The C form of n-hexadecanoic acid

3 pages, 2 tables, 2 figures.In the crystal structure of the title compound, C16H32O2, the molecules are arranged into dimers through O-HO hydrogen bonds. These dimers are packed in bilayers with terminal methyl groups at both external faces, and these layers are parallel to the crystallographic (100) plane. All C-C bonds of the alkyl chain show an antiperiplanar (trans) conformation, with slight deviations from the ideal value in the C-C bonds close to the intermolecular hydrogen bonds. The similarity between the carboxyl C-O bond distances is consistent with the existence of cis-trans tautomerism.This research was supported through CICYT grant No. MAT2001±3352 and DGICYT grant No. BQU2002±1729.Peer reviewe

Synthesis, structural characterization, and ligand replacement reactions of gem-dithiolato-bridged rhodium and iridium complexes

The reaction of gem-dithiol compounds R2C(SH)2 (R = Bn (benzyl), iPr; R2 = −(CH2)4−) with dinuclear rhodium or iridium complexes containing basic ligands such as [M(μ-OH)(cod)]2 and [M(μ-OMe)(cod)]2, or the mononuclear [M(acac)(cod)] (M = Rh, Ir, cod = 1,5-cyclooctadiene) in the presence of a external base, afforded the dinuclear complexes [M2(μ-S2CR2)(cod)2] (1−4). The monodeprotonation of 1,1-dimercaptocyclopentane gave the mononuclear complex [Rh(HS2Cptn)(cod)] (5) that is a precursor for the dinuclear compound [Rh2(μ-S2Cptn)(cod)2] (6). Carbonylation of the diolefin compounds gave the complexes [Rh2(μ-S2CR2)(CO)4] (7−9), which reacted with P-donor ligands to stereoselectively produce the trans isomer of the disubstituted complexes [Rh2(μ-S2CR2)(CO)2(PR′3)2] (R′ = Ph, Cy (cyclohexyl)) (10−13) and [Rh2(μ-S2CBn2)(CO)2{P(OR′)3}2] (R′ = Me, Ph) (14−15). The substitution process in [Rh2(μ-S2CBn2)(CO)4] (7) by P(OMe)3 has been studied by spectroscopic means and the full series of substituted complexes [Rh2(μ-S2CBn2)(CO)4−n{P(OR)3}n] (n = 1, 4) has been identified in solution. The cis complex [Rh2(μ-S2CBn2)(CO)2(μ-dppb)] (16) was obtained by reaction of 7 with the diphosphine dppb (1,4-bis(diphenylphosphino)butane). The molecular structures of the diolefinic dinuclear complexes [Rh2(μ-S2CR2)(cod)2] (R = Bn (1), iPr (2); R2 = −(CH2)4− (6)) and that of the cis complex 16 have been studied by X-ray diffraction.The financial support from Ministerio de Educación y Ciencia (MEC/FEDER) Project CTQ2006-03973/BQU is gratefully acknowledged. A. B. R. thanks the Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED) for a fellowship. Also, A.B. R. and A.J. P. thank to Fonacit-Venezuela (S1-2002000260) for financial support.Peer Reviewe

The C form of n-hexadecanoic acid

3 pages, 2 tables, 2 figures.In the crystal structure of the title compound, C16H32O2, the molecules are arranged into dimers through O-HO hydrogen bonds. These dimers are packed in bilayers with terminal methyl groups at both external faces, and these layers are parallel to the crystallographic (100) plane. All C-C bonds of the alkyl chain show an antiperiplanar (trans) conformation, with slight deviations from the ideal value in the C-C bonds close to the intermolecular hydrogen bonds. The similarity between the carboxyl C-O bond distances is consistent with the existence of cis-trans tautomerism.This research was supported through CICYT grant No. MAT2001±3352 and DGICYT grant No. BQU2002±1729.Peer reviewe

Cyclometallated platinum(II) complexes containing the chiral ligand [2-(diphenyl-phosphanyl)-benzylidene]-(1-phenyl-ethyl)-amine: Synthesis and molecular structures of the compounds [PtCl(Me){κ2-(R)-Ph2P(C6H 4)CH{double bond, long}NCH(Ph)Me-P,N}]

Diastoreoisomeric mixtures of the complex [PtIMe3{κ2-Ph2P(C6H4)CHdouble bondNCH(Ph)Me-P,N}] (Rc-1) react with AgBF4 and SMePh to give a mixture of complexes [PtMe(SMePh){κ2-Ph2P(C6H4)CHdouble bondNCH(Ph)Me-P,N}]BF4 (2) and [Pt{κ3-Ph2P(C6H4)CHdouble bondNCH(C6H4)Me-P,N,C}(PhSMe)]BF4 (3) which subsequently render the corresponding chloride compounds [PtClMe{κ2-(R)-Ph2P(C6H4)CHdouble bondNCH(Ph)Me-P,N}] (4) and [PtCl{κ3-(R)-Ph2P(C6H4)CHdouble bondNCH(C6H4)Me-P,N,C}] (5), by elution with CH2Cl2 on a aluminium oxide chromatography column. Refluxing of [PtIMe3{κ2-Ph2P(C6H4)CHdouble bondNC∗H(Ph)Me-P,N}] (Sc-1) with AgBF4 in a 1:1, CH2Cl2:Me2CO mixture followed by the addition of SMePh, NCMe or pyridine (Py) affords the corresponding cyclometallated compounds [Pt{κ3-(S)-Ph2P(C6H4)CHdouble bondNCH(C6H4)Me-P,N,C}(L)]BF4 [L = SMePh (3), NCMe (9), Py (10)]. These compounds have been characterised by analytical and spectroscopic means and by the molecular structure determination of complexes 4 and 10.We thank “Fondo de Desarrollo Científico y Tecnológico” (FONDECYT), Chile, for financial support (Grant 1030520).Peer reviewe