Mauricio Valderrama

Determination of chromium in urine samples by complexation–supercritical fluid extraction and liquid or gas chromatography

A method was developed for the determination of chromium as the Cr(acac)(3) complex in urine using SFE and chromatography. Quantitative extractions were achieved when the experiments were carried out under 3000 p.s.i. of pressure, at a temperature of 120 degrees C, with 2.0 ml of methanol, 30 min of static extraction and 5 min of dynamic extraction. The chromium was quantified by GC-FID detection. The calibration graph of Cr(acac)(3) solutions was linear between 0.50 and 43.0 microg ml(-1) of chromium (DL 0.18 microg ml(-1), R=0.9994). The same extracts were quantified by HPLC-340 nm detection. The calibration curve of the Cr(acac)(3) solutions was linear over a range of 0.013 to 60.0 microg ml(-1) (DL 0.02 microg ml(-1), R=0.9999). This method was applied to urine samples from 60 diabetic patients and 21 healthy volunteers. Chromium concentration ranges were 2.5-29.5 microg l(-1) for the diabetics and 5.9-12.3 microg l(-1) for the normal subjects.

Bis(diphenylphosphino)amine and their dichalcogenide derivatives as ligands in rhodium(III), iridium(III), and ruthenium(II) complexes. Crystal structures of [(η5-C5Me5)MCl{η2-(SePPh2)2N}] (M=Rh, Ir)

Abstract Reaction of the dimers [{(η 5 -C 5 Me 5 )MCl} 2 (μ-Cl) 2 ] (M=Rh, Ir) or [{(η 6 -arene)RuCl} 2 (μ-Cl) 2 ] (arene= p -MeC 6 H 4 i Pr, C 6 Me 6 ) with NH(PPh 2 ) 2 in the presence of AgA (A=BF 4 , PF 6 ) leads to the mononuclear cationic complexes [(η 5 -C 5 Me 5 )MCl{η 2 -(PPh 2 ) 2 NH}]A (M=Rh ( 1 ), Ir ( 2 )) or [(η 6 -arene)RuCl{η 2 -(PPh 2 ) 2 NH}]A (arene= p -MeC 6 H 4 i Pr ( 3 ), C 6 Me 6 ( 4 )). Similar reactions using the chalcogenide derivatives NH(EPPh 2 ) 2 (E=S, Se) yield the neutral complexes [(η 5 -C 5 Me 5 )RhCl{η 2 -(EPPh 2 ) 2 N}] (E=S ( 5 ), Se ( 6 )), [(η 5 -C 5 Me 5 )IrCl{η 2 -(EPPh 2 ) 2 N}] (E=S ( 7 ), Se ( 8 )), [(η 6 -arene)RuCl{η 2 -(SPPh 2 ) 2 N}] (arene=C 6 H 6 ( 9 ), p -MeC 6 H 4 i Pr ( 10 )) and [(η 6 -arene)RuCl{η 2 -(SePPh 2 ) 2 N}] (arene=C 6 Me 6 ( 11 ), p -MeC 6 H 4 i Pr ( 12 )). Chloride abstraction from complexes 5 – 8 with AgPF 6 in the presence of PPh 3 gives the cationic complexes [(η 5 -C 5 Me 5 )Rh{η 2 -(EPPh 2 ) 2 N}(PPh 3 )]PF 6 (E=S ( 13 ), Se ( 14 )) and [(η 5 -C 5 Me 5 )Ir{η 2 -(EPPh 2 ) 2 N}(PPh 3 )]PF 6 (E=S ( 15 ), Se ( 16 )). Complexes 13 – 16 can also be synthesised from the starting dinuclear complexes, AgPF 6 , NH(EPPh 2 ) 2 and PPh 3 . Using this alternative synthetic route the related ruthenium complexes [(η 6 -C 6 Me 6 )Ru{η 2 -(EPPh 2 ) 2 N}(C 5 H 5 N)] BF 4 (E=S ( 17 ), Se ( 18 )) can be prepared. All described compounds have been characterised by microanalysis and NMR ( 1 H, 31 P) and IR spectroscopy. The crystal structures of the neutral complexes [(η 5 -C 5 Me 5 )MCl{η 2 -(SePPh 2 ) 2 N}] (M=Rh ( 6 ), Ir ( 8 )) have been determined by X-ray diffraction methods. Both complexes exhibit analogous pseudo-octahedral molecular structures with a C 5 Me 5 group occupying three coordination positions and a bidentate chelate Se,Se′-bonded ligand and a chloride atom completing the coordination sphere.

Cationic rhodium tetrafluorobenzobarrelene complexes with diolefin or arene ligands, crystal structures of [Rh(TFB)(arene)] ClO4, (arene = C6Me6, C6H3Me3, C6H4Me2)

Abstract The preparation and properties of complexes of the general formulae [Rh(TFB)(diolefin)]ClO4, [Rh(TFB)(arene)]ClO4 and [Rh(TFB)L2]ClO4, (TFB = tetrafluorobenzobarrelene, L = dimethylsulfoxide and tetrahydrothiophen) are described. The crystal structures of the arene complexes (arene = C6Me6, C6H3Me3 and C6H4Me2) have been solved by X-ray methods. The three compounds crystallize in quite similar lattices: R3c, a = b = 27.122, 26.233, 25.731 and c = 17.079, 16.388, 16.256 A, respectively. δR-plots for about 2000 reflections show the agreement in the refinements carried out up to R-values of 5%, 5% and 4% respectively. The Rh atom is coordinated to the double bonds of the TFB and to the arene ring in all three compounds, but the deviation from planarity of the arene and its relative position with respect to the TFB moiety varies.

Arene-rhodium(I) complexes with trimethyltetrafluorobenzobarrelene. Crystal structure of [Rh(Me3TFB)(1,4-C6H4Me2)]ClO4

Abstract The preparation of arene-rhodium(I) complexes of the general formula Rh(Me3TFB)PhBPh3 and [Rh(Me3TFB)(arene)]ClO4 (Me3TFB = trimethyltetrafluorobenzobarrelene; arene = C6H6−nMen (n = 0, 1, 2, 3, 4 or 6); C6H6−nXn (X = F, n = 2 or 6; X = Cl, n = 1 or 2) are described. For arenes of the type C6H6−nXn the dissociation of the coordinated arene (studied by NMR spectroscopy in deuteroacetone) is complete, but for arenes of the type C6H6−nMen it decreases with increasing methyl substitution in the arene ligand. The crystal structure of [Rh(Me3TFB)(1,4-C6H4Me2)]ClO4 has been determined by X-ray diffraction. The compound crystallizes in the Pbca space group, with lattice periodicities of 17.7393(4), 15.7816(3) and 16.0071(3) A. δR-analysis, for the 3953 total recorded reflections, support the refinement carried out to a final R-value of 0.062. The bonding of the arene to the rhodium is η6, with the ring slightly puckered to give a distorted skew conformation.

Chiral sulfur diphosphazanes derived from S-(Ph2P)2N(CHMePh) and its rhodium(I), (III) and iridium(III) complexes. Crystal structures of Ph2P(S)N(CHMePh)PPh2, {Ph2P(S)}2N(CHMePh) and [(Cp*)MCl{η2-P, S-Ph2PNHP(S)Ph2}]BF4, Cp* = η5-C5Me5; M = Rh, Ir

Abstract The reaction of S-(Ph 2 P) 2 N(CHMePh) with sulfur (1:1 molar ratio) in diethyl ether solution leads to S-Ph 2 P(S)N(CHMePh)PPh 2 ( 1 ). The disulphide S-{Ph 2 P(S)} 2 N(CHMePh) ( 2 ), was obtained when the reaction was carried out in tetrahydrofuran with an excess of sulfur (1:5 molar ratio). 1 reacts with the solvated rhodium (I) complex [Rh(cod)S x ]BF 4 to afford the cationic complex [Rh(cod){η 2 -S,P-Ph 2 P(S)N(CHMePh)PPh 2 }]BF 4 ( 3 ). However, when the above reaction was carried out with 2 , cleavage of the CN bond of the ligand occurred, to yield the complex [Rh(cod)(η 2 -S,S-{Ph 2 P(S)} 2 NH)]BF 4 ( 4 ). Reactions of 1 with the fragments of Rh (III) and Ir (III) [Cp*MClS x ]BF 4 lead to cleavage of the CN bond of the ligand yielding cationic complexes, [(Cp*)MCl{η 2 -P,S-Ph 2 PNHP(S)Ph 2 }]BF 4 (M=Rh, 5 ; Ir, 6 ]. Crystal structures of 1 , 2 , 5 and 6 have been determined by X-ray diffraction methods. Compounds 1 and 2 crystallize in the same space group P 2(1)2(1)2(1). The molecular structure of 1 shows a nearly trigonal planar nitrogen atom bound to two different phosphorus atoms and to the chiral carbon atom. Compound 2 acquires a twisted conformation with the two sulfur atoms adopting mutually trans positions with respect to the PNP backbone.

Bis(diphenylphosphino)methane and its sulphide or selenide derivatives as ligands in ruthenium(II) and rhodium(III) complexes: Crystal structure of [(η6C6Me6)Ru{η3(SPPh2)2CH}]ClO4

Abstract Reaction of complexes [( η 6 C 6 Me 6 )RuCl 2 ] 2 and [( η 5 C 5 Me 5 )RhCl 2 ] 2 with the ligands L  Ph 2 PCH 2 PPh 2 (dppm) or Ph 2 PCH 2 P(Se)Ph 2 in benzene solutions led to neutral complexes with the general formula [(ring)MCl 2 ( η 1 L)]. The reactivity of the uncoordinated P atom of dppm has been studied. When the reaction was carried out in methanol solutions, cationic complexes, with the ligands acting in their bidentate form, were obtained. Similar cationic perchlorate complexes were prepared using acetone as solvent in the presence of sodium perchlorate, yielding [(ring)MCl( η 2 L)ClO 4 , where L  Ph 2 PCH 2 PPh 2 , Ph 2 PCH 2 P(Se)Ph 2 or Ph 2 P(S)CH 2 P(S)Ph 2 . The complex [( η 6 C 6 Me 6 )RuCl{ η 2 (SPPh) 2 CH 2 -S,S′}]ClO 4 reacted with sodium hydride in tetrahydrofuran or thallium pyrazolate in dichloromethane solution by deprotonation of the coordinated bidentate ligand giving the complex [( η 6 C 6 Me 6 )Ru{ η 3 (SPPh 2 ) 2 CH-C,S,S′}]ClO 4 . The structure of this compl has been determined by single crystal X-ray diffraction methods. The complex contains a tridentate C,S,S′-bonded ligand occupying three coordination positions of a distorted octahedral ruthenium centre, with an η 6 C 6 Me 6 group completing the coordination sphere.

New coordination mode of bis(diphenylphosphine) methanide diselenide. Synthesis and X-ray crystal structure of [(η5 C5Me5)Rh{η3 (SePPh2)2CH&}]ClO4

Abstract The dinuclear complexes [(η5 C5Me5)RhCl2]2 and [(η6 C6Me6)RuCl2]2 reacted with dppmSe2 giving the cationic compounds [(η5 C5Me5)RhCl{η2 (SePPh2)2CH2&}]+ (1) and [(η6 C6Me6)RuCl{η2 (SePPh2)2CH2&}]+ (2), which were isolated as perchlorate salts. Deprotonation reactions of these compounds yielded the new complexes [(η5 C5Me5)Rh{η3 (SePPh2)2CH&}]ClO4 (3) and [(η6 C6Me6)Ru{η3 (SePPh2)2CH&}]ClO4 (4), respectively, in which the anionic methanide diselenide ligand is acting as a tripod ligand, with a C,Se,Se′-donor set. The structure of3 has been determined by X-ray crystallography.

Synthesis and characterization of heterodinuclear RuPt and IrPt complexes containing pyrazolate bridging ligands. Crystal structure of [(η5-C5Me5)Ir(μ-pz)3PtMe3] (pz=pyrazolate)

The reaction of the metallo–ligand [Ru(η 6 - p -cymene)(pz) 2 (Hpz)] with the platinum complex [{PtIMe 3 } 4 ] affords mixtures of the heterodinuclear complexes [(η 6 - p -cymene)Ru(μ-pz) 3 PtMe 3 ] ( 1 ) and [(η 6 - p -cymene)Ru(μ-pz) 2 (μ-I)PtMe 3 ] ( 2 ). The reaction of the iridium derivative [Ir(η 5 -C 5 Me 5 )(pz) 2 (Hpz)] with [{PtIMe 3 } 4 ] gives [(η 5 -C 5 Me 5 )Ir(μ-pz) 2 (μ-I)PtMe 3 ] ( 3 ). Both [Ru(η 6 - p -cymene)(pz) 2 (Hpz)] and [Ir(η 5 -C 5 Me 5 )(pz) 2 (Hpz)] react with [{PtIMe 3 } 4 ] in the presence of NaOH yielding 1 and [(η 5 -C 5 Me 5 )Ir(μ-pz) 3 PtMe 3 ] ( 4 ), respectively. While [Ru(η 6 - p -cymene)(pz) 2 (Hpz)] reacts with [PtBr 2 Me 2 S x ] to give mixtures of [(η 6 - p -cymene)Ru(μ-pz) 3 PtBrMe 2 ] ( 5 ) and [(η 6 - p -cymene)Ru(μ-pz) 2 (μ-Br)PtBrMe 2 ] ( 6 ), the reaction of [Ir(η 5 -C 5 Me 5 )(pz) 2 (Hpz)] with [PtBr 2 Me 2 S x ] gives [(η 5 -C 5 Me 5 )Ir(μ-pz) 2 (μ-Br)PtBrMe 2 ] ( 7 ) as the sole product. All species were characterized in solution by 1 H-NMR spectroscopy. The crystal structure of complex 4 has been determined by single-crystal X-ray diffraction.

Diphenylphosphino(phenylthio)methane as a monodentate or bidentate chelate ligand in rhodium, iridium and ruthenium complexes, 3rystal structure of [(η5-C5Me5) IrCl(η2-Ph2PCH2SPhP,S)]BF4·Me2CO

Abstract Reactions of complexes [∗(η 5 - C 5 Me 5 ) MCl 2 ∗ 2 ] ( M = Rh, Ir ) and [∗(η 6 - MeC 6 H 4 Pr i ) RuCl 2 ∗ 2 ] with the ligand Ph2PCH2SPh in acetone solution led to neutral complexes with the general formula [(ring)MCl2(η1-Ph2PCH2SPhP)] (1–3). These compounds react with thallium tetrafluoroborate in acetone solution to yield new cationic complexes in which the ligand is acting in its chelate P,S-donor fashion, [(ring)MCl(η2-Ph2PCH2SPhP,S)]BF4 (4–6). When the removal of the chloride ligand in complexes 1–3 was carried out in the presence of a stoichiometric amount of Ph2PCH2SPh, cationic compounds containing two P-donor monodentate ligands of the type [(η5-C5Me5)MCl (η1-Ph2PCH2SPhP)2]BF4 (7 and 8) were obtained. The structure of the iridium derivative [(η5-C5Me5)IrCl(η2-Ph2PCH2SPhP,S)]BF4 · Me2CO has been determined by single-crystal X-ray diffraction methods. The complex cation contains a C5Me5 group occupying three coordination positions of a distorted octahedral iridium centre, a bidentate chelate P,S-bonded ligand and a chloride atom completing the coordination sphere.

Pentamethylcyclopentadienyliridium(III) complexes containing tertiary phosphorus chalcogenide ligands: crystal structure of [(η5C5Me5)Ir{PO(OMe)2}{η2(SPPh2)2CH2S, S′}] BF4 · 0.5Me2CO

Abstract Neutral iridium(III) complexes of the unidentate P-donor ligands dppm, dppmS and dppmSe, and cationic complexes with these ligands acting in their bidentate form have prepared and characterized. Similar cationic complexes with the symmetrical bidentate dichalcogenide ligands dppmS 2 and dppmSe 2 have been described. These compounds react with sodium hydride in tetrahydrofuran or with thallium pyrazolate in dichloromethane to yield the new cationic complexes [( η 5 C 5 Me 5 )Ir{ η 3 (EPPh 2 ) 2 CHC,E,E′}] + (E = S, Se) in which the anionic methanide dichalcogenide ligand is acting as a tripod ligand with a C,E,E′-donor set. However, the complexes [( η 5 C 5 Me 5 )IrCl( η 2 dppmE 2 )]BF 4 react with P(OMe) 3 in the presence of TIBF 4 , to give the dicationic compounds [( η 5 C 5 Me 5 )Ir{P(OMe) 3 }( η 2 dppmE 2 )](BF 4 ) 2 . In these complexes, the P(MOe) 3 l is transformed into a coordinated PO(OMe) 2 group by reaction with sodium iodide in acetone. the structure of the complex [( η 5 C 5 Me 5 )Ir{PO(OMe) 2 }( η 2 dppmS 2 S,S′)]BF 4 · 0.5Me 2 CO have been determined by single crystal X-ray diffraction methods.