Reaction Of CrCl3 Research Articles

Chromium nitrides (CrN, Cr2N) from solid state metathesis reactions: effects of dilution and nitriding reagent

The solid state metathesis (SSM) reaction of CrCl3 with Li3N in a sealed evacuated Pyrex ampoule at 445C produces a propagation wave and enables phase pure Cr2N to be isolated. The SSM reaction of CrCl2 and Mg3N2 at 350-500C with dilutant MgCl2 under similar conditions produces single phase CrN. Reaction of chromium oxide with Li3N at 500C produces CrN after 2h and Cr2N after 60h. This is the first report of a metal nitride being formed in a SSM reaction using an oxide starting material. The SSM nitrides were shown to have superior bulk nitridation levels (combustion analysis) and equivalent microscopic compositions (EELS, XRD) to commercial materials. The phases of chromium nitride produced were correlated with reaction enthalpy, dilution conditions and nitriding agent. The products were analysed by X-ray powder diffraction, FTIR, combustion microelemental analysis, SEM/EDAX, XPS and ELNES.

Preparation and characterization of a new series of Cr(II) hydroborates

The synthesis and characterization of a new series of mono-, di-, and trinuclear Cr(II) borohydride compounds is described. The reaction of CrCl2(TMEDA) with two equivalents of NaBH4 afforded the thermally unstable (TMEDA)Cr(BH4)2 (1), which was converted by treatment with pyridine into the octahedral monomeric (Py)4Cr(BH4)2 (2). The reaction proceeds via formation of an intermediate trinuclear complex {[(TMEDA)(Py)Cr(η2-BH4)]2[(Py)2Cr(η2-BH4)2]}(µ,η1-BH4)2 (3), which was isolated and characterized by X-ray crystallography. Reaction of 1 and 2 with both CO2 and RN=C=NR (R = Cy, iPr) afforded hydride insertion and formation of the corresponding diamagnetic lantern-type Cr(II) formate (HCO2)4Cr2Py2 (4) and formamidinate compounds [RNC(H)NR]2Cr2(µ-BH)4 (R = Cy (5a), iPr (5b)), respectively, with supershort Cr—Cr quadruple bonds. The structures of 1, 2, 3, and 5b were elucidated by X-ray analysis. Crystal data are as follows. 1: C6H24N2B2Cr, monoclinic, Cc, a = 8.517(2) Å, b = 15.921(5) Å, c = 9.624(2) Å, β = 115.59(1)°, Z = 4, R = 0.022, Rw = 0.029; 2: C28H44N4B2O2Cr, monoclinic, P21/n, a = 12.021(1) Å, b = 15.555(1) Å, c = 15.723(1) Å, β = 90.13(2)°, Z = 4, R = 0.074, Rw = 0.086; 3: C32H76N8B6Cr3, monoclinic, P21/n, a = 8.515(1) Å, b = 14.525(1) Å, c = 18.286(2) Å, β = 91.38(1)°, Z = 2, R = 0.051, Rw = 0.060; 5b: C21H49N6BCr2, monoclinic, C2/c, a = 17.000(1) Å, b = 9.033(1) Å, c = 19.160(1) Å, β = 105.579(9)°, Z = 4, R = 0.069, Rw = 0.078. Keywords: divalent chromium, borohydride, Cr—Cr quadruple bond.

Co-ordination behaviour of potentially tridentate diphosphinoamido ligands: synthesis and crystal structures of the complexes [CrCl{N(CH2CH2PMe2)2}2], [Cr2Cl3{N(CH2CH2PMe2)2}{CH2P(Me)CH2CH2NCH2CH2PMe2}] and [Cr2Cl4{N(CH2CH2PPri 2)2}2

The reaction of CrCl3·3tHf (thf = tetrahydrofuran) with bis(2-dialkylphosphinoethyl)amidolithium reagents, LiN(CH2CH2PR2)2′ resulted in the formation of the new compounds [CrCl{N(CH2CH2PMe2)2}2]1, [Cr2Cl3{N(CH2CH2PMe2)2}{CH2P(Me)CH2CH2NCH2CH2PMe2}]2 and [Cr2Cl4{N(CH2CH2PPri2)2}2]3 depending on reaction conditions and stoichiometry. Thus, if 2 equivalents (per Cr) of LiN(CH2CH2PMe2)2′are used 1 may be isolated where chromium is bound to two amido ligands each in different co-ordination modes (bi- and tri-dentate). With 1.5 equivalents of LiN(CH2CH2PMe2)2′2is formed which has a binuclear structure with bridging amido ligands and an unusual α-metallated PCH2 group. With the more bulky LiN(CH2CH2PPri2)2′3 may be isolated in which a binuclear structure is bridged by both bi- and tri-dentate amido ligands. All complexes have been characterised by analysis, mass spectroscopy, and single-crystal X-ray crystallography.

Kinetics of base hydrolysis of trans-{Cr([15]aneN4)Cl2}+ ([15]aneN4 = 1,4,8,12-tetra-azacyclopentadecane)

Reaction of CrCl3(DMF)3 with [15]aneN4 (L; L = 1,4,8,12-tetra-azacyclopentadecane) gives the green trans-{Cr([15]-aneN 4)Cl2}Cl in high yield. The base hydrolysis kinetics of the cations [CrLCl2]+ and [CrLCl(OH)] + have been investigated over a temperature range. For the dichloro complex, kOH = 1.03 dm3 mol−1 s−1] at 25° C with ΔH‡ =30.4 kJmol−1 and ΔS inf298 sup‡ = -143 JK−1 mol−1. The substantial negative entropy of activation implies more association of water in the loss of Cl− from the conjugate base in a DCB mechanism. The kinetic parameters for the chlorohydroxo complex are kOH = 1.9 × 10−2dm3mol−1 s−1 at 25°C with ΔH‡ = 78.3kJmol−1 and ΔH inf298 sup‡ = -15 J K−1 mol −1. The chlorohydroxo complex probably has the transVI configuration with the chloride ligand on the same side of the equatorial plane as the four chiral sec-NH groups. The visible spectra of a variety of complexes trans-[Cr(L)XY]n+ (X = Y = Cl, OH, OH2; X = Cl, Y = OH) have been determined.

Kooperative Wirkung in π1‐Ligand‐verbrückten Zweikernkomplexen, XIII. Unerwartet schwache d‐d‐Wechselwirkungen in synfacialen heterodinuklearen μ1‐Cyclooctatetraenkomplexen vom Typ {(CpCr)[(CO)3M′]}μ1‐Cot (M′Fe, Cr, W)

Cooperative Effects in π1‐Ligand‐Bridged Dinuclear Complexes, XIII[1]. – Unexpected Weak d‐d Interactions in Synfacial Heterodinuclear μ1‐Cyclooctatetraene Complexes of the Type {(CpCr)[(CO)3M′]}μ1‐Cot (M′Fe, Cr, W)The heterodinuclear complexes {(CpCr)[(CO)3M′]}μ1‐Cot (CotC8H8; M′Fe, Cr, W) (5 – 7) and {(Cp*Cr)[(CO)3Cr]}μ1‐Cot (Cp*C5Me5) (9) are synthesized by the reaction of the corresponding mononuclear Cot complexes CpCr(η61‐Cot) (4) and Cp*Cr(η61‐Cot) (8), respectively, with M′(CO)3(EtCN)3 (M′Cr, W) and with Fe2(CO)9. The CrFe compound 5 is obtained in very low yield only. However, much better yields of 5 are achieved in the reaction of CrCl2 and CrCp2 with (CO)3Fe(η41‐Cot) (10) in the presence of an excess of Zn. X‐ray structure determinations of 5 and 6 reveal synfacial configurations of the CpCr and M′(CO)3 units with a μ1‐η5:3‐ and μ1‐η4:51‐Cot bonding mode for 5 and 6, respectively. The metal – metal distances are 2.9369(13) Å for 5 and 2.81(2) Å for 6 indicating metal – metal single bonds. 5 contains 33 valence electrons (ve) and is paramagnetic with one unpaired electron. A well‐resolved fluid‐solution ESR spectrum of 5 shows a 53Cr and 1H hyperfine structure (hfs). The 1H hfs can be calculated with three different 1H hyperfine coupling constants (1H hfcc) indicative of protons in α1‐position with respect to the paramagnetic metal center: one 1H hfcc of the five Cp protons (1.68 G), one of three (3.32 G) and one of two protons of the Cot ligand (5.04 G). This agrees with the Cot bonding mode of the CpCr unit in the crystalline phase. The ratio of 3:2 protons for the Cot ligand prove the rigidity of the Cot ligand on the ESR time scale. The excellent agreement of the ESR data of the liquid and frozen solution ESR spectra of 5 with the ESR data of the mononuclear complex CpCr(η61‐Cot) leads to the conclusion that the unpaired electron in 5 must predominantly be chromium‐centered. 6, 7, and 9 have 31 ve and are paramagnetic with three unpaired electrons as shown by means of ESR spectroscopy and magnetic measurements. The calculations of the quartet ESR spectra of 6, 7, and 9 reveal zero‐field splitting parameters D ranging from 3.6 to 4.8 cm–1 which are similar to that of the mononuclear quartet compound vanadocene. The small range in the parameters D prove the minor influence of the second metal on going from Cr to W. Hence, the three unpaired electrons are assumed to be mainly localized on the Cr center of the CpCr unit. Cyclic voltammetry studies result in the redoxcascade − 2 ⇄ − 1 ⇄ 0 ⇄ + 1 for 5 and 7 at +20°C and for 6 at –35°C. However, at +20°C 6 and 9 only show one electrochemically reversible reduction wave 0/–1, whereas the oxidation 0/+1 and the second reduction –1/–2 are irreversible. The redox potentials indicate a considerable influence of the metal combinations. On the strength of the ESR spectroscopic results and according to the results of crystal structure determinations, an isolobal relationship is drawn between the (CO)3M′(η8 – ×1‐Cot) fragment and a cyclic organic π1‐ligand with the hapticity × + 1.

Dimeric and monomeric chromium(II) and monomeric chromium(III) aryls. Crystal structure of pyramidal Mz2Cr(py) (Mz = o-Me2NCH2C6H4, py = pyridine), dimeric [(Me2NC6H4)2Cr]2, and octahedral (Me2NC6H4)3Cr

Reaction of CrCl2(THF)2 with 2 equiv of [omicron-Me2NCH2C6H4]Li and [omicron-Me2NC6H4]Li led to formation of the monomeric pyramidal [omicron-Me2NCH2C6H4]2Cr(pyridine) (2) and dimeric [(omicron-Me2NC6H4)2Cr]2 (3) with a supershort Cr-Cr contact. Both compounds can be thermolyzed in toluene to form the corresponding monomeric Cr(III) [Me2NC6H4]3Cr (4) and (omicron-Me2NCH2C6H4)3Cr (5) derivatives. The structures of 2-4 have been clarified by X-ray diffraction analysis. Complex 2: triclinic, P1, a = 8.766 (2) angstrom, b = 8.825 (1) angstrom, c = 23.582 (3) angstrom, alpha = 81.41 (1)-degrees, beta = 85.33 (1)-degrees, gamma = 60.31 (1)-degrees, V = 1567.0 (5) angstrom3, Z = 3, R = 0.034 (R(w) = 0.044), T = 130 K for 986 parameters and 6269 significant reflections out of 8191. Complex 3: monoclinic, C2/c, a = 10.563 (3) angstrom, b = 13.563 (2) angstrom, c = 19.813 (8) angstrom, beta = 92.92 (1)-degrees, V = 2835 (1) angstrom3, Z = 4, R = 0.066 (R(w) = 0.092), T = 130 K for 261 parameters and 2583 significant reflections out of 3406. Complex 4: trigonal, P31c a = b = 12.821 (1) angstrom, c = 7.860 (1) angstrom, V = 1118.9 (2) angstrom3, Z = 2, R = 0.060 (R(w) = 0.066), T = 300 K for 92 parameters and 573 significant reflections out of 928.

Symmetric versus unsymmetric ligand orientations in (pentadienyl)Cr(I or II)(L) 2(L′) species, and a spontaneous reduction of Cr II to Cr I

The reaction of CrCl 2(PEt 3) x with potassium pentadienide leads to a compound with the stoichiometry of a phosphine adduct of Cr(C 5H 7) 2, “Cr(C 5H 7) 2PEt 3”; however, dimerization through pentadienyl—pentadienyl coupling actually leads to a Cr I species. Its structure has been determined and suggests little if any contribution from an enediyl Cr III resonance form. The structure of the known Cr(2,4-C 7H 11)(CH 3)(dmpe) has also been determined to allow comparison with the former compound.

Ligand and alkali metal cation control on the molecular complexity of anionic chromium(II) aryloxides. Preparation and crystal structure of dimeric (PhO)10Cr2Li6(THF)6 and (2,6-Me2C6H3O)6Cr2Li2(THF)4 and trimeric (GuO)14Cr3Na9Cl [GuO = (o-CH3O)C6H4O] with an encapsulated chloride ion

Two new anionic, dimeric chromium(II) alkoxides, (PhO)10Cr2Li6(THF)6 (3) and (2,6-Me2C6H3O)6Cr2Li2(THF)4 (4), have been prepared and characterized by X-ray structure determination. The two complexes possess similar Cr2(OR)2 cores with a fairly long Cr-Cr distance [Cr...Cr' = 3.149 (2) and 3.091 (1) angstrom for 3 and 4, respectively]. In complex 3, the unit Cr2(OPh)2 is incorporated into two separated (PhO)4Li3(THF)3 polyhedra, while in complex 4 the same core is attached to two (RO)Li(THF)2 units with an overall linear arrangement of the Li-Cr-Cr-Li backbone. Replacement with TMEDA of the four THF molecules attached to lithium cleaved the dimeric structure of 3 and 4, forming the monomeric (RO)4CrLi2(TMEDA)2 [R = Ph (5a), 2,6-Me2C6H3O (5b)]. Reaction of CrCl2(THF)2 with 2 equiv of GuONa [GuO = (omicron-CH3O)C6H4O] led to the formation of the polymer [(GuO)2Cr]n, as an insoluble, pyrophoric solid. Further reaction with an excess of (GuO)Na formed the trinuclear (GuO)14Cr3Na9Cl (6). Treatment of 6 with 18-crown-6 led to the disruption of the trinuclear arrangement and formation of the polymeric [(GuO)2Cr]n species. Crystal data for 3, 4, and 6 are as follows. 3 is triclinic, space group P1BAR, with a = 12.511 (1) angstrom, b = 13.145 (1) angstrom, c = 15.260 (2) angstrom, alpha = 98.77 (1)-degrees, beta = 106.27 (1)-degree, gamma = 117.18 (1)-degrees, V = 2024.2 (3) angstrom-3, and Z = 1; 4 is monoclinic, space group C2/c, with a = 15.318 (4) angstrom, b = 18.245 (4) angstrom, c = 22.113 (6) angstrom, beta = 100.90 (2)-degrees, V = 6069 (3) angstrom-3, and Z = 4; 6 is orthorhombic, space group Pba2, with a = 26.720 (1) angstrom, b = 26.916 (2) angstrom, c = 15.670 (2) angstrom, V = 11269.8 (17) angstrom-3, and Z = 4.

Preparation and Reactions of Chromium(III)alkoxides

Abstract Reactions of CrCl3.3THF with lithium alkoxides in 1:3 molar ratio in the respective primary alcohols yield insoluble trialkoxides, Cr(OR)3 (where R = Me, Et, Bu-n). The corresponding reactions with isopropyl and tertiary butyl alcohols, however, yield hydrolysed products only. We have been able to synthesize the isopropoxide and t. butoxide also by alternative routes. All the alkoxides have been characterized by physico-chemical methods and attempts have been made to study their alcoholysis reactions.

Synthese und Kristallstruktur von [CrCl3(H2O)(15-Krone-5)] / Synthesis and Crystal Structure of [CrCl3(H2O)( 15-Crown-5)

The title compound has been prepared by the reaction of CrCl3 with 15-crown-5 in acetonitrile suspension in the presence of water. It forms violet crystals, which are sparingly soluble in acetonitrile; they were characterized by their IR spectrum as well as by an X-ray structure determination. Space group P21/c, Z = 4, 2902 observed unique reflexions, R = 0.029. Lattice dimensions at —70 °C: a = 1018.8(5), b = 780.0(4), c = 2097.1(10) pm, β = 93.21(3)°. [CrCl3(H2O)(15-crown-5)] has a molecular structure, in which the chromium atom is coordinated by three chlorine atoms, by the oxygen atom of the water molecule, and by two oxygen atoms of the crown ether molecule in a distorted octahedral fashion.

Monomeric arylchromium(II) complexes: the crystal structures of [ cis-Mes 2Cr(THF) 2](THF), [ cis-Mes 2Cr(bipy)](THF), [Mes 4CrLi 2(THF) 2](THF) and Ph 4CrLi 2(THF) 4 (Mes = 2,4,6-mesityl; bipy = 2,2′-bipyridine)

The square-planar geometry of the monomeric [Mes 2Cr(THF) 2](THF) ( 1) and [Mes 2Cr(bipy)](THF) ( 2) (Mes = 2,4,6-mesityl; bipy = 2,2′-bipyridine) was determined by X-ray diffraction analysis. Crystal data are as follows. 1: orthorhombic, Pccn with a 12.447(3), b 14.500(2), c 16.593(2) Å), V 2994.7(9) Å 3, Z = 4, R = 0.121, R w = 0.121. 2: Monoclinic, P2 1/ c with a 14.316(2), b 11.071(2), c 17.645(3) Å, β 91.24(1)°, V 2795.9(3) Å 3, Z = 4, R = 0.060, R w = 0.068. Further reaction of 1 with an excess of MesLi or reaction of CrCl 2(THF) 2 with 4 equiv. of PhLi, allows the isolation of the monomeric chromates [Mes 4CrLi 2(THF) 2](THF) ( 3) and Ph 4CrLi 2(THF) 4 ( 4) in crystalline form. Crystal data for 3 and 4 are as follows. 3: orthorhombic, I222 with a 8.703(1), b 14.129(1), c 17.993(1) Å, V 2212.6(3) Å 3, Z = 2, R = 0.052, R w = 0.054. 4: Triclinic, P 1 with a 9.187(1), b 10.263(1), c 10.851(1) Å, α 110.77(1), β 92.16(1), γ 97.48(1)°, V 944.7(2) Å 3, Z = 1, R = 0.059, R w = 0.057.

ChemInform Abstract: Crystal Structure and Magnetic Measurements of (Cr(en)3) (ZnCl4)Cl.

AbstractThe title compound is obtained by reaction of CrCl3·6 H2O, Zn, and (Cr(en)3)2(SO4)3 in conc.

Crystal structure and magnetic measurements of [Cr(en) 3] [ZnCl 4]Cl

The compound [Cr(en) 3][ZnCl 4]Cl has been synthesized by reaction of CrCl 3·6H 2O, Zn and [Cr(en) 3] 2(SO 4) 3 in HCl. Its molecular and crystalline structure was determined by X-ray diffraction methods, being monoclinic, P2 1/ c, a=21.215(3), b=12.532(2), c=13.707(2) Å, β=95.21°, V= 3629(2) Å 3, D x=1.738g cm −3, MW=474.9, Z= 8, F(000)=1928, λ(Mo Kα)=0.71069 Å, μ(Mo Kα)= 27.04 cm −1, 288 K. No significant exchange interactions between Cr(III) cations in the crystalline lattice were found. Curie-Weiss behavior was found in the three directions tested ( g 1=2.06±0.02, g 2= 2.08±0.02, g 3=2.09±0.01), T=1.2-1.4 K.

ChemInform Abstract: Chromium(III) Complexes with 1,5,9-Triazanonane (3,3-tri) - CrX3(3,3-tri)n+ and CrCl(diamine)(3,3-tri)2+.

The reaction of hydrated CrCl3 with (I) gives (III) whose configuration is established by isomorphism with the corresponding Co(III) complex.

Chromium(III) complexes with 1,5,9-triazanonane (3,3-tri) - CrX 3(3,3-tri) n+ and CrCl(diamine)(3,3-tri) 2+

The reaction of CrCl 3 · 6H 2O (dehydrated in DMSO) with 1,5,9-triazanonane (3,3-tri) gives mer- CrCl 3(3,3-tri), the configuration being established by isomorphism with the corresponding Co(III) complex. This non-electrolyte is hydrolyzed in aqueous acidic solution and mer-[CrCl 2(3,3-tri)- (OH 2)]ClO 4 can be isolated by anation with HCl in the presence of HClO 4. Reaction of mer-CrCl 3- (3,3-tri) in DMF with diamines produces complexes of the type [CrCl(diamine)(3,3-tri)] Cl 2 [diamine= 1,2-diaminoethane (en), 1.2-diaminopropane (pn), 1,3-diaminopropane (tn), 2,2-dimethyl-1,3-diaminopropane (Me 2tn) and cyclohexanediamine (chxn, cis plus trans mixture; two isomers A and B)] and these have been characterized as the ZnCl 4 2− salts. The configuration of the triamine ligand in these complexes has been established as mer-(H↓)- by a single crystal X-ray analysis of [CrCl(en)(3,3-tri)]- ZnCl 4, monoclinic, P2 1, a=7.932, b= 14.711, c= 8.312 Å, β=104.6° and Z=2, refined to a conventional R factor of 0.034. The kinetics of the Hg 2+- assisted chloride release from [CrCl(diamine)(3,3- tri)]ZnCl 4 salts were measured spectrophotometrically (μ=1.0 M HClO 4 or HNO 3) over 15 K temperature ranges to give, in order, 10 4 k Hg (298.2 K) (M −1 s −1), E a(kJ mol −1), ΔS # (J K −1 mol −1): en- (HClO 4): 5.95, 78.1, -53; pn(HClO 4); 5.24, 81.2; -44; tn(HClO 4): 26.7, 85.6, -15; Me 2tn(HClO 4): 21.8, 78.6, -40; A-chxn(HNO 3): 7.60, 81.0,-41; B-chxn(HNO 3): 18.3, 56.8, -115. A ‘non-replaced ligand effect’ on the rate is observed for the first time in this series of homologous Cr(III) complexes. The kinetics of the thermal aquation ( k H, 0.1 M HClO 4) were measured titrimetrically for CrCl(diamine) (3,3-tri) 2+ to give the following kinetic parameters: diamine=en: 10 7 k H (298.2)=5.34 s −1, E a=99.2 kJ mol −1, ΔS #=-40 J K −1 mol -1; diamine =tn: 10 7 k H (298.2)=5.04 s −1, E a= 82.8, ΔS #= -96.

ChemInform Abstract: Preparation and Characterization of the Three Geometrical Isomers of (1,3‐Propanediamine‐N,N′‐diacetato‐N,N′‐di‐3‐propionato)chromate(III). Crystal Structure of trans‐(O6)‐K(Cr(1,3‐pddda))·3 H2O.

AbstractThe reaction of CrCl3·6 H2O with the sixdentate ligand 1,3‐propanediamine‐N,N'‐diacetate‐N,N'‐di‐3‐propionate prepared by alkylation of 1,3‐propanediamine‐N,N'‐diacetic acid with 3‐chloropropionic acid in the presence of KOH leads to geometric isomers of the title chromate.

ChemInform Abstract: Transition‐Metal Complexes with Polyamino Alcohols. Part 1. Structures of a Dinuclear Chromium(III) Complex and a Trinuclear Cobalt Complex with N‐(3‐Aminopropyl)diethanolamine, a Bifurcated Quadridentate Tripod Ligand.

AbstractThe reaction of CrCl3 with the tripod ligand in boiling DMF yields the complex (I) which on addition of NaClO4 precipitates as the salt (II), crystallizing in the space group P21/c with Z=4.

ChemInform Abstract: Optically Active Chromium(III) Complexes. Part 7. Chiroptical and Kinetic Properties of Chloro(1,5‐diazahexane)(1,4,7‐triazaheptane)chromium(III) Tetrachlorozincate(II), (CrCl(N‐Me‐tn)(dien))ZnCl4.

AbstractOne isomer of the title complex (I) has been isolated from the reaction of CrCl3·6 H2O, dehydrated in DMF, with the appropriate polyamines.

Optically active chromium(III) complexes. VII. Chiroptical and kinetic properties of chloro(1,5-diazahexane)( 1,4,7-triazaheptane)chromium(III) tetrachlorozincate(II), [CrCl(NMetn)(dien)]ZnCl 4

One isomer of [CrCl( N-Me-tn)(dien)]ZnCl 4 has been isolated from the reaction of CrCl 3·6H 2O, dehydrated in DMF, with the polyamines N-methyl- 1,3-diaminopropane and diethylenetriamine. This complex is isomorphous with δλ-( R,S)usft-[CoCl( N-Me-tn)(dien)] ZnCl 4 and thus has the unsym-fac- configuration with the N-Me group trans to the sec-NH group of the coordinated triamine. The Cr(III) complex has been resolved with NH 4BCS and the chiroptical parameters of (-) 488-[CrCl( N-Me-tn)(dien)]- ZnCl 4, derived from the less soluble diastereoisomeride by metathesis, are similar to those obtained for the less soluble (-) 534-λ-( S)- a, cb, edf-Co(III) analogue, of known absolute configuration. Kinetic parameters for the rates of thermal aquation (μ= 1.0 M, HClO 4) and Hg 2+-assisted chloride release (μ= 1.0 M) for usft-[CrCl( N-Me-tn)(dien)]ZnCl 4 are k H= 3.7 × 10 −6 s −1, E a=93 ± 8 kJ mol −1, Δ S 2984t #= −45 ± 16 J K −1 mol −1 and k Hg=2.01 × 10 −3 M −1 s −1, E a=64.2 ± 3.3, Δ S 298 #=−89.5 ± 7, respectively at 298 K.

Synthesis and Characterization of Some N-Benzoylglicinato Complexes of Chromium(III)

Abstract Tris(N-benzoylglycinato) chromium(III) has been prepared by the reaction of CrCl3.3THF and the sodium salt of N-benzoylglycine (hippuric acid, hipH) in 1:3 molar ratio in refluxing methanol. A number of its addition complexes with the general formula Cr(hip)3.xL (where L = EtOH, PriOH, ButOH, THF, py, pd, HexnNH2, 2,2′-bipy and x = 1 or 2) have been isolated by treating the chromium(III) hippurate with excess of the ligands under refluxing conditions. A few mixed (carboxylato) (N-benzoyl-glycinato) complexes of chromium(III) with the general formula Cr(OOCR)3-n(hip)n (where R = C13H27, C15H31, C17H35 and n=1 or 2) have also been synthesized. All the complexes have been characterized by elemental analyses, conductivity, molecular weight, infrared, electronic and e.s.r. spectra and magnetic susceptibility measurements, which indicate the bidentate nature of N-benzoylglycine in all the complexes with octahedral geometry around the chromium in the high spin (3d3) state.