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A new Au(III) complex was synthesized from an amidrazone derivative and HAuCl4. Cyclization of amidrazone moiety lead to the 1,2,4-triazolo[1,5a]pyridine ring system, followed by Au(III) chelation. The crystal and molecular structure of the final compound was studied by single crystal X-ray diffraction as well as by 1H 13C and 1H 15N HMQC- and HMBC-NMR spectroscopy, which resulted in the assignment of all detected signals. This species was tested in vitro as an antibacterial and antiproliferative agent. It exhibited good antibacterial activity against Staphylococcus aureus and was proved to be more potent than amoxicillin against Bacillus subtilis and the drug resistant strain of Klebsiella pneumoniae. In contrast, its antiproliferative properties against cancer cell lines A549, HT-29, MV-4-11 and MCF-7 were relatively low.

One of the main tactics to access C-N bonds from inactivated C-H functionalities is direct transition metal-supported aminations. Due to the often harsh reaction conditions, the current goal in the field is the search for more mild and sustainable transformations. Herein, we present the first solvent-free thermally induced C-N bond formation driven by Au(III) salts. The general structure of the products was confirmed by 1H, 13C, 15N NMR, TGA-DTA and ATR/FT-IR analysis. Additionally, all derivatives were tested as catalysts in a three-component coupling reaction between phenylacetylene, benzaldehyde and piperidine and as anticancer agents on HL-60 and MCF-7 cell lines.

An update of a review paper published in 2013 (L. Pazderski, 15N and 31P NMR coordination shifts in transition metal complexes with nitrogen- and phosphorus-containing heterocycles, Annu. Rep. NMR Spectr. 2013, 80, 33–180), devoted to 31P NMR and covering years 2012–20 (till June), with 90 references. It collects 31P NMR data for 108 complexes of such transition metal ions as Ni(II), Pd(II), Pt(II), Pt(IV), Rh(I), Ir(I), Co(III), Rh(III), Ir(III), Fe(II), Ru(II), Os(II), Cu(I), Ag(I), Au(I), Au(III), Zn(II), Cd(II) and Hg(II) with phosphorus-containing heterocycles (phosphinines and phospholes). 31P NMR coordination shifts, i.e., differences between 31P chemical shifts of the same phosphorus in the molecules of the complex and the ligand (Δ31Pcoord = δ31Pcompl—δ31Plig) are discussed in relation to some structural features of the reviewed coordination compounds, mainly to the type of the metal central ion and the donor atom in trans position in respect to the concerned P atom.

An update of a review paper published in 2013 (L. Pazderski, 15N and 31P NMR coordination shifts in transition metal complexes with nitrogen- and phosphorus-containing heterocycles, Annu. Rep. NMR Spectr. 80 (2013) 33–180), devoted to 15N NMR and covering years 2012–20 (till June), with 184 references. It collects 15N NMR data for 407 complexes or organometallics of such transition metal ions as Ni(II), Pd(II), Pt(II), Pt(IV), Rh(I), Ir(I), Co(III), Rh(III), Ir(III), Fe(II), Ru(II), Os(II), Cu(I), Ag(I), Au(I), Au(III), Zn(II), Cd(II) and Hg(II) with nitrogen-containing heterocycles (azines, azoles, purines and 1,2,4-triazolo-[1,5a]-pyrimidines). 15N NMR coordination shifts, i.e., differences between 15N chemical shifts of the same nitrogen in the molecules of the complex or organometallic and the ligand ( Δ 15 N coord = δ 15 N compl / organomet − δ 15 N lig ) are discussed in relation to some structural features of the reviewed coordination compounds, mainly to the type of the metal central ion and the donor atom in trans-position in respect to the concerned N atom.

Au(III) chloride compounds with 7,8-benzoquinoline (bqn) – [Au(bqn)Cl3] and [Au(bqn∗)Cl2] (bqn∗ being deprotonated, at the C(10) carbon, monoanionic form of bqn) were studied by 1H–13C, 1H–15N HMQC and HMBC–NMR. 1H, 13C and 15N coordination shifts were discussed in relation to the molecular structures, revealing characteristic variability patterns. Analogous NMR measurements were performed for the new (bqnH+)2(AuCl4−)Cl− salt, studied also by single crystal X-ray diffraction. All compounds exhibited fluorescence.

2-Phenylsulfanylpyridine (1), its analogues 2-phenylsulfinylpyridine (2), 2-phenylselanylpyridine (3) and 2-phenylseleninylpyridine (4), as well as 4′-substituted derivatives (methyl-, tert-butyl-, bromo- and nitro-, i.e. 5–8) were characterized by 1H, 13C, 15N and 77Se NMR, including full assignment of all signals. Au(III) chloride complexes with these heterocycles (except from 4; denoted generally as L2Ar(S/SO/Se)py) of the general formula [Au(L2Ar(S/SO/Se)py)Cl3] (1a-3a and 5a-8a) were also studied by the same NMR methods. During an attempt to prepare 3a in the standard reaction between NaAuCl4 and 3, the new selenoxide 4 was unexpectedly obtained. 1H, 13C, 15N and 77Se NMR chemical shifts of all heterocycles and the resulting coordination shifts of the corresponding Au(III) complexes were discussed in relation to the molecular structures. The catalytic properties of 1a-3a and 5a-8a complexes were exhibited in the three-component reaction between phenylacetylene, benzaldehyde and piperidine, yielding 1-(1,3-diphenylprop-2-yn-1-yl)piperidine. 1a and 7a were also studied by single crystal X-ray diffraction, revealing typical Au(III) square-planar coordination sphere with slight deviations towards tetrahedral geometry.

Pd(II) chloride organometallics with 2-phenylpyridine and pyridines of general formula [Pd(2ppy∗)LCl] (2ppy∗ = C(2′)-deprotonated form of 2-phenylpyridine (2ppy), acting as N(1),C(2′)-chelating ligand; L = NH3, pyridine, 2-, 3-, 4-methylpyridine, 2,3-, 2,4-, 2,6-, 3,5-dimethylpyridine, 2,4,6-trimethylpyridine) were studied by 1H, 13C and 15N NMR. 1H, 13C and 15N NMR coordination shifts (i.e. differences of chemical shifts for the same atom in the complex and ligand molecules) were discussed in relation to the molecular structures. Single crystal X-ray structure of trans(N,N)-[Pd(2ppy∗)(2,4,6col)Cl] was solved. The analysis of 15N NMR coordination shifts for the whole series of the studied organometallics exhibited that all of them had an analogous trans(N,N) geometry.

Au(III) and Pd(II) chloride complexes with 2-benzylpyridine (2bzpy) – [Au(2bzpy)Cl3] and trans-[Pd(2bzpy)2Cl2], as well as Au(III) chloride organometallics with monoanionic form of 2bzpy, deprotonated in the benzyl side group at the ortho-carbon C(2′) (2bzpy*) – [Au(2bzpy*)Cl2], were studied by 1H, 13C and 15N NMR. 1H, 13C and 15N coordination shifts (i.e. differences of chemical shifts for the same atom in the complex and ligand molecules) were discussed in relation to the molecular structures and the coordination modes, as well as to the factors influencing nuclear shielding. Analogous NMR measurements were performed for the new (2bzpyH)[AuCl4] salt, studied also by single crystal X-ray diffraction.

Au(III) and Pd(II) chloride complexes with N(1),O-chelating 2-acetylpyridine (2apy) and N(1)- monodentately binding 2-benzoylpyridine (2bz′py)-[Pd(2apy)Cl2], [Au(2bz′py)Cl3],trans-[Pd(2bz′py)2Cl2], as well as Au(III) chloride organometallics with monoanionic forms of 2apy or 2bz′py, deprotonated at the acetyl or benzyl side groups (2apy*, 2bz′py*)-[Au(2apy*)Cl2], [Au(2bz′py*)Cl2], were studied by1H,13C, and15N NMR.1H,13C, and15N coordination shifts (i.e., differences between the respective , , and chemical shifts of the same atom in the complex and ligand molecules: , , ) were discussed in relation to the molecular structures and coordination modes, as well as to the factors potentially influencing nuclear shielding. Analogous NMR measurements were performed for the new (2bz′pyH)[AuCl4] salt.

(1)H, (13)C and (15)N NMR studies of iron(II), ruthenium(II) and osmium(II) bis-chelated cationic complexes with 2,2':6',2″-terpyridine ([M(terpy)(2) ](2+) ; M = Fe, Ru, Os) were performed. Significant shielding of nitrogen-adjacent H(6) and deshielding of H(3'), H(4') protons were observed, both effects being mostly expressed for Fe(II) compounds. The metal-bonded nitrogens were shielded, this effect being much larger for the outer N(1), N(1″) than the inner N(1') atoms, and enhanced in the Fe(II) → Ru(II) → Os(II) series.

(1)H, (13)C, (195)Pt and (15)N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with such alkyl and aryl derivatives of 2,2'-bipyridine and 1,10-phenanthroline as LL = 6,6'-dimethyl-bpy, 5,5'-dimethyl-bpy, 4,4'-di-tert-butyl-bpy, 2,9-dimethyl-phen, 2,9-dimethyl-4,7-diphenyl-phen, 3,4,7,8-tetramethyl-phen, having the general [M(LL)Cl(2)] formula were performed and the respective chemical shifts (δ(1H), δ(13C), δ(195Pt), δ(15N)) reported. (1)H high-frequency coordination shifts (Δ(coord)(1H) = δ(complex)(1H)-δ(ligand)(1H)) mostly pronounced for nitrogen-adjacent protons and methyl groups in the nearest adjacency of nitrogen, as well as (15)N low-frequency coordination shifts (Δ(coord)(15H) = δ(complex)(15H)-δ(ligand)(15H)) were discussed in relation to the molecular structures.

(1)H, (13)C, (15)N and (195)Pt NMR studies of gold(III) and platinum(II) chloride organometallics with N(1),C(2')-chelated, deprotonated 2-phenylpyridine (2ppy*) of the formulae [Au(2ppy*)Cl(2)], trans(N,N)-[Pt(2ppy*)(2ppy)Cl] and trans(S,N)-[Pt(2ppy*)(DMSO-d(6))Cl] (formed in situ upon dissolving [Pt(2ppy*)(micro-Cl)](2) in DMSO-d(6)) were performed. All signals were unambiguously assigned by HMBC/HSQC methods and the respective (1)H, (13)C and (15)N coordination shifts (i.e. differences between chemical shifts of the same atom in the complex and ligand molecules: Delta(1H)(coord) = delta(1H)(complex) - delta(1H)(ligand), Delta(13C)(coord) = delta(13C)(complex) - delta(13C)(ligand), Delta(15N)(coord) = delta(15N)(complex) - delta(15N)(ligand)), as well as (195)Pt chemical shifts and (1)H-(195)Pt coupling constants discussed in relation to the known molecular structures. Characteristic deshielding of nitrogen-adjacent H(6) protons and metallated C(2') atoms as well as significant shielding of coordinated N(1) nitrogens is discussed in respect to a large set of literature NMR data available for related cyclometallated compounds.

1H, 13C and 15N nuclear magnetic resonance studies of gold(III), palladium(II) and platinum(II) chloride complexes with phenylpyridines (PPY: 4-phenylpyridine, 4ppy; 3-phenylpyridine, 3ppy; and 2-phenylpyridine, 2ppy) having the general formulae [Au(PPY)Cl3], trans-/cis-[Pd(PPY)2Cl2] and trans-/cis-[Pt(PPY)2Cl2] were performed and the respective chemical shifts (delta1H, delta13C and delta15N) reported. 1H, 13C and 15N coordination shifts (i.e. differences between chemical shifts of the same atom in the complex and ligand molecules: Delta(coord)(1H) = delta(complex)(1H)-delta(ligand)(1H), Delta(coord)(13C) = delta(complex)(13C)-delta(ligand)(13C), Delta(coord)(15N) = delta(complex)(15N)-delta(ligand)(15N)) were discussed in relation to the type of the central atom (Au(III), Pd(II) and Pt(II)), geometry (trans-/cis-) and the position of a phenyl group in the pyridine ring system.

(1)H, (13)C and (15)N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with picolines, [Au(PIC)Cl(3)], trans-[Pd(PIC)(2)Cl(2)], trans/cis-[Pt(PIC)(2)Cl(2)] and [Pt(PIC)(4)]Cl(2), were performed. After complexation, the (1)H and (13)C signals were shifted to higher frequency, whereas the (15)N ones to lower (by ca 80-110 ppm), with respect to the free ligands. The (15)N shielding phenomenon was enhanced in the series [Au(PIC)Cl(3)] Pt(II) replacement, but decreased upon the trans --> cis-transition. Experimental (1)H, (13)C and (15)N NMR chemical shifts were compared to those quantum-chemically calculated by B3LYP/LanL2DZ + 6-31G**//B3LYP/LanL2DZ + 6-31G*.

The crystal and molecular structure of potassium aquapentachloroiridate(III) (K2[Ir(H2O)Cl5]) was reported. The [Ir(H2O)Cl5]2− anions are nearly octahedral, the axial Ir–Cl bond (2.322(2) A) being shorter than the equatorial ones (2.346(2)–2.360(2) A); the Ir–O bond length is 2.090(4) A. Ir(III) chloride complexes with 2,2′-bipyridine (LL = bpy) or 1,10-phenanthroline (LL = phen), of the general formulae K[Ir(LL)Cl4] and cis-[Ir(LL)2Cl2]Cl, were studied by far-IR and 1H–13C, 1H–15N HMBC/HMQC/HSQC–NMR. High-frequency 1H NMR coordination shifts (Δ1Hcoord = δ1Hcomplex − δ1Hligand; max. ca. +1 ppm) were noted for [Ir(LL)Cl4]− anions, while for cis-[Ir(LL)2Cl2]+ cations they had variable sign and magnitude (max. ca. ±1 ppm); they were dependent on the proton position, being mostly expressed for the nitrogen-adjacent hydrogens (H(6) for bpy, H(2) for phen). 13C NMR signals were high-frequency shifted (by max. ca. 8 ppm), whereas all 15N nuclei were shifted to the lower frequency (by ca. 105–120 ppm). The experimental 1H, 13C, 15N NMR chemical shifts were reproduced by semi-empirical quantum-chemical calculations (B3LYP/LanL2DZ+6-31G∗∗//B3LYP/LanL2DZ+6-31G∗).

trans-[Co(py)4Cl2]Cl·6H2O, mer-[Co(py)3Cl3] and mer-[Co(py)3(CO3)Cl] were studied by UV-Vis, far-IR and 1H, 13C, 15N NMR. The formation of Co-N bonds lead to variable in sign and magnitude changes of 1H NMR chemical shifts, heavily dependent on proton position, coordination sphere geometry and character of auxiliary ligands. 13C nuclei were deshielded upon Co(III) coordination, while 15N NMR studies exhibited ca. 85–110 ppm shielding effects (ca. 15–25 ppm more expressed for nitrogens trans to N than trans to Cl or O). 13C and 15N CPMAS spectra revealed a slight inequivalency of formally identical Co-py bonds in trans-[Co(py)4Cl2]Cl·6H2O and mer-[Co(py)3Cl3], suggesting for the latter complex an existence of distortion isomers. In chloroform, a spontaneous trans-[Co(py)4Cl2]Cl → mer-[Co(py)3Cl3] + py reaction was monitored by 1H NMR and UV-Vis. This process of py → Cl substitution allowed the design of a more convenient and efficient method of mer-[Co(py)3Cl3] preparation.

1H, 13C, and 15N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with quinolines (L = quinoline–quin, or isoquinoline–isoquin; LL = 2,2′-biquinoline–bquin), having the general formulae trans-/cis-[ML2Cl2] and [M(LL)Cl2], were performed and the respective chemical shifts (δ1H, δ13C, δ15N) reported. 1H coordination shifts of various signs and magnitudes (Δ1Hcoord = δ1Hcomplex − δ1Hligand) are discussed in relation to the changes of diamagnetic contribution to the relevant 1H shielding constants. The comparison to the literature data for similar complexes containing auxiliary ligands other than chlorides exhibited a large dependence of δ1H parameters on electron density variations and ring-current effects (inductive and anisotropic phenomena). The influence of deviations from planarity, concerning either MN2Cl2 chromophores or azine ring systems, revealed by the known X-ray structures of [Pd(bquin)Cl2] and [Pt(bquin)Cl2], is discussed in respect to 1H NMR spectra. 15N coordination shifts (Δ15Ncoord = δ15Ncomplex − δ15Nligand) of ca. 78–100 ppm (to lower frequency) are attributed mainly to the decrease of the absolute value of paramagnetic contribution in the relevant 15N shielding constants, this phenomenon being noticeably dependent on the type of a platinide metal and coordination sphere geometry. The absolute magnitude of Δ15Ncoord parameter increased by ca 15 ppm upon Pd(II) Pt(II) replacement but decreased by ca. 15 ppm following trans cis transition. Experimental 1H, 13C, 15N NMR chemical shifts are compared to those quantum-chemically calculated by B3LYP/LanL2DZ + 6–31G**//B3LYP/LanL2DZ + 6–31G*, both in vacuo and in CHCl3 or DMF solution. Copyright © 2007 John Wiley & Sons, Ltd.

1H, 13C and 15N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with methyl and phenyl derivatives of 2,2′-bipyridine and 1,10-phenanthroline [LL = 4,4′-dimethyl-2,2′-bipyridine (dmbpy); 4,4′-diphenyl-2,2′-bipyridine (dpbpy); 4,7-dimethyl-1,10-phenanthroline (dmphen); 4,7-diphenyl-1,10-phenanthroline (dpphen)] having a general [M(LL)Cl2] formula were performed and the respective chemical shifts (δ1H, δ13C, δ15N) reported. 1H high-frequency coordination shifts (Δ1Hcoord = δ1Hcomplex − δ1Hligand) were discussed in relation to the changes of diamagnetic contribution in the relevant 1H shielding constants. The comparison to literature data for similar [M(LL)(XX)], [M(LL)X2] and [M(LL)XY] coordination or organometallic compounds containing various auxiliary ligands revealed a large dependence of δ1H parameters on inductive and anisotropic effects. 15N low-frequency coordination shifts (Δ15Ncoord = δ15Ncomplex − δ15Nligand) of ca 88–96 ppm for M = Pd and ca 103–111 ppm for M = Pt were attributed to both the decrease of the absolute value of paramagnetic contribution and the increase of the diamagnetic term in the expression for 15N shielding constants. The absolute magnitude of Δ15Ncoord parameter increased by ca 15 ppm upon Pd(II) Pt(II) transition and by ca 6–7 ppm following dmbpy dmphen or dpbpy dpphen ligand replacement; variations between analogous complexes containing methyl and phenyl ligands (dmbpy vs dpbpy; dmphen vs dpphen) did not exceed ± 1.5 ppm. Experimental 1H, 13C, 15N NMR chemical shifts were compared to those quantum-chemically calculated by B3LYP/LanL2DZ + 6–31G**//B3LYP/LanL2DZ + 6–31G*, both in vacuo and in DMSO or DMF solution. Copyright © 2007 John Wiley & Sons, Ltd.

Recently implemented hybrid density functional methods of calculating nuclear magnetic shielding using the two-component zeroth-order regular approximation approach (J. Phys. Chem. A2009, 113, 11495) have been employed for a series of compounds containing heavy transition-metal atoms. These include Pt(2+), Pd(2+), and Au(3+) organometallics and metal complexes with azines, some of which exhibit interesting biological and catalytic activities. In this study we investigate the effects of geometry, exchange-correlation functional, solvent, and scalar relativistic and spin-orbit corrections on the nuclear magnetic shielding-mainly for (13)C and (15)N atoms connected to a heavy-atom center. Our calculations demonstrate that the B3LYP method using effective core potentials and a cc-pwCVTZ-PP/6-31G** basis set augmented with the polarizable continuum model of the dimethylsulfoxide solvent provides geometries for the complexes in question which are compatible with the experimental NMR results in terms of both the trends and the absolute values of the (13)C shifts. The important role of the exact exchange admixture parameter for hybrid functionals based on B3LYP and PBE0 is investigated systematically for selected Pt(2+) and Au(3+) complexes. The (13)C and (15)N NMR chemical shifts are found to be best reproduced by using a B3LYP or PBE0 approach with 30% and 40-50% exact exchange admixtures for the Pt(2+) and Au(3+) complexes, respectively. The spin-orbit contributions to the (15)N NMR chemical shifts reflect metal-ligand bonding that is much more ionic for the Au(3+) than for the Pt(2+) complex. Finally, an optimized density functional method is applied to a series of transition-metal complexes to estimate the scope and the limitations of the current approach.

Tautomerism in 6-mercaptopurine (6mpH), 2,6-dimercaptopurine (2,6dmp) and 6-mercaptopurine-9-riboside (6mp-9rb) was studied in the solution with 2D NMR methods-1H–13C HMBC and 1H–15N HMQC. The 15N NMR signals were assigned and the distribution of mobile protons proposed on the basis of δ13C, δ15N chemical shifts and JHC, JHN coupling constants, determined with HECADE. These heterocycles appear in DMSO-d6 as the thionic species with predominance of the following tautomers: N(1)H, N(7)H for 6mpH; N(1)H, N(3)H, N(7)H for 2,6dmp; N(1)H for 6mp-9rb. Quantum-chemical NMR calculations by GIAO method(RHF/6-31G**//B3LYP/6-31G**) allowed to evaluate the ratios of N(7)H, N(9): N(7), N(9)H tautomeric forms as ca. 3:1 for 6mpH and nearly 10:0 for 2,6dmp. The 13C and 15N CPMAS spectra were measured for solid 6mpH·H2O, anhydrous 6mpH, 2,6dmp and 6-mercaptopurinium chloride (6mpH2Cl), confirming the thionic character of all compounds. The 15N chemical shifts in the solid phase were calculated (B3LYP/6–31G**) for 6mpH·H2O and 6mpH2Cl, basing on the re-determined single crystal X-ray data (optimised with RHF/3-21G**).

Au(III), Co(III) and Rh(III) chloride complexes with pyridine (py), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) of the general formulae [(MLCl3)-L-1], trans-[(ML4Cl2)-L-2](+), mer-[(ML3Cl3)-L-2], [M-1(LL)Cl-2](+), cis-[M-2(LL)(2)Cl-2](+), where M-1 = Au; M-2 = Co, Rh; L = py; LL = bpy, phen, were studied by H-1-C-13 HMBC and H-1-N-15 HMQC/HSQC. The H-1, C-13 and N-15 coordination shifts (the latter from ca -78 to ca -10 7 ppm) are discussed in relation to the type of metal, electron configuration, coordination sphere geometry and the type of ligand. The C-13 and N-15 chemical shifts were also calculated by quantum-chemical NMR methods, which reproduced well the experimental tendencies concerning the coordination sphere geometry and the ligand type.

A series of Pd(II) and Pt(II) complexes with 6-mercaptopurine (6-Hmp) of formulae Pd(6-Hmp) 2 Cl 2 ( 1 ), Pd(6-mp) 2 ·2H 2 O ( 2 ), Pt(6-mp) 2 ·2H 2 O ( 3 ), Pt(6-mp)(dmso)Cl ( 4 ) was synthesized and studied by IR, far-IR, 1 H, 13 C, 15 N NMR. ( 1 ) has an ionic character and consists of distinct [Pd(6-Hmp) 2 ] 2+ cations and uncoordinated Cl − anions, whereas ( 2,3 ) are neutral species with central atoms bis-chelated by the deprotonated 6-mp − ligands. NMR studies suggest that S and N(7) are the complexation sites, while far-IR spectra indicate the square-planar geometry of Pd(II) or Pt(II). In ( 4 ) the Pt(II) atom is coordinated by one chelating 6-mp − anion, S-bonded dmso molecule and a terminal chloride. The antiproliferative activity in vitro of ( 2–4 ) was tested against human leukaemia HL-60 cells, being exhibited for ( 2 ) at the level ca. six times lower than in case of cisplatin.

The zinc triad metal chloride complexes with pyridazine of [M(pyridazine)Cl2]n type, M=Zn(II) (1), Cd(II) (2), Hg(II) (3), were synthesized. The crystal and molecular structures of 2 and 3 were studied by single crystal X-ray diffraction. They are isostructural polymers of formulae catena[bis(μ2-chloro)-(μ2-pyridazine-N,N′)]cadmium(II) and catena[bis(μ2-chloro)-(μ2-pyridazine-N,N′)]mercury(II). They crystallize in the orthorhombic Imma space group (2: a=7.056(1), b=7.447(1), c=13.113(1) A; 3: a=7.129(1), b=7.398(1), c=13.073(2) A). The central atoms have the geometry of square bipyramid and are bridged by axial pyridazines and equatorial chlorides. The Cd–N and Hg–N bonds are 2.371(3) and 2.407(5) A, the Cd–Cl and Hg–Cl being 2.6279(7) and 2.6626(12) A, respectively. The X-ray powder diffractograms suggest 1 has a similar structure, being different from the monomeric species Zn(pyridazine)2Cl2 (4), already described by several authors as the sole product of ZnCl2+pyridazine reaction. The 15N CPMAS-NMR measurements of 1–3 reveal significant shielding (65–90 ppm) of nitrogen nuclei upon the formation of coordination bondings, the observed low-frequency shifts decreasing with the atomic mass of the metal.

A comparison of hydrogen bond strengths in various enamines was made by monitoring the differential shifts Δδ(X) as the difference of NMR chemical shifts between E and Z forms of the nuclei directly involved in hydrogen bonding, i.e., X = 15N, 1H, 17O atoms. The interpretation of these differential values was aided by ab initio calculations and X-ray derived geometric parameters for selected compounds. It is shown that Δδ(N1H) and Δδ(15N) give conclusive results and their changes are rationally interpreted by invoking established contributing effects that influence the values of chemical shifts. The Δδ(17O) parameter is sensitive to intramolecular geometry, mainly bond angles around oxygen and co-planarity of the atoms forming the hydrogen bonds. The latter factor is important in determining the strength of hydrogen bonds. Even a weak acceptor such as the lactone function gives a relatively strong hydrogen bond as compared with sp3-hybridized sulfonyl or sulfinyl acceptors. The hybridization of the penultimate atom of an acceptor plays a crucial role in determining the strength of hydrogen bonding.

Cu(I) complexes with 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppB) and perfluorinated carboxylates of the general formula [Cu(diphosphine)2](RCOO), R=C2F5, C4F9, C6F13, C8F17, C9F19, have been prepared and characterized with MS, IR and 1H, 31P, 13C, 19F, 63Cu NMR spectroscopy. The presence of distinct bis-chelated cations of [Cu(diphosphine)2]+ type and uncoordinated carboxylate anions has been proposed.

The 1 H{ 15 N} heteronuclear correlation and 15 N cross-polarized magic angle spinning NMR spectra of purine ( 1 ) were measured. The Zn(II) chloride complexes with 1 , 7-methylpurine ( 2 ) and 9-methylpurine ( 3 ) were synthesised and studied by analytical methods, far-IR and 15 N NMR. The formulae of ZnL 2 Cl 2 (L= 1 ) and [ZnLCl 2 ] n (L= 2 , 3 ) were found. The formation of Zn(II)N coordination bonds resulted in 3–15 ppm low-frequency shifts of the respective 15 N NMR signals: N-7 for 1 ; N-1, N-9 for 2 ; N-1, N-7 for 3 .

Platinum(II) complexes with 1,2,4-triazolo[1,5-a]pyrimidines of general formula trans-[PtCl2(dmso)(L)], where L=1,2,4-triazolo[1,5-a]pyrimidine (tp), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp), 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) have been prepared by direct reaction between cis-[PtCl2(dmso)2] and respective 1,2,4-triazolo[1,5-a]pyrimidine in molar ratio M:L=1:1. All new platinum(II) compounds were characterized by 1H, 13C, 15N, 195Pt NMR and IR. Significant 15N NMR upfield shifts (75–87 ppm) were observed for N(3) atom indicating this nitrogen atom as a coordination site. Crystal structure of trans-[PtCl2(dmso)(dmtp)] (2) has been determinated. The molecular structure indicates that Pt(II) ion has the square-planar geometry with N(3) bonded dmtp, S-bonded dimethylsulfoxide and two trans chloride anions.

Pt(II) and Pt(IV) chloride complexes with 1,2,4-triazolo-[1,5α]-pyrimidines: trans-[Pt(tp)2Cl2], trans-[Pt(dmtp)2Cl2], trans-[Pt(tp)2Cl4] and trans-[Pt(dmtp)2Cl4] where tp=1,2,4-triazolo-[1,5α]-pyrimidine and dmtp=5,7-dimethyl-1,2,4-triazolo-[1,5α]-pyrimidine were synthesised and studied by 1H, 13C, 15N, 195Pt NMR and IR spectroscopies. Significant 15N NMR upfield coordination shifts (92–96 ppm) were observed for the N(3) atom indicating that this nitrogen is the metallation site. The X-ray structure of an ionic pair (dmtpH)2[PtCl6] {bis(5,7-dimethyl-1,2,4-triazolo-[1,5α]-pyrimidinium) hexachloroplatinate(IV)} was determined, exhibiting the presence of unique (dmtpH)22+ dimeric cations, protonated at N(3), N(3′) atoms and linked by hydrogen bonding.

The 1H{15N} NMR spectrum of 5,7-diphenyl-1,2,4-triazolo[1,5-a]-pyrimidine (3) was measured by GHMQC, unambiguously assigned and compared with the spectra of 1,2,4-triazolo[1,5-a]pyrimidine (1) and 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (2). A series of Au(III) chloride complexes of general formula AuLCl3, where L = 1, 2, 3, was synthesized and studied by 1HH{15N} GHMQC and 1H{13C} GHMBC. Low-frequency shifts of 72–74 ppm (15N) and 5–6 ppm (13C) were observed upon complexation by Au(III) ions for the coordination site N-3 and adjacent C-2, C-3a atoms, respectively. The 13C signals of C-5, C-6, C-7 and the 1H resonances of H-2, H-6 were shifted to higher frequency. Comparison with analogous Pd(II), Pt(II) and Pt(IV) complexes revealed that in the case of Au(III) coordination the 15N shifts were relatively smaller, whereas those for 13C and 1H were larger. Copyright © 2002 John Wiley & Sons, Ltd.

Pd(II) and Pt(II) chloride organometallics with the deprotonated, N(1), C(2′)-chelating form of 2-phenylpyridine (2ppy*), i.e. [Pd(2ppy*)(μ-Cl)]2 (1) and [Pt(2ppy*)(μ-Cl)]2 (2), were studied by 1H, 13C, 15N, and 195Pt NMR in DMF-d7 and by 15N CP/MAS in the solid state. Both dimers immediately decompose in DMSO-d6, however, the products of this process are entirely different for 1 and 2. The cleavage of 1 is unusual among all described [M(2ppy*)(μ-X)]2 dimeric compounds as it yields, most likely, the [Pd(2ppy*)(DMSO-d6)2]+ [Pd(2ppy*)Cl2]− ionic pair, whereas 2 is known to undergo a more classical conversion into trans(S,N)-[Pt(2ppy*)(DMSO-d6)Cl]. The conclusions formulated for the above ionic pair were supported by quantum-chemical NMR calculations, calibrated specifically for this class of compounds (geometry optimization tested on molecular cluster, calibration of exact-exchange admixture in the PBE0 functional). The proposed computational approach is shown to be valid and suitable also for similar systems.

1,2,4-Triazolo-[1,5α]-pyrimidine (tp) was studied by gradient heteronuclear multiple-quantum correlation 15N–1H NMR and by cross-polarized magic angle spinning 13C, 15N NMR. The 15N signals were unambiguously assigned. The assignments of some IR absorption bands were proposed by comparison to purine and adenine spectra. The obtained results were used for the investigation of Zn(tp)2X2-type complexes (X=Cl, Br, I, NCS), suggesting a pseudo-tetrahedral configuration around the Zn(II) ion with unidentately N(3) bonded heterocycles and halides or thiocyanates (N bonded) in terminal positions. A slight shielding effect on the N(3) nucleus upon the formation of Zn(II)–N coordination bonding was observed.

Palladium(II) complexes of formula [Pd(tp)2Cl2] 1, [Pd(dmtp)2Cl2]·H2O 2, [Pd(dptp)2Cl2]·H2O 3, [Pd(dbtp)2Cl2] 4a, 4b, where tp = 1,2,4-triazolo[1,5-a]pyrimidine, dmtp = 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine, dptp = 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine, dbtp = 5,7-di-tert-butyl-1,2,4-triazolo[1,5-a]pyrimidine, were prepared. The crystal structure of [Pd(dbtp)2Cl2]·0.5 C2H5OH 4c was resolved by X-ray diffraction analysis, exhibiting monomeric, nearly square-planar cis geometry and N(3) co-ordination. A small tetrahedral distortion from the co-ordination plane was observed. The Pd–Cl distances are 2.276(1) and 2.283(1) A, and Pd–N 2.042(3) and 2.040(3) A. Spectroscopic measurements (UV-VIS, IR, NMR) suggested analogous structures for 1, 2 and 3. Compounds 4a and 4b are most likely rotational isomers in solution and distortional isomers in the solid state. 15N–1H heteronuclear correlation NMR was measured for 2, 4a and 4b whereas 1 and 3 were characterized with 13C and 15N CP MAS. Significant shielding of the co-ordinated N(3) and adjacent C(2) or C(3a) nuclei was observed.

Copper(II) complexes of formula Cu2(CH2ClCOO)4(dmtp)2 (1) and Cu2(CN2ClCOO)4(dptp)2 (2), wheredmtp=5,7-dimethyl-1,2,4-triazolo-[1,5-α]-pyrimidine anddptp=5,7-diphenyl-1,2,4-triazolo-[1,5-α]-pyrimidine, were obtained. The X-ray diffraction analysis of 1 exhibited the dimeric structure with chloroacetate bridges. The coordination sphere of Cu(II) ion is a slightly distorted square pyramid, with 4 equatorial carboxylic oxygens and anaxially N(3) bonded dmtp molecule. The distance Cu–Cu is 2.7035(7) Aand the distance between Cu and O4 plane is 0.239(1) A(towards the axial ligand). The distances Cu–O are 1.954(2)–1.981(2) A,Cu–N 2.150(1) A. The angles O–Cu–O are 87.88(8)–90.56(8)° and166.04(6)–166.07(5)°, O–Cu–N 90.08(7)–103.76(7)°. The O4 plane is not perpendicular to the Cu · · · Cu line, the angles O–Cu–Cu being 82.04(5)–84.00(5)° and N–Cu–Cu169.54(4)°. Spectroscopic (IR, UV, EPR) and magnetic studies suggested that 2 has the analogous structure to 1.

A review with 351 references. It collects the 15N and 31P NMR data for ca. 390 and ca. 340, respectively, complexes of transition metal ions such as Ni(0), Pd(0), Pt(0), Ni(II), Pd(II), Pt(II), Pd(IV), Pt(IV), Co(− 1), Rh(− 1), Rh(I), Ir(I), Co(III), Rh(III), Ir(III), Fe(− 2), Ru(− 2), Fe(II), Ru(II), Os(II), Cu(I), Ag(I), Au(I), Au(III), Zn(II), Cd(II), and Hg(II) with nitrogen-containing heterocycles (azines, azoles and azoloazines like purines or 1,2,4-triazolo-[1,5a]-pyrimidines), and their phosphorus analogues (phosphinines and phospholes). The 15N and 31P NMR coordination shifts, that is, the differences between 15N or 31P chemical shifts of the same nitrogen or phosphorus in the molecules of the complex and the ligand (Δ15Ncoord = δ15Ncompl − δ15Nlig; Δ31Pcoord = δ31Pcompl − δ31Plig), have been discussed in relation to some structural features of the reviewed coordination compounds, mainly to the type of the metal central ion and the donor atom in trans-position in respect to the concerned 15N or 31P nucleus.

In the title compound, [ZnCl2(C4H4N2)2], the tetrahedral coordination sphere of ZnII is formed by two Cl ions and two pyridazine ligands. The rings of the two pyridazine ligands in the coordination sphere are almost perpendicular to each other. Each pyridazine is involved in one C—H⋯Cl interaction but only one chloride participates in these contacts.

(1)H, (13)C, (195)Pt and (15)N NMR studies of platinide(II) (M = Pd, Pt) chloride complexes with such alkyl and aryl derivatives of 2,2'-bipyridine and 1,10-phenanthroline as LL = 6,6'-dimethyl-bpy, 5,5'-dimethyl-bpy, 4,4'-di-tert-butyl-bpy, 2,9-dimethyl-phen, 2,9-dimethyl-4,7-diphenyl-phen, 3,4,7,8-tetramethyl-phen, having the general [M(LL)Cl(2)] formula were performed and the respective chemical shifts (δ(1H), δ(13C), δ(195Pt), δ(15N)) reported. (1)H high-frequency coordination shifts (Δ(coord)(1H) = δ(complex)(1H)-δ(ligand)(1H)) mostly pronounced for nitrogen-adjacent protons and methyl groups in the nearest adjacency of nitrogen, as well as (15)N low-frequency coordination shifts (Δ(coord)(15H) = δ(complex)(15H)-δ(ligand)(15H)) were discussed in relation to the molecular structures.

(1)H, (13)C and (15)N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with dimethylpyridines (lutidines: 2,3-lutidine, 2,3lut; 2,4-lutidine, 2,4lut; 3,5-lutidine, 3,5lut; 2,6-lutidine, 2,6lut) and 2,4,6-trimethylpyridine (2,4,6-collidine, 2,4,6col) having general formulae [AuLCl(3)], trans-[PdL(2)Cl(2)] and trans-/cis-[PtL(2)Cl(2)] were performed and the respective chemical shifts (delta(1H), delta(13C), delta(15N)) reported. The deshielding of protons and carbons, as well as the shielding of nitrogens was observed. The (1)H, (13)C and (15)N NMR coordination shifts (Delta(1H) (coord), Delta(13C) (coord), Delta(15N) (coord); Delta(coord) = delta(complex) - delta(ligand)) were discussed in relation to some structural features of the title complexes, such as the type of the central atom [Au(III), Pd(II), Pt(II)], geometry (trans- or cis-), metal-nitrogen bond lengths and the position of both methyl groups in the pyridine ring system.

1H, 13C and 15N NMR studies of iron(II), ruthenium(II) and osmium(II) tris-chelated cationic complexes with 2,2′-bipyridine and 1,10-phenanthroline of the general formula [M(LL)3]2+ (M = Fe, Ru, Os; LL = bpy, phen) were performed. Inconsistent literature 1H signal assignments were corrected. Significant shielding of nitrogen-adjacent protons [H(6) in bpy, H(2) in phen] and metal-bonded nitrogens was observed, being enhanced in the series Ru(II) → Os(II) → Fe(II) for 1H, Fe(II) → Ru(II) → Os(II) for 15N and bpy → phen for both nuclei. The carbons are deshielded, the effect increasing in the order Ru(II) → Os(II) → Fe(II). Copyright © 2010 John Wiley & Sons, Ltd.

(1)H, (13)C and (15)N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with picolines, [Au(PIC)Cl(3)], trans-[Pd(PIC)(2)Cl(2)], trans/cis-[Pt(PIC)(2)Cl(2)] and [Pt(PIC)(4)]Cl(2), were performed. After complexation, the (1)H and (13)C signals were shifted to higher frequency, whereas the (15)N ones to lower (by ca 80-110 ppm), with respect to the free ligands. The (15)N shielding phenomenon was enhanced in the series [Au(PIC)Cl(3)]trans-[Pd(PIC)(2)Cl(2)]cis-[Pt(PIC)(2)Cl(2)]trans-[Pt(PIC)(2)Cl(2)]; it increased following the Pd(II) --Pt(II) replacement, but decreased upon the trans --cis-transition. Experimental (1)H, (13)C and (15)N NMR chemical shifts were compared to those quantum-chemically calculated by B3LYP/LanL2DZ + 6-31G**//B3LYP/LanL2DZ + 6-31G*.

The 15N NMR data for 105 complexes of Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with simple azines such as pyridine, 2,2'-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2'-biquinoline, 2,2':6', 2''-terpyridine and their alkyl or aryl derivatives have been reviewed. The 15N NMR coordination shifts, i.e. the differences between the 15N chemical shifts of the same nitrogen in the molecules of the complex and the ligand (Delta(15N) (coord) = delta(15N) (compl)--delta(15N) (lig)), have been related to some structural features of the reviewed coordination compounds, like the type of the central ion and the character of auxiliary ligands (mainly in trans position). These Delta(15N) (coord) parameters are negative, their absolute magnitudes (ca 30-150 ppm) generally increasing in the metal order Au(III) < Pd(II) < Pt(II) and Rh(III) < Co(III) < Pt(IV) < Ir(III), as well as with the enhanced trans influence of the other donor atoms (H, C << Cl < N).

Pd(II) and Pt(II) chloride complexes with LL = methyl cis-3,4-diamino-2,3,4,6-tetradeoxy-alpha-l-lyxo-hexopyranoside of the formulae [Pd(LL)Cl(2)] and [Pt(LL)Cl(2)], 1, were studied by (1)H, (2)H, (13)C, (15)N and (195)Pt NMR spectroscopy. These techniques were applied for characterization of the structure and ligand exchange dynamics, in case of diastereomeric species formed from 1 in DMSO-d(6), DMSO-h(6) and H(2)O; their general formula was [Pt(LL)XY](+) (X = Cl, Y = DMSO-d(6), 2a; X = DMSO-d(6), Y = Cl, 2b; X = Cl, Y = DMSO-h(6), 2a'; X = DMSO-h(6), Y = Cl, 2b'; X = Cl, Y = H(2)O, 3a; X = H(2)O, Y = Cl, 3b). Their theoretical structures and NMR parameters, calculated at the level of DFT approach, were also presented and compared to the experimental data. The model complex [Pt(trans-diaminocyclohexane)Cl(2)], 4, was studied as well. To the best of our knowledge, this work is the first account dealing with the detailed analysis of structure and dynamics of ligand exchange processes in organic solvents and water, performed for a PtCl(2) complex containing a diaminosugar moiety. The kinetic behavior of the studied coordination compounds suggests that some of them may be potentially active in bioassays against cancer cells. Compound 1 exhibits noticeable versatile ligand exchange possibilities in DMSO and H(2)O. Particularly, it undergoes solvolysis in DMSO-d(6), exchanging one chloride atom and yielding two diastereomers 2a and 2b; the former, being the kinetically favored species, has the DMSO-d(6) ligand syn to the N(3) atom. The lyophilisate of the respective 2a + 2b mixture, earlier equilibrated in DMSO-d(6), after dissolving in H(2)O yields only the latter isomer, which is thermodynamically favored. The solvolysis of 1 in H(2)O yields instantaneously two diastereomeric monoaquated species, 3a and 3b, amounting to 10% of each.

A series of Pd and Pt chloride complexes with pyridine (py), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), of general formulae trans-/cis-[M(pY)(2)Cl-2], [M(py)(4)]Cl-2, trans-/cis-[M(py)(2)Cl-4], [M(bpy)Cl-2], [M(bPy)Cl-4], [M(phen)Cl-2], [M(phen)Cl-4], where M = Pd, Pt, was studied by H-1, Pt-195, and N-15 NMR. The 90-140 ppm low-frequency N-15 coordination shifts are discussed in terms of such structural features of the complexes as the type of platinide metal, oxidation state, coordination sphere geometry and the type of ligand. The results of quantum-chemical NMR calculations were compared with the experimental N-15 coordination shifts, well reproducing their magnitude and correlation with the molecular structure.