Angeles Sánchez González

The crystal structure and hydrolysis equilibrium of triphenyl(2-mercapto-1-methylimidazolato)tin(IV)

Abstract The title compound was prepared from 1-methyl-2(3H)-inidazolinethione and triphenyltin(IV) hydroxide, and its crystal structure was determined by X-ray diffraction. The crystal consists of discrete molecules with the tin atom coordinated to one carbon atom of each of the three phenyl groups and to the sulfur atom of the deprotonated ligand. An SnN interaction [2.920(3) A] slightly distorts the tin coordination geometry from that of a perfect tetrahedron. NMR spectroscopy was used to study the hydrolysis of this compound in CDC13.

Comparative structural study of dimethyl(pyridine-2-thiolato)thallium(III) and dimethylbis(pyridine-2-thiolato)tin(IV)

The crystal structures of the [TlMe2L] and [SnMe2L2](L = pyridine-2-thiolate) have been determined. Dimethyl(pyridine-2-thiolato)thallium(III) crystallizes in the monoclinic space group P21/n(no 14) with a= 8.169(1), b= 13.214(1), c= 8.876(2)A, β= 104.61 (1)°, and Z= 4. Refinement converged to R= 0.047 for 1 531 independent observed reflections. The thallium atom co-ordinates to the two methyl carbons [Tl–C 2.159(8) and 2.199(8)A], to the pyridine nitrogen [Tl–N 2.494(7)A], and to two sulphur atoms [Tl–S 3.160(3) and 2.870(2)A]. Dimethylbis(pyridine-2-thiolato)tin(IV) crystallizes in the monoclinic space group P21/m(no 11) with a= 6.664(5), b= 17.342(5), c= 6.943(3)A, β= 112.53(5)°, and Z= 2. Refinement converged to R= 0.038 for 1 105 independent observed reflections. The tin atom co-ordinates to the two methyl carbons [Sn–C 2.133(9)A], the two pyridine nitrogens [Sn–N 2.702(5)A], and the two sulphur atoms [Sn–S 2.487(2)A]. The structural characteristics of the free ligand are compared with those of the co-ordination compounds, and the mass and 13C n.m.r. spectra of the two complexes are compared.

Complexes of Ag(I) with 1-methyl-2(3H)-imidazolinethione. The crystal structure of tris[1-methyl-2(3H)-imidazolinethione]-silver(I) nitrate

Three ionic complexes, [Ag(Hmimt)](NO3), [Ag(Hmimt)2](NO3) and [Ag(Hmimt)3(NO3) (Hmimt = 1-methyl-2(3H)-imidazolinethione), were synthesized by reacting AgNO3 with Hmimt and characterized spectroscopically (mass, IR and 1H, 13C, 15N and 109Ag NMR). The structure of [Ag(Hmimt)3](NO3) was determined by X-ray crystallography. In this compound, which crystallizes in the monoclinic system (space group P21/n; a = 7.621(2), b = 27.281(5), c = 10.256(4) A, β = 107.89(1)°, Z = 4) the Ag+ ion is trigonally coordinated in the [Ag(Hmimt)3]+ cation, with a mean Ag⋯S distance of 2.489 A. The shortest Ag3.O distance is 2.929 A, and the crystal lattice features an extensive network of hydrogen bonds.

Imidazole and pyrazole complexes of phenyltin(IV) halides: The crystal structures of dichlorodiphenyl bis(pyrazole)tin(IV) and trichlorophenylbis(pyrazole)tin(IV)

Abstract The reaction of diphenyltin(IV) dichloride with imidazole (HIm) and pyrazole (HPz) afforded [SnPh2Cl2 (HIm)2] and [SnPh2C12(HPz)2] respectively. The crystal structure of [SnPh2Cl2(HPz)2] was determined by X-ray analysis. The crystal consists of discrete all-trans SnPh2Cl2(HPz)2; units with the tin atom octahedrally coordinated to two phenyl carbons, two Cl atoms and two pyrazole N atoms. The pyrazole ligands are also bound intramolecularly via hydrogen bonds to the chlorine atoms. Recrystallization of this compound in hot chloroform afforded [SnPhCl3(HPz)2], the structure of which was likewise determined by X-ray analysis as consisting of discrete mer-SnPhCl3(HPz)2 units with the tin atom octahedrally coordinated to a phenyl carbon, three Cl atoms and two pyrazole N atoms. Both pyrazole ligands are bound intramolecularly via hydrogen bonds to the chlorine atoms, and one of them is also bound intermolecularly to a chlorine atom of a neighbouring molecule. All three compounds were studied in the solid state by vibrational spectroscopy, and the formation of [SnPhCl3(HPz)2] from [SnPh2C12(HPz)2] was investigated by means of 1H and 119Sn NMR spectroscopy.

The influence of hydrogen bonding, hydration and the R substituent on the structure of [SnR2(Hmimt)4](NO3)2 complexes [Hmimt = 1-methyl-2(3H)-imidazolinethione]. The crystal structure of tetrakis[1-methyl-2(3H)-imidazolinethione]diphenyltin(IV) nitrate dihydrate

Abstract [SnPh 2 (Hmimt) 4 ](NO 3 ) 2 [Hmimt = 1-methyl-2(3H)-imidazolinethione] was synthesized and characterized by IR, Raman, Mossbauer and 1 H, 13 C and 119 Sn NMR spectroscopy. The crystal structure of its dihydrate, consisting of [SnPh 2 (Hmimt) 4 ] 2+ cations, nitrate anions and water of crystallization, was determined by X-ray diffraction: in the cation the tin atom is coordinated to a carbon atom of each of the phenyl groups and to the S atoms of four Hmimt ligands in a distorted octahedral arrangement. This structure is compared with those of the corresponding SnMe 2 2+ and SnEt 2 2+ complexes.

Synthesis and characterization of adducts of dimethyltin(IV) dihalides (Cl, Br) with 1-hydroxymethylpyrazole. The crystal and molecular structure of dichloro(1-hydroxymethylpyrazole) dimethyltin(IV)

Abstract Two adducts of 1-hydroxymethylpyrazole (PzCH2OH) with dimethyltin(IV) dihalides, Sn- Me2X2(PzCH2OH) (X=Cl, Br), were prepared and characterized by mass, IR, Raman and NMR techniques. The crystal structure of SnMe2Cl2(PzCH2OH) was determined by X-ray crystallography and refined to R=0.053, based on 2124 observed reflections. The compound is monoclinic, space group P21/n, with a=9.740(2), b=7.325(2), c=15.983(3) A and β=90.27(3)°. The organic ligand is weakly bonded to Sn through the oxygen atom. The tin atom is five-coordinate trigonal bipyramidal with one Cl and the O atom in apical positions. It is reasonable to think that a similar structure is adopted by the bromine homologue.

Crystal structure of bis(2-aminopyridinium)dimethyltetrachlorostannate(IV) and its formation by hydrolysis of dimethyltin dichloride

Abstract The structure of (C 5 H 7 N 2 ) 2 [Sn(CH 3 ) 2 Cl 4 ] has been determined by X-ray diffraction. The compound crystallizes in the orthorhombic system, space group Pbca (No. 61), with unit cell dimensions a 15.585(2), b 17.561(2), c 7.088(1) A, and Z = 4. The structure consists of hydrogen-bonded chains of alternating [Sn(CH 3 ) 2 Cl 4 ] 2− anions and pairs of C 5 H 7 N 2 + cations. Each trans -dimethyltetrachlorostannate(IV) octahedral unit is surrounded by four 2-aminopyridinium ions and is involved in ten hydrogen-bonding interactions with d (NH⋯ Cl) ranging from 3.242(12) to 3.463(12) A. 1 H NMR data show that (C 5 H 7 N 2 ) 2 [Sn(CH 3 ) 2 Cl 4 ] is formed along with 1,3-dichloro-1,1,3,3-tetramethyldistannoxane in the reaction of Sn(CH 3 ) 2 Cl 2 and C 5 H 6 N 2 in moist CDCl 3 ; the fact that hydrolysis of the dimethyltin dichloride takes place is related to the relatively high basicity and low coordinating tendency of 2-aminopyridine.

Gold(I) complexes of thio- and dithiocarbamate esters. The structure of bis(N-methyl-O-ethyl-thiocarbamate)gold(I) chloride

Abstract The complexes Au(TMDT)Br, Au(TMDT)Cl, [Au(PPh3)(TMDT)]NO3 and Au(MTC)2Cl (TMDT = N,N-dimethyl-S-methyl-dithiocarbamate, MTC = N-methyl-O-ethyl-thiocarbamate) have been prepared and characterized. The crystal structure of Au(MTC)2Cl was determined by X-ray crystallography and refined to R = 0.035 based on 2654 observed reflections. The compound is triclinic, space group P 1 , with a = 6.937(6), b = 9.439(5), c = 12.286(4) A, α = 74.16(3), β = 99.54(3), γ = 108.06(3)°. The structure consists of Au(MTC)2+ cations significantly distorted from the linear coordination, with a SAuS angle of 155.3(1)° and AuS bond distances of 2.286(2) and 2.284(2) A, and uncoordinated Cl− anions hydrogen bonded to the two MTC ligands in each cation, with NH···Cl distances of 3.04(1) A. 1H NMR spectra of the dithiocarbamate complexes are consistent with coordination of the ligand through its thiocarbonyl sulfur atom.

Reduction reactions of gold(III) bromocomplexes in dimethyl sulfoxide

Abstract The reactions of AuBr 4 − with uracil and uridine in dimethyl sulfoxide (Me 2 SO) lead to the reduction of gold(III) to gold(I) and to the formation of the corresponding 5-bromopyrimidine. In Me 2 SO containing water the 5-bromo-6-hydroxy-5,6-dihydro-pyrimidine is also formed. The observed redox kinetics are consistent with a mechanism involving reductive elimination of bromine from the gold(III) complex followed by halogenation of the pyrimidine. The specific rates for the reduction of AuBr 4 − with both pyrimidines in Me 2 SO and in the partially aqueous solvent are greater than those for the corresponding reactions in water, uracil being more reactive than uridine. The tetrabromoaurate(III) ion is also reduced by Me 2 SO. The triphenylphosphine complex Au(PPh 3 )Br 3 reacts with uridine in Me 2 SO to give 5-bromouridine. Reduction of gold(III) to gold(I) also occurs through a reaction involving the formation of triphenylphosphine oxide.

Crystal structure and mass spectrometry of dibromodimethyl[1-methyl-2(3H)-imidazolinethione-S]tin(IV)

The structure of Sn(CH3)2Br2·C4H6N2S [C4H6N2S = 1 -methyl-2(3H)-imidazolinethione] consists of trigonal-bipyramidal molecules held together in pairs by two N–H ⋯ Br hydrogen bonds. The ligand is bonded to the metal through the sulphur atom. The bromine atoms occupy apical positions with a greater Sn–Br bond length for the hydrogen-bonded atom. The mass spectra of Sn(CH3)2Br2·C4H6N2S and Sn(CH3)2Cl2·C4H6N2S show a much lower tendency for the bromine complex to form ions containing the deprotonated ligand through elimination of hydrogen halide.