A series of racemic and optically pure aminoalkylferrocenyldichlorophosphanes has been prepared by reaction of phosphorus trichloride with the corresponding lithiated aminoalkylferrocene precursors. Crystal structures of racemic 1-dichlorophosphanyl-2-N,N-dimethylaminomethylferrocene, racemic 1-dichlorophosphanyl-2-N,N-dimethylaminomethyl-3-triphenylsilylferrocene and (S)-N,N-dimethyl-1-[(R)-2-(dichlorophosphanyl)ferrocenyl]ethylamine reveal short intramolecular N[dot dot dot]P distances, which are suggestive of weak N --> P dative bonds. The aminoalkylferrocenyldichlorophosphanes can be used for the preparation of the corresponding primary phosphanes, one of which was characterised by X-ray crystallography. Optically pure (R)-N,N-dimethyl-1-[(S)-2-(phosphanyl)ferrocenyl]ethylamine can easily be lithiated twice to give the first enantiomerically pure lithium-phosphorus closo cluster compound, which was also structurally characterised.

The reaction of sodium with RPCl2 and PCl3 (12:4:1) in THF gives Na[cyclo‐(P5R4)] [R = iPr (1), Ph (2)], while four equivalents of RPCl2 [R = Ph, 2,4,6‐Me3C6H2 (Mes), tBu] react with ten equivalents of sodium sand or elemental potassium in refluxing THF to yield the compounds [Na2(THF)5(P4Ph4)] (3), [Na2(THF)4(P4Mes4)] (4), and [Na2(THF)4(P4tBu4)] (5), or the potassium salt [K2(THF)6(P4Mes4)] (6). Recrystallizing 6 from 1,4‐dioxane/pentane (1:3) also led to [{K(L)2}2{K(L)}6(P4Mes4)4·0.5THF]∞ (L = 1,4‐dioxane) (7). In the solid state, compounds 3−6 exist as isolated ion‐contact complexes, in which the P4 chain of the (P4R4)2− ligand has a syn arrangement, while a polymeric helical arrangement was observed for 7. A minor product, [{K(pmdeta)(HP3Mes3)}2{K2(P4Mes4)}]·0.25hexane (8), was isolated from the reaction of MesPCl2 and K (1:2.5). Compound 8 contains the first structurally characterized example of a triphosphanide anion, (HP3Mes3)−, besides K2(P4Mes4). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Mefenamic acid represents a widely used nonsteroidal anti-inflammatory drug (NSAID) to treat the pain of postoperative surgery and heavy menstrual bleeding. Like other NSAIDs, mefenamic acid inhibits the synthesis of prostaglandins by nonselectively blocking cyclooxygenase (COX) isoforms COX-1 and COX-2. For the improved selectivity of the drug and, therefore, reduced related side effects, the carborane analogues of mefenamic acid were evaluated. The ortho -, meta -, and para -carborane derivatives were synthesized in three steps: halogenation of the respective cluster, followed by a Pd-catalyzed B–N coupling and hydrolysis of the nitrile derivatives under acidic conditions. The COX inhibitory activity and cytotoxicity for different cancer cell lines revealed that the carborane analogues have stronger antitumor potential compared to their parent organic compound.

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[Na{cyclo-(P(5)tBu(4))}] (1) reacts with [CuCl(PCyp(3))(2)] (Cyp=cyclo-C(5)H(9)) and [CuCl(PPh(3))(3)] (1:1) to give the corresponding copper(I) complexes with a tetra-tert-butylcyclopentaphosphanide ligand, [Cu{cyclo- (P(5)tBu(4))}(PCyp(3))(2)] (2) and [Cu{cyclo-(P(5)tBu(4))}(PPh(3))(2)] (3). The CuCl adduct of 2, [Cu(2)(mu-Cl){cyclo-(P(5)tBu(4))}(PCyp(3))(2)] (4), was obtained from the reaction of 1 with [CuCl(PCyp(3))(2)] (1:2). Compounds 2 and 3 rearrange, even at -27 degrees C, to give [Cu(4){cyclo- (P(4)tBu(3))PtBu}(4)] (5), in which ring contraction of the [cyclo-(P(5)tBu(4))](-) anion has occurred. The reaction of 1 with [AgCl(PCyp(3))](4) or [AgCl(PPh(3))(2)] (1:1) leads to the formation of [Ag(4){cyclo-(P(4)tBu(3))PtBu}(4)] (6). Intermediates, which are most probably mononuclear, "[Ag{cyclo-(P(5)tBu(4))}(PR(3))(2)]" (R=Cyp, Ph) could be detected in the reaction mixtures, but not isolated. Finally, the reaction of 1 with [AuCl(PCyp(3))] (1:1) yielded [Au{cyclo-(P(5)tBu(4))}(PCyp(3))] (7), whereas an inseparable mixture of [Au(3){cyclo-(P(5)tBu(4))}(3)] (8) and [Au(4){cyclo-(P(4)tBu(3))PtBu}(4)] (9) was obtained from the analogous reaction with [AuCl(PPh(3))]. Complexes 3-7 were characterised by (31)P NMR spectroscopy, and X-ray crystal structures were determined for 3-9.

The presence of a trimethylsilyl substituent in place of one of the methyl groups of each of the cyclopentadienyl ligands of decamethyltitanocene enhances the thermal stability of the resulting complex, [Ti II {η 5 -C 5 Me 4 (SiMe 3 )} 2 ] (1), and controls the products formed in thermolysis of its methyl derivatives. Titanocene 1 was found to be stable in toluene solution up to 90 °C, while under vacuum at 140 °C it liberated hydrogen to give the asymmetrical doubly tucked-in titanocene [Ti II {η 3 :η 4 -C 5 Me 2 (SiMe 3 )(CH 2 ) 2 }-{η 5 -C 5 Me 4 (SiMe 3 )}] (3). The mono-and dimethyl derivatives of 1, the complexes [Ti III Me{η 5 -C 5 Me 4 -(SiMe 3 )} 2 ] (5) and [Ti IV Me 2 {η 5 -C 5 Me 4 (SiMe 3 )} 2 ] (6), undergo thermolysis at lower temperature than do the corresponding permethyltitanocene derivatives and eliminate hydrogen from their trimethylsilyl group. Thus, the known [Ti III {η 5 :η 1 -C 5 Me 4 (SiMe 2 CH 2 )}{η 5 -C 5 Me 4 (SiMe 3 )}] (4) was obtained from 5, and compound 6 afforded [Ti II {η 6 :η 1 -C 5 Me 3 (CH 2 )(SiMe 2 CH 2 )}{η 5 -C 5 Me 4 (SiMe 3 )}] (7) at only 90 °C, both with liberation of methane. Crystal structures of 3, 5, and 7 were determined. DFT calculations for titanocene 1 revealed that the metal-cyclopentadienyl bonding is accomplished via a three-centerfour-electron orbital interaction. An auxiliary long-range Si-C bond interaction with the Ti center was also established, providing a reason for the enhanced thermal stability of 1. The molecular orbitals participating in the exo methylene-titanium bonds for 3 and 7 are also three-centered and are compatible with the assignment of their activated ligands to η 3 :η 4 -allyldiene and η 6 -fulvene structures, respectively. Qualitatively, the much higher thermal stability of 3 and 7 compared to that of 1 is due to the exploitation of four d orbitals in the bonding molecular orbitals for 3 and 7 versus only two d orbitals for 1.

Dehydrocoupling of the ferrocenylphosphine-borane adducts [FcPH 2 (BH 3 )] (1) [Fc = Fe(C 5 H 5 )(C 5 H 4 )] and [FcCH 2 PH 2 (BH 3 )] (2) with [{Rh(μ-Cl)(cod)} 2 ] (cod = 1,5-cyclooctadiene) as catalyst gave the corresponding phosphorusboron-based polymers [FcPH(BH 2 )] n (3) and [FcCH 2 -PH(BH 2 )] n (4) as low-(heating in toluene, 3 low and 4 low ) or high-molecular-weight (heating without solvent, 3 high or 4 high ) poly(ferrocenylphosphinoborane)s depending on the reaction conditions. Dehydrocoupling of a racemic mixture of [2-N,N-dimethyl(N-borane)aminomethyl-1-ferrocenyl]phosphine-borane (6) resulted in several products, as both BH 3 moieties are apparently involved in polymer formation. Quaternization of the amino group in planar-chiral [Fe(C 5 H 5 ){C 5 H 3 (CH 2 NMe 2 )PH 2 }] (5) with MeI and treatment of the corresponding ammonium salt [Fe(C 5 H 5 )- [a]2457 bond angles at phosphorus vary from 99.6(1) to 115.5(7)°, and those at boron from 102.7(1) to 113.9(2)°.