to adopt the icosahedral geometry in which the carbon and boron atoms are hexacoordinate. This feature of the icosahedral structure gives rise to the unusual properties of such molecules and their carbon and boron derivatives. The use of carborane clusters has been directed toward broadening of their applications in organometallic chemistry, pharmaceutical chemistry, and materials science, such as molecular sensing, modular construction systems, nonlinear optics (NLO) materials, special polymers, catalysis for olefin polymerization, and boron neutron capture therapy for cancer (BNCT).This dissertation describes the synthesis and structural characterization of organometallic complexes with 71,2-dichalcogenolato-1,2-dicarba-closo-dodecaborane [E2C2(BioH10)]2- (E= S, Se) ligands, with emphasis being placed on two fields. One is the synthesis of those complexes containing metal-metal bond, the other is the building of multi-cluster complexes. The chemistry described here demonstrates both metal and sulfur undergo redox reactions that may involve induced internal electron transfer. And without assistance of a second ligand metal-induced B-H activation of carborane can occur as well if steric and electronic requirements are met. The study was focused on synthesis and structures of (p-cymene)Ru halfsandwich complexes containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolate ligand and their reactivity towards alcohols (HC=CC(OH)RR’), and addition of alkynes to diruthenium halfsandwich complexes containing one μ-S2 unit and two chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligands. In addition, the resulting mixture of ortho-carborane, n-butyl lithium, selenium and [(p-cymene)RuCl2]2 under argon were evaporated under reduced pressure. followed by addition of HC=CCH(OH)CH3,HC=C(OH)cyclo-C6H10,HC=CCH(OH)(CH3)2. The components of the residue were separated gave three novel ruthenium compounds.The results are shown below:1. Controlled Assembly of Ruthenium Complexes through ortho-Carborane Dithiolate and Polysulfide LigandsTreatment of ortho-carborane, n-butyl lithium, sulfur and [(p-cymene)RuCl2]2 in varying ratio led to four new compounds (p-cymene)Ru[S3(C2B10H10)2] (3), [(p-cymene)Ru2(μ2-S2C2B10H9)(μ3-S2C2B10H10)]2(4),[(p-cymene)Ru]2Ru(μ2-η2:η2-S2) S2C2B10H10)2 (5) and (6), respectively. In 3, the ruthenium atom is coordinated by three S atoms from a in situ generated tridentate [S3(C2B10H10)2]2- ligand.4 consists of two identical dinuclear (p-cymene)Ru2(μ2-S2C2B10H9)(μ3-S2C2B10H10) subunits which connect to each other via the Ru-Ru bond and two bridging o-carborane-1,2-dithiolate ligands. In 4 a Ru-B bond is present.5 contains a Ru3(μ2-S)2(μ2-S2)(μ2-S2Cl) core, and the central ruthenium atom is coordinated by seven S atoms in a distorted pentagonal bipyramidal geometry. In 5 a S-Cl bond is generated.6 has a novel Ru3(μ2-S)2(μ2-S2)(μ3-S4) core, and the three ruthenium atoms are connected through the two terminal sulfur atoms of the S-S-S-S chain in a μ3 binding fashion. All the four complexes have been characterized by elemental analysis, mass, NMR, and X-ray crystallography.2. Multinuclear Self-assembly via (p-Cymene)ruthenium Unit and ortho-Carborane Selenolate LigandTreatment of ortho-carborane, n-butyl lithium, selenium and [(p-cymene)RuCl2]2 under argon leads to complexes (p-cymene)Ru(Se2C2B10H10) (S1), [(p-cymene)RuCl(Se-SeC2B10H11)][(p-cymene)Ru(Se2C2B10H10)] (7), [(p-cymene) Ru2(Se2C2B10H10)2][(p-cymene)Ru(Se2C2B10H9)] (8) and [(p-cymene)Ru(Se2C2B10H9) Ru(Se2C2B10H10)]2 (9).7 contains a rhombic Ru2Se2 core and can be considered as an adduct of two 16e half-sandwich monomers (p-cymene)Ru(Se2C2B10H10) (S1) and (p-cymene)RuCl(Se-SeC2B10H11). In 8 three ortho-carborane-1,2-diselenolate ligands bridge the adjacent Ru atoms, and one [Se2C2B10H9]3- unit acts as a tridentate binding mode with a Ru-B bond. In 9, two identical dinuclear (p-cymene)Ru2(Se2C2B10H9)(Se2C2B10H10) subunits connect to each other through two Se atoms of two individual [Se2C2B10H10]2- ligands, and a metal-induced B-H activation occurs as well. However, if above reaction is exposed to air an unexpected product [(p-cymene)Ru]2(Se2C2B9H10)Ru2(Se2C2B10H10)3(μ-O) (10) can be isolated in a moderate yield. It contains a novel Ru4Se8O core generated from three [Se2C2B10H10]2-, one nido-[Se2C2B9H10]3- and one μ-oxo unit. Complexes 7-10 have been characterized by elemental analyses, mass, NMR, and X-ray crystallography.3. Study on the reactivity of (p-cymene)Ru2(μ-S2)(S2C2B10H10)2 toward (cyclo-C6H10)(OH)C≡CH and PhC(O)C=CHThe reaction of (p-cymene)Ru2(μ-S2)(S2C2B10H10)2 (2) with (cyclo-C6H10)(OH)CsCH and PhC(O)C≡CH affords addition complexes, (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(R1C=CR2) (R1= (cyclo-C6H10)(OH), R2= H (11); R1= H, R2= (cyclo-C6H10)(OH) (12); R1= PhCO, R2= H (15); R1= H, R2= PhCO (16)). Complexes 11 and 12 in chloroform at 62℃ spontaneously lose water and convert to two geometrical isomers (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(R1C=CR2) (R1= cyclo-C6H9, R2= H (13); R1= H, R2= cyclo-C6H9 (14)). Alkyne addition occurs at sulfur atoms of two different chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligands that leads to a change of 16e Ru(Ⅳ) in 2 to 18e Ru(Ⅱ) in 11-16, respectively. Moreover, the reaction of 2 with PhC(O)C=CH produces an unprecedented species (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(PhC(O)C=CH) (CH=CHC(O)Ph) (17) consisting of one p-cymene group, one S2 unit, two PhC(O)C=C units, and two 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligands. The most interesting structural feature of 17 is the terminal carbon atom from one PhC(O)C=CH is bonded to S(3) rather than S(1), and the alkyne addition selectively occurs at S(1) and S(3) sites. However, the terminal carbon atom from another PhC(O)C=CH is bonded to S(4) by coordinative bond. The alkyne addition has been extensively observed in the reaction system, but such a coordination mode is not known in the ortho-carborane.4. Study on the reactivity of (p-cymene)Ru(S2C2B10H10) toward alkyne alcoholsTreatment of (p-cymene)Ru(S2C2B10H10) (1) with HC=CCH(OH)CH3 afforded compounds (p-cymene)Ru(S2C2B10H9)(H2C=CCH(OH)CH3) 18, (p-cymene)Ru(S2C2B10H9)(H2C=CCH=CH2) 19 and (p-cymene)Ru(S2C2B10H9) (CH3CH=CCH2OCH(CH3)C=CH) 20. Upon heating in CHC13, the compound 18 spontaneously loses water and converts to 19. The reaction of (p-cymene)Ru(S2C2B10H10) (1) with HOCCH(OH)Ph generated a sole compound 21. The solid-state structures of 20,21 show that the reaction of (p-cymene)Ru(S2C2B10H10) with HC=CCH(OH)R lead to the formation of allenylidene intermediates (p-cymene)Ru(S2C2B10H10)(=C=C=CHR), and via nucleophilic attack of HOCCH(OH)R at the Ca atom of the allenylidene intermediates. Treatment of (p-cymene)Ru(S2C2B10H10) (1) with HOCCH(OH)(Ph)2 afforded compounds 22 and 23. Treatment of (p-cymene)Ru(S2C2B10H10) (1) with (cyclo-C6H10)(OH)C=CH, HOCCH(OH)(CH3)2, HOCCH(OH)Fc afforded compounds (p-cymene)Ru(S2C2B10H9)(H2C=CR), (R= cyclo-C6H9,24; R= C(CH3)=CH2,25; R= CH(OH)Fc,26), respectively. The structures of 18,19,22,24, 25 and 26 indicate that alkyne addition and insertion into one of Ru-S bonds, followed by B-H activation, Ru-B bond formation and the hydrogen atom transfers from boron via ruthenium to the terminal carbon of the inserted alkyne to form a CH2 group. In 23, a nido-C2B9 cluster is present, and the B(6)-H is activated to connect to metal which is arranged at the same side of the cup-shaped nido-carborane.5. Study on the reactivity of (p-cymene)Ru halfsandwich complexes containing ortho-carborane-diselenolate ligands toward alkyne alcoholsThe reaction of HO≡CCH(OH)CH3 with (p-cymene)Ru(Se2C2B10H10), (S1), generated a sole compound (p-cymene)Ru(Se2C2B10H10)(HC=CCH(OH)CH3), (27). The structure of 27 indicates that the addition of alkyne to one of the Ru-Se bonds has taken place to give a four-membered RuC(3)C(4)Se(l) planar ring without B-H activation and Ru-B bond formation. Under the same condition, treatment of ortho-carborane, n-butyl lithium, selenium and [(p-cymene)RuCl2]2 with HC≡C (OH)(cyclo-C6H10), HC≡CC(OH)(CH3)2 afforded compounds (28), (29), respectively. The solid-state structures of (28), (29) indicate that they are unprecedented trinuclear Ru-Se cluster, containing one p-cymene group, two (Se2C2B10H10)2-units and one (Se2C2B10H9)3- unit. |
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