Masato Nanjo

Lithiosilanes and their application to the synthesis of polysilane dendrimers

Abstract An account is given of the preparation and structural investigations of silyllithium compounds, including X-ray and NMR data. This review covers the chemistry of lithiosilanes with alkyl, aryl, functional substituents and lithiooligosilanes with SiSi bonds. Application of lithiosilanes for the synthesis of polysilane dendritic molecules is also described.

Preparation and structural characterization of trimethylsilyl-substituted germylzinc halides, (Me3Si)3GeZnX (X=Cl, Br, and I) and silylzinc chloride, R(Me3Si)2SiZnCl (R=SiMe3 and Ph)

Abstract The trimethylsilyl-substituted germylzinc halides, (Me3Si)3GeZnX (X=Cl, Br, and I), and silylzinc chlorides, R(Me3Si)2SiZnCl (R=SiMe3, Ph), have been prepared and their molecular structures have been full determined by spectroscopic and single-crystal X-ray diffraction methods. The germylzinc halides and silylzinc chlorides have dimeric structures consisting of two μ-halogen atoms. The reactivity of germylzinc chloride with substrates is also examined.

Crystal structures of the first generation of phenyl-substituted and permethyl-substituted dendritic polysilanes

Abstract The structures of the first generation of phenyl-substituted and permethyl-substituted dendritic polysilanes (1G(Ph)6 and 1G) have been established by single crystal X-ray diffraction. The dendrimer 1G has two types of conformations designated A (anti-like conformation) and O (orthogonal-like) in the chain of Si–Si bonds. However, 1G(Ph)6 has an unprecedented new type of conformation, E, which has an intermediate torsion angle between A and O.

Electron-transfer reactions of 1,2-dimetallacyclohexa-3,5-dienes with TCNE

Abstract Thermal reactions of 1,2-dimetallacyclohexa-3,5-dienes (1–3) with tetracyanoethylene (TCNE) were investigated. The reaction of 1,2-disilacyclohexa-3,5-diene (1) with TCNE mainly gave 4-amino-5,6-dicyano-2,2,11,11-tetramethyl-1,8,9,10-tetraphenyl-3-aza-2,11-disilatricyclo[6.2.1.03,7]undeca-4,6,9-triene through a charge-transfer complex. The reaction of 1,2-digermacyclohexa-3,5-diene (2) with TCNE afforded 4-amino-5,6-dicyano-2,2,11,11-tetramethyl-1,8,9,10-tetraphenyl-3-aza-2,11-digermatricyclo[6.2.1.03,7]undeca-4,6,9-triene. 2,2,3,3-Tetracyano-7,7-dimethyl-1,4,5,6-tetraphenyl-7-germabicyclo[2.2.1]hept-5-ene was also detected. On the other hand, 1-germa-2-silacyclohexa-3,5-diene (3) reacted with TCNE to give 4-amino-5,6-dicyano-2,2,11,11-tetramethyl-1,8,9,10-tetraphenyl-3-aza-11-germa-2-silatricyclo[6.2.1.03,7]undeca-4,6,9-triene, 4-amino-5,6-dicyano-2,2,11,11-tetramethyl-1,8,9,10-tetraphenyl-3-aza-11-germa-2-silatricyclo[6.3.01,8.03,7]undeca-4,6,9-triene, and 2,2,3,3-tetracyano-7,7-dimethyl-1,4,5,6-tetraphenyl-7-germabicyclo[2.2.1]hept-5-ene as main products. The mechanism of the formation of new heterocyclic compounds through electron-transfer reactions of 1,2-dimetallacyclohexa-3,5-dienes with TCNE is discussed.

Polymeric and dimeric structures of lithium(triethylgermyl)(triphenyl)borate: synthesis and characterization

Abstract The germyl borate 1 was prepared by the reaction of triphenylborane with an excess of unsolvated triethylgermyllithium in a hexane/benzene mixed solvent. The polymeric structure of 1 was observed in the solid state and in a hydrocarbon solvent. The lithium atoms were located near the center of the benzene ring and interacted with the neighboring borate molecules by the Li+–π interaction. The polymeric structure was destroyed by the addition of MeOH, however, 1 was coordinated by three MeOH molecules to form the dimeric structure without alcoholysis reaction.