The infrared spectra of imidazole complexes of platinum(II) halides and nitrite

Summary The i.r. spectra (4000-90 cm^–1) of the [Pt(Him)₄]X₂ complexes (Him = imidazole, X = Cl, Br or I) andcis- andtrans-[Pt(Him)₂X₂] (X = Cl, Br, I or NO₂) and their D₃-labelled analogues have been determined. The distinction between the ring and C-H (or N-H) modes of imidazole is based on the relative shifts which these bands undergo on D₃-labelling. Assignments, based on the effects of imidazole deuteriation and halide substitution, are provided for the v(Pt-Him) and v(Pt-X) modes.     

Copper(I) complexes of neutral,deprotonated and protonated 4,6-dimethylpyrimidine-2 (1H)-thione

Summary The following copper(I) complexes of 4,6-dimethylpyrimidine-2(1H)-thione (HL), its protonated cation (H₂L⁺) and deprotonated anion (L^–) have been prepared: CuL, Cu(HL)X (X = Cl, Br or I), Cu(HL)₂X (X = C1 or Br), Cu₂(HL)₃Br₂, Cu(H₂L)X₂ (X = Cl or Br), Cu₃(HL)₂LA₂ (A = ClO₄ or BF₄ ). The i.r. spectra show that in all the HL and L^– complexes and in the Cu(H₂L)Br₂ complex, the ligands are S, N coordinated to the metal ion, while in Cu(H₂L)Cl₂ only the thiocarbonylic sulphur is coordinated, probably bridging two copper(I) atoms. Thev(CuN) (288–317 cm^–1 ) andv(CuS) (191–225 cm^–1 ) have uniform frequency values in all the complexes. The halide ions are, in all their complexes, wholly or in part coordinated giving twov(CuX) bands which may indicate an asymmetrical Cu-X Cu halide bridging bond.Author to whom all correspondence should be directed.     

The preparation and characterisation of chromium(III) complexes of C-meso-5, 12-dimethyl-1, 4, 8, 11-tetraazacyclotetradecane (LM). Aquation and base hydrolysis kinetics ofcis- andtrans-[CrLMCl2]+

Summary The reaction of [CrCl₃(DMF)₃] with C-meso-5, 12-dimethyl-1, 4, 8, 11-tetra-azacyclotetradecane(L_M) in DMF gives a mixture ofcis-[CrL_MCl₂]Cl (ca. 90%) andtrans-[CrL_MCl₂]Cl (ca. 10%). These complexes are readily separated, as thecis-isomer is insoluble in warm methanol while thetrans-isomer is soluble. Using the dichlorocomplexes as precursors it has been possible to prepare a range ofcis-[CrL_MX₂]⁺ complexes (X=Br^–, NO ₃ ^– , N ₃ ^– , NCS^– and X₂=bidentate oxalate) and alsotrans-[CrL_MX₂]⁺ complexes (X=Br^–, H₂O or NCS^–). The spectroscopic properties and detailed stereochemistry of the complexes are discussed.The aquation and base hydrolysis kinetics ofcis- andtrans-[CrL_MCl₂]⁺ have been studied at 25° C. Base hydrolysis of thecis-complex is extremely rapid with K_OH =1.46×10⁵ dm³ mol^–1 at 25° C. This unusual reactivity appears to be associated with thetrans II stereochemistry of thesec-NH centres of the macrocycle. Base hydrolysis of thetrans complex with thetrans III chiral nitrogen stereochemistry is quite normal with k_OH =1.1 dm³ mol^–1 s^–1 at 25° C.     

Rhodium(III) halide complexes with sulphur donors. The crystal structure ofmer-tris(o-ethylthiocarbamate)-trichlororhodium(III)acetone(1/1)

Summary The complexes [Rh(TC)₃Cl₃] · Me₂CO and [Rh(TC)₃X₃] · 0.5 Me₂CO (TC=O-ethylthiocarbamate; X=Br or I) have been prepared and characterized by i.r. and¹H n.m.r. spectroscopy.The crystal structure of [Rh(TC)₃Cl₃] · Me₂CO has been determined by x-ray diffractometer data and refined to R=0.040. Crystals are monoclinic, space group P2₁, with a=9.101(5), b=15.785(8), c=8.776(5) Å, and =103.00(3)°; Dx=1.57 gcn^–3 for Z=2. The complex is monomeric with octahedral Rh. Relevant distances are Rh-Cl (trans to one another) 2.354(2) and 2.353(2) Å, Rh-Cl (trans to S) 2.388(2) Å; Rh-S (trans to one another) 2.376(3) and 2.369(3) Å, Rh-S (trans to Cl) 2.332(3) Å. There is intramolecular, and possibly intermolecular, hydrogen bonding in the structure.     

Kinetics of base hydrolysis of trans-{Cr([15]aneN4)Cl2}+ ([15]aneN4 = 1,4,8,12-tetra-azacyclopentadecane)

Summary Reaction of CrCl₃(DMF)₃ with [15]aneN₄ (L; L = 1,4,8,12-tetra-azacyclopentadecane) gives the green trans-{Cr([15]-aneN ₄)Cl₂}Cl in high yield. The base hydrolysis kinetics of the cations [CrLCl₂]⁺ and [CrLCl(OH)] ⁺ have been investigated over a temperature range. For the dichloro complex, k _OH = 1.03 dm³ mol^–1 s^–1] at 25° C with H =30.4 kJmol^–1 and S _inf298 ^sup = -143 JK^–1 mol^–1. The substantial negative entropy of activation implies more association of water in the loss of Cl^– from the conjugate base in a D_CB mechanism. The kinetic parameters for the chlorohydroxo complex are k _OH = 1.9 × 10^–2dm³mol^–1 s^–1 at 25°C with H = 78.3kJmol^–1 and H _inf298 ^sup = -15 J K^–1 mol ^–1. The chlorohydroxo complex probably has the trans VI configuration with the chloride ligand on the same side of the equatorial plane as the four chiral sec-NH groups. The visible spectra of a variety of complexes trans-[Cr(L)XY] ⁿ⁺ (X = Y = Cl, OH, OH₂; X = Cl, Y = OH) have been determined.     

(N,N, N′, N′-tetramethylethylenediammonium)Cu2X6 (X=Cl,Br): crystal structure and magnetic interactions

Summary The crystal structures of (Me₄enH₂)Cu₂Cl₆ and (Me₄enH₂)Cu₂Br₆ have been determined. The triclinic crystals contain chains of symmetrically bibridged [Cu₂X₆]^2– dimers. Within the dimers the Cu–X distances average 2.299 Å (Cl) and 2.408 Å (Br) and the Cu–X–Cu angles are 96.4(1)^o (Cl) and 95.7(1)^o (Br). Longer Cu–X bonds, 2.679(1)Å (Cl) and 2.761(3)Å (Br), link dimers together into infinite chains via asymmetrical bridges. The bridging angles for the asymmetric bridge are 92.2(1)^o (Cl) and 89.4(1)^o (Br). Magnetic susceptibility data for both compounds are indicative of antiferromagnetic coupling. Analyses of the data yields J/k=–23(1)K (Cl) and –82(2)K (Br) for the interdimer coupling and J/k=–5(1)K (Cl) and –4(1)K (Br). The intradimer coupling for the chloride is in accord with magneto-structure relations deduced for similar salts. Similarly, the increased antiferromagnetic contribution upon substitution of Cl by Br follows trends previously observed.     

Mixed dimethyl sulfoxide-thiocarbamic ester complexes of platinum(II) halides

Summary The platinum(II) halidecis-[Pt(DMTC)(DMSO)X₂] andcis-[Pt(DETC)(DMSO)X₂](X=Cl or Br; DMSO=dimethyl sulfoxide; DMTC=EtOSCN-Me₂; DETC=EtOSCNEt₂) adducts and the platinum(II) and palladium(II) halide adducts,trans-[M(DETC)₂X₂] (M=Pt or Pd; X=Cl or Br), have been prepared. The complexes were characterized by i.r., and¹H and¹³Cn.m.r. spectroscopy. Both DMTC and DETC coordinate through the sulphur atoms. The 1:2 DETC complexes present the usualtrans configuration, whereas the presence of DMSO favourscis geometry in the mixed species.     

Gold(I) complexes of thioamides

Summary Gold(I) forms linear [AuL₂]X complexes (X = Cl, Br, I or CIO₄) with thioacetamide and thiobenzamide, AuLX compounds with thiobenzamide (X = CI or Br),N, N-dimethylthioformamide (X = Cl, Br or 1) andN-dimethylthioacetamide (X = CI, Br or 1). Thev(AuS) vibrations are assigned in the 320-260 cm^–1 range. The i.r. spectra further suggest hydrogen bonding between the ligands and the anions. The conductivity measurements indicate dissociation of the [AuL₂]X complexes (X = halide) and coordination of X in solution.Presented in part at the XIX ICCC, Prague, 1978.     

Complexes of palladium,platinum and rhodium with 2,2′-biquinoline and 2-(2′-pyridyl)quinoline

Summary The reactions of 2,2-biquinoline(biq) with M(PhCN)₂X₂ (M=Pd; X=Cl or Br; M=Pt, X=Cl, Br or I), K₂PtCl₄ and RhCl₃·3H₂O and of 2-(2-pyridyl)quinoline (pq) with K₂PtCl₄ and RhCl₃·3H₂O have been investigated. The isolated complexescis-[Pd(biq)X₂] (X=Cl or Br),cis-[Pt(biq)Cl₂],cis-[Pt(biq)Cl₂]·H₂O,trans-[Pt(biq)₂Br₂]·5H₂O, [Pt₃(biq)₂I₆],mer-[Rh(biq)Cl₃-(H₂O)] andmer-[Rh(pq)Cl₃(H₂O)] have been characterized by elemental analyses, conductivity measurements, i.r., electronic, and¹H n.m.r. spectra. The reaction of pq with K₂PtCl₄ in 1M H₂SO₄ gave the salt 2-(2-pyridyl) quinolinium tetrachloroplatinate(II) pentahydrate, (pqH)₂[PtCl₄]·5H₂O; when the reaction was carried out in aqueous acetone,cis-[Pt(pq)Cl₂] was obtained. A new method for the synthesis ofcis-[Rh(biq)₂X₂]X (X=Cl or Br) is described; both compounds have been further characterized by¹H n.m.r.     

Palladium(II) and platinum(II) complexes with N-substituted methionines

Summary As an approach to systems containing methionine residues, 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one (HDh, dehydroacetic acid) was treated with L-methionine (MetH) or L-methionine methylester (MetM). By condensation at the acyl group and transfer of the phenolic hydrogen on the nitrogen atom, the related ligands DhMetH and DhMetM, were isolated, and form complexes of formula [MX₂(L)₂](M = Pd or Pt, L = DhMetM, X = Cl, Br or I; L = DhMetH, X = Cl or Br) and [MI₂(DhMetH)] with palladium and platinum dihalides. The reaction of the DhMetK carboxylate with MCl₂ in various media is discussed. Ligands and complexes were characterized by i.r. and n.m.r. (¹H and¹³C) spectroscopy and, in some cases, by thermogravimetric measurements. The ligands behave as monodentate sulphur donors, the 12 complexes showing atrans geometry except for [PtCl₂(DhMetH)₂], which is probably a mixture ofcis andtrans isomers.     

Preparation,characterization and antifungal properties of transition metal ion complexes of quadridentate N3S ligands

Summary New metal complexes [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; NNNS^– = anion of the quadridentate ligands formed from S-methyl--N-(2-aminophenyl)-methylenedithiocarbazate and pyridine-2-aldehyde or 6-methylpyridine-2-aldehyde; X = Cl, NCS, NO₃ or I) and [Co(NNNS)Cl₂]·2H₂O have been prepared and characterized by elemental analysis and conductance measurements. Magnetic and spectroscopic evidence support a five-coordinate structure for [M(NNNS)X] (M = Ni^II, Cu^II, Zn^II and Cd^II; X = Cl, NCS) and a squareplanar structure for [Ni(NNNS)]X (X = NO₃ or I). The [Co(NNNS)Cl₃]·2H₂O complex is low-spin and octahedral. The Schiff bases and some of their metal complexes were tested against three pathogenic fungi, Alternaria alternata, Curvularia geniculata and Fusarium palidoroseum. The metal complexes are less fungitoxic than the free ligands.     

Transition Metal Halide Salts of 1,3-bis(4-Pyridyl)propane: Synthesis and Structural Characterization

The resulting salts of (H₂bpp)MX₄ · n H₂O (M = Zn, X = Cl, n = 1, 1; M = Cd, X = Br, n = 0, 2; M = Hg, X = Cl, n = 1, 3; M = Cu, X = Cl, n = 0, 4; M = Cu, X = Br, n = 1, 5; M = Pt, X = Cl, n = 1, 6) were crystallized from the reaction mixture prepared by adding MX₂ to the HX solution of 1,3-bis(4-pyridyl)propane (bpp), while the salt of colorless (H₂bpp)SnCl₆, 7, was crystallized from the reaction mixture prepared by adding SnCl₂ to the HCl solution of bpp. Their structures have been determined by X-ray crystallography. All the compounds show supramolecular structures in the solid state by intermolecular hydrogen bondings and aromatic – interactions. The H₂bpp²⁺ cations in these metal salts adopt the gauche–gauche and anti–anti conformations with different dihedral angles for the two pyridyl rings.     

Structure and Conformational Stability of 1,3-Dihalo-2,2,4,4-tetrachloro-1λ3,3λ3-diphosphetidines

The optimal geometry of isomeric molecules of (XP-CCl₂)₂ with X = F, Cl, Br was determined by RHF/6-31G(d) calculations. With X = F and Cl, the electronic correlation was considered on the MP2/6-31G(d) level. The P₂C₂ ring is nonplanar. With X = Cl and Br, the trans conformation is energetically preferable compared to the two possible cis conformations: by 7.8 and 14.2 kJ mol^{- 1} for X = Cl and by 7.5 and 14.1 kJ mol^{- 1} with X = Br. respectively. With X = F, the calculated energies of the cis and trans forms are very close.     

Copper(I) complexes of nitrogen-sulphur ligands. 1-Phenyl-4,6-dimethylpyrimidine-2-thione and its protonated form as ligands in copper(I) complexes. Chemical,spectroscopic, conductivity and polarographic studies

Summary 1-Phenyl-4,6-dimethylpyrimidine-2-thione (L) and its protonated cation 1-phenyl-4,6-dimethyl pyrimidinium-2-thione , have been employed to prepare the following copper(I) complexes: CuXL (X=Cl, Br, I, ClO₄ or BF₄), (CuX)₃L₂ (X=Cl, Br, I or SCN), (CuX)₂L₅ (X= ClO₄ or BF₄) and the zwitterionic species CuXY(LH) X=Y=Cl, Br or I; X=Br; Y=Cl; X=I; Y=Br). Chemical analysis, conductivity, and near-and far-i.r. spectroscopic data are presented and the chemical relationships between them discussed in terms of postulated dinuclear or polynuclear species for the complexes. Metalligand vibrations suggest that the neutral ligand is N, S-bidentate in its copper(I) complexes as well as S-coordinat for the cation in the zwitterionic compounds. Diagnostic i.r. bands frequencies of counterions and (Cu–X) modes indicate the coordinating character of Cl^–, Br^–, I^–, SCN^– and of ClO ₄ ^– , BF ₄ ^– (in CuXL) anions. For the chloro-complexes CuClL and (CuCl)₃L₂, salt-like species of the [CuL₂][CuCl₂] and [{Cu₂L₂Cl}_n] [CuCl₂]_n type respectively, are proposed. The polarographic data for the perchlorate complexes have shown that in dimethylformamide (DMF) solution, the prevailing species are CuClO₄L, CuClO₄L₂ and (CuClO₄)₂L₅; their overall stability constants were determined.     

Coordination Polyhedra OsXn(X = F, Cl, Br, I) in Crystal Structures

The Voronoi–Dirichlet polyhedra (VDP) and the method of intersecting spheres were used to perform crystal-chemical analysis of compounds containing complexes [Os _a X _b ] ^z–(X = F, Cl, Br, I). Atoms of Os(V) at X = F and Cl, of Os(IV) at X = Cl, Br, and of Os(III) at X = Br were found to exhibit a coordination number of 6 with respect to the halogen atoms and to form OsX₆octahedra. The coordination polyhedra of Os(III) for X = Cl, I are square pyramids OsX₄. Each Os(III) atom forms one Os–Os bond; as a consequence, the OsBr₆octahedra share a face in forming Os₂Br^3– ₉complexes, while the OsX₄pyramids (X = Cl, I) dimerize to produce [X₄Os–OsX₄]^2–ions. The influence of the valence state of the Os atoms and of the nature of the halogen atoms on the composition and structure of the complexes formed and some characteristics of the coordination sphere of Os were considered.     

Synthesis of Silver Complexes in DMSO–HX and DMSO–HX–Ketone Systems

Comparative analysis of the oxidizing and complexing properties of the DMSO–HX (X = Cl, Br, I) and DMSO–HX–ketone (X = Br, I; the ketone is acetone, acetylacetone, or acetophenone) systems toward silver was performed. The reaction products are AgX (X = Cl, Br, I), [Me₃S⁺]Ag _n X^– _m (n= 1, 2; m= 2, 3; X = Br, I) and [Me₂S⁺CH₂COR]AgX^– ₂(R = Me, Ph; X = Br, I). The composition of the obtained complexes depends on both the DMSO : HX ratio and the nature of HX, as well as on the methods used to isolate solid products from the solution. It was noted that the formation of the [Me₂S⁺CH₂COMe]AgBr^– ₂complex in the Ag⁰–DMSO–HBr–acetylacetone system occurs with cleavage of the acetylacetone C–C bond and follows a specific reaction course. The optimum conditions for production of the silver compounds in the title systems are determined.     

Thermally induced isomerisation and decomposition of diethylenetriamine complexes of nickel(II) in the solid state

Summary Complexes [NiL₂]X₂·nH₂O (L=diethylenetriamine; n=O when X=CF₃CO₂ or CCl₃CO₂; n=1 when X=Cl or Br, and n=3 when X=0.5SO₄ or 0.5SeO₄) and NiLX₂·nH₂O (n=1 when X=Cl or Br; n=3 when X=0.5SO₄ or 0.5SeO₄) have been synthesised and investigated thermally in the solid state. NiLSO₄ was synthesised pyrolytically in the solid state from [NiL₂]SO₄·[NiL₂]X₂ (X=Cl or Br) undergo exothermic irreversible phase transitions (242–282° C and 207–228° C; H=–11.3 kJ mol^–1 and –1.9 kJ mol^–1 for [NiL₂]Cl₂ and [NiL₂]Br₂, respectively). [NiL₂]-phenomenon (158–185° C; H=2.0 kJ mol^–1). NiLX₂· nH₂O (n=1 or 3) undergo simultaneous deaquation-isomerisation upon heating. All the complexes possess octahedral geometry.     

Synthesis,characterization and structural assessment of nitrato,chloro, bromo,perchlorato, thiocyanato and sulphato mono-(benzoin thiosemicarbazonato) copper(II) complexes

Summary Some copper(II) complexes of the type Cu(HL)X·nH₂O (where H₂L = benzoin thiosemicarbazone; X=NO₃; Cl, Br, SCN, ClO₄ or 1/2SO₄; n=O–2) have been prepared and characterized. All complexes have tetragonally distorted octahedral stereochemistry except the sulphatocomplex which is square pyramidal. The i.r. spectra reveal that HL acts as a monobasic tridentate ligand coordinating through the azine group nitrogen atom, thiocarbonyl sulphur atom and hydroxylic oxygen atom while NO₃, Cl, Br and ClO₄ act as terminal monodentate ligands and SCN and SO₄ act as bidentate bridging ligands. The polycrystalline e.s.r. spectra suggest tetragonal symmetry for the copper(II) ion, involving a dx ²–y² ground state.     

Porous Solids of Divalent Metal Complexes Assembled Through Hydrogen Bonding and π–π Stacking Interactions

The compound N, N-di(6-methyl-2-pyridyl)formamidine (HDMepyF) has been exploited in preparation of porous materials of divalent metal complexes of the formulae M(HDMepyF)₂(NO₃)₂ (M=Cd, 1; Co, 2; Ni, 3) and M(HDMepyF)₂X₂ (M=Mn, X=Cl, 4; M=Mn, X=Br, 5; M=Ni, X=Cl, 6; M=Ni, X=Br, 7). Their structures have been determined by X-ray crystallography. Each metal center of these complexes is approximately octahedrally coordinated by four nitrogen and two halogen or oxygen donor atoms. Complexes 1– 5 and 7 self-assemble through similar hydrogen bonding motifs which involve the C–HsX (X=Cl, Br or O) hydrogen bondings and – stacking interactions between the HDMepyF ligand and the X atoms to form porous structures.     

Carbonyl nitrosyl derivatives of rhodium and their reaction with silver nitrate

Summary Solid sodium nitrite and moderately concentrated hydrochloric acid react with [ittrans]-Rh(CO)XL₂ (X = Cl, Br, I and L = PPh₃, AsPh₃) dissolved in either DMF or CHCl₃ to yield carbonyl nitrosyl derivatives of the type Rh(CO)(NO)L₂XCI. These brown crystalline products are monomeric nonelectrolytes. Their absorption bands atca. 1630 cm^–1 andca. 2 100 cm^–1 indicate the presence of nitrosyl as well as carbonyl groups. Silver nitrate reacts with the Rh(CO)(NO)L₂XCI complexes to yield pentacoordinate species having the general composition Rh(NO)(NO₃)₂L2.