Shoujian Li

Substituent effect on the carborane coupling reaction: synthesis and crystal structure of 1-phenyl-2-[2,3-benzobicyclo(3,3,0)-1-oxo-4-oxa-7-aza-8-yl]-1,2-dicarba-closo-dodecaborane(12)

Abstract The reaction between the lithium salt of [closo-1-(C6H5)-1,2-C2B10H10]− anion and N-(2-bromoethyl)phthalimide in anhydrous toluene did not result in the expected coupling product, but rather produced an unprecedented carborane species, 1-phenyl-2-[2,3-benzobicyclo(3,3,0)-1-oxo-4-oxa-7-aza-8-yl]-1,2-dicarba-closo-dodecaborane(12) (3), in 63% yield.

Unsolvated “carbons apart” neodymacarborane sandwich stabilized by bis(η6-benzene)potassium cation: a unique dimeric mixed-metal sandwiched ion-pair

Abstract The reaction between NdCl3 and potassium metal in a 1:4 molar ratio in THF, followed by the addition of 2 equivalents of 1,2-(SiMe3)2-1,2-closo-C2B4H4 (1), produced the novel dimeric, mixed-metal sandwiched ion-pair, {2,2′,4,4′-(SiMe3)4-5,6-[(μ-H)2K(η6-C6H6)2]-1,1′-commo-Nd(η5-2,4-C2B4H4)2}2 (2), in 78% yield, after re-crystallization in benzene. The simultaneous cage opening/metalation product 2 was verified by single crystal X-ray diffraction.

Synthesis and crystal structure of the first “carbons apart” diamagnetic lutetiacarborane sandwich complex

Abstract The reaction of closo-exo-5,6-Na(THF)2-1-Na(THF)2-2,4-(SiMe3)2-2,4-C2B4H4 (1) and anhydrous LuCl3, in a molar ratio of 2:1, in dry benzene at 60 °C produced the first full-sandwiched lutetiacarborane complex, 2,2′,4,4′-(SiMe3)4-3,5′,6′-[(μ-H)3Na(THF)2]-1,1′-commo-Lu(η5-2,4-C2B4H4)2 (2), as an off-white crystalline solid in 88% yield.

Allylpalladium Complexes of Mixed-Donor Diphosphazane Ligands Bearing a Stereogenic Phosphorus Centre: Structure and Stereodynamics

( 3-Allyl)palladium complexes of general formula [Pd( 3-R C3H4){ 2-Ph2PN(R)PPh(N2C3HMe2-3,5)}](PF6) (3-6) and [Pd( 3-R C3H4){ 2-Ph2P(S)N(CHMe2)PPh(N2C3HMe2-3,5)}](PF6) (7-8), containing pyrazolyl-substituted diphosphazane ligands bearing a stereogenic phosphorus centre, have been synthesised. NMR spectroscopic and X-ray diffraction studies showed that the diphosphazane ligand in [Pd( 3-R C3H4){ 2-Ph2PN(R)PPh(N2C3HMe2-3,5)}](PF6) [R = Me or Ph; R = CHMe2 (3 and 5) or (S)-*CHMePh (4 and 6)] displayed unprecedented P,N-coordination instead of the hitherto observed P,P-coordination. These complexes existed in solution as mixtures of endo,syn,trans, exo,syn,trans, and endo,syn,cis diastereomers. In the solid state, only the endo,syn,trans isomer was observed for complex 5. Phase-sensitive 2-D NOESY and ROESY spectra showed that the complexes 3-5 underwent syn,anti isomerisation; the NMR spectroscopic data were consistent with a mechanism involving the opening of the 3-allyl group at the trans position with respect to the phosphorus centre. The isomerisation thus appeared to be electronically controlled. The complexes [Pd( 3-MeC3H4){ 2-Ph2P(S)N(CHMe2)PPh(N2C3HMe23,5)}](PF6) (7) and [Pd( 3-PhC3H4){ 2-Ph2P(S)N(CHMe2)PPh(N2C3HMe2-3,5)}](PF6) (8), bearing the diphosphazane monosulfide Ph2P(S)N(CHMe2)PPh(N2C3HMe2-3,5) (1c), displayed P,S-coordination and existed in solution as six and four isomers, respectively. Exchange was observed among four of the six isomers of 7 and among all the four isomers of 8 at 298 K, through the opening of the 3-allyl moiety, which appeared to be subject to both electronic and steric control.

The first dimeric half-sandwich gadolinacarborane of the "carbons apart" C2B4-carborane ligand system

Abstract The reaction between the THF solvated “carbons apart” dinatracarborane, closo-exo-4,5-Na(THF)2–1-Na(THF)2–2,4-(SiMe3)2C2B4H4 (1), and anhydrous GdCl3 in a 1:1 molar ratio in dry benzene at 0°C, followed by extraction and crystallization of the product from an anhydrous n-hexane/TMEDA/THF solution mixture resulted in the isolation of off-white crystals of the dimeric half-sandwich dichlorogadolinacarborane, {1,1-Cl2[μ,μ′-Na(TMEDA)]–1-(THF)-2,4-(SiMe3)2–closo-η5-1-Gd-2,4-C2B4H4}2 (2) in 88% yield.

Metallacarboranes as an anion and a cation in a single species: a unique example for ion pairs

Abstract The reaction of closo-exo-5,6-Na(THF)2-1-Na(THF)2-2,4-(SiMe3)2-2,4-C2B4H4 (1) with anhydrous NdCl3, in a molar ratio of 2:1, produced the full-sandwiched neodymacarborane, 2,2′,4,4′-(SiMe3)4-5,6-[(μ-H)2Na(THF)2]-1,1′-commo-Nd(η5-2,4-C2B4H4)2 (2), as a yellow-green crystalline solid in 80% yield. Compound 2 was further reacted with NdCl3, in 3:1 molar ratio, in a solvent mixture of dry benzene and THF to produce, in 75% yield, the novel dimeric ion-pair, {[closo-1-Nd(μ-H)6-2,4-(SiMe3)2-2,4-C2B4H4]+[1,1′-(THF)2-2,2′,4,4′-(SiMe3)4-5,5′,6,6′-(μ-H)4-1,1′-commo-Nd(η5-2,4-C2B4H4)]−(C4H8O)(C6H6)2}2 (3), consisting of a half-sandwich cationic neodymacarborane that is coordinated to anionic full-sandwiched neodymacarborane. Thus, a dual role of metallacarboranes as both the cation and the anion in a single species has been exemplified.

CRYSTAL STRUCTURE OF AN ANTI-NEOPLASTIC AGENT, O-TOLUIDINECYANOBORANE, C8H11BN2

Figure 1. Molecu la r s t ructure ( 5 0 % d i sp lacemen t e l l ipso ids ) of CSHMBNI. T h e selected bond d i s t ances and ang les are: B C 1.584(4) , B N ( l ) 1.593(4), C N 1.147(3), N ( l ) C ( l ) 1 .466(3) , C ( l ) C ( 6 ) 1 .390(3) , C ( l ) C ( 2 ) 1.380(3) , C ( 2 ) C ( 3 ) 1.398(4) , C ( 2 ) C ( 2 1 ) 1.502(4), C(3) -C(4) 1.375(4) A ; C B N ( l ) 111.7(2) , N C B 174.0(3) , C ( l ) N ( l ) B 117.1(2) , C ( 6 ) C ( l ) C ( 2 ) 122.2(2) , C ( 6 ) C ( l ) N ( l ) 117.5(2) , C ( 2 ) C ( l ) N ( l ) 120.4(2) , C ( l ) C ( 2 ) C(3 ) 116.9(2) , C ( l ) C ( 2 ) C ( 2 1 ) 122.5(2), C(3) -C(2) -C(21) 120.6(2) , C (4 ) -C(3 ) -C(2 ) 121.6(2) , C(5 ) -C(4) -C(3) 120.1(3)°.

CRYSTAL STRUCTURE OF A NEW POLYMORPH 1-(METHYL)-2- (PHTHALIMID0METHYL)-1,2-DICARBA-CLOSO-DODECARBORANE, C12H19B10NO2

Figure 1. Molecular structure (50% displacement ellipsoids) of CPH^BIONO·· (I). The selected bond distances and angles are: B( l ) -C(2) 1.715(3), B ( l ) C ( l ) 1.724(3), B( l ) -B(9) 1.758(3), B( l ) -B(8) 1.770(3), B(l ) -B(2) 1.770(3), C C ( l ) 1.509(3), C( l ) -C(2) 1.671(3), C(2)-C(3) 1.527(3), C(3)-N 1.443(3), C ( 1 0 ) 0 ( l 0 ) 1.200(2), C(10)-N 1.407(2), C(17) -0(17) 1.203, C(17)-N 1.399(2), C(2) -B( l ) -C( l ) 58.13(1 1), C(2)-B(2)-B( I) 59.08(12), C(2)-B(3)-B(4) 58.79(12), C(2)-B(4)-C( 1) 58.19(11), C(l)-C(2)-B(4) 61.44(12), C( 12)-C( I 1 )-C( 16) 121.8(2), C(11)-C(12)-C(I3) I 16.8(2), C ( I4 ) -C( I3 ) -C( I2 ) 121.7(2).

Synthesis of substituted-borane adducts of amines and amino acids. The crystal structure of pyridine-N-ethylcarbamoylborane

AbstractSubstituted-borane adducts of amines and a-amino acids, pyridine-N-ethylcarbamoylborane (1), (carboxy or cyano)-dihydro[{1-(R)-2-amino-2-oxoethyl] amino}boron] (2a / g)(R / CH 2 Ph, CH PhOH, CH 3 , CH(C H 6 ) and N-[(trimethylamineboryl)-carbonyl]-{(3, 4-dihydroxyphenyl)- L -alanine}-methylester (3) are synthesized in 63 / 93% yields. All compounds were characterized byelemental analysis, 1 H, 11 B and 13 C NMR and IR spectroscopy. Additionally, the structure of compound 1 was determined by singlecrystal X-ray diffraction.# 2002 Elsevier Science B.V. All rights reserved. Keywords: Borobetaine; Borane; Carboxyborane; Hypolipidaemic; L -Dopa 1. IntroductionThe biological activity of amine / borane adducts iswell established in the literature [1 / 6].Several com-pounds have demonstrated significant antitumor activ-ity in vivo [2,4], and the borane adducts with aliphaticand aromatic amines, such as a-amino acids, peptides,and nucleic acids, have been examined for cytotoxicaction in both murine and tumor cells [7]. In addition,the cyano-, carboxy-, carbomethoxy-, and carbamoyl-borane adducts of piperidines, piperazine, morpholinesand imidazoles were shown to be potent cytotoxicagents in various cancer cell lines [8], while the boronanalogs of a-amino acids and their derivatives haveshown to have antitumor [3,4], antiarthritic [1], anti-inflammatory and hypolipidaemic activities [9]. Re-cently, we have reported the crystal structures of someimportant amineboranes [10]. As part of this continuinginvestigation, we report herein, the synthesis of thecarbamoylborane adduct of pyridine, pyridine-N-ethyl-carbamoylborane, substituted-borane adducts of a-ami-no acids and the borane analogue of {3,4-dihydroxyphenyl}-

Convenient one-pot synthesis of triphenylphosphinecarbomethoxyborane: antitumor activity and structural investigation

Abstract The reaction of equimolar quantities of trimethylaminecarbomethoxyborane and triphenylphosphine, in anhydrous 1, 2-dimethoxyethane (monoglyme), produced triphenylphosphinecarbomethoxyborane in 63% yield, via a Lewis-base exchange reaction. The structure of 1 unambiguously shows that the triphenylphosphine moiety coordinates to the boron atom with the C(O)OCH3 group intact.