Spectroscopic and kinetic study of the reaction of trans-nitrosylchlorobis(dimethylglyoximate)ruthenium(II) with acetone in the presence of amines

Summary The complex trans-[Ru(NO)(dmgH)₂Cl] (dmgH = dimethylglyoximate ion) reacts with Me₂CO in the presence of NH₃ or substituted amines such as MeNH₂ and 4-NH₂CH₂py (py = pyridine), to yield intermediate addition compounds of the general formula trans-[Ru(dmgH)₂Cl{N(OH)CHC(NHR)Me}]^-. The kinetic, analytical and spectroscopic (electronic, resonance Raman and i.r.) results are consistent with nucleophilic attack by enamines, e.g. CH₂=C(NHR)Me, on the coordinated NO⁺ ligand.     

Base hydrolysis of mono-alkylsubstituted chloropentaamminecobalt(III) complexes

Summary The preparation of the series ofcis- andtrans-[Co(NH₃)₄(RNH₂)Cl]²⁺ complexes (withcis, R = Me orn-Pr andtrans, R = Me, Et,n-Pr,n-Bu ori-Bu) is described. The u.v-visible spectra indicate a decrease of the ligand field on increasing chain length. Infrared spectra show an enhanced Co-Cl bond strength compared to the pentaammine. Partial molar volumes of the complex cations do not reveal steric compression. From proton exchange studies in D₂O it follows that [Co(NH₃)₅Cl]²⁺ and thecis- andtrans-[Co(NH₃)₄-(CH₃NH₂)C1]²⁺ complexes exchange the amine protons on the grouptrans to the chloro faster than those on thecis. A coordinated methylamine group exchanges its amine protons slower than a corresponding NH₃ group in the parent pentaammine, but the methyl introduction accelerates the exchange of the other NH₃ groups. The aquation of thetrans-alkylamine complexes (studied at 52° C) is acceleratedca. 10 times compared to the parent pentaammine, irrespective of the nature of the alkyl group. Thecis complexes do not show this acceleration of aquation. In base hydrolysis (studied at 25° C) thecis complexes are the most reactive (a factor 20 over the parent ion). Thecis/trans product ratio in base hydrolysis and the competition ratio in the presence of azide ions were calculated from the 500 MHz¹H n.m.r. spectra, which display distinctly different alkyl resonances for each individual complex. Thecis ions react under stereochemical retention of configuration; thetrans compounds give 10±1%trans tocis rearrangement. The ionic strength (4 mol dm^–3) and the pH do not affect this result. The same product ratio is obtained in methanol-water and DMSO-water mixtures. Ammoniation in liquid ammonia gives the same ratios as in base hydrolysis, base-catalyzed solvolysis in neat methylamine gives stereochemical retention for both thecis- andtrans-methylamine ion. The product competition ratio (Co-N₃)/(Co-OH₂) for thecis compounds and the bulkier amines (R =n- andi-Bu), 15–25% at 1 mol dm^–3N ₃ ^– , isca. twice that of thetrans compounds and the pentaammine. The results are interpreted in the classical conjugate base mechanism, and discussed in the context of current ideas about stereochemistry of base hydrolysis.Prof. C. R. Píriz Mac-Coll from Uruguay is a guest at the Free University of Amsterdam.     

A spectroscopic study of cobalt(III) furyldioximates

Summary The electronic properties of a series of cobalt(III)trans-furyldioximato-complexes of the type [CoB(FH)₂X] (B=NH₃, X=Cl, Br, I or NO₂; B=pyridine (py) or thiocarbamide (thio), X=Cl or Br; B=imidazole (imid), X=Br), [Co(FH₂)(FH)Cl₂] and [Co(thio)₂(FH)₂]NO₃ were studied by i.r., u.v. and¹H and¹³C n.m.r. spectra The results were compared with those from the corresponding dimethylglyoximato-complexes. It was concluded that -conjugation over the equatorial plane in the furyldioximates is greater than in the dimethylglyoximates. There is some evidence of thetrans-influence of the anionic ligands in the ammines which are in the order NO ₂ ^– >Br^–>Cl^–.     

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.     

Orientation and Restricted Rotation of Lopsided Aromatic Ligands. Octahedral Complexes Derived from cis-RuCl(2)(Me(2)SO)(4)

The solution and solid state structures of two octahedral Ru(II) complexes, cis,cis,cis-RuCl(2)(Me(2)SO)(2)(py)(Me(3)Bzm) (Me(3)Bzm = 1,5,6-trimethylbenzimidazole, py = pyridine) (1) and cis,cis,cis-RuCl(2)(Me(2)SO)(2)(Me(3)Bzm)(2) (2), were compared. 2, the subject of a preliminary report, is described in more detail here. 1 has two possible geometric isomers with py trans to Cl in one (position "a") and trans to Me(2)SO in the other (position "b"), Me(3)Bzm occupying the other position in each isomer. The X-ray structure of 1 revealed that py is at "a". Since Me(3)Bzm is lopsided, each Me(3)Bzm has two possible orientations related by a rotation of approximately 180 degrees about the Ru-N3 bond; there are two possible atropisomers for each geometric isomer of 1 and four for 2. For 1, the solid state structure shows that Me(3)Bzm adopts the orientation with H2 (H on C between the two N's) pointing between the two cis Cl ligands, the same disposition as Me(3)Bzm "b" in 2 in the solid. For 1, the py signals (two broad py alpha and beta signals, a sharp gamma signal) in CDCl(3) show that py "a" is rotating on the NMR time scale and that only one atropisomer is present. This interpretation was supported by ROESY and EXSY (1)H NMR spectra. The (1)H NMR shift pattern and the NOE data can be understood best if Me(3)Bzm "b" remains primarily in the orientation found in the solid. The solution data for 1, with the nonlopsided and sterically less demanding py ligand, provide insight into the more complicated properties of 2. For 2, there is a marked dispersion of (1)H NMR signals of Me(3)Bzm "a" between the two atropisomers, which have nearly equal stability. One atropisomer is a head-to-head (HH) and the other a head-to-tail (HT) species. Me(3)Bzm "a" flips between the two species. Thus, ligand "a" is fluxional in both complexes. The dispersion of Me(3)Bzm "a" signals is due to the effect of Me(3)Bzm "b" anisotropy. For 1 and both atropisomers of 2, Me(3)Bzm "b" prefers one orientation, which appears to be the most hindered orientation. We postulate that the H2 of Me(3)Bzm "b" is electrostatically attracted to the two cis halides, accounting for this surprising result. Crystallographic details for 1 are as follows: C(19)H(29)Cl(2)N(3)O(2)RuS(2), P2(1)/c, a = 10.947(1) ?, b = 9.046(1) ?, c = 24.221(2) ?, D(calcd) = 1.580 g cm(-)(3), Z = 4, R = 0.026 for 4627 independent reflections.     

Cobalt(II), nickel(II) and copper(II) complexes of 1-hydroxy-2-naphthyl(4-X-styryl)ketones

Summary Metal(II) bis-chelates of the type ML₂nB [M=Co^II, Ni^II, and Cu^II, L=1-hydroxy-2-naphthyl(4-X-styryl)ketone, (X=H, Me, Cl, MeO), B=H₂O, Py; n=0, 2] have been prepared and characterised by element analyses, i.r., ligand field spectra, magnetic moments and thermal studies. The copper(II) chelates are anhydrous monomers oftrans-square-planar configuration. The cobalt(II) and nickel(II) chelates, obtained as dihydrates, possess a high-spintrans-octahedral structure. Their anhydrides are polymeric. All the pyridine adducts have high-spintrans-octahedral geometry. The (M–O), order, namely Cu >Ni>Co, parallels the Irving-Williams order. The weak ligand field strength of 1-hydroxy-2-naphthyl(4-X-styryl)ketones is ascribed to inhibition of extensive conjugation arising from deviation of the naphthoyl group from planarity.     

Kinetic studies on the reactions of some tetrakis(arylisocyanide)cobalt(II) complexes with pyridine in 2,2,2-trifluoroethanol

The interaction of pyridine with four tetrakis(arylisocyanide)cobalt(II) complexes, [Co(CNR)₄(ClO₄)₂] R = 2,6-Me₂C₆H₃ (A), 2,4,6-Me₃C₆H₂ (B), 2,6-Et₂C₆H₃ (C) and 2,6-iPr₂C₆H₃ (D), have been studied in 2,2,2-trifluoroethanol medium. The kinetics of the reactions were investigated over the 293–318 K temperature range. The reaction profile exhibited two distinct processes, proposed to be an initial fast substitution followed by a slow reduction, for each of the reactions. The pseudo first-order rate constants for both processes increased with increasing concentration of pyridine with the reduction processes exhibiting saturation kinetics at high pyridine concentrations. Steric hindrance plays a significant role in the rates of the reactions, as the rates decrease in the order k(A) > k(B) > k(C) > k(D). The activation enthalpies, ΔH^‡, increase from A to D while the activation entropies, ΔS^‡, are relatively similar for the four reactions, indicating similar transition states and hence similar mechanisms. Complex B was first synthesized and characterized in this study.     

The crystal structure of tetraphenylarsonium tricyanooxopyridine-2-carboxylatotungstate(IV) dihydrate

Summary The structure of (AsPh₄)₂[WO(CN)₃(Pic)] · 2H₂O has been determined from three dimensional x-ray data. The cell dimensions are:a=17.699(8),b=13.546(6),c= 13.590(6) Å, =117.39(8), = 71.54(7) and = 115.04(8)°, space group P¯1, Z = 2, The structure was solved from 5279 observed reflections. The anisotropic refinement converged to R = 0.060.The [WO(CN)₃(Pic)]^2–-ion is a distorted octahedron. The structure indicates that the aqua group in [WO(CN)₄(H₂O)]^2– was displaced by an oxygen atom of the carboxylate of 2-picolinate, while a cyanide ligand was substituted by the pyridine nitrogen atom. Themer-arrangement of the three cyanide ligands has two normaltrans W-C_av = 2.17(2) Å bond distances and a significant shorter W-C = 2.042(18) Å bond trans to the W-N [2.188(18) Å] bond. The W=O and W-O bond lengths are 1.676(9)Å and 2.171 Å, respectively.     

Luminescent Palladium(II) Complexes with π‐Extended Cyclometalated [RC^N^NR′] and Pentafluorophenylacetylide Ligands: Spectroscopic,Photophysical, and Photochemical Properties

A series of cyclometalated Pd^II complexes that contain π‐extended R? C^N^N? R′ (R? C^N^N? R′=3‐(6′‐aryl‐2′‐pyridinyl)isoquinoline) and chloride/pentafluorophenylacetylide ligands have been synthesized and their photophysical and photochemical properties examined. The complexes with the chloride ligand are emissive only in the solid state and in glassy solutions at 77 K, whereas the ones with the pentafluorophenylacetylide ligand show phosphorescence in the solid state (λ_max=584–632 nm) and in solution (λ_max=533–602 nm) at room temperature. Some of the complexes with the pentafluorophenylacetylide ligand show emission with λ_max at 585–602 nm upon an increase in the complex concentration in solutions. These Pd^II complexes can act as photosensitizers for the light‐induced aerobic oxidation of amines. In the presence of 0.1 mol % Pd^II complex, secondary amines can be oxidized to the corresponding imines with substrate conversions and product yields up to 100 and 99 %, respectively. In the presence of 0.15 mol % Pd^II complex, the oxidative cyanation of tertiary amines could be performed with product yields up to 91 %. The Pd^II complexes have also been used to sensitize photochemical hydrogen production with a three‐component system that comprises the Pd^II complex, [Co(dmgH)₂(py)Cl] (dmgH=dimethylglyoxime; py=pyridine), and triethanolamine, and a maximum turnover of hydrogen production of 175 in 4 h was achieved. The excited‐state electron‐transfer properties of the Pd^II complexes have been examined.     

Crystal structure of tris(2-pyridylthio-2-pyridinium)pentaisothiocyanato-dioxouranate(VI)

Summary The crystal structure of [DPSH] ₃ ⁺ [UO₂[NCS)₅]^3– (DPSH = 2 pyridylthio-2-pyridinium) has been determined by standard methods using diffractometer data. Crystals are monoclinic, space groupP2₁/a, witha=33.16 (3),b=16.68(2),c=7.85(1) Å, and=97.3(1); D_c=1.65 g · cm^–3 for Z=4. The structure has been refined to R=5.8% by least squares methods. Five thiocyanate groups are equatorially bonded to the linear uranyl group. The mean of the five U-N, N-C, and C-S bond distances are 2.45, 1.17, and 1.59 Å respectively. The protonated DPS molecules have the N,N-inside conformations.     

Monodentate substitution reactions of [MO2(CN)4]n− type complexes: The crystal structure of the sodium thiocyanate adduct of tetramethylammonium tetracyanooxothiocyanatotungstate(IV)

The crystal structure of (Me₄N)₃[WO(CN)₄(NCS)]·NaNCS was determined from three-dimensional x-ray diffraction data. The dark blue crystals are monoclinic, space group C2/m, with cell dimensions a=13.105(4), b=12.688(2), c=18.871(3) Å, =100.4(8)°, z=4 and D=1.46 g cm^–3. Anisotropic refinement of 1333 observed reflections converged to R=0.068. The [WO(CN)₄(NCS)]^3– ion is a distorted octahedron with the tungsten atom displaced by 0.35 Å out of the plane formed by the four cyano ligands, towards the oxo ligand. The coordinated thiocyanate ligand is bonded to the tungsten atomvia the nitrogen atomtrans to the oxo ligand. Bond distances found: W–CN_av=2.14(3), W–O=1.61(2) and W–NCS=2.23(2) Å. The compound crystallizes as an adduct with an additional thiocyanate anion, ionically bonded to a severely disordered sodium cation. The results correlate with available data from similar complexes.     

Molecular structure and bonding properties of bis(1-methylimidazole)bis(perchlorato)bis(pyridineN-oxide)copper(II)

Summary The crystal and molecular structure of bis(1-methylimidazole)bis(perchlorato)bis(pyridineN-oxide)copper(II) have been determined using three-dimensional x-ray diffraction data. The complex crystallizes in space group P2₁/c with Z=2. The cell dimensions area=9.355(3),b=14.363(4),c=9.698(4) Å, and =106.40(3)^o. Least-squares refinement of the structure has yielded a final R value of 0.049 for 1235 independent reflections. The centrosymmetric structure consists oftrans pairs of 1-methylimidazole and pyridineN-oxide figands forming a square planar geometry with Cu–N and Cu–O bond lengths of 1.963(4) Å and 1.948(4) Å, respectively. The two perchlorate ions are located above and below the square plane with Cu–O distances of 2.590(5) Å. The uv-vis and i.r. spectra and bonding properties of the title compound are discussed with reference to the structure.     

The kinetics of base hydrolysis of [Co(trien)(amine)Cl]2+ complexes (amine=imidazole,pyridine,n-butylamine and 2,2-dimethoxyethylamine)

Summary The complexescis--[Co(trien)(ImH)Cl]²⁺ (ImH=imidazole, trien=1,8-diamino-3,6-diazaoctane),cis--[Co(trien)(Buⁿ-NH₂)Cl^–]²⁺,cis--[Co(trien)(NH₂CH₂-CH(OMe)₂)Cl^–]²⁺ andcis-₂-[Co(trien)(py)Cl]²⁺ (py=pyridine) have been characterised and their kinetics of base hydrolysis studied. Thecis--isomers which have afac-fac arrangement of the trien ligand have values of k _OH ²⁵ in the 73 to 253 dm³ mol^–1 s^–1 range at I=0.1 mol dm^–3. Extremely rapid base hydrolysis is observed withcis-₂-[Co(trien)(py)Cl]²⁺ where k _OH ²⁵ is 6.65×10⁶ mol³ mol^–1 s^–1 at I=0.1 mol dm^–3. This complex has amer-fac arrangement of the trien ligand with flatsec-NH donor leading to rapid base hydrolysis due to good -overlap between the conjugate base and cobalt(III). The pyridine ligand causes aca. 30 fold rate increase compared with the hydrolysis ofcis-₂-[Co(trien)(NH₃)Cl]²⁺.     

Kinetics and mechanism of the base hydrolysis of thecis-chlorobis(ethylenediamme)(benzimidazole)cobalt(III) cation

Summary The hydrolysis ofcis-[CoCl(en)₂(bzmH)]²⁺ (en=ethylenediamine, bzmH=benzimidazole) has been studied over the pH range 8.31–11.58 at I=0.1 mol dm^–3 and 25°. Potentiometric titration of aqueous solutions of the [Co(en)₂(bzmH)OH₂]³⁺ complex obtained by silver(I) catalysed aquation of the chloro-complex give pK₁=5.81 and pK₂ = 8.84 for Equilibria (1) and (2) at 25° and I=0.1 mol dm^–3. Spectrophotometric titration of the hydroxy complex also gives a value of pK₂=8.88 for the ionisation of the coordinated benzimidazole. The kinetic data can be interpreted in terms of base hydrolysis ofcis-[CoCl(en)₂(bzmH)]²⁺ (k_OH=220 dm³ mol^–1s^–1) andcis-[CoCl(en)₂(bzm)]⁺ (k_OH=14.9 dm³ mol^–1s^–1). Comparisons with the corresponding imidazole and pyridine complexes are made.     

Syntheses of organorhodium(I) and organ oplatinum(II) compounds by decarboxylation

Summary Decarboxylation of metal carboxylates provides a route to numerous main group element organometallics^{(1, 2)}, and to several transition metal organometaliics in which the central metal has a closed shell (d¹⁰) configuration^{(1, 2)}, e.g. organocopper(I) derivatives^(3–5). Extensions to compounds with non-d¹⁰ central metals are restricted to some organonickel(II) derivatives⁽⁶⁾. In addition,-allylplatinum(II) complexes have been prepared by decarboxylation of allyloxycarbonyl-andN-allylcarbamoylplatinum(II) compounds⁽⁷⁾, but the reactants are not carboxylato complexes since the -C(O)O-groups arecarbon-bonded to platinum. We now report decarboxylation syntheses of some organorhodium(I) and organoplatinum(II) compounds from suitable metal carboxylates.Reaction oftrans-RhCl(CO)(Ph₃P)₂ with some thallous polyfluorobenzoates, TlO₂CR, in pyridine at room temperature (R = C₆F₅) or on heating (R = C₆F₅,p-HC₆F₄ or m-HC₆F₄) resulted in decarboxylation and formation of the corresponding organorhodium compound (Table).     

Kinetics of acid- and iron(III)-catalysed aquation of cis-(salicylato)-(methyl/ethylamine) bis(ethylenediamine)cobalt(III)

Summary The kinetics of spontaneous, acid- and Fe^III-catalysed aquation of cis-[Co(en)₂(RNH₂)(SalH)]²⁺ complexes (R = Me, Et; SalH = C₆H₄(OH)CO _inf2 ^sup- ) were studied in acid perchlorate medium, I = 1.5 mol dm^–3 (NaClO₄) at 70–80°C. The Fe^III-catalysed aquation proceeds via formation of a binuclear species, the evidence of which follows from aquation, complexation and equilibrium studies. The spontaneous aquation rate shows steric acceleration with the increase of the nonlabile amine chain length, while that of acid- and Fe^III-catalysed aquation shows the opposite trend. An attempt is made to explain the discrepancy in the rate on the basis of solvent cosphere effects.     

Observedtrans influence of donor atoms in monocharged bidentate ligands: Crystal structure of the acetone solvate of 2-carboxyquinolinatocarbonyltriphenylphosphinerhodium(I)

Summary 2-Carboxyquinolinatocarbonyltriphenylphosphinerhodium(I), [Rh(Quin)(CO)(PPh₃)], was prepared by replacement of CO by PPh₃ in the corresponding dicarbonyl. The compound crystallizes in the triclinic space group Åb=17.168(6) Å,c=9.254(5) Å, =101.49(5)°, =95.74(4)°, =98.41(4)°, d_cxp=1.45g cm^–3 and Z=2. The crystal structure was dermined from 3496 observed reflections. The final R value was 0.061. This structure determination indicates that the nitrogen atom of the chelate ring has the largesttrans influence since the carbonyl grouptrans to this atom was substituted by the PPh₃ ligand. The effects of different donor atoms in bidentate ligands, as well as the ring size of the chelate ring, on the relativetrans influence of the donor atoms are discussed.     

Metal ion catalysed aquation of carboxylatoamine cobalt(III) complexes. Kinetics of copper(II) catalysed aquation ofcis(diformato)bis(ethylenediamine)cobalt(III) ion

Summary The aquation ofcis-[(en)₂Co(CO₂H)₂]⁺ tocis-[(en)₂Co(OH₂)(CO₂H)]²⁺ is catalysed by Cu²⁺ and the rate equation, –d[complex]_t/dt=(k_Cu[Cu²⁺]+k_H [H⁺]) [complex)_T is valid at [Cu²⁺]_T=0.01–0.1, I=0.5 and [HClO₄]=0.005 mol dm^–3. The rate measurements are reported at 30, 35, 40 and 45°C and the rate and activation parameters for the Cu²⁺ and H⁺-catalysed paths are: k_H(35°C)=(2.44±0.09)×10^–2 dm³ mol^–1 s^–1, H=83±13 kJ mol^–1, S=–8±42 JK^–1 mol^–1, k _Cu (35°C)=(3.30±0.09)×10^–3 dm³ mol^–1 s^–1, H=73.2±6.1 kJ mol^–1, S=–55±20 JK^–1 mol^–1. The formate-bridged innersphere binuclear complex,cis-[(en)₂Co{(O₂CH)₂Cu}]³⁺ may be involved as the catalytically active intermediate in the copper(II)-catalysed path, just as the corresponding H⁺-bridged species presumed to be present in the acidcatalysed path.     

(Imido)vanadium Complexes as Efficient Catalyst Precursors for Olefin Polymerization/Oligomerization

(Arylimido)vanadium(V) complexes containing anionic ancillary donor ligands of type, V(NAr)Cl₂(L) (Ar = 2,6-Me₂C₆H₃, L = aryloxo, ketimide phenoxyimine, etc.) exhibited high catalytic activities for ethylene polymerization in the presence of Al cocatalyst; V(NAr)Cl₂(O-2,6-Me₂C₆H₃) showed the exceptionally high activities in the presence of halogenated Al alkyls such as Et₂AlCl, EtAlCl₂, etc. (Arylimido)vanadium(V)-alkylidene complexes, V(CHSiMe₃)(NAr)(L′) (L′ = N=C ^t Bu₂, O-2,6- ⁱ Pr₂C₆H₃) exhibited the remarkable catalytic activities for ring-opening metathesis polymerization of norbornene. (Imido)vanadium(V) complexes containing the (2-anilidomethyl)pyridine ligand, V(NR)Cl₂[2-Ar′NCH₂(C₅H₄N)] (R = 1-adamantyl, cyclohexyl, phenyl, Ar′ = 2,6-Me₂C₆H₃, 2,6- ⁱ Pr₂C₆H₃), exhibit the remarkable activities for ethylene dimerization in the presence of MAO, affording 1-butene exclusively (selectivity 90.4 to >99%). The steric bulk of the imido ligand plays an important role in the selectivity, and the electronic nature directly affects the activity.     

Transition metal complexes with thiosemicarbazide-based ligands,Part IX. Cobalt(II) and nickel(II) complexes with 2-furaldehydeS-methylisothiosemicarbazone; crystal and molecular structure of aqua-bis(2-furaldehydeS-methylisothiosemicarbazone)cobalt(II)-diperchlorate

Summary The reaction of a warm ethanolic solution of Co^II perchlorate or rodanide and Ni^II acetate with 2-furaldehydeS-methylisothiosemicarbazone (HL), yielded the complexes [Co(HL)₂(H₂O)](ClO₄)₂ (1), [Co(HL)₃] [Co(NCS)₄] (2) and NiL₂, respectively. Both Co^II complexes are high-spin, whereas the Ni^II complex is in lowspin state (diamagnetic). An x-ray analysis of (1) showed it to have atrans-trigonal bipyramidal configuration in which one coordination site in the equatorial plane is occupied by one H₂O molecule. HL, a bidentate ligand, is coordinatedvia N(1) and N(4). The tris(ligand) cation in complex (2) has an octahedral configuration. Complex NiL₂ has a square-planar configuration.The deep purple plate-like crystals of (1) are monoclinic with space group C2/c, having cell parameters:a=11.369(3),b=13.029(4),c=17.438(5) Å; =103.39(2)^o. The structure was solved by the heavy-atom method and refined by least-squares method to an R value of 0.060 for 1761 observed reflections.