Acetylacetonato Complexes Research Articles

Studies on Coloring to Titanium (IV) Acetylacetonato Complex and Its Application to Coloring Pattern (Part 1)

Studies on Coloring to Titanium (IV) Acetylacetonato Complex and Its Application to Coloring Pattern (Part 1)

Composition related properties of (Yb,Y) 2O 3 nanoparticles synthesized by controlled thermal degradation of AA complexes

After controlled thermal degradation of acetylacetonato (AA) complexes, mixtures of monodisperse ∼5 nm large isometric particles of Y 2− x Yb x O 3 ( x = 0.06, 0.10, 0.20, 0.40) were synthesized. Detailed information on nanoparticles’ microstructure and core crystal structure is reported. The Yb 3+ ions occupy preferently C 3i sites for low Yb 3+ concentrations, while for 20 at.% Yb 3+, a random distribution was found. It was shown that the particle/crystallite size and strain as well as Raman modes positions and widths are influenced by Yb 3+ concentration. Crystallographic and Raman spectroscopy results indicate that the particles are core/shell structured with cubic crystalline core and monoclinic-like disordered shell. Most probable particle's shell/core volume ratio decreased with annealing at 500 °C and the shell disappeared when annealed at 1000 °C.

Synthesis, Characterization, Defect Chemistry, and FET Properties of Microwave-Derived Nanoscaled Zinc Oxide

The formation of nanoscale zinc oxide particles with an almost-monomodal size distribution synthesized by microwave heating of solutions of mononuclear zinc oximato or zinc acetylacetonato complexes in various alkoxyethanols is investigated. Transparent stable suspensions that contain these particles can be obtained from the zinc oximato precursor. Based on electron paramagnetic resonance (EPR) studies, a core/shell model with a finite surface shell thickness of 1.000 ± 0.025 nm is proposed for the ZnO nanoparticles. Field-effect transistor (FET) devices with these ZnO particles as the active semiconducting layer exhibited a charge carrier mobility of 0.045 cm2/(V s) and Ion/off current ratios of ∼460.000, with a threshold voltage of 8.78 V.

Steric vs. electronic anomaly observed from iodomethane oxidative addition to tertiary phosphine modified rhodium(i) acetylacetonato complexes following progressive phenyl replacement by cyclohexyl [PR3 = PPh3, PPh2Cy, PPhCy2 and PCy3

Rhodium(i) acetylacetonato complexes of the formula [Rh(acac)(CO)(PR(3))] [acac = acetylacetonate, PR(3) = PPh(3) 1, PCyPh(2) 2, PCy(2)Ph 3, PCy(3) 4] were synthesized and the iodomethane oxidative addition to these complexes were studied. Spectroscopic and low temperature (100 K) single crystal X-ray crystallographic data of the rhodium complexes (1-4) indicate a systematic increase in both steric and electronic parameters of the phosphine ligands as phenyl groups on the tertiary phosphine are progressively replaced by cyclohexyl groups in the series. Second order rate constants for the alkyl formation in the oxidative addition of iodomethane in dichloromethane at 25 degrees C vary with approximately one order-of-magnitude from 6.98(6) x 10(-3) M(-1)s(-1) (PCyPh(2)) to 55(1) x 10(-3) M(-1) s(-1) (PCy(2)Ph 3) and do not follow the expected electronic pattern from to 1-4, which indicates a flexibility of the cyclohexyl group, significantly influencing the reactivity. Activation parameters for the reactions range from 35(3) to 44(1) kJ mol(-1) for DeltaH( not equal) and -140(5) to -154(9) J K(-1) mol(-1) for DeltaS( not equal), and are supporting evidence for an associative activation for the oxidative addition step.

On the Synthesis and Chemical Behaviour of the Elusive Bis(hydrosulfido)-Bridged Dinuclear Rhodium(I) Complexes [{Rh(μ-SH)(CO)(PR3)}2

Several bis(hydrosulfido)-bridged dinuclear rhodium(I) compounds, [{Rh(mu-SH)(L)(2)}(2)], have been prepared from rhodium(I) acetylacetonato complexes, [Rh(acac)(L)(2)], and H(2)S(g). Reaction of [Rh(acac){P(OPh)(3)}(2)] with H(2)S(g) affords the dinuclear bis(hydrosulfido)-bridged compound [{Rh(mu-SH){P(OPh)(3)}(2)}(2)] (1). However, reaction of complexes [Rh(acac)(CO)(PR(3))] with H(2)S(g) gives the dinuclear compound [{Rh(mu-SH)(CO)(PR(3))}(2)] (R=Cy, 2; R=Ph, 4) and the trinuclear cluster [Rh(3)(mu-H)(mu(3)-S)(2)(CO)(3)(PR(3))(3)] (R=Cy, 3; R=Ph, 5). The selective synthesis of both type of compounds has been carried out by control of the H(2)S(g) concentration in the reaction media. The trinuclear hydrido-sulfido cluster [Rh(3)(mu-H)(mu(3)-S)(2)(CO)(3)(PPh(3))(3)] (5) has been also obtained by reaction of [{Rh(mu-SH)(CO)(PPh(3))}(2)] (4) with [Rh(acac)(CO)(PPh(3))], proceeding through the trinuclear hydrosulfido-sulfido intermediate [Rh(3)(mu(3)-SH)(mu(3)-S)(CO)(3)(PPh(3))(3)]. The molecular structures of complexes 1 and 3 have been determined by X-ray diffraction methods. Compound 1 is stable in solution, but complexes 2 and 4 slowly transform in solution into the trinuclear hydrido-sulfido clusters 3 and 5, respectively, with the release of H(2)S(g) in a reversible way. (1)H NMR kinetic experiments for the transformation of 4 into 5 have revealed that this transformation follows second-order-type kinetic. The following activation parameters, DeltaH( not equal)=24+/-3 kJ mol(-1) and of DeltaS( not equal)=-223+/-8 J K(-1) mol(-1), have been calculated from the determination of the second-order rate constants in the temperature range 30-45 degrees C. The large negative value of the activation entropy is consistent with an associative character of the rate-determining step. A plausible multistep mechanism based on the chemical behaviour of hydrosulfido-metal complexes and compatible with the kinetic behaviour has been proposed.

Metal Oxide Nanocrystals from the Injection of Metal Oxide Sols in a Coordinating Environment: Principles, Applicability, and Investigation of the Synthesis Variables in the Case Study of CeO2 and SnO2

Metal oxide sols (ZnO, SnO2, TiO2, ZrO2, Fe2O3, NiO, Ga2O3, MnO2, In2O3, CeO2) were prepared by hydrolysis of chloro-alkoxo or acetylacetonato complexes, preventing precipitation. The sols were injected in a solution of tetradecene and an aliphatic amine at 160 °C and heated at the resulting temperature for 3 h, resulting in the formation of metal oxide nanoparticles. The crystallization degree of the resulting nanoparticles depended on the particular system, and nanocrystals were obtained for ZnO, SnO2, Fe2O3, Ga2O3, In2O3, CeO2 systems. The chemical features of the process were investigated on SnO2 and CeO2 as case systems, by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. The initial hypothesis that the amine present in the injection solution may act at the same time as a catalyst of the inorganic condensation reactions and as a growth stopper by bonding to the surface metal atoms of the nanoparticles, was thoroughly investigated and it resulted that the alkylamine structure and the processing of the starting sol can influence the nanocrystal formation pathway. In particular, bulkier amines favor the formation of smaller nanocrystals, whereas favoring the condensation reactions in the starting sols results in larger nanocrystals.

New Bis(oxazolinyl)phenyl−Ruthenium(II) Complexes and Their Catalytic Activity for Enantioselective Hydrogenation and Transfer Hydrogenation of Ketones

Synthesis and characterization of ruthenium(II) complexes having a meridional bis(oxazolinyl)benzene (dm-Phebox-R)H (1a: R = ip, 1b: R = ph, 1c: R = dm; ip = isopropyl, dm = dimethyl, ph = phenyl) ligand and their applications to enantioselective hydrogenation and transfer hydrogenation of simple ketones are described. Reaction of (dm-Phebox-R)H with RuCl3·3(H2O) in the presence of Zn and 1,5-cyclooctadiene (cod) afforded a ZnCl4-bridged (Phebox)Ru dimer [(dm-Phebox-R)RuCl(CO)]2(ZnCl2) (2a, 2b, and 2c) in 73%, 58%, and 83% yield, respectively, through C−H bond activation. Treatment of 2a−c with an excess amount of sodium acetylacetonate gave the corresponding acetylacetonato complexes (dm-Phebox-R)Ru(CO)(acac) (3a−c) in high yields. Such acetylacetonato complexes (3) were prepared by a one-pot reaction of 1 with RuCl3·3(H2O) in the presence of Zn and cod under reflux in ethanol, followed by treatment of acetylacetone at room temperature. The reaction of 2 generated in situ with CO (1 atm) also provided th...

Synthesis, Characterization, and Reactivity of Rhodium(I) Acetylacetonato Complexes Containing Pyridinecarboxaldimine Ligands

Addition of o-C 6H 4NCHNAr to Rh(coe) 2(acac) (coe = cis-cyclooctene, acac = acetylacetonato) gave several new iminopyridine rhodium(I) complexes of the type Rh(acac)(kappa (2)- o-C 6H 4 NCH NAr) ( 1a Ar = 4-C 6H 4-OMe; 1b Ar = 2,6-C 6H 3-Me 2; 1c Ar = 2,6-C 6H 3-Et 2; 1d Ar = 2,6-C 6H 3- i-Pr 2). All new rhodium complexes have been characterized by a number of physical methods, including multinuclear NMR spectroscopy and X-ray diffraction studies for 1b and 1c. Addition of CHCl 3 to 1a afforded the corresponding rhodium(III) complex trans-Rh(kappa (2)- o-C 6H 4 NCH NAr)(CHCl 2)(Cl)(acac) ( 2). Addition of B 2cat 3 (cat = 1,2-O 2C 6H 4) to 1 gave zwitterionic Rh(eta (6)-catBcat)(kappa (2)- o-C 6H 4 NCH NAr) ( 3). The molecular structure of 3b has been confirmed by a single crystal X-ray diffraction study and shows that the N 2Rh fragment is bound to the catBcat anion via one of the catecholato groups in a eta (6)-fashion. These complexes have also been examined for their ability to catalyze the hydroboration of a series of vinylarenes. Reactions using catecholborane and pinacolborane seem to proceed largely through a dehydrogenative borylation mechanism to give a number of boronated products.

Binuclear Nickel and Copper Complexes with Bridging 2,5-Diamino-1,4-benzoquinonediimines: Synthesis, Structures, and Catalytic Olefin Polymerization

A series of binuclear, divalent nickel and copper acetylacetonato complexes of the type [M(acac){µ-C6H2(═NAr)4}M(acac)] (M = Ni, Cu) have been synthesized by reaction of the corresponding M(acac)2 precursor with various bulky steric hindrace π-acceptor N-substituted 2,5-diamino-1,4-benzoquinonediimines C6H2(NHAr)2(=NAr)2 (1a, Ar = 4-C6H4Me; 1b, Ar = 2-C6H4Me; 1c, Ar = 2,6-C6H3Me2), which are metalated and become bridging ligands. The ligands and complexes were determined by IR and UV–visible spectra and element analysis. Cyclic voltammetric behavior of complexes 2c and 3c has been tested. The molecular structures of the ligand 1c and the complexes [Ni(acac){µ-C6H2(═N(4-methyl-Ph))4}Ni(acac)]) (2a), [Ni(acac){µ-C6H2(═N(2,6-dimethyl-Ph))4}Ni(acac)]) (2c), and [Cu(acac){µ-6H2(═N(2,6-dimethyl-Ph))4}Cu(acac)]) (3c) have been determined by X-ray diffraction. The coordination geometry around the metal ions of the Ni and Cu complexes is square-planar, and a complete electronic delocalization of the quinonoid π-system occurs between the metal centers over the two N═C–C═C═N halves of the ligand. In the presence of MAO as cocatalyst, all the Ni complexes exhibited high activities both for addition polymerization of norbornene and for methyl methacrylate (MMA) polymerization, which produce syndiotactic-rich poly(methyl methacrylate) (PMMA) with broad molecular weight distribution; however, the Cu complexes show moderate activities for norbornene polymerization and are inactive for MMA polymerization.

Structure and Bonding in Some Gd(III) Metal Complexes Studied by Three-Dimensional X-Ray Analysis and 155Gd Mössbauer Spectroscopy

Some functional lanthanide metal complexes, such as acetylacetonato complexes, ethylenediaminetetraacetato complexes, were successfully applied for diagnostic technique. The authors are interested in investigating the structure and bonding in lanthanide and actinide metal complexes using 166Er, 155Gd, and 237Np Mössbauer spectroscopies in connection with single-crystal and/or powder X-ray diffraction, making clear the differences on their structures as well as the differences in the participation of 4f and 5f orbitals in the chemical bonds. In this article, the crystal structures of two novel Gd(III) acetylacetonato complexes, Gd(pta) 3 · 2H 2O (pta = 1, 1, 1-trifluoro-5, 5-dimethyl-2, 4-hexanedione) and Gd(bfa) 3 · 2H 2O (bfa = 1, 1, 1-trifluoro-4-phenyl-2-4-butanedione) were reported. Though both of them were dihydrate and had distorted square antiprismatical structure, Gd(pta) 3 · 2H 2O crystallizes in the P 2 1/n (#14) monoclinic space group and its lattice parameters are a =1.4141(6) nm, b = 1.0708(3) nm, c =2.2344(4) nm, β=95.24(2)°, and Gd(bfa) 3 · 2H 2O crystallizes in P2 12 12 1 orthorhombic space group and its lattice parameters were a= 1.322(1) nm, b =2.295(1) nm, c = 1.0786(8) nm. In the meantime, the authors had finished a systematic investigation on the 155Gd Mössbauer isomer shift (δ) of various Gd(III) metal complexes having a different coordination number (C.N.) and different ratios coordinating oxygen to nitrogen. A tendency for the δ value to decrease with an increase in the C.N, and the number of the nitrogen atom coordinating to Gd was confirmed. This indicated that the Gd-O and/or Gd-N bond in the investigated Gd(III) metal complexes had a small covalent contribution, which was possible to be deduced from the O and/or N atoms of the ligands donating electrons to 6s, 5d, and 4f orbitals of Gd.

Synthesis, Coordination and Catalytic Utility of Novel Phosphanyl–ferrocenecarboxylic Ligands Combining Planar and Central Chirality

AbstractThe chiral ferrocene derivative (R,Rp)‐2‐[1‐(diphenylphosphanyl)ethyl]ferrocenecarboxylic acid (1) is prepared together with selected derivatives resulting from modification at the phosphane moiety [P‐oxide (5) and P‐sulfide (4)] and the carboxyl group {amides bearing benzyl (6) and (R)‐ or (S)‐1‐phenylethyl substituents [(R)‐7 and (S)‐7] at the amide nitrogen atom}. Acid 1 and amide 6 are studied as ligands in rhodium and palladium complexes. Bridge cleavage of the dimer [{Rh(μ‐Cl)Cl(η5‐C5Me5)}2] with 1 gives [RhCl2(η5‐C5Me5)(1‐κP)] (9) containing P‐monodentate 1, which undergoes smooth conversion to the (phosphanylalkyl)ferrocenecarboxylato complex [RhCl(η5‐C5Me5){Fe(η5‐C5H5)(η5‐C5H3‐1‐CH(Me)PPh2‐2‐COO‐κ2O,P}] (10) upon treatment with silica gel or alumina. Yet another O,P‐chelate complex,[Rh{Fe(η5‐C5H5)(η5‐C5H3‐1‐CH(Me)PPh2‐2‐COO‐κ2O,P}(CO)(PCy3)] (11; Cy = cyclohexyl) is obtained directly by an acid‐base reaction between the acetylacetonato complex [Rh(acac)(CO)(PCy3)] and 1. Amide 6 reacts with [{Pd(μ‐Cl)(η3‐C3H5)}2] to give the expected phosphane complex [PdCl(η3‐C3H5)(6‐κP)] (12), while the replacement of the cyclooctadiene (cod) ligand in [PdCl(Me)(cod)] affords the chelate complex [PdCl(Me)(6‐κ2O,P)] (13). All compounds are characterised by spectroscopic methods and the solid‐state structures of 5, 9, 11, 13, (R,Sp)‐2‐[1‐(diphenylphosphoryl)ethyl]‐1‐[N‐(R)‐(1‐phenylethyl)carbamoyl]ferrocene [(R)‐8; phosphane oxide from (R)‐7], and the synthetic precursors (R,Sp)‐1‐bromo‐2‐[1‐(diphenylphosphanyl)ethyl]ferrocene (2) and (R,Sp)‐1‐bromo‐2‐[1‐(diphenylthiophosphoryl)ethyl]ferrocene (3) determined by single‐crystal X‐ray diffraction. The catalytic properties of 1 and the amides are probed in enanatioselective rhodium‐catalysed hydrogenation and palladium‐catalysed asymmetric allylic alkylation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Investigation of Nanocrystalline Phases in Li—La—Fe—O System Formed by the Decomposition of Acetylacetonato Complexes.

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Zn,Ni ferrite/NiO nanocomposite powder obtained from acetylacetonato complexes

The results on the synthesis, microstructure, structure and DC magnetization studies ofnanocomposite Zn,Ni ferrite/NiO powder obtained by thermal decomposition ofacetylacetonato complexes are reported in this paper. According to the resultsobtained by inductively coupled plasma optical emission spectroscopy (ICP-OES)element analysis and multiphase Rietveld refinement, the three samples made arecomposed of spinel-ferrite (86.7%–96.7%) and NiO (3.3%–13.3%) phases. Thecompositions of the spinel-ferrite (SP) phase in the investigated samples, S1–S3, areZn0.72Ni0.24Fe1.98O4,Zn0.56Ni0.29Fe2.07O4 and Zn0.40Ni0.40Fe2.10O4, respectively. Due to the cation deficiency in spinels, created vacancies induce a partialchange in the cation valence, . The vacancy distribution is found to be random at 8a and 16d cation sites, except insample S3, where all vacancies are over octahedral sites. The x-ray line broadening dueto crystallite size effect is found to be isotropic for all spinels, while the x-rayline broadening due to the strain effect is anisotropic. A correlation between theZn2+ occupancy of thetetrahedral site and the 650 cm−1 Raman peak intensities is shown. The observed coercivity decrease and shift in hysteresis loopin the samples are caused by the interaction between spinel and NiO phase. The results ofM(H) measurements point to the properties of an ensemble of interacting nanoparticles. Highsaturation magnetization values and superparamagnetic behaviour at room temperaturepoint to the technological significance of the title compounds.

Investigation of nanocrystalline phases in Li–La–Fe–O system formed by the decomposition of acetylacetonato complexes

Applying a new synthesis route based on the thermal decomposition of a mixture acetylacetonato complexes, Li(AA) , La(AA) 3 and Fe(AA) 3, Li, La ferrite (Li 0.5La 0.08Fe 2.42O 4) was formed. The element analysis performed by ICP technique and the Rietveld refinement data indicate that the sample is composed of three phases: Li 0.5La 0.08Fe 2.42O 4 (69%, SG P4 332, a = 8.3445(3) Å) , La 0.14Fe 3O 4 (16%, SG F d 3 ¯ m , a = 8.403(1) Å) and LiFeO 2 (15%, SG F m 3 ¯ m , a = 4.2291(8) Å). A partial substitution Fe 3+ → La 3+ in Li ferrite and La insertion at 16c site in Fe 3O 4 occur at low concentrations. A partial cation ordering at 4b and 12d octahedral sites in Li 0.5La 0.08Fe 2.42O 4 was noticed. TEM micrograph shows that the nanoparticles are spherically shaped and that the particle distribution is in the range between 7 and 33 nm. The sample exhibits superparamagnetic behavior, thus the composite has potential industrial applications.

Rhodium(I) acetylacetonato complexes containing phosphinoalkynes as catalysts for the hydroboration of vinylarenes

Three novel rhodium(I) acetylacetonato (acac) complexes bearing phosphinoalkynes (Ph2PC≡C-t-Bu, Ph2PC≡CPPh2, and Ph2PC≡CC≡CPPh2) have been prepared and characterized fully. Addition of B2cat3 (cat = 1,2-O2C6H4) to Rh(acac)(Ph2PC≡C-t-Bu)2 (1a) led to zwitterionic Rh(η6-catBcat)(Ph2PC≡C-t-Bu)2 (2a), the first example of this type of compound to contain monodentate phosphine ligands. All new rhodium complexes have been investigated for their ability to catalyse the hydroboration of vinylarenes.Key words: catalysis, hydroboration, phosphinoalkynes, regioselectivity, rhodium.

Formation of nanosize Li-ferrites from acetylacetonato complexes and their crystal structure, microstructure and order–disorder phase transition

Nanosize Li-ferrites were synthesised by the thermal decomposition of an appropriate mixture of complex compounds with acetylacetone - (2,4 pentadione) ligands ([M(AA)x]; M=Li and Fe) at 500 °C. The obtained sample is composed of three phases determined by the standard Rietveld procedure: Li0.5Fe2.5O4 (S.G. P4332), Li1.16Fe3O4 (S.G. Fd 3 m) and LiFeO2 (S.G. Fm 3 m). Cation distribution in nanosize ordered spinel Li0.5Fe2.5O4 deviates from that of the bulk counterpart. Microstructure parameters (crystallite size of ∼23 nm and strain of 3.2526(9)×103) were determined by the Rietveld refinement of the TCH-pV parameters. SEM microphotographs show a particle size of ∼50–60 nm. An order–disorder phase transition in ordered spinel Li0.5Fe2.5O4was studied by DSC measurements and in situ XRPD technique.The temperature of phase transition was found to be 762 °C (DSC) and (±) 7455°C.(XRPD)

CH/π interactions between chelate and phenyl rings in acetylacetonato complexes

CH/π interactions between chelate and phenyl rings in acetylacetonato complexes

X-ray powder diffraction line broadening analysis and magnetism of interacting ferritenanoparticles obtained from acetylacetonato complexes

A study of the microstructures and magnetic properties of nanosize Zn ferrite(ZnFe2O4), Mn ferrite(MnFe2O4), and the cationdeficit Zn–Mn ferrites Zn0.70Mn0.23Fe1.89O4 (S1), Zn0.41Mn0.50Fe1.84O4 (S2) and Zn0.18Mn0.67Fe1.85O4 (S3) was performed. The crystallite size for all samples was determined by x-ray powderdiffraction (XRPD) analysis using four different methods, and was close to the particle sizefound from transmission electron microphotography. Among different methods of XRPDline broadening analysis it seems that the cubic harmonic function method is more preciseand reliable than the Warren–Averbach and simplified integral breadth methods.M(T) and M(H) magnetization curves at different fields/temperatures indicate superparamagneticbehaviour of the samples. Asymmetric hysteresis loops and differences in coercive fields,HC−(FC) −HC−(ZFC), are discussed by both the core/shell model of nanoparticles and spin canting. The magneticmeasurements with a maximum in the FC magnetization branches, the difference inM/MS versusH/T curvesabove Tmax (temperature of maximum in ZFC magnetization), the nonlinearity inHC versusT1/2, the remanence/saturationratio value, MR/MS and observation of the Almeida–Thouless line for low-field magnetization data(Tmax versus H2/3) indicate that the samples consist of an interacting ferrite nanoparticle ensemble.

Manganese(III) bis(2-hydroxyanil)acetylacetonato complex as effective catalyst for acylation of alcohols, amines and phenols with acetic anhydride

Acylation of alcohols, amines and phenols with acetic anhydride in an efficient manner using [bis(2-hydroxyanil)acetylacetonato]manganese(III)chloride, [Mn(haacac)Cl], as a catalyst. Using this method acylation of a primary NH 2 group in the presence of secondary NH and primary OH have been achieved with high selectivity.

Syntheses, properties, and structural characteristics of several new [tetrakis(1-pyrazolyl)borato]samarium(III) complexes: comparative study of the B(pyrazolyl) 4 and BH(pyrazolyl) 3 ligation

Although reactions of samarium(III) chloride, SmCl 3 · 6H 2O, with potassium hydrotris(1-pyrazolyl)borate K[BH(pz) 3] (pz = 1-pyrazolyl) in a molar ratio of (1/1) in THF afford [SmCl{BH(pz) 3} 2(Hpz)], similar reactions with K[B(pz) 4] gave rise to separation of anhydrous H[B(pz) 4]. The homoleptic eight-coordinate complex [Sm{B(pz) 4} 3] obtained from SmCl 3 · 6H 2O and threefold moles of K[B(pz) 4] was allowed to react with twofold moles of K[BH(pz) 3] to give a mixture of three major species [Sm{B(pz) 4} n {BH(pz) 3} (3 − n) ] ( n = 2, 1, 0), whereas similar reactions of [Sm{BH(pz) 3} 3] with K[B(pz) 4] did not proceed at all. The acetylacetonato (acac) complex [Sm{B(pz) 4} 2(acac)], derived from the triflate “Sm{B(pz) 4} 2(OTf)”, was treated with twofold moles of K[BH(pz) 3] and showed its quantitative conversion to [Sm{BH(pz) 3} 2(acac)]. However, analogous reaction of [Sm{BH(pz) 3} 2(acac)] with K[B(pz) 4] did not proceed. Accordingly, samarium(III) ion was determined to prefer coordination of BH(pz) 3 ligand to that of B(pz) 4, indicating less σ-donating electronic character of the latter. The complexes [Sm{B(pz) 4} 2(L–L)] (L–L = β-ketoenolato) in toluene-d 8 exhibited 1H NMR spectroscopic equivalence of all four pyrazolyl groups at high temperatures, and are regarded as a new class of B(pz) 4 complexes, showing fast intramolecular exchange of their coordinated and uncoordinated pyrazolyl groups. Four compounds were crystallographically characterized.