Reaction between palladium(II) and gallium(III) halogenides in arenes: influence of halogen nature on the formation of binuclear palladium(I) clusters

Palladium(II) bromide reacts with gallium(III) bromide in the presence of arenes yielding binuclear palladium(I) complexes [Pd₂(GaBr₄)₂(arene)₂], where arene=benzene (1), toluene (2) and p-xylene (3). Reaction of palladium(II) chloride with gallium(III) chloride in p-xylene leads to the analogous palladium(I) compound [Pd₂(GaCl₄)₂(p-xylene)₂] (4); the X-ray structures of 1-4 were determined.     

Thiacalix[4]arene-alkali metal assemblies: crystal structures and guest-binding capabilities of supramolecular architectures supported by metal coordination and cation-π interactions

To investigate alkali metal complexation with sulfur-linked calixarene analogues and their guest-binding properties for gaseous organic guest molecules, we elucidated a crystal structure of a cesium complex with p-H-thiacalix[4]arene (1·4H) ligands and guest-binding properties of the cesium complex (2) and the previously reported rubidium complex (3). In crystals of the complex 2, a ‘sandwich-like’ binuclear complex was formed by inter-molecular coordination of cesium cations to the thiacalixarene molecules and methanol molecules, mutually interacting by aromatic-H?S hydrogen bonding and alkali metal cation-π interactions between the alkali metal cation and thiacalixarene aromatic rings outside of the cavities. On the guest-binding behaviors both complexes 2 and 3 toward organic guest molecules, methanol, ethanol, and 1-propanol as polar molecules, the complex 2 has no methanol adsorption ability, but the complex 3 showed vapor adsorption properties for all guest molecules. In particular, both complexes exhibited a high adsorption capability toward ethanol molecule. As results of gaseous guest adsorption measurements for alcohol molecules, the guest-binding of these complexes are significantly different because the properties depend heavily on structural natures between complexes 2 and 3.     

Synthesis, characterization and structural studies of diorganotin(IV) complexes with Schiff base ligand salicylaldehyde isonicotinylhydrazone

Eight diorganotin(IV) complexes of salicylaldehyde isonicotinylhydrazone (H₂SalN) R₂Sn(SalN) R = t-Bu 1, Ph 2, PhCH₂3, o-ClC₆H₄CH₂4, p-ClC₆H₄CH₂5,m-ClC₆H₄CH₂6,o-FPhCH₂7, p-FC₆H₄CH₂8 were prepared. All complexes 1-8 have been characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR analyses. The crystal structures of H₂SalN and complex 1 were determined by X-ray crystallography diffraction analyses. Studies show that H₂SalN is a tridentate planar ligand. For complex 1, the tin atom lies in this plane and forms a five- and six-membered chelate ring with the tridentate ligand. A comparison of the IR spectra of the ligand with those of the corresponding complexes, reveals that the disappearance of the bands assigned to carbonyl unambiguously confirms that the ligand coordinate with the tin in the enol form.     

Synthesis, characterization and structural studies of palladium(II) complexes with N-(aroyl)-N′-(2,4-dimethoxybenzylidene)hydrazines

Reactions of Li₂[PdCl₄] with N-(aroyl)-N′-(2,4-dimethoxybenzylidene)hydrazines (H₂L = (4-R-C₆H₄)C(O)NHNCH(2,4-(CH₃O)₂C₆H₃)) in presence of PPh₃ have provided cyclopalladated complexes having the general formula [PdL(PPh₃)] (1, 2 and 3 where R = OCH₃, CH₃ and Cl, respectively) and a coordination complex trans-[Pd(HL)(PPh₃)₂Cl] (4 where R = NO₂). The complexes have been characterized by elemental analysis, infrared, ¹H NMR and electronic absorption spectroscopy. X-ray structures of all the complexes have been determined. In 1, 2 and 3, the C,N,O-donor dianionic ligand (L²⁻) forms two fused five-membered chelate rings at the metal centre. On the other hand, the monoanionic ligand (HL⁻) acts as deprotonated amide N-donor in 4. The strong electron withdrawing effect of the nitro group on the aroyl fragment is possibly responsible for the monodentate amide N-coordinating behavior of HL⁻ in 4. The orientation of the 4-methoxy group in 1 is different than that in 2 and 3 due to intramolecular C-H?π interaction in the last two complexes. The structure of 4 shows an apical C-H?Pd interaction involving the azomethine (-CHN-) group of HL⁻. In the crystal lattice of all the structures, various types of intermolecular non-covalent interactions are present. The self-assembly of the molecules of 1, 2 and 3 leads to two-dimensional networks. The same network observed for 2 and 3 reflects the interchangeability of the chloro and methyl groups due to their similar volumes. In the case of 4, the complex and the water molecules present in the crystal lattice form parallel homo-chiral helices and finally interhelical interactions lead to a three-dimensional network.     

Syntheses, characterization and crystal structures of di- and triorganotin (IV) derivatives with 6-amino-1,3,5-triazine-2,4-dithiol

A series of organotin (IV) complexes with 6-amino-1,3,5-triazine-2,4-dithiol of the type [(R_nSnCl_4−n)₂ (C₃H₂N₄S₂)] (n = 3: R = Me 1, n-Bu 2, PhCH₂3, Ph 4; n = 2: R = Me 5, n-Bu 6, PhCH₂7, Ph 8) have been synthesized. All the complexes 1-8 have been characterized by elemental analysis, IR, ¹H and ¹³C NMR spectra. Among them complexes 1, 4, 5 and 8 have also been characterized by X-ray crystallography diffraction analyses, which revealed that the tin atoms of complexes 1, 4, 5 and 8 are all five-coordinated with distorted trigonal bipyramid geometries.     

Syntheses, crystal structures and coordination modes of tri- and di-organotin derivatives with 2-mercapto-4-methylpyrimidine

The organotin (IV) derivatives of 2-mercapto-4-methylpyrimidine (Hmpymt) R₃SnL (R = Ph 1, PhCH₂2, n-Bu 3), R₂SnCl_mL_n (m = 1, n = 1, R = CH₃4, Ph 5, n-Bu 6, PhCH₂7; m = 0, n = 2, R = CH₃8, n-Bu 9, Ph 10, PhCH₂11) were obtained by the reaction of the organotin(IV) chlorides R₃SnCl or R₂SnCl₂ with 2-mercapto-4-methylpyrimidine hydrochloride (HCl · Hmpymt) in 1:1 or 1:2 molar ratio. All complexes 1-11 were characterized by elemental analyses, IR, ¹H, ¹³C and temperature-dependent ¹¹⁹Sn NMR spectra. Except for complexes 3 and 6, the structures of complexes 1, 2, 4, 5, 7, 8-11 were confirmed by X-ray crystallography. Including tin-nitrogen intramolecular interaction, the tin atoms of complexes 1-7 are all five-coordinated and their geometries are distorted trigonal bipyramidal. While the tin atoms of complexes 8-11 are six-coordinated and their geometries are distorted octahedral. Besides, the ligand adopts the different coordination modes to bond to tin atom between the complexes 1, 6, 7 and 2, 3, 4, 5, 8-11. Furthermore, intermolecular Sn?N or Sn?S interactions were recognized in crystal structures of complexes 4, 7 and 11, respectively.     

Ruthenium(III) and iridium(III) complexes with nicotine

A new chloride-dimethylsulfoxide-ruthenium(III) complex with nicotine trans-[Ru^IIICl₄(DMSO)[H-(Nicotine)]] (1) and three related iridium(III) complexes; [H-(Nicotine)]trans-[Ir^IIICl₄(DMSO)₂] (2), trans-[Ir^IIICl₄(DMSO)[H-(Nicotine)]] (3) and mer-[Ir^IIICl₃(DMSO)(Nicotine)₂] (4) have been synthesized and characterized by spectroscopic techniques and by single crystal X-ray diffraction (1, 2, and 4). Protonated nicotine at pyrrolidine nitrogen is present in complexes 1 and 3 while two neutral nicotine ligands are observed in 4. In these three inner-sphere complexes coordination occurs through the pyridine nitrogen. Moreover, in the outer-sphere complex 2, an electrostatic interaction is observed between a cationic protonated nicotine at the pyrrolidine nitrogen and the anionic trans-[Ir^IIICl₄(DMSO)₂]^¯ complex.     

Two three-dimensional silver(I) coordination architectures with pyridine-3,5-dicarboxylate: Luminescence and structural dependence on preparing conditions

The hydrothermal reactions of pyridine-3,5-dicarboxylic acid (H₂pydc) with AgNO₃ in the mixed solvent of acetonitrile and water with different ratios lead to the formation of two three-dimensional network complexes, [Ag₅(pydc)₂(CN)]_n (1) and {[Ag₄(pydc)₂]CH₃CN}_n (2), which have been characterized by IR, single-crystal X-ray diffraction and thermogravimetric analyses. It has been demonstrated that the ratio of acetonitrile and water have great effect on the structures of products. The high ratio of acetonitrile and water is favorable for the formation of complex 1, while the low volume ratio is propitious to complex 2. The luminescent properties of complex 1 and 2 have been further investigated, and show that the luminescence intensity of 2 is much stronger than that of 1 probably due to the direct metal-metal interactions and a larger HOMO-LUMO gap in complex 2.     

NMR, potentiometric and ESI-MS combined studies on the zinc(II) magnesium(II) and calcium(II) complexation by (morpholin-1-yl)methane-1,1-diphosphonic acid and its thio-analog

The crystal structures of the two derivatives of aminomethane-1,1-diphosphonic acid with morpholinyl- (1) and thiomorpholinyl- (2) side chains were determined by single crystal X-ray diffraction and discussed with respect to molecular geometry and solid state organization. The protonation equilibria, solution behavior and complex-formation equilibria in solutions of 1 and 2 with the Zn(II), Mg(II) and Ca(II) ions were studied by means of NMR, pH-potentiometry and ESI-MS methods.As the pK_(NH⁺) protonation constants of 1 and 2 are high (11.65 and 11.91, respectively) two different approaches were used to evaluate the pH-potentiometric data. The first approach disregarded the proton-dissociation from the NH⁺ group. In the second one, all the pK_a values were considered in the M(II):ligand formation equilibria. For 1, the accuracy of the pK_(NH⁺) determination was shown to be sufficient to calculate reliable stability constants of metal complexes with the use of both approaches. For 2, only approach neglecting the pK_(NH⁺) protonation constant was shown to be correct.The studied acids form dinuclear, [M₂L₃H_x], [M₂L₂H_x] and mononuclear MLH_x and ML₂H_x complexes with different degree of ligand protonation. Tendency to undergo some oligomerization with the increase in the metal and ligand concentration was demonstrated for the [CaLH] complex of 1 and 2. As far as 1 and 2 remain protonated, the Zn(II), Mg(II) and Ca(II) ions are coordinated exclusively through oxygen atoms of the phosphonate groups. The metal promoted proton dissociation from the NH⁺ ring atom takes place in alkaline pH.     

Synthesis, characterization, and coordination chemistry of two new tartaric acid-derived bis(phosphite) ligands

The syntheses of two chiral bis(phosphite) ligands with tartaric acid-derived backbones: 1 (from dimethyl tartrate) and 2 (from dipyrollidene tartramide), three complexes of 1: cis-Mo(CO)₄(1), cis-PtCl₂(1), and cis-PdCl₂(1) and two complexes of 2: cis-Mo(CO)₄(2) and cis-PdCl₂(2) are described. Each ligand and complex has been fully characterized by ¹H, ¹³C, and ³¹P NMR spectroscopy, and the coordination ³¹P NMR chemical shifts have been compared to those observed for complexes of related ligands. The X-ray crystal structures of each of the metal complexes have also been determined. The X-ray crystal structures indicate that the conformation of the seven-membered chelate ring varies depending on the substituents on the tartrate backbone. However, the conformations of the seven-membered rings do not change when the metal center is changed or when the coordination environment around the metal center is changed.     

Pyridine mediated supramolecular assemblies of 3,5-dinitro substituted benzoic acid, benzamide and benzonitrile

Synthesis and characterization of molecular assemblies of pyridine adducts, 1a, 2a and 3a, of 3,5-dinitrobenzoic acid, 1, 3,5-dinitrobenzamide, 2 and 3,5-dinitrobenzonitrile, 3, respectively, have been reported. All these adducts were obtained by crystallization of 1, 2 and 3 from pyridine. However, crystallization of 1 from pyridine in the presence of benzene resulted in the formation of a pyridinium adduct, 1b, along with a water molecule. All the adducts crystallize in a 1:1 molecular ratio except 1a, which forms a 1:2 adduct, as characterized by single crystal X-ray diffraction method. The adducts crystallize in different space groups—1a, orthorhombic, Pna2₁; 1b, monoclinic, P2₁; 2a, monoclinc, C2/c; 3a, triclinic, . In two-dimensional arrangement, 1a, 1b and 3a form sheet structures. In 1a, within the two-dimensional sheets, large cavities are formed, which are occupied by pyridine molecules. In 1b, the sheets are catenated to form a chicken-wire network. However, 2a formed a crossed ribbon packing pattern with empty channels in the three-dimensional structure.     

Synthesis and characterization of metal complexes of N-alkyl-N-phenyl dithiocarbamates

Ammonium N-ethyl-N-phenyl dithiocarbamate (L¹) and N-butyl-N-phenyl dithiocarbamate (L²), and their group 12 metal complexes formulated as Zn₂L¹₄, CdL¹₂, HgL¹₂, Zn₂L²₄, CdL²₂, HgL²₂ have been synthesized and characterized by elemental analyses, IR, ¹H and ¹³C NMR spectroscopy. The crystal structures of the zinc complexes (Zn₂L¹₄ and Zn₂L²₄) are also reported. Single crystal analyses of the two complexes revealed the presence of distorted trigonal bipyramidal and tetrahedral coordination geometry about the metal ions. The dithiocarbamate acts as bidentate chelating and bidentate bridging ligands between the metal ions giving centrosymmetric dimeric molecules. The apparent substitution of the ethyl substituents in L¹ by the butyl groups in L² results in profound change in structure.     

Synthesis,spectral, and structural investigation of [ML(NO3)2]: M = Co,Ni, Cu; L = N-(2-pyridylethyl)pyridine-2-methylketimine

Synthesis and structural characterization of distorted pentagonal bipyramidal Co(II), pseudo-octahedral Ni(II) and Cu(II) complexes of the type [ML(NO₃)₂], {L = N-(2-pyridylethyl)pyridine-2-methylketimine} are reported. Characterization includes elemental analysis, spectral, magnetism, and X-ray crystallographic studies. In case of cobalt (1) both the nitrates coordinate in bidentate fashion resulting overall distorted pentagonal bipyramidal geometry. In nickel (2) and copper (3) complexes, bivalent metal ion is coordinated by the three nitrogen atoms of the tridentate L with two pyridine-N occupying trans positions and amongst the two nitrates one coordinates in a bidentate fashion while other adopts a monodentate fashion. All the complexes exhibit d–d transitions in the visible region. Complex 1 is high-spin in nature and the X-band EPR spectra of 1, and 3 at room temperature and 77 K are reported.     

New N-pyrazole, P-phosphinite hybrid ligands and corresponding Rh(I) complexes: X-ray crystal structures of complexes with [Rh, N, P-phosphinite, Cl, (CO)] core

Two new N-pyrazole, P-phosphinite hybrid ligands 3-(3,5-dimethyl-1H-pyrazol-1-yl)propyldiphenylphosphinite (L³) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L⁴) are presented. The reactivity of these ligands and two other ligands reported in the literature (3,5-dimethyl-1H-pyrazol-1-yl)methyldiphenylphosphinite (L¹) and 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L²) towards [RhCl(CO)₂]₂ (1) have been studied and complexes [RhCl(CO)L] (L = L² (2), L³ (3) and L⁴ (4)) have been obtained. For L¹ only decomposition products have been achieved. All complexes were fully characterised by analytical and spectroscopic methods and the resolution of the crystalline structure of complexes 2 and 3 by single-crystal X-ray diffraction are also presented. In these complexes, the ligands are coordinated via κ²(N,P) to Rh(I), forming metallocycles of seven (2 and 4) or eight (3) members and finish its coordination with a carbonyl monoxide and a trans-chlorine to phosphorus atom. In both complexes, weak intermolecular interactions are present. NMR studies of complexes 2-4 show the chain N-(CH₂)_x-O becomes rigid and the protons diastereotopic.     

Syntheses, characterizations and crystal structures of triorganotin(IV) derivatives with 2-mercapto-4-quinazolinone

The triorganotin(IV) derivatives of 2-mercapto-4-quinazolinone (HSqualone) of the type, R₃SnL (R = Ph 1, CH₃2, PhCH₂3, p-F-PhCH₂4, o-F-PhCH₂5, n-Bu 6), were obtained by the reaction of the R₃SnCl and HSqualone with 1:1 molar ratio in benzene. All complexes 1-6 were characterized by elemental analyses, IR, ¹H and ¹³C NMR spectroscopy and the crystal structures of complexes 1-3 were also confirmed by X-ray crystallography. The structure analyses reveal that the tin atoms of complexes 1-3 are all distorted tetrahedral geometries. Furthermore, the dimeric structures in complexes 1-3 have also been found linked by intermolecular O-H?N or N-H?O hydrogen bonding interaction. Interestingly, the dimers of complexes 2 and 3 are further linked into one-dimensional chain through intermolecular C-H?S and C-H?O weak hydrogen bonding interactions, respectively.     

Half-sandwich binuclear carbaborane compounds: Closo-carbaboranes as good σ-donar ligands

The synthesis of half-sandwich binuclear transition-metal complexes containing the Cab^C,C chelate ligands (Cab^C,C = C₂B₁₀H₁₀ (1)) is described. 1Li₂ was reacted with chloride-bridged dimers [Cp∗RhCl(μ-Cl)]₂ (Cp∗ = η⁵-C₅(CH₃)₅), [Cp′RhCl(μ-Cl)]₂ (Cp′ = η⁵-1,3-^tBu₂C₅H₃), [Cp∗IrCl(μ-Cl)]₂ and [(p-cymene)RuCl(μ-Cl)]₂ to give half-sandwich binuclear complexes [Cp∗Rh(μ-Cl)]₂(Cab^C,C) (2), [Cp′Rh(μ-Cl)]₂(Cab^C,C) [3),[Cp∗Ir(μ-Cl)]₂(Cab^C,C) (4) and [(p-cymene)Ru(μ-Cl)]₂(Cab^C,C) (5), respectively. Addition reactions of the ruthenium complex 5 with air gave [(p-cymene)₂Ru₂(μ-OH)(μ-Cl)](Cab^C,C) (6), rhodium complex 2 with LiSPh gave [Cp∗Rh(μ-SPh)]₂(Cab^C,C) (7). The complexes were characterized by IR, NMR spectroscopy and elemental analysis. In addition, X-ray structure analysis were performed on complexes 2-7 where the potential C,C-chelate ligand was found to coordinate in a bidentate mode as a bridge.     

Synthesis,structure and properties of a series of scorpionate oxovanadium(IV)–carboxylate complexes

A series of oxovanadium(IV) complexes: TpVO(pzH)(2,4-Cl–C₆H₃–OCH₂COO) (1), TpVO(pzH)(C₆H₅–OCH₂COO) (2), TpVO(pzH)(p-Cl–C₆H₄–COO) (3), TpVO(pzH)(3,5-NO₂–C₆H₃–COO) (4), Tp∗VO(pzH∗)(p-Cl–C₆H₄–COO) (5) and Tp∗VO(pzH∗)(p-Cl–C₆H₄–COO) · CH₃OH (6) (Tp = hydrotris(pyrazolyl)borate, pzH = pyrazole, Tp∗ = hydrotris(3,5-dimethylpyrazolyl)borate, pzH∗ = 3,5-dimethylpyrazole) were synthesized and their crystal structures were determined by X-ray diffraction. In all the complexes, the vanadium ions are in a distorted-octahedral environment with a N₄O₂ donor set. Hydrogen bonding interaction exists in each complex. Complexes 1 and 2 are hydrogen-bonded dimers. Dimeric units of 2 are connected to one another via weak inter-molecular C–H···O interactions to form a 2D network on the bc-face. In 3–6 there exist intramolecular N–H···O hydrogen bonds between the neutral pyrazole/3,5-dimethylpyrazole and the uncoordinated carboxyl oxygen atom. In addition, the catalytic activity of complex 2 in a bromination reaction in phosphate buffer with phenol red as a trap was evaluated by UV–Vis spectroscopy. Furthermore, the elemental analyses, IR spectra and thermal stabilities were recorded.     

Cadmium–halide and mixed cadmium–halide–dicyanamide polymers mediated by ancillary 2-aminoalkyl-pyridine ligands: Synthesis,X-ray single crystal structures and luminescence property

A series of mixed halide–dicyanamide and halide complexes of cadmium(II) mediated by 2-aminoalkyl-pyridine ligands [2-aminomethylpyridine (ampy) and 2-aminoethylpyridine (aepy)] have been synthesized. Five of them, [CdCl(dca)(aepy)]_n (1), [CdBr(dca)(ampy)]_n (2), [CdCl(dca)(ampy)]_n (3) (dca = dicyanamide); [CdI₂(aepy)]_n (4), and [CdI₂(ampy)]_n (5), (dca = dicyanamide) have been characterized by X-ray single crystal structure analysis. The structural determination shows that the compounds are 1D coordination polymers, with the exception of 3 that gives origin to a 2D sheet-like network. The ampy and aepy ligands (also with the occurrence of dca anions in 1–3) reveal to be useful ancillary fragments for the construction of unprecedented Cd–halide polymeric species. The crystal packing shows that the dimensionality of all compounds is enlarged to 2D, and 3D in the case of complex 3, through π–π interactions occurring between the pyridine rings. All the species exhibit interesting luminescence property in solution as well in solid state which is originated from ligand-centered π–π^∗ transitions. The fluorescence band maxima and fluorescence efficiency (in methanol) are found to be dependent not only on the pyridine ligand but also on the type of halide, and the co-ligand. Solid state luminescent study implies that π–π interactions occurring between pyridine rings are also important in controlling the fluorescence intensity. Amongst the synthesized complexes reported, complex 5 exhibits the highest fluorescence efficiency in methanol.     

Synthesis and characterization of half-sandwich Rh, Ir complexes containing mono-thiolate-ortho-carborane ligand

Two binuclear complexes [Cp^∗M(Cl)Carb^S]₂ (Cp^∗ = η⁵-C₅Me₅, M = Rh (1a), Carb^S = SC₂(H)B₁₀H₁₀, Ir (1b)) were synthesized by the reaction of LiCarb^S with the dimeric metal complexes [Cp^∗MCl(μ-Cl)]₂ (M = Rh, Ir). Four mononuclear complexes Cp^∗M(Cl)(L)Carb^S (L = BuⁿPPh₂, M = Rh (2a), Ir (2b); L = PPh₃, M = Rh (4a), Ir (4b)) were synthesized by reactions of 1a or 1b with L (L = BuⁿPPh₂ (2); PPh₃ (4)) in moderate yields, respectively. Complexes 3a, 3b, 5a, 5b were obtained by treatment of 2a, 2b, 4a, 4b with AgPF₆ in high yields, respectively. All of these compounds were fully characterized by IR, NMR, and elemental analysis, and the crystal structures of 1a, 1b, 2a, 2b, 4a, 4b were also confirmed by X-ray crystallography. Their structures showed 3a, 3b and 5a, 5b could be expected as good candidates for heterolytic dihydrogen activation. Preliminary experiments on the dihydrogen activation driven by these half-sandwich Rh, Ir complexes were done under mild conditions.     

Mixed ligand complexes of AEE hexafluoroacetylacetonates with diglyme: Synthesis,crystal structure and thermal behavior

The novel mixed ligand complexes [Ca(hfa)₂(diglyme)(H₂O)] (I), [Sr(hfa)₂(diglyme)(H₂O)] (II) and [Ba(hfa)₂(diglyme)₂] (III) (Hhfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, diglyme = 2,5,8-trioxanonane) were synthesized by the reactions of the alkaline earth element (AEE) carbonates in n-hexane with a mixture of Hhfa and diglyme, and they were characterized by elemental analysis, ¹H and ¹³C NMR, and FTIR spectroscopy. The crystal structures of I–III, consisting of mononuclear isolated molecules, have been determined. The thermal behavior and composition of the vapor phase have been studied for I–III by thermal analysis at low pressure and mass spectrometry using a Knudsen cell. The stability of the mixed ligand complexes [M(hfa)₂(diglyme)_n] to the removal of diglyme molecules under heating decreases in the row I > II ≈ III, and only I evaporates as the mixed ligand complex after water removal.