Cobalt(II), nickel(II), copper(II) and copper(I) complexes of 2-mercapto-5-methyl-1,3,4-thiadiazole and 2,5-bis(methylmercapto)-1,3,4-thiadiazole

Summary Some cobalt(II), nickel(II), copper(II) and copper(I) complexes of 2-mercapto-5-methyl-1,3,4-thiadiazole (mttz) and 2,5-bis(methylmercapto)-1,3,4-thiadiazole (bmttz) have been prepared and studied by conductometric and magnetochemical methods and by electronic and i. r. spectroscopy. The complexes CoX₂ · 2L (L=mttz, X=Cl, Br or I; L=bmttz, X=Br or I), CoCl₂ · bmttz are pseudotetrahedral, and the complexes NiX₂ · mttz (X=Cl or Br), NiCl₂ · 1.3 bmttz, NiBr₂ · 1.5 bmttz are pseudooctahedral. The complex Co₃(OAc)₂ · 4(mttz-H) · 2H₂O has an undefinite constitution. The polynuclear complexes CuCl₂ · 1.3 mttz and CuBr₂ · 1.2 mttz contain presumably pseudotetrahedral chromophores, the chloride having a subnormal magnetic moment. The CuX₂ · 2 bmttz (X=Cl, Br or NO₃) complexes have a six coordination with bridging ligand molecules. In the CuX · 2 mttz (X=Cl, Br or ClO₄) complexes the anions are coordinated, while in the CuClO₄ · 2 bmttz complex the perchlorate anion is ionically bonded.     

Palladium(II) halide complexes with 2,5-dimethyl-, 2-amino-, 2-amino-5-methyl-, 2-ethylamino- and 2-mercapto-5-methyl-1,3,4-thiadiazole

Some palladium(II) halide complexes with 2,5-dimethyl- (DTZ), 2-amino- (ATZ), 2-amino-5-methyl- (MATZ), 2-ethylamino- (EATZ) and 2-mercapto-5-methyl-1,3,4-thiadiazole (MTTZ) have been prepared and studied: PdX₂ · 2L (L = DTZ, ATZ, MATZ : X = Cl, Br, I; L = EATZ: X = Br, I; L = MTTZ: X = I), PdCl₂ · 2.5EATZ, PdCl₂ · 3MTTZ, PdBr₂ · 1.5MTTZ and PdX₂ · L (L = DTZ, ATZ, MATZ, EATZ: X = Cl, Br; L = MTTZ: X = Cl(H₂O), Br). In the PdX₂ · 2L, PdCl₂ · 2.5EATZ and PdCl₂ · 3MTTZ complexes the palladium ions are cis-(2X, 2L)-coordinated, the coordination sites being N_ring for DTZ, NR₂ for ATZ, MATZ, EATZ and C = S for MTTZ. PdBr₂ · 1.5MTTZ may be formulated as cis[PdBr₂-2L] · [PdBr₂ · L]. In the PdX₂ · L complexes the ligand very likely acts as bidentate by using a ring-nitrogen atom as the second coordination site.     

Copper(II) complexes of 2-amino-1,3,4-thiadiazole and 2-ethylamino-1,3,4-thiadiazole

Summary Some copper(II) complexes of 2-amino-1,3,4-thiadiazole (atz) and 2-ethylamino-1,3,4-thiadiazole (eatz) have been prepared and studied by electronic, i.r. and e.p.r. spectra and by magnetochemical and conductometric methods. The CuX₂ · atz (X=Cl, Br) and CuCl₂ · eatz complexes are presumably six-coordinate with bridging ligand molecules and asymmetrically bridging halide ions, while the CuX₂ · 2 atz (X=Cl, Br) complexes probably have a flattened tetrahedral N₂X₂ moiety with apical interactions. The CuBr₂ · 5/3 eatz · 2/3 MeOH and Cu(OAc)₂ · L (L=atz or eatz) complexes have subnormal magnetic moments (1.53-1.40 B.M.). The acetato-complexes have a dimeric structure with bridging acetato-groups, copper-copper interactions and apical ligand molecules. The ligands bond principally through the amine nitrogen atom and, when bridging, also through one ring-nitrogen.     

Tetragonal-pyramidal complex of copper nitrate with 2-Amino-5-ethyl-1,3,4-thiadiazole

A complex compound of Cu(II) nitrate with 2-amino-5-ethyl-1,3,4-thiadiazole was synthesized and its structure was studied by the methods of IR spectroscopy and X-ray crystal analysis. The complex has the composition Cu(NO₃)₂(2-amino-5-ethyl-1,3,4-thiadiazole)₄ with four molecules of the heterocyclic ligand (coordination through nitrogen atoms of thiadiazole rings) and one of nitrate ions (the other is replaced in the second sphere) entering into the coordination sphere of the complex polyhedron. The internal coordination sphere of the complex has the form of a tetragonal pyramid with 2-amino-5-ethyl-1,3,4-thiadiazole ligands in the sites of its base and the oxygen atom of the nitrate ion in a slightly distorted vertex of the pyramid.     

Coordination behaviour of 2-halo-1,3,4-thiadiazoles towards cobalt(ii) and nickel(ii)

Summary A series of cobalt(II) and nickel(II) 2-X-1,3,4-thiadiazole complexes (X=Cl or Br) were investigated by electronic, n.m.r., Raman and i.r. spectroscopy, and by thermogravimetric analyses, magnetic moments and conductivity measurements.The complexes havepseudo-tetrahedral or pseudo-octa-hedral stereochemistries with MN₂X₂ (X=Cl or Br), MN₄X₂ (X=Cl, Br or O) or MN₃O₃ chromophores.The ligands are mono- or bi-dentate without involving the sulphur atom. Surprisingly, the chloro-derivative ligand seems to be more nucleophilic than the bromo-analogue.The computed (CNDO/2) molecular orbital indices for the uncomplexed ligands indicate that the coordination sites are the nitrogen atoms.In connection with our previous work⁽¹⁾ on the coordination ability of heterocyclic ligands with interesting biological^(2,3) and pharmaceutical⁽⁴⁾ properties and containing endocyclic nitrogen and sulphur donor atoms, we have considered the 1,3,4-thiadiazole ring, which is the main framework of a very important class of diuretic drugs, the sulphonamide inhibitors⁽⁵⁾ of the zinc m tallo-enzyme carbonic anhydrase.In this study we have investigated the coordination behaviour of the 2-chloro-1,3,4-thiadiazole(ctz) and the 2-bromo-1,3,4-thiadiazole (btz).     

Mono and Poly‐nuclear Silver(I) Complexes with Thiosaccharin and Triphenylphosphine. Synthesis,Spectroscopic and Structural Characterization of Thiosaccharinato‐bis(triphenylphosphine)silver(I) and Tetrakis{thiosaccharinato(triphenylphosphine)silver(I)}

The reaction of Ag₆(tsac)₆ ( 1 ) (tsac = thiosaccharinate anion) with triphenylphosphine gives rise to the already reported [Ag(tsac)(PPh₃)₃] complex ( 2 ) and to two new silver‐thiosaccharinate‐phosphine complexes, [Ag(tsac)(PPh₃)₂] ( 3 ) and [Ag₄(tsac)₄(PPh₃)₄] ( 4 ) (PPh₃= triphenylphosphine). Spectroscopic characterization was carried out using IR, UV‐Visible and NMR techniques and confirmed by single crystal X‐ray diffraction. In each complex a singular coordination mode for the thiosaccharinate ligand is observed. The most important features of the different coordination modes of the thionates are discussed. Compound 3 crystallizes in monoclinic system, space group Pn, with a = 11.2293(3) Å, b = 12.7282(3) Å, c = 13.6056(4) Å, β = 94.985(2)°, Z = 2; while crystals of compound 4 are monoclinic, space group P2₁/n, a = 15.024(3) Å, b = 14.681(3) Å, c = 21.914(4) Å, β = 95.31(3)°, Z = 2. The coordination around the silver atoms in both complexes consists of almost trigonal‐planar arrangements, AgP₂S in 3 and AgS₂P in 4 .     

Four- and five-coordinate metal atoms in a supramolecular polymeric assembly of silver(I) with (4-methyl-2-quinolylthio)acetate

The coordination compound [Ag₂L₂(H₂O)₂] · ₂H₂O (I), L = C₁₂H₁₀NO₂S has been synthesized by the reaction of AgNO₃ with 4-methyl-2-quinolylthioacetic acid (HL) preliminarily neutralized with an equimolar amount of NBu₄OH. Its crystal structure has been determined, and luminescence properties have been studied. Crystals of I are monoclinic, space group C2/_c, _a = 31.239(6) Å, _b = 12.056(2) Å, _c = 16.846(3) Å, β = 122.17(3)°, V = 5370.4(2) ų, ρ_calc = 1.861 g/cm³, Z = 16. The structure is formed by two crystallographically nonequivalent silver atoms Ag(1) and Ag(2) and two tridentate bridging ligands L coordinated through the S, N, and O atoms. These atoms, together with water molecules, form the coordination environments of the metal atoms with CN = 5 and 4, respectively. The Ag⁺ ions and the tridentate ligands form infinite [Ag₄L₄]_n bands extended in the [001] direction. The presence of outer-sphere water molecules involved in O–H···O hydrogen bonding is responsible for the formation of a supramolecular framework structure. The photoluminescence spectrum of compound I shows two bands at ~450 and ~485 nm corresponding to the blue spectral range.     

A silver(I) coordination derivative of 2,3-dimethylthio-6-pyridyl tetrathiafulvalene,synthesis, crystal structure and electrochemical properties

A silver coordination compound [Ag(I)(DMT–TTF-py)₂CH₃CN] ClO₄?·?CH₂Cl₂ has been synthesized by reaction of DMT–TTF-py with AgClO₄. Structure analysis shows that the cations self-assemble to dimeric units through Ag?···?Ag interactions. Each silver(I) has a T-shaped AgN₃ coordination geometry. In the dimeric units, there are short C?···?S and C?···?C contacts between the two DMT–TTF-py molecules. The dimeric units are further assembled to a zigzag packing structure. The cyclic voltametric behavior of the ligand shows two-step reversible redox waves, which are shifted to lower values due to coordination to silver.     

Synthesis of formazans from Mannich base of 5-(4-chlorophenyl amino)-2-mercapto-1,3,4-thiadiazole as antimicrobial agents

5-(4-Chlorophenyl amino)-2-mercapto-1,3,4-thiadiazole (I) was refluxed with formaldehyde and ammonium chloride in ethanol yielding the Mannich base 5-(4-chloro phenyl amino)-3-aminomethyl-2-mercapto-1,3,4-thiadiazole (II). Esterification with 4-chloro-(2,6-dinitro phenoxy)-ethyl acetate (III) under anhydrous conditions gave the intermediate (IV). Subsequent hydrazinolysis with hydrazine hydrate gave the corresponding hydrazide 3-amino methyl-5-(4-chloro phenyl amino)-2-mercapto-4′-(2′,6′-dinitro phenoxy)-acetyl hydrazide (V). The hydrazide was converted into the Schiff bases (VI_a–b) by reacting with 2-chlorobenzaldehyde and 3-methoxy-4-hydroxy benzaldehyde in presence of methanol containing 2–3 drops of acetic acid. Diazotisation with aromatic amines, sulphanilic acid and sulphur drugs gave the formazans (VII_a–g) respectively. Chemical structures have been established by elemental analysis and the spectral techniques of FTIR, ¹H NMR and mass. Antimicrobial activity (in vitro) was evaluated against the two pathogenic bacterial strains. Escherichia coli and Salmonella typhi, three fungal strains Aspergillus niger, Penicillium species and Candida albicans. The compounds have shown moderate activity.     

Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole

Summary Nickel(II) and copper(II) complexes of 2,5-dimethyl-1,3,4-thiadiazole Ni(DTZ)X₂ (X = Cl or Br) and M(DTZ)₂X₂ (M = Ni, X = 1 or N03; M = Cu, X = Cl, Br or NO₃) have been prepared. The i.r. spectra show that in all the complexes the ligand is N,N- or N-bonded to the metal while the sulfur atom does not participate in coordination, and that the halide ions are coordinated forming terminal M-X bonds. The NO ₃ ^- group is coordinated in both the nitrato complexes. Magnetic moments of 3.07–3.29 B.M. for the nickel(II) and 1.86–1.92 B.M. for the copper(II) complexes were observed. The Ni(DTZ)X₂ complexes have a pseudo-tetrahedral [N₂X₂] coordination with N,N-bridging ligand molecules. The Ni(DTZ)₂X₂ and Cu(DTZ)₂X₂ complexes, with predominantly monodentate ligand, involve six-coordinate metal atoms with strong equatorial [N₂X₂] bonds and weaker axial bonds.Author to whom all correspondence should be directed.     

Synthesis and characterization of a Cu(II) complex of 2-benzylmercapto-5-methyl-1,3,4-thiadiazole (C10H10N2S2)

A Cu(II) complex of 2-benzylmercapto-5-methyl-1,3,4-thiadiazole was synthesized and characterized. The crystal structure of the copper complex and the free ligand were determined by single-crystal X-ray diffraction at room temperature: {[Cu(C₁₀H₁₀N₂S₂)₂(Cl)₂], P 1 triclinic, a = 8.1450(2) Å, b = 8.1690(2) Å, c = 10.8180(3) Å, α = 97.4040(12)°, β = 101.6270(11)°, γ = 116.1431(14)°; C₁₀H₁₀N₂S₂ ligand, Pbca orthorhombic, a = 8.7938(7) Å, b = 9.6491(7) Å, c = 25.3552(18) Å}. The metal complex framework consists of discrete units that provide crystalline stability through a network of van der Waals contacts. The Cu(II) is coordinated by two chloride ions and two 2-benzylmercapto-5-methyl-1,3,4-thiadiazole monodentate ligands showing a distorted square planar configuration. Both thiadiazole ligands coordinate through the N atom bonded to the benzylthio substituted C atom.

The FTIR spectroscopic data are consistent with this structural model. Analysis of the magnetic susceptibility from 5 K to room temperature indicates the presence of paramagnetic Cu(II), confirmed by the EPR spectrum.     

2-Propylamino-5-[4-(2-hydroxy-3,5-dichlorobenzylideneamino) phenyl]-1,3,4-thiadiazole: X-ray and DFT-calculated structures

2-Propylamino-5-[4-(2-hydroxy-3,5-dichlorobenzylideneamino) phenyl]-1,3,4-thiadiazole, formulated as C₁₈H₁₆Cl₂N₄OS (I), was synthesized. The crystal and molecular structure of (I) have been determined by ¹H-NMR, IR, and X-ray single crystal diffraction. The compound (I) crystallizes in the monoclinic, space group P2(1)/c with unit cell parameters a = 9.0576(2) Å, b = 24.3382(8) Å, c = 9.0585(2) Å, M _r = 407.31, V = 1851.13(9) Å³, Z = 4, R ₁ = 0.036, and wR ₂ = 0.096. Molecular geometry from X-ray experiment of (I) in the ground state has been compared using the density functional method (B3LYP) with 6-31G(d) basis set. To determine conformational flexibility, molecular energy profile of (I) was obtained by semi-empirical (PM3) calculations with respect to selected degree of torsional freedom, which was varied from ?180° to +180° in steps of 10°. The results are indicative that the Schiff base, which contains a thiadiazole ring, prefers to be in E-configuration. In addition, molecular electrostatic potential, frontier molecular orbitals, and natural bond orbitals analysis were performed by the B3LYP/6-31G(d) method.     

2,5-二苯腙基-1,3,4-噻二唑类化合物的合成及抗腐蚀性能研究

以2,5-二巯基-1,3,4-噻二唑为原料, 与水合肼反应制得2,5-二肼基-1,3,4-噻二唑, 再将其与取代苯甲醛缩合, 得到了6种新的2,5-二苯腙基-1,3,4-噻二唑类化合物, 其结构经元素分析、红外、¹H NMR及质谱等方法所证实. 6种噻二唑衍生物对喷气燃料银片腐蚀有一定的抑制作用.     

Synthesis,Structures, and Photophysics of Polynuclear Silver(I) Thiolate and Silver(I) Thiocarboxylate Complexes with Dppm Ligands

Trinuclear silver(I) thiolate and silver(I) thiocarboxylate complexes [Ag₃(μ‐dppm)₃(μ_n‐SR)₂](ClO₄) [n = 2, R = C₆H₄Cl‐4 ( 1 ) and C{O}Ph ( 2 ); n = 3, R = tBu ( 3 )], pentanuclear silver(I) thiolate complex [Ag₅(μ‐dppm)₄(μ₃‐SC₆H₄NO₂‐4)₄](PF₆) ( 4 ), and hexanuclear silver(I) thiolate complexes [Ag₆(μ‐dppm)₄(μ₃‐SR)₄]Y₂ [Y = ClO₄, R =C₆H₄CH₃‐4 ( 5 ) and C₁₀H₇ (2‐naphthyl) ( 7 ); Y = PF₆, R = C₆H₄OCH₃‐4( 6 )], were synthesized [dppm = bis(diphenylphosphanyl)methane] and their crystal structures as well as photophysical properties were studied. In the solid state at 77 K, trinuclear silver(I) thiolate and silver(I) thiocarboxylate complexes 1 and 2 exhibit luminescence at 470–523 nm, tentatively attributed to originate from the ³IL (intraligand) of thiolate or thiocarboxylate ligands, whereas hexanuclaer silver(I) thiolate complexes 5 and 7 produce dual emission, in which high‐energy emission is tentatively attributed to come from the ³IL of thiolate ligands and low‐energy emission is tentatively assigned to come from the admixture of metal ··· metal bond‐to‐ligand charge‐transfer (MMLCT) and metal‐centered (MC) excited states.     

Cobalt(II) Complexes of 4,6-Dimethylpyrimidine-2(1H)-one

Some cobalt(II) complexes of 4,6-dimethylpyrimidine-2(1H)-one (HL) have been prepared and studied by infrared and electronic spectra and by magneto-chemical and conductometric measurements. The ligand is coordinated through the unprotonated ring-nitrogen atom and in one case also through the carbonylic oxygen atom. The “blue” complexes [CoX₂ · 2HL] (X₂ = Cl₂, ClBr, Br₂, (NCS)₂) and [CoX₂ · 2HL] · 2HL (X = Cl, Br) have a distorted C_2v [CoX₂N₂] coordination; the thiocyanate ion is N-bonded to the metal. The “green” complexes CoX₂ · 2HL (X = Cl(4H₂O), Br) have a square-pyramidal [CoX₂N₂O] coordination. The “pink” CoX₂ · 4HL · nH₂O (X = ClO₄, n = 2; X = BF₄, n = 8; X = F₃Ac, n = 4) and “cream” CoX₂ · 4HL · 6 H₂O (X = I, ClO₄) complexes have an octahedral coordination; only the F₃Ac^? ion is coordinated. The “cyclamen” CoAcL · 2HL · 2 H₂O and Co₃Ac₄L₂ · 2HL · 2H₂O complexes have a polynuclear constitution; the Ac^? ion behaves as bidentate ligand.     

Synthese,Schwingungsspektren und Kristallstrukturen der Nitratoargentate (Ph4P)[Ag(NO3)2(CH3CN)]·CH3CN und (Ph4P)[Ag2(NO3)3]

Synthesis, Vibrational Spectra, and Crystal Structures of the Nitrato Argentates (Ph₄P)[Ag(NO₃)₂(CH₃CN)]·CH₃CN and (Ph₄P)[Ag₂(NO₃)₃] Tetraphenylphosphonium bromide reacts in acetonitril suspension with excess silver nitrate to give (Ph₄P)[Ag(NO₃)₂(CH₃CN)]·CH₃CN ( 1 ), whereas (Ph₄P)[Ag₂(NO₃)₃] ( 2 ) is obtained in a long‐time reaction from (Ph₄P)Br and excess AgNO₃ in dichloromethane suspension. Both complexes were characterized by vibrational spectroscopy (IR, Raman) and by single crystal structure determinations. 1 : Space group P2₁/c, Z = 4, lattice dimensions at 193 K: a = 1781.5(3), b = 724.8(1), c = 2224.2(3) pm, β = 96.83(1)°, R₁ = 0.0348. 1 contains isolated complex units [Ag(NO₃)₂(CH₃CN)]^?, in which the silver atom is coordinated by the chelating nitrate groups and by the nitrogen atom of the solvated CH₃CN molecule with a short Ag—N distance of 220.7(4) pm. 2 : Space group I2, Z = 4, lattice dimensions at 193 K: a = 1753.4(4), b = 701.7(1), c = 2105.5(4) pm, R₁ = 0.072. In the polymeric anions [Ag₂(NO₃)₃]^? each silver atom is coordinated in a chelating manner by one nitrate group and by two oxygen atoms of two bridging nitrate ions. In addition, each silver atom forms a weak π‐bonding contact with a phenyl group of the (Ph₄P)⁺ ions with shortest Ag···C separations of 266 and 299 pm, respectively, indicating a (4+1) coordination of silver atoms.     

Charge-transfer molecular complexes of 2-amino-1,3,4-thiadiazoles

Charge-transfer molecular complexes of 2-amino-5-X-1,3,4-thiadiazole (D) (X = H, I; = CH₃, II; = phenyl, III) with some π-electron acceptors (A) have been studied in methanol. It is concluded that these complexes are predominantly of the π-π type. Solid 1:1 CT complexes of the donors I–III with π-acceptors DDQ and TCNE have been synthesized and characterized.     

Optimized POCl3-assisted synthesis of 2-amino-1,3,4-thiadiazole/1,3,4-oxadiazole derivatives as anti-influenza agents

Although recent decades have witnessed the synthesis of 1,3,4-thiadiazoles via phosphorus POCl₃-promoted cyclization reaction, simultaneous access to 2-amino-1,3,4-thiadiazole and 2-amino-1,3,4-oxadiazole analogs remains unexpected and elusive. Herein, a detailed regiocontrolled synthesis of 2-amino-1,3,4-thiadiazoles in good to high yields with good regioselectivities from readily available thiosemicarbazides using POCl₃ was disclosed. Meantime, to establish a comprehensive structure–activity relationship, 2-amino-1,3,4-oxadiazole derivatives as single regioisomers were prepared via EDCI·HCl-triggered cyclization of the thiosemicarbazide intermediates. The in vitro anti-influenza assays proved that the selected compounds with the pyrazine/pyridine ring exhibited certain inhibitory activities against influenza A virus strains A/HK/68 (H3N2) and A/PR/8/34 (H1N1) in MDCK cells. Among them, N-(adamantan-1-yl)-5-(5-(azepan-1-yl)pyrazin-2-yl)-1,3,4-thiadiazol-2-amine (4j) was the most active compound, and exhibited favorable activity with EC₅₀ values of 3.5 μM and 7.5 μM, respectively. In addition, the molecular docking results explained the reason why compound 4j had dual inhibitory activity and revealed the reasonable binding mode of this compound with the M2-S31N and M2-WT ion channels. This compound had the potential to be further developed as an anti-influenza drug.     

Syntheses and structures of nine-coordinate K3[DyIII(nta)2(H2O)]·5H2O and eight-coordinate (NH4)3[DyIII(nta)2] complexes

K₃[Dy^III(nta)₂(H₂O)]·5H₂O and (NH₄)₃[Dy^III(nta)₂] have been synthesized in aqueous solution and characterized by IR, elemental analysis and single-crystal X-ray diffraction techniques. In K₃[Dy^III(nta)₂(H₂O)]·5H₂O the Dy^III ion is nine coordinated yielding a tricapped trigonal prismatic conformation, and its crystal belongs to monoclinic system and C2/c space group. The crystal data are as follows: a = 15.373(5) Å, b = 12.896(4) Å, c = 26.202(9) Å; β = 96.122(5)°, V = 5165(3) ų, Z = 8, D _c = 1.965 g·cm^?3, μ = 3.458 mm^?1, F(000) = 3016, R ₁ = 0.0452 and wR ₂ = 0.1025 for 4550 observed reflections with I ≥ 2σ(I). In (NH₄)₃[Dy^III(nta)₂] the Dy^III ion is eight coordinated yielding a usual dicapped trigonal anti-prismatic conformation, and its crystal belongs to monoclinic system and C2/c space group. The crystal data are as follows: a = 13.736(3) Å, b = 7.9389(16) Å, c = 18.781(4) Å; β = 104.099(3)°, V = 1986.3(7) ų, Z = 2, D _c = 1.983 g·cm^?3, μ = 3.834 mm^?1, F(000) = 1172, R ₁ = 0.0208 and wR ₂ = 0.0500 for 2022 observed reflections with I ≥ 2σ(I). The results indicate that the difference in counter ion also influences coordination numbers and structures of rare earth metal complexes with aminopolycarboxylic acid ligands.     

Apparent molar heat capacities and volumes of silver nitrate and silver perchlorate in aqueous solution at 298 K

We have made calorimetric and density measurements leading to apparent molar heat capacities and volumes of dilute aqueous solutions of silver nitrate and silver perchlorate at 298 K. Resulting apparent molar properties at infinite dilution are the following: φ^o_c(AgNO₃) = ? 36.8 J K^?1 mol^?1, φ^o_v(AgNO₃) = 29.1 cm³ mol^?1, φ^o_c(AgClO₄) = 11.0 J K^?1 mol^?1, and φ^o_v(AgClO₄) = 43.5 cm³ mol^?1.