Daravong Soulivong

Syntheses of highly functionalized cube-octameric polyhedral oligosilsesquioxanes (R8Si8O12)

Reactions of [H2N(CH2)3]8Si8O12 or its octahydrochloride salt with a variety of electrophiles, including anhydrides, lactones, acid chlorides, α,β-unsaturated esters and isocyanates, afforded functionalized R8Si8O12 frameworks in good to excellent yields. Practical methods for the synthesis of [HO(CH2)3]8Si8O12, [OCN(CH2)3]8Si8O12 and [(Ph2PCH2)2N(CH2)3]8Si8O12 are also reported.

Synthesis and coordination properties of novel polyfunctional phosphine ligands

Abstract 4′-formyl-2-diphenylphosphino-acetophenone 5 has been prepared in four steps (50%) starting from terephtalaldehyde mono -(diethylacetal) 1 . Condensation of 5 with the para -substituted anilines H 2 NA-i gives quantitatively the phosphine-imines 6–8 . Phosphines 4–6 instantaneously react with Pd II (acac) 2 to yield the bis-enolato complexes cis -[Pd II {[4′-(R)C 6 H 4 ]C(O)=CHPPh 2 } 2 ] (R=CH(OC 2 H 5 ) 2 , CH(O), CH=NA-12).

Polyfunctional phosphine ligands. Preparation of 4'-formyl-2-diphenylphosphinoacetophenone and its coordination properties

Abstract The trifunctional ligand [4′-(CHO)C 6 H 4 ]C(O)CH 2 PPh 2 ( 5 ) has been prepared in four steps (overall yield 50%) starting from terephthaialdehyde mono-(diethylacetal) ( 1 ): reaction of 1 with CH 3 MgBr gives [4′-{CH(OC 2 H 5 ) 2 }C 6 H 4 ]CH(OH) CH 3 ( 2 ). This is oxidized with MnO 2 to yield the key ketone [4′-{CH(OC 2 H 5 ) 2 }C 6 H 4 ]C(O)CH 3 ( 3 ). Metallation of 3 with LiN[(CH 3 ) 3 Si] 2 and subsequent reaction with Ph 2 PCl affords the phosphine [4′-{CH(OC 2 H 5 ) 2 }C 6 H 4 ]C(O)CH 2 PPh 2 ( 4 ) which after deprotection of the aldehyde function yields 5 . Condensation of 5 with the p -substituted anilines H 2 NA-i and H 2 NA*-12 gives quantitatively the corresponding phosphine-imines 6–9 . Compound 4 reacts instantaneously with [Pd(acac) 2 ] to yield quantitatively the bis-(enolato)-complex cis -[Pd{{{4′-[CH(OC 2 H 5 ) 2 ] C 6 H 4 }C(O)CHPPh 2 } 2 ] ( 10 ). Controlled deprotection of 10 gives the corresponding bis-(enolato)-bis-(aldehyde) complex 11 . Reaction of 11 with H 2 NA-i and H 2 NA*-12 allows the straightforward synthesis of the bis-(enolato)-bis-(imine) complexes 12–15 . All compounds have been characterized by elemental analysis, and 1 H, 13 C{ 1 H} and 31 P { 1 H} NMR and IR and mass spectroscopy.

Hybrid ligands: synthesis, characterization and co-ordinative propertiesof a mixed phosphine–β-ketophosphorus ylide

Direct C-phosphination at the methyl carbon of the keto-stabilized ylide MeC(O)CHPPh 3 was achieved using 2 equivalents of LiBu and 1 equivalent of PPh 2 Cl. The structure of the resultant phosphine–phosphorus ylide, Ph 2 PCH 2 C(O)CHPPh 3 , was shown by an X-ray diffraction study to comprise a 1:1 mixture of two rotamers built around the CH 2 –C(O) axis, the C(O)CHPPh 3 moiety of both conformers adopting a cisoid form. A rotational barrier of 10 kJ mol -1 between the two isomers was found using molecular-mechanics simulation. Oxidation of the ylide with sulfur resulted in quantitative formation of the corresponding phosphine sulfide Ph 2 P(S)CH 2 C(O)CHPPh 3 . By treating 2 equivalents of Ph 3 PCHC(O)CH 2 PPh 2 (L) with [{Pd(η 3 -C 3 H 4 Me-2)Cl} 2 ], the P-monodentate complex [PdCl(η 3 -C 3 H 4 Me-2)L] 1 was formed quantitatively. Reaction of 2 equivalents of L with [{PdCl(C 6 H 4 CH 2 NMe 2 - o)} 2 ] in tetrahydrofuran afforded, in quantitative yield, the stable cationic complex [Pd(C 6 H 4 CH 2 NMe 2 -o) L]Cl 2 where the hybrid ligand is P,O-bonded to the palladium, thus illustrating the nucleophilic character of the oxygen atom of the ylide. The BF 4 - analogue of the latter complex, 3, prepared in order to exclude counter-anion effects, was obtained by treating 1 with AgBF 4 . The nickel complexes [Ni(η 5 -C 5 Ph 5 )L]X (X = I 4 or Br 5), in which the ligand is bound as in 1 and 2, were obtained by treating the corresponding [Ni(η 5 -C 5 Ph 5 )X(CO)] complexes with the ylide L.

A Long-Chain Phosphine Designed as a Metallomesogen Generator—Synthesis and Coordination Properties

The long-chain phosphine Me2PC≡C(p-C6H4CHNR C8) [L; RC8 = p-C6H4OC(O)(p-C6H4OC8H17)] has been prepared in two steps starting from 4-ethynylbenzaldehyde (1): (a) condensation of 1 with H2NRC8 (2) afforded the corresponding imine 3 (yield 86%) which displays liquid-crystalline behaviour; (b) deprotonation of 3 with LiNPri2 and subsequent reaction with Me2PCl gave a mixture of the phosphine–alkyne L and the precursor 3 (L : 3 = 60 : 40). Reaction of this mixture with [PtCl2(PhCN)2] produced cis-[PtCl2L2] (4) and provided an efficient means of separating the phosphine from 3. The crystal structure of imine 3 has been determined by single-crystal X-ray diffraction and analysis of this structure provides a basis for understanding both the mesogenic character of 3 and its absence in the complex 4.

Methods for effecting monofunctionalization of (CH 2 [double bond, length half m-dash]CH) 8 Si 8 O 12

A new method is described for effecting selective monofunctionalization of CH2CH)8Si8O12 2: reaction of 2 with triflic acid (TfOH) produces (TfOCH2CH2)(CH2 CH)7Si8O12 3, which reacts with nucleophiles (e.g. H2O or 2-mercaptopyridine) to produce (XCH2CH2)(CH2CH)7Si8O12 (4 X = OH, 5 X = SC5H4N); acylation of 4 with p-O2NC6H4COCl affords (p-O2NC6H4CO2- CH2CH2)(CH2CH)7Si8O12 6; catalytic hydrogenation of 4 affords (HOCH2CH2) Et7Si8O12 7.