Reactivity of [MO] (M = Tc, Re) core towards 2-mercapto-1,3-azole ligands. Formation of a new organometallic complex of Re(IV) and X-ray crystal structures

Imidazole-2-thiol derivatives H₂L^1-3 (H₂L¹ = 1H-benzoimidazole-2-thiol, H₂L² = 5-methyl-1H-benzoimidazole-2-thiol, and H₂L³ = 1H-imidazole-2-thiol) act as neutral monodentate ligands in a number of technetium and rhenium complexes. Disubstituted M(V) (M = Tc, Re) complexes of the type [AsPh₄]{[MOCl₂(H₂Lⁿ)₂(H₂O)]Cl₂} are formed when [MOCl₄]⁻ react with H₂L^1-3 in 1:2 stoichiometric ratio. Single crystal X-ray structure determinations were carried out on [AsPh₄]{[TcOCl₂(H₂L¹)₂(H₂O)]Cl₂}. The coordination sphere is pseudo-octahedral in which the sulfur atoms of two ligands sit in the equatorial plane and a water molecule is in trans to the TcO multiple bond. All the complexes react with an excess of the corresponding ligand to form tetrasubstituted cationic species {[MO(H₂Lⁿ)₄]Cl₃}. These complexes can be also isolated by reaction of [MOCl₄]⁻ with an excess of ligand. No complex is obtained with benzothiazole-2-thiol (HL⁴) and benzoxazole-2-thiol (HL⁵). Ligand exchange reactions of [ReOCl₃(PPh₃)₂] with HL^4,5 have also been investigated. Treating the oxo-precursor with HL⁴ no product is isolated, while with HL⁵ the chelate oxo-compound [ReOCl₂(L⁵)(PPh₃)] is formed as two isomers. An interesting organometallic complex of Re(IV) [ReCl₃(L^5∗)(PPh₃)₂] is obtained when a slight excess of HL⁵ reacts with [ReOCl₃(PPh₃)₂] in refluxing benzene solution and in air. Geometry about the Re atom is approximately octahedral in which the equatorial plane contains three Cl atoms and the carbon atom of the benzoxazole ligand anion, the apical positions are occupied by two PPh₃. The reaction with O-ethyl S-hydrogen p-tolyl carbonothioimidate HL⁶ which contains the same heteroatoms of HL⁵ does not form an organometallic species, but forms the chelate oxo-Re(V) complex [ReOCl₂(L⁶)(PPh₃)]. The solid-state structure has been authenticated by X-ray crystallography.     

Synthesis, characterizations and crystal structures of antimony(III) complexes with nitrogen-containing ligands

Six antimony adducts with N-donor neutral ligands (1,10-phenanthroline, 4,4′-bipyridine) have been obtained following the reaction of antimony halides with phenanthroline and 4,4′-bipyridine. By changing the solvent and stoichiometry, we obtained six different complexes, Sb(phen)Cl₃ (1), Sb(phen)Br₃ (2), Sb₂(phen)₄Br₈ (3) and Sb(bpy)Cl₃ (4), Sb(bpy)₂Cl₃ (5), Sb(bpyH · bpyH₂)Br₆ (6) (where phen = 1,10-phenanthroline, bpy = 4,4′-bipyridine). All the complexes have been characterized via elemental analysis, FT-IR and NMR (¹H, ¹³C) spectroscopy. The crystal structures of complexes 2, 3 and 6 have been determined by X-ray single crystal diffraction.The structural analysis show that the coordination sphere around antimony atom in complex 2 is a distorted square pyramid, coordinated by three bromine atoms and two nitrogen atoms from phen. In complex 3, the central antimony atom is six-coordinated through four bromine atoms and two nitrogen atoms forming a distorted octahedral geometry. Besides that, there are also uncoordinated 1,10-phenanthroline bonded by hydrogen bonds and π-π stacking interactions, which is rarely observed in previous reports. The crystal structure of complex 6 consists of bpyH · bpyH₂ trications and hexabromoantimonate trianions. The antimony atom in the anion has a distorted octahedral environment. Additionally, all complexes present a 3D framework built up by N-H?Br, C-H?Br and C-H?Cl weak hydrogen bonds interactions.     

Synthesis and crystal structures of water-soluble rhodium(III) complexes with 1,4,7-triazacyclononane and 2,2-bipyridine supporting ligands

New water-soluble rhodium(III) complexes with a tacn (1,4,7-triazacyclononane) and a bpy (2,2^′-bipyridine) supporting ligands were synthesized. The reaction of [Rh^III(tacn)Cl₃] (1) with equimolar amount of bpy and two equivalents of AgNO₃ in H₂O at reflux for 10 h gave a water-soluble chloro complex [Rh^III(tacn)(bpy)Cl](NO₃)₂ {2(NO₃)₂}. Complex 2(NO₃)₂ was treated with equimolar amount of AgNO₃ in H₂O at reflux for 10 h to give a water-soluble nitrato complex [Rh^III(tacn)(bpy)(NO₃)](NO₃)₂ {3(NO₃)₂}. Water-solubility of 3 with NO₃ ⁻ ligand (46.5 mg/mL) is high compared with that of 2 with Cl⁻ ligand (14.5 mg/mL) under the same conditions (at pH 7.0 at 25 °C). The structures of 2 and 3 were unequivocally determined by X-ray analysis. Their structures in H₂O were also examined by ¹H NMR, IR, and electrospray ionization mass spectrometry (ESI-MS).     

The synthesis and characterization of a cationic technetium(V) phenylimido complex. The X-ray crystal structure of [TcCl2(NPh)(PMe2Ph)3](BPh4)

The reaction of the neutral Tc(V) phenylimido complex [TcCl₃(NPh)(PPh₃)₂] with excess PMe₂Ph in refluxing MeOH gives the cationic, tris-dimethylphenylphosphine complex [TcCl₂(NPh)(PMe₂Ph)₃]⁺, which is isolated as the tetraphenylborate salt. The IR spectrum of the crystalline product shows a medium intensity band at 1102 cm⁻¹ which is assigned to ν(TcN) from the phenylimido core. The ¹H NMR spectrum of the diamagnetic complex shows a series of multiplets in the aryl region and three distinct signals near 2 ppm from the phosphine methyl groups. The X-ray crystal structure, which is the first for a cationic technetium organoimido complex, shows a meridional arrangement of phosphine ligands with a chloride ligand coordinated trans to the phenylimido unit. The TcN bond length of 1.711(2) Å is consistent with the dianionic nature of the organonitrogen core. The Tc---N---C bond angle of 178.8(2)° reflects the sp hybridization of the phenylimido nitrogen atom. The coordination geometry is best described as a distorted octahedron. Crystal data for C₅₄H₅₈BCl₂NP₃Tc: triclinic space group

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. Structure solution based on 9986 observed reflections converged at R = 3.65%, R_w = 5.43%, GOF = 1.82.     

Reactions of thioether carboxylic acids with mercury(II). Formation and X-ray crystal structure of mercury(II) mercaptoacetate

Reactions of Hg(II) salts with thioether carboxylic acids o-C₆H₄[CH(SCH₂COOH)₂]₂ (1a) and PhCH(SCH₂COOH)₂ (3) in water were found to lead to the decomposition of these ligands with the formation of mercury(II) mercaptoacetate Hg(SCH₂COOH)₂ (2) and aldehydes o-C₆H₄(CHO)₂ and PhCHO, respectively. A similar reaction was observed between Hg(NO₃)₂ and CH₃(CH₂)₂CH(SCH₂COOH)₂ (4). The X-ray structure of Hg(SCH₂COOH)₂ (2) shows a linear -S-Hg-S- moiety. The mechanism of the formation of 2 in the reactions between Hg²⁺ and thioether carboxylic acids in water is discussed.     

Synthesis and structural characterization of neutral “3 + 2” oxorhenium and oxotechnetium complexes of the 2-mercaptoethyl-N-glycine (SNO)/2,2′-bipyridine (NN) mixed ligand system

Neutral, hexacoordinated “3 + 2” mixed ligand oxorhenium (1) and oxotechnetium (2) complexes of the general formula MO[SNO][NN], where M = Re or ⁹⁹Tc, SNO is 2-mercaptoethyl-N-glycine and NN is 2,2′-bipyridine (bpy), were synthesized by simultaneous action of the tridentate SNO and the bidentate NN ligand on ReOCl₃(PPh₃)₂ or ⁹⁹TcO-gluconate precursors in a 1:1:1 molar ratio. Both complexes were characterized by elemental analysis, IR and NMR spectroscopy. X-ray structure determination of rhenium complex 1 revealed a distorted octahedral coordination geometry where the SNO donor atoms of the tridentate ligand and one bpy nitrogen atom occupy the equatorial positions of the octahedron, whereas the second bpy nitrogen atom and the oxo-group fill the apical positions.     

Synthesis, characterization and X-ray crystal structures of copper(II) and nickel(II) complexes with potentially hexadentate Schiff base ligands

Copper(II) and nickel(II) complexes of potentially N₂O₄ Schiff base ligands 2-({[2-(2-{2-[(1-{2-hydroxy-5-[2-phenyl-1-diazenyl]phenyl}methylidene)amino] phenoxy}ethoxy) phenyl]imino}methyl)4-[2-phenyl-1-diazenyl]phenol (H₂L¹) and 2-({[2-(4-{2-[(1-{2-hydroxy-5-[2-phenyl-1-diazenyl]phenyl}methylidene)amino] phenoxy}butoxy) phenyl]imino}methyl)4-[2-phenyl-1-diazenyl]phenol (H₂L²) prepared of 5-phenylazo salicylaldehyde (1) and two various diamines 2-[2-(2-aminophenoxy)ethoxy]aniline (2) and 2-[4-(2-aminophenoxy)butoxy]aniline (3) were synthesized and characterized by a variety of physico-chemical techniques. The single-crystal X-ray diffractions are reported for CuL¹ and NiL². The CuL¹ complex contains copper(II) in a near square-planar environment of N₂O₂ donors. The NiL² complex contains nickel(II) in a distorted octahedral geometry coordination of N₂O₄ donors. In all complexes, H₂L¹ behaves as a tetradentate and H₂L² acts as a hexadentate ligand. Cyclic voltammetry of copper(II) complexes indicate a quasi-reversible redox wave in the negative potential range.     

Linear and bent oxo-bridged dinuclear rhenium(V) complexes with terminal and bridging pyrazole ligands

The [ReOX₃(AsPh₃)(OAsPh₃)] (X = Cl or Br) complexes react with two equivalents of 3,5-dimetylopyrazole (3,5-Me₂pzH) in acetone at room temperature to give [{Re(O)X₂(3,5- Me₂pzH)₂}₂(μ-O)] (1 and 2). In the case of [ReOBr₃(AsPh₃)(OAsPh₃)], a small quantity of the dinuclear rhenium complex [{Re(O)Br(3,5-Me₂pzH)}₂(μ-O)(μ-3,5-Me₂pz)₂] (3) has been isolated next to the main product 2. Treatment of [ReOX₃(PPh₃)₂] compounds with two equivalents of 3,5-Me₂pzH in acetone at room temperature leads to the isolation of symmetrically substituted dinuclear rhenium complexes [{Re(O)X(PPh₃)}₂(μ-O)(μ-3,5-Me₂pz)₂] (4 and 5). Refluxing of [ReO(OEt)X₂(PPh₃)₂] complexes with 3,5-Me₂pzH in ethanol affords unsymmetrically substituted dinuclear rhenium [{Re(O)X(PPh₃)}(μ-O)(μ-3,5-Me₂pz)₂{Re(O)X(3,5- Me₂pzH)}] complexes (6 and 7). The complexes obtained in these reactions have been characterised by IR, UV-Vis, ¹H and ³¹P NMR. The crystal and molecular structures have been determined for 1, 2, 3, 4, 6 and 7 complexes.     

Syntheses, crystal structures, and characterization of heteronuclear complexes based on a versatile ligand with both acetylacetonate and bis(2-pyridyl) units

A new type of multidentate ligand with both acetylacetonate and bis(2-pyridyl) units on the 1,3-dithiole moiety, 3-[2-(dipyridin-2-yl-methylene)-5-methylsulfanyl-[1,3]dithiol-4-ylsulfanyl]-pentane-2, 4-dione (L), has been prepared. Through reactions of the ligand with Re(CO)₅X (X = Cl, Br), new rhenium(I) tricarbonyl complexes ClRe(CO)₃(L) (2) and BrRe(CO)₃(L) (3), have been obtained. With the use of 2 or 3 as the precursors, the further reactions with (Tp^Ph2)Co(OAc)(Hpz^Ph2) (Tp^Ph2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate); Hpz^Ph2 = 3,5-diphenyl-pyrazole) or M(OAc)₂(M = Mn, Zn), afford four new heteronuclear complexes: ClRe(CO)₃(L)Co(Tp^Ph2) (4), BrRe(CO)₃(L)Co(Tp^Ph2) (5), [ClRe(CO)₃(L)]₂Mn(CH₃OH)₂ (6) and [ClRe(CO)₃(L)]₂Zn(CH₃OH)₂ (7), respectively. Crystal structures of complexes 2 and 4-7 have been determined by X-ray diffraction. Their absorption spectra, photoluminescence and magnetic properties have been studied.     

Re(I)(tricarbonyl) complexes with the 2-(2-pyridyl)-N-methyl-benzimidazole, 2-(2-pyridyl)benzoxazole and 2-(2-pyridyl)benzothiazole ligands - syntheses, structures, electrochemical and spectroscopic studies

The reactions of Re(CO)₅Cl with the chelating ligands 2-(2-pyridyl)-N-methylbenzimidazole, 2-(2-pyridyl)benzoxazole and 2-(2-pyridyl)benzothiazole afforded neutral fac-Re(CO)₃(L)Cl and ionic complexes with structures confirmed by means of X-ray measurements. UV-vis absorption and emission properties have been studied at room and 77 K temperatures in order to determine the nature of the lowest electronically excited states. Electrochemical behaviour of the investigated fac-Re(CO)₃(L)Cl and complexes has been studied using cyclic and square-wave voltammetry. Preliminary results from the electrogenerated chemiluminescence studies of the ionic and the neutral fac-Re(CO)₃(MPBI)Cl complexes are briefly presented.     

Structural and magnetic properties of Ln(III) complexes with diimines and crotonato as a bridging ligand

Five new lanthanide complexes displaying crotonato bridges have been prepared: [Gd₂(crot)₆(H₂O)₄] · 4(bpa) (1); [Ho₂(crot)₇]_n · (Hbpa) (2); [Gd₂(crot)₆(bipy)₂] (3); [Ho₂(crot)₆(bipy)₂] (4) and [Nd₂(crot)₆(H₂O)₃]_n (5), where bipy=2,2^′-bipyridine; bpa=di(2-pyridyl)amine; crot=crotonato. The compounds were characterized by magnetic susceptibility measurements and their crystal structures were determined by single crystal X-ray diffraction. These studies showed complexes 1, 3 and 4 to be dimers while structures 2 and 5 are polymeric in nature.     

Rhenium(III) and rhenium(V) complexes stabilized by the potentially tetradentate ligand tris(2-diphenylphosphinoethyl)amine

The reaction of the rhenium(V) nitrido complex [Re(N)Cl₂(PPh₃)₂] with the tripodal ligand N(CH₂CH₂PPh₂)₃ (NP₃) in THF gave [Re(N)Cl₂(η²-P,P-NP₃)] (1) in which NP₃ acts as a tridentate ligand using the nitrogen and two phosphorus donors for coordination. Refluxing 1 in a polar solvent such as ethanol produced [(η⁴-NP₃)Re(N)Cl]Cl (2) in which NP₃ acts as a tetradentate ligand. Treatment of complex [Re(O)Cl₃(AsPh₃)₂] containing the [ReO]³⁺ core with NP₃ in THF yielded [ReCl₃{η³-N,P,P-(N{CH₂CH₂Ph₂}₂{CH₂CH₂P(O)Ph₂})}] (3). Complexes 1 and 3 have been characterized by single-crystal X-ray analyses.     

Syntheses and crystal structures of mononuclear and dinuclear (pentamethylcyclopentadienyl)iridium(III) complexes containing 2-mercaptobenzimidazole

A reaction of [Cp*IrCl₂]₂ {Cp* = η⁵-C₅(CH₃)₅} and 2-mercaptobenzimidazole (H₂bimt) in methanol in a 1:2 molar ratio gave a yellow complex of [Cp*IrCl₂(H₂bimt)]·CH₃OH (1). In compound 1 the H₂bimt acts as a monodentately S-donating (κS) ligand. A similar reaction of [Cp*IrCl₂]₂ and H₂bimt in the presence of NaOCH₃ (molar ratio of 1:2:2) gave an orange product (2) on addition of excess amount of NH₄PF₆. Compound 2 was composed of an unsymmetrical dinuclear complex cation, [(Cp*IrCl)₂(μ-Hbimt)(μ-H₂bimt)]⁺, a PF₆⁻ anion, and water molecules of crystallization. In the complex cation, H₂bimt bridges two Ir^III centers by S atom in the μ-κS:κS mode, while the monodeprotonated Hbimt⁻ ligand bridges via S and N atoms in the μ-κS:κN¹ mode.     

Photophysical properties, electronic and crystal structures of luminescent diphosphine digold(I)-pyridine-2-thiolate complexes

Treatment of diphosphine digold(I) complexes, PP(AuCl)₂ [PP=bis(diphenylphosphino)methane, dppm; 1,6-bis(diphenylphosphino)hexane, dpph], with two equivalents of pyridine-2-thiol (HNS) in the presence of NaOCH₃ affords two luminescent diphosphine digold(I)-pyridine-2-thiolate complexes, dppm(AuSN)₂ (1) and dpph(AuSN)₂ (2), respectively. Both crystal structures have been determined by crystallographic studies. The intramolecular aurophilic contact of 3.0478(3) Å is observed in the crystal structure of 1, whereas there is not any aurophilic interaction present in the crystal lattices of 2. At room temperature, 1 shows a low-energy emission at ca. 660 nm as well as a very weak high-energy emission at ca. 496 nm in the solid state, but 2 shows only a strong high-energy one at ca. 482 nm. Thus, the emission energy strongly dependent on the Au(I)?Au(I) interaction can be demonstrated in the diphosphine digold(I) thiolates studied herein.     

Tunable polymerization of silver complexes with organosulfur ligand: counterions effect, solvent- and temperature-dependence in the formation of silver(I)-thiolate(and/or thione) complexes

The reaction of pyridine-2-thiol with AgBF₄ and AgClO₄ in MeCN gave rise to polymeric compounds [{Ag(HPyS)₂}₂(BF₄)₂]_n (1) and [{Ag(HPyS)₂}₂(ClO₄)₂]_n (2) (HPyS=pyridine-2-thione), respectively, while the similar reaction of pyridine-2-thiol with AgNO₃ resulted in a polymeric compound [{Ag₄(HPyS)₆}(NO₃)₄]_n (3). X-ray single-crystal diffraction analyses showed that the cations of both 1 and 2 possess a single-metal-atom chain structure but that of 3 is a double-metal-atom chain structure. The difference between 1 (or 2) and 3 showed counterion effect in polymerization of silver-thione compounds. In the presence of water, the treatment of pyridine-2-thiol with AgBF₄ in DMF at 0 °C generated a polymeric compound [Ag(SPy)]_n (4) (Spy=pyridine-2-thiolate) with graphite-like layered array of silver ions. Compound 4 can convert into its isomer [Ag₆(SPy)₆]_n (5) through soaking in DMF for 1 month. However, the similar reaction of pyridine-2-thiol with AgBF₄ in MeCN-H₂O (v:v=40:1) at room temperature gave another layered polymeric compound [{Ag₅(Spy)₄(HPyS)}BF₄]_n (6). The preparation of 4, 5, and 6 showed that temperature and solvent exert influence on formation of silver-thiolate polymers. The reaction of AgNO₃ with K₂i-mnt (i-mnt=2,2-dicyanoethene-1,1,-dithiolate) and pyridine-2-thiol gave a polymer [Ag₄(μ₄-i-mnt)₂(μ-HPyS)₂(μ-HPyS)_4/2]_n (7) with one-dimensional (1-D) chain structure consisting of Ag₄ square planar cluster units linked by 1H-pyridine-2-thione ligand. The treatment of AgNO₃ with NaS₂CNEt₂ and pyridine-2-thiol in DMF resulted in another polymeric compound [Ag₄(μ₃-S₂CNEt₂)₂(μ₂-SPy)_4/2]_n (8). The preparation and characterization of these polymeric compounds demonstrated that polymerization of silver(I)-thione and silver(I)-thiolate complexes is tunable through controlling reaction conditions. Semiconducting property studies of 1-8 demonstrated that the electrical conductivity of 4 is 2.04×10⁻⁵ S cm⁻¹ at 25 °C and increases as temperature rises, and those of 1-3 and 5-8 are in the range of 1×10⁻¹²-1×10⁻¹⁵ S cm⁻¹ at room temperature and independent on the temperature, indicating that 1 is a semiconductor and the others are insulators.     

Manganese(II) complexes with croconate and 2-(2-pyridyl)imidazole ligands: Syntheses, X-ray structures and magnetic properties

The mixed-ligand complexes of manganese(II) of formula [Mn(pyim)₂(C₅O₅)] (1) and [Mn(pyim)(H₂O)(C₅O₅)]_n · 2.5nH₂O (2) [pyim = 2-(2-pyridyl)imidazole and  = croconate (dianion of 4,5-dihydroxy-4-cyclopentene-1,2,3-trione)] have been prepared and their structures determined by X-ray crystallographic methods. Compound 1 is a tris-chelated mononuclear complex where the manganese atom is six-coordinate: four nitrogen atoms from two pyim molecules and two oxygen atoms from a croconate group build a somewhat distorted octahedral surrounding around the metal atom. The resulting neutral mononuclear units are linked to each other through double bridges which are constituted by the imidazole N-H and the metal-coordinated croconate-oxygen atom, the metal-metal separation through this supramolecular pathway being 7.6856(11) Å. Compound 2 is a croconato-bridged manganese(II) uniform chain with an intrachain metal-metal distance of 7.5118(9) Å. A bidentate pyim group, a water molecule and four oxygen atoms from two bis-bidentate croconate ligands build an irregular seven-coordination polyhedron around each manganese atom in 2. The investigation of the magnetic properties of 2 in the temperature range 1.9-295 K has shown the occurrence of a weak antiferromagnetic interaction [J = −0.066 cm⁻¹ with the Hamiltonian defined as H = −J ∑_i S_i · S_i+1] through the bis-bidentate croconate. The ability of the bis-chelating croconate to mediante magnetic interactions between paramagnetic first-row transition metal ions is discussed and compared to that of the related oxalate ligand.     

Half-sandwich Mo(III) complexes with asymmetric diazadiene ligands

The asymmetric 1,4-diazadiene ligands R^∗NCHCHNR^∗ [R^∗ = (S)-CH(CH₃)Ph], , and 2,2′-bis(4-ethyloxazoline), as-ox, have been used to generate half-sandwich Mo^III derivatives by addition to Cp₂Mo₂Cl₄. Ligand affords a mononuclear, paramagnetic 17-electron product, , whereas as-ox leads to the isolation of a dinuclear compound where only one molecule of ligand has been added per two Mo atoms, Cp₂Mo₂Cl₄(as-ox). In the presence of free as-ox, this compound coexists with the paramagnetic mononuclear complex in solution. Both products are capable of controlling the radical polymerization of styrene under typical atom transfer radical polymerization (ATRP) conditions. However, the tacticity of the resulting polystyrene does not differ from that given by conventional free radical polymerization.     

Rhenium(IV) cyanate complexes: Synthesis, crystal structures and magnetic properties of NBu4[ReBr4(OCN)(DMF)] and (NBu4)2[ReBr(OCN)2(NCO)3]

Two new rhenium(IV) mononuclear compounds of formula NBu₄[ReBr₄(OCN)(DMF)] (1) and (NBu₄)₂[ReBr(OCN)₂(NCO)₃] (2) (NBu₄ = tetrabutylammonium cation, OCN = O-bonded cyanate anion, NCO = N-bonded cyanate anion and DMF = N,N-dimethylformamide) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. 1 crystallizes in the monoclinic system with the space group P2₁/n, whereas 2 crystallizes in the triclinic one with as space group. In both complexes the rhenium atom is six-coordinated, in 1 by four Br atoms in the equatorial plane, and two trans-oxygen atoms, one of a DMF molecule and another one from a cyanato group, while in 2 by one bromide anion and five cyanate ligands, two of which are O-bonded and three N-bonded, forming a somewhat distorted octahedral surrounding. Magnetic susceptibility measurements on polycrystalline samples of 1 and 2 in the temperature range 1.9-300 K are interpreted in terms of magnetically isolated spin quartets with large values of the zero-field splitting (|2D| is ca. 41.6 and 39.2 cm⁻¹ for 1 and 2, respectively).     

The synthesis and structural characterization of the technetium nitrosyl complexes [TcCl(NO)(SC5H4N)(PPh3)2] and [Tc(NO)(SC5H4N)2(PPh3)]

The reaction of the Tc(I) complex [Tc(NO)Cl₂(HOMe)(PPh₃)₂] with stoichiometric amounts of 2-mercatopyridine and a proton scavenger yields [Tc(NO)Cl(Spy)(PPh₃)₂] or [Tc(NO)(Spy)₂(PPh₃)], depending upon quantities of ligands employed. These two complexes have been structurally characterized. The small bite angles of the bidentate mercaptopyridine ligands cause significant deviation from octahedral coordination geometry.