A. R. Al-Arfaj

Synthesis and spectroscopic characterization of (trialkll/triaryl)-phosphine gold(I) thiocyanate complexes

Abstract R 3 PAuS 13 C 15 N (where R 3 P = Me 3 P, Et 3 P, i -Pr 3 P, p -TolPh 2 P, Ph 3 P and cyanoethyl-phosphine CEP) complexes have been prepared. The AuNCS/AuSCN ratios for these complexes have been determined, using IR spectroscopy ( v CN integrated absorption intensity ratios). The observation that the AuNCS/AuSCN ratio increases as the trans influence of the phosphine ligand increases is completely in agreement with the trend predicted by the antisymbiotic trans influence theory. In the solid state only the S-bonded isomer of each complex is observed. The 13 C, 15 N and 31 P NMR chemical shifts of these complexes were also measured and are compared with R 3 PAu 13 C 15 N complexes. The results show that unlike R 3 PAu 13 C 15 N complexes, which undergo disproportion in solution, the R 3 PAuS 13 C 15 N complexes do not undergo disproportion.

Silver(I) complexes of imidazolidine-2-thione and triphenylphosphines: Solid-state, solution NMR and antimicrobial activity studies

Mixed ligand complexes of Ag(I) with triphenylphosphine (PPh3), triphenylphosphine sulfide (SPPh3), triph- enylphosphine selenide (SePPh3) and Imidazolidine-2-thione (Imt) have been prepared. The solution as well as solid state NMR studies have been carried out to characterize these complexes. Both solid and solution NMR show the coordination via thione group on one side and (S/Se) or PPh3 on the other side. A higher antimicrobial activity is shown by (ImtAgPPh3)Cl complex against gram negative Pseudomonas aeruginosa (P. aeruginosa )a ndEscherichia coli (E. coli) compared to the other two complexes i.e. (ImtAgSPPh3)Cl and (ImtAgSePPh3)Cl.

Gold(I) Complexation with Trialkyl/Triaryl Phosphine Selenide Ligands

Abstract A number of phosphine selenide ligands and their gold(I) complexes of general formula R3P˭Se‒Au‒X (where X is Cl−, Br− and CN− and R = phenyl, cyclohexyl and tolyl) were prepared. The complexes were characterized by elemental analysis, IR and 31P NMR spectroscopic methods. In the IR spectra of all complexes a decrease in frequency of P˭Se bond upon coordination was observed, indicating a decrease in P˭Se bond order. 31P NMR showed that the electronegativity of the substituents is the most important factor determining the 31P NMR chemical shift. It was observed that phosphorus resonance is more downfield in alkyl substituted phosphine selenides, as compared to the aryl substituted ones. Ligand disproportionation in the complex Cy3P˭SeAuCN in solution to form [Au(CN)2]− and [(Cy3P˭Se)2Au]+ was investigated by 13C and 15N NMR spectroscopy.

Complexation of palladium cyanide with imidazolidine-2-thione and its derivatives

SummaryPd(CN)2 reacts with imidazolidine-2-thione (Imt), 1,3-diazinane-2-thione(Diaz), 1,3-diazipnane-2-thione (Diap) and their derivatives to yield complexes of stoichiometry [PdL2(CN)2] or [PdL′(CN)2] (L = Imt, Diaz or Diap and L′ = Imt having N-Me, Et or Pr substituents), which were characterized by elemental analysis, i.r., 1H and 13C n.m.r. spectroscopy. Both mono- and bis ligand complexes are thought to be square planar with the monoligand binding to metal via sulphur (bridging) and the bis ligand via the monodentate thione group. The 13C enriched Pd(13CN)2 complex was prepared and the 13C n.m.r. recorded. The C-2 resonance of 13C n.m.r. of Imt, Diaz or Diap complexes of the copper(I), silver(I), gold(I) and palladium(II) were compared.

13 C and 15 N NMR Studies of the Interaction of Gold(I) Thiolates with Thiourea ( 13 C and 15 N Labelled)

The interaction of gold(I) thiomalate [(Autm) n ] and gold(I) thioglucose [(Autg) n ] with thiourea (Tu) has been studied using 13 C and 15 N NMR spectroscopy. It is observed that thiourea binds to (Autm) n to form a ternary complex, Tu-Au-tm. An upfield shift of 2.6 ppm in the >C=S resonance of Tu in 13 C NMR and a downfield shift of 1.0 ppm in 15 N NMR are indicative of gold(I) binding with Tu through sulfur only. In the case of (Autg) n , the >C=S resonance of Tu remains unchanged throughout the titration, suggesting that Tu could not break the (Autg) n polymer completely. Imidazolidine-2-thione (Imt) also shows a weak interaction towards (Autg) n , similar to that of Tu.

Intramolecular short hydrogen bond : the structure of benzenesulphonylhydrazone derivative of salicylaldehyde

The title compound crystallizes in the monoclinic space group P21/c, witha=10.449(2),b=11.555(1),c=10.854(2) Å, β=90.46(2)° andV=1310.3 Å3. ForZ=4 and F.W.=274.32 the calculated density is 1.39 g/cm3. The structure was solved by direct method, and refined by full-matrix least-squares methods toR=0.034 for 3013 observed reflections. The stereochemistry of the 6/5-ring-H-bonded moiety is found to be planar, the rings being fused at the C(8)−C(13) bond. The-NSO2Ph group is linked with the fused-6/5 H-bonded ring through the N(4)−S(1) bond and the phenyl ring in the group is disposed perpendicular to the former ring system. The structure of the ligand appears to be suitable for bis-chelate formation with metals such as Cu(II) or Ni(II).

Short Intramolecular Hydrogen Bonds: Proton-NMR and IR Spectra as a Function of O - - - O Distance

Abstract Infrared absorption frequencies and 1H NMR chemical shifts have been measured as a function of O—O distances in compounds with short intramolecular hydrogen bonds. Two types of molecules were investigated, those with intramolecular O-H-O bonds within chelate or constrained systems having no degree of rotational freedom along the O-H-O axis, and molecules possessing symmetry-restricted or unrestricted hydrogen bonds with complete rotational freedom along the O - - H - - O axis. While electronic factors are most important for the nature of the short hydrogen bond in the latter compounds (such as dimeric hydronium ions of pyridine-N-oxides), steric constraints play a dominant role for the former (such as metal glyoximates). 1H MMR chemical shifts δ(O-H-O) (ppm) and IR absorption frequencies v(O-H-O) (cm−1) as a function of the O — O distance are discussed.

Synthesis ofbis- and multinuclear gold(I) complexes of hexahydro-1,3-diazepine-2-thione

SummaryNewbis- and multinuclear Au1 complexes of the type [Au(Diap)2]X and [Au2(Diap)3X2], where Diap = hexa-hydro-1,3-diazepine-2-thione, have been prepared and characterized. The spectroscopic studies reveal that both free Diap and its Au1 complexes exist in the thione form in the solid as well as the solution state. The13C-n.m.r. chemical shift of the C-2 resonance indicates that Diap binds more strongly to Au1 compared to the analogous five membered imidazolidine-2-thione and six membered 1,3-diazinane-2-thione.