Tri- and tetraphenylantimony propiolates: Syntheses and structures

The reaction of triphenylantimony with propiolic acid in the presence of hydrogen peroxide (molar ratios 1 : 2 : 1 and 1 : 1 : 1) in diethyl ether affords triphenylantimony dipropiolate Ph₃Sb[OC(O)C≡CH]₂ (I) and μ₂-oxobis[(propiolato)triphenylantimony] [Ph₃SbOC(O)C≡CH]₂O (II). Tetraphenylantimony propiolate Ph₄SbOC(O)C≡CH (III) is synthesized from pentaphenylantimony and propiolic or acetylenedicarboxylic acid in toluene. According to the X-ray diffraction data, the crystals of compounds I and III include two types of crystallographically independent molecules (a and b). The antimony atoms in molecules Ia, Ib, II, IIIa, and IIIb have the trigonal-bipyramidal coordination mode with different degrees of distortion. The OSbO and OSbC axial angles are 176.8(2)° (Ia, Ib), 170.17(15)°, 178.78(14)° (II), and 173.2(5)°, 174.4(5)° (IIIa, IIIb). The CSbC equatorial angles lie in the ranges 108.2(3)°–143.1(3)° (I), 109.0(2)°–131.0(2)° (II), and 113.1(4)°–125.4(4)° (III). The SbOSb angle in II is 141.55(19)°. The Sb-C bond lengths are 2.103(8)–2.141(5) (I), 2.105(5)–2.119(5) (II), and 2.076(12)–2.166(13) Å (III). The Sb-O distances increase in a series of I, II, and III: 2.139(6)–2.156(7) (Ia, Ib); 2.206(4), 2.218(3) (II); and 2.338(10), 2.340(10) Å (III).     

Synthesis and Structure of Tetra- and Triphenylantimony Organosulfonates

Tetraphenylantimony 2-naphthalenesulfonate (I), tetraphenylantimony phenylmethanesulfonate (II), and bis(tetraphenylantimony) sulfate (III) were synthesized via reaction of pentaphenylantimony with 2-naphthalenesulfonic acid, triphenylantimony bis(phenylmethanesulfonate), and triphenylantimony sulfate, respectively, in toluene. Triphenylantimony bis(phenylmethanesulfonate) (IV) was synthesized from triphenylstibine, phenylmethanesulfonic acid, and hydrogen peroxide (taken in the molar ratio of 1 : 2 : 1). Organoantimony betaine (V) was obtained by reacting triphenylstibine with phenylmethanesulfonyl chloride in the presence of hydrogen peroxide. The structures of the compounds synthesized were determined using X-ray diffraction analysis. The Sb atoms in I–IV have distorted trigonal bipyramidal coordination. The Sb–C and Sb–O distances are equal to 2.100(4)–2.140(3) and 2.644(2) Å in molecule I, 2.105(2)–2.131(2) and 2.699(1) Å in II, 2.096(6)–2.169(6) and 2.101(6), 2.271(3) Å in III, and 2.101(3)–2.102(5) and 2.111(2) Å in IV. In V, the Sb atoms have close tetrahedral (2.105–2.115 Å) and remote (2.65, 3.019 Å) octahedral environment (the oxygen atoms of sulfo group of their own and neighboring molecules). Two betaine molecules are joined through the O atoms of the sulfo groups of bidentate phenylmethanesulfonate ligands to form a centrosymmetrical dimer. The intermolecular C(1)–H(1)···O(1) hydrogen bonds (3.10 Å) are formed that strengthen the dimer.     

Synthesis and Structure of Tetraphenylantimony 2-Furoinate and Benzoate

Tetraphenylantimony 2-furoinate Ph₄SbOC(O)C₄H₃O is synthesized by the reaction of pentaphenyl-antimony with triphenylantimony bis(2-furoinate). The structure of the compound is determined by X-ray diffraction analysis. The Sb atom in the compound has a distorted trigonal-bipyramidal coordination with the phenyl and 2-furoinate groups in the axial positions. The Sb(1)–C(Ph)_eq distances lie in the 2.119(1)–2.121(1) Å interval; the Sb–O(1) and Sb–C(Ph)_ax bond lengths are equal to 2.273(1) and 2.161(1) Å, respectively; and the Sb(1)···(2) intramolecular contact is 3.234(1) Å.     

Synthesis and Structure of Triphenylbismuth Dinitrite and Dinitrate

Triphenylbismuth dinitrate (I) and triphenylbismuth dinitrite (II) were synthesized through the reaction of triphenylbismuth dichloride with silver nitrate in an acetone–alcohol (1 : 1) solution or with sodium nitrite in acetone–water (1 : 1) solution. According to X-ray diffraction data, bismuth atoms in Iand II have a distorted trigonal bipyramidal configuration. The intramolecular Bi···N(1,2) contacts in II (2.997(3), 2.982(4) Å) are shorter than similar contacts in I(3.038(3), 3.031(3) Å); the Bi···O(2,4) distances in II and Bi···O(2,5) distances in I are equal to 2.879(2), 2.913(3) and 2.893(3), 2.896(3) Å, respectively.     

Homo- and hetero-bimetallic glycolates and triethanolaminates of niobium

[Nb(OⁱPr)₅] reacts with 2,5-dimethylhexane-2,5-diol (LH₂), 2,3-dimethylbutane-2,3-diol (L¹H₂) and triethanolamine (teaH₃) in different stoichiometric ratios to yield complexes of the types: [Nb(OⁱPr)₃(L)] (1), [Nb(OⁱPr)(L)₂] (2), [Nb(L)₂(LH)] (3), [Nb(L¹)₂(L¹H)] (4) and [Nb(tea)(teaH)] (5). Equimolar reactions of (3), (4) and (5) with Al(OⁱPr)₃, Ti(OⁱPr)₄ and [Ta(OⁱPr)₅] yield novel heterobimetallic isopropoxide-glycolate (6)–(9) and -triethanolaminate (10)–(12) derivatives. Reactions in appropriate molar ratios of (1), (2) and (10) with alkoxyethanols [ROC₂H₄OH; R = Me, Et] and acetylacetone [acacH] give derivatives [(MeOC₂H₄O)₃Nb(L)] (13), [(acac)Nb(L)₂] (14), [Nb(tea)₂{Al(OC₂H₄OMe)₂}] (15), [Nb(tea)₂{Al(OC₂H₄OEt)₂}] (16) and [Nb(tea)₂{Al(acac)₂}] (17). The complexes (6), (8) and (10) on reaction with an excess of t-BuOH give the tert-butoxo analogues (18), (19) and (20), respectively. These new derivatives have been characterized by elemental analyses, spectroscopic studies and molecular weight measurements.     

Preparation and properties of perfluorochloromethyl-mercaptophosphoryldichlorides and -chlorophosphanes

In Arbuzov-type reactions CF_nCl_3?nSCl reacts with ROPCl₂ (R = CH₃, C₂H₅) to give CF_nCl_3?nSP(O)Cl₂ (n = 3,2,1,0). The corresponding reaction with CF₃SeX (X = Cl, Br) produces CF₃SeP(O)Cl₂ in good yields only in the presence of catalysts such as SbCl₅ or BCl₃. Reactions between P₄ and the sulfenylchlorides produce (CF_nCl_3?nS)_xPCl_3?n (n = 3,2,1 and x = 1,2). On heating CF_n′ Cl_3?n′ SP(O)Cl₂ (n′ = 2,1,0) decompose to P(O)Cl₃ and SCF_n′ Cl_2?n′. During this process fluorination of P(O)Cl₃ to P(O)F₃ by SCF₂ is observed. A Cl/Br exchange between CF_nCl_3?nSP(O)Cl₂ (n = 3,2) and PBr₃ was proved ¹⁹F? and ³¹P-NMR-spectroscopically.Chemical and physical properties of the newly synthesized compounds will be discussed.     

Chalcone-derived thiosemicarbazones and their zinc(II) and gallium(III) complexes: spectral studies and antimicrobial activity

Chalcone-derived 3-phenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCTPh) (1), 3-(4-chlorophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4ClPh) (2), 3-(4-bromophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4BrPh) (3), and 3-(4-nitrophenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4NO₂Ph) (4) were obtained as well as their gallium(III) and zinc(II) complexes [Ga(PyCTPh)₂]NO₃ (Ga1), [Ga(PyCT4ClPh)₂]NO₃ (Ga2), [Ga(PyCT4BrPh)₂]NO₃ (Ga3), [Ga(PyCT4NO₂Ph)₂]NO₃ (Ga4), [Zn(PyCTPh)₂] (Zn1), [Zn(PyCT4ClPh)₂] (Zn2), [Zn(PyCT4BrPh)₂] (Zn3), and [Zn(PyCT4NO₂Ph)₂] (Zn4). The chalcones, thiosemicarbazones, and zinc(II) complexes were not active against Pseudomonas aeruginosa. The thiosemicarbazones proved to be more active than the parent chalcones against Staphylococcus aureus and Candida albicans. Coordination to zinc(II) resulted in activity improvement of most thiosemicarbazones against S. aureus. Coordination to gallium(III) significantly improved the antimicrobial activity of all thiosemicarbazones against the studied micro-organisms, suggesting this to be an effective strategy for antimicrobial activity enhancement.     

Tetraphenylphosphonium carboxylates and sulfonates. Synthesis and structure

The reaction of the pentaphenyphosphorus solvate Ph₅P·1/2PhH (I) with carboxylic and sulfonic acids was used to synthesize tetraphenylphosphonium carboxylates Ph₄POC(O)R, R = C₆H₄(2-OH) (II), C₆H₄ (2-COOH) (III), H (IV), Me (V), CCl₃ (VI), Ph (VII), PhCH=CH (VIII), CH₂CH₂C(O)OH (IX), CH=CHC(O) OH(X), and CH₂C(O)OH (XI) and tetraphenylphosphonium sulfonates Ph₄POSO₂Ar, Ar = Ph (XII), C₆H₄Me₄ (XIII), and C₆H₃(-COOH)(4-OH) (XIV). Compound XII was also prepared from compound I and SO₃ in benzene. According to X-ray diffraction data, the crystals of I contain two types of crystallographically independent molecules with a slightly distorted trigonal-bipyramidal configuration [Ia, CaxPCax 178.44(8)°, P- C_ax 1.985(2), 1.987(2) Å, P-C_eq 1.854(2), 1.846(2), 1.840(2) Å; Ib, C_axPC_ax 178.45(9)°, P-C_ax 1.980(2), 1.975 (2) Å, P-C_eq 1.840(2), 1.846(2), 1.854(2) Å]. In the cations of compounds II, III and XIV, the coordination of the phosphorus atom is tetrahedral [CPC angle: II, 106.2(2)?111.6(1)°; III, 104.01(6)?113.03(6)°; XIV, 107.54 (6)?112.79(6)°]; the anions contain intramolecular O-H?O hydrogen bonds between the hydroxyl hydrogen atom and carboxyl oxygen atom (II, 1.34; III, 1.23; and XIV, 1.83 Å).     

Synthesis and characterization of double hydrophilic block copolymers containing semi-rigid and flexible segments

3-Methyl-(E)-stilbene (3MSti) and 4-(diethylamino)-(E)-stilbene (DEASti) monomers are synthesized and polymerized separately with maleic anhydride (MAn) in a strictly alternating fashion using reversible addition-fragmentation chain transfer (RAFT) polymerization techniques. The optimal RAFT chain transfer agents (CTAs) for each copolymerization affect the reaction kinetics and CTA compatibilities. Psuedo-first order polymerization kinetics are demonstrated for the synthesis of poly((3-methyl-(E)-stilbene)-alt-maleic anhydride) (3MSti-alt-MAn) with a thiocarbonylthio CTA (methyl 2-(dodecylthiocarbonothioylthio)−2-methylpropionate, TTCMe). In contrast, a dithioester CTA (cumyl dithiobenzoate, CDB) controls the synthesis of poly((4-(diethylamino)-(E)-stilbene)-alt-maleic anhydride) (DEASti-alt-MAn) with pseudo-first order polymerization kinetics. DEASti-alt-MAn is chain extended with 4-acryloylmorpholine (ACMO) to synthesize diblock copolymers and subsequently converted to a double hydrophilic polyampholyte block copolymers (poly((4-(diethylamino)-(E)-stilbene)-alt-maleic acid))-b-acryloylmorpholine) (DEASti-alt-MA)-b-ACMO) via acid hydrolysis. The isoelectric point and dissociation behavior of these maleic acid-containing copolymers are determined using ζ-potential and acid–base titrations, respectively. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 219–227     

Homo- and copolymerizaton of norbornene and norbornene derivative with Ni- and Pd-based β-ketoiminato complexes and MAO

Neutral nickel(II) and palladium(II) complexes bearing β-ketoiminato ligand have been synthesized. The two complexes have been investigated as catalyst for the polymerization. Using methylaluminoxane (MAO) as a cocatalyst, both complexes produce vinyl-addition polynorbornenes, but palladium(II) complex displays much higher activity up to 8.0 × 10⁷ g/(molPd h). Furthermore, both Ni(II) and Pd(II)/MAO system can efficiently copolymerize norbornene and 5-norbornene-2-yl acetate (NB-OCOMe) in moderate yields and in relatively high molecular weights. The analyses of the product by FTIR, ¹H NMR and ¹³C NMR spectra give the verification of vinyl addition copolymer. The copolymers show narrow molecular weight distribution and good solubility in common organic solvents.     

Synthesis and structure of tetraphenylantimony and triphenylantimony 4-oxybenzoates

Solvate Ph₃Sb[OC(O)C₆H₄(OH-4)]₂ · 1/2Et₂O (I) has been synthesized by the reaction between triphenylantimony and 4-oxybenzoic acid in the presence of hydrogen peroxide in diethyl ether. Tetraphenylantimony 4-oxybenzoate, which crystallizes from DMSO in the form of solvate Ph₄SbOC(O)C₆H₄(OH-4) · DMSO (II), has been synthesized from pentaphenylantimony and triphenylantimony bis(4-oxybenzoate) or 4-oxybenzoic acid. According to X-ray diffraction data, an antimony atom in molecules of compounds I and II has a trigonal bipyramidal coordination. Crystals of compound I contain two crystallographically independent types of molecules (A and B). The Sb-C and Sb-O distances, the equatorial CSbC and axial OSbO angles are, respectively, 2.083(9)–2.103(8)Å; 2.068(5), 2.128(5)Å; 117.6(3)°–124.2(3)° and 171.5(2)° (IA); 2.103(9)–2.135(8)Å; 2.086(5), 2.154(6)Å;110.2(3)°–138.0(4)° and 174.8(2)° (IB). In compound II, Sb-C is 2.117(2)–2.175(2) Å, Sb-O is 2.247(2) Å, and C_eqSbC_eq and OSbC_ax angles are 110.89(9)°–133.30(9)° and 177.05(7)°, respectively. The Sb…O=C intramolecular contacts are 3.151(7), 3.153(8) Å (IA), 2.985(8), 3.008(9) Å (IB), and 2.975(5) Å (II). Molecules IA and IB are conformation isomers, which differ from each other by the arrangement of carboxyl groups with respect to the equatorial plane.     

The polarographic and voltammetric behaviour of acetylacetonato and hexafluoroacetylacetonato complexes in acetonitrile

The polarographic behaviour of Ce(acac)₄, Ce(acac)₃, Eu(acac)₃, Fe(acac)₃, Cr(acac)₃, Co(acac)₃, Mn(acac)₃, NaMn(acac)₃, Mn(acac)₂, Ni(acac)₂, Cu(acac)₂, VO(acac)₂, Fe(hfacac)₃, Cr(hfacac)₃ and Cu(hfacac)₂ has been studied in acetonitrile on the dropping mercury electrode. Half-wave potentials versus bisbiphenylchromium(I)/(0), the reversibility of the electrode reaction and the number of electrons participating in the electrode processes measured by coulometry are reported. Cyclovoltammetric measurements have been performed on the hanging mercury drop electrode and on the stationary platinum electrode, the data of these studies are given. quite different behaviour has been observed on the platinum electrode compared to the dropping mercury electrode. Large scale electrolysis was employed to obtain information on the reaction products. The influence of the electrode material and the reaction mechanisms are discussed.     

Halogen oxidation and nitrosylation of some aldimine and ketimine carbonyl complexes of chromium and molybdenum

Summary The halogen oxidation and nitrosylation of cis-[(SB)M-(CO)₄] [M = Cr or Mo, SB = N,N-ethylenebis(p-tolualideneimine), N,N-ethylenebis(p-N,N-dimethylaminobenzalideneimine) or N,N-ethylenebis(methyl-p-methoxyphenylketimine); M = Mo, SB = N,N-ethylenebis-(cinnamylideneimine) or N,N-ethylenebis(methyl-p-methylphenylketimine)] have been studied. Halogenation of [(SB)Cr(CO)₄] yielded [(SB)CrX₂] (X = Cl, Br or I) where-as [(SB)Mo(CO)₄] gave [(SB)Mo(CO)₃X₂] (X = Br or I) and [(SB)MoX _x ] (X = I, n = 2; X = Cl or Br, n = 4). NOCl produced [(SB)Cr(NO)₂Cl₂] and [(SB)Mo(CO)₂(NO)Cl] when reacted with the corresponding [(SB)M(CO)₄]. The complexes were characterized by physico-chemical and spectroscopic measurements.     

Synthesis and characterization of new thiazolidinones containing coumarin moieties and their antibacterial and antioxidant activities

New coumarin derivatives, namely (2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-phenylthiazolidin-3-yl)acetamide, N-(2-(3-methoxyphenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide, 2-(4-methyl-2-oxo-2H-chromen-7-yloxy)-N-(4-oxo-2-(2,3,4trimethoxyphenyl)thiazolidin-3-yl)acetamide and N-(2-(4-bromophenyl)-4-oxothiazolidin-3-yl)-2-(4-methyl-2-oxo-2H-chromen-7-yloxy)acetamide) were synthesized starting from 4-methyl-7-hydroxycoumarin. The structures of the obtained compounds were confirmed by analytical IR and NMR spectra to elucidate the different positions of protons and carbons and as well as theoretical studies (DFT/B3LYP). The new compounds were screened for antibacterial activity. Most of them are more active against E. coli S. aureus and B. subtilis than standard references.     

Photoelectron spectroscopy of mono and binuclear iron and chromium cyclooctatetraene complexes

The ultraviolet photoelectron spectra of mono and binuclear cyclooctatetraene (COT) complexes (CO)₃FeCOT (I) [(CO)₃Fe]₂COT (II), CpCrCOT (Cp: 1,3 cyclopentadienyl) (III) and (CpCr)₂COT (IV) are reported. The interpretation of the low energy part of the spectra is followed by a discussion concerning the metal–ligand (COT) and metal–metal interactions. The calculated gas phase structure of CpCrCOT is presented and its main features are discussed.     

Structure and properties of terbium(III) dipivaloylmethanate and its adducts with Bipy and Phen

The complex of terbium(III) with dipivaloylmethane (2,2,6,6-tetramethylheptane-3,5-dione = Htmhd) [Tb(tmhd)₃]₂ (1) and two its adducts with bipyridyl (Bipy) and phenanthroline (Tb(tmhd)₃·Bipy (2) and Tb(tmhd)₃·Phen (3)) are synthesized and analyzed by single crystal X-ray diffraction. The crystals of [Tb(tmhd)₃]₂ (1) belong to the monoclinic crystal system: P2₁/n space group, a = 12.2238(2) Å, b = 27.6369(5) Å, c = 21.8740(4) Å, β = 105.146(1)°, V = 7133.0(2)ų, Z = 4; the crystals of Tb(tmhd)₃·Bipy (2) and Tb(tmhd)₃·Phen (3) belong to the triclinic crystal system with unit cell parameters: (2) \(P\bar 1\) space group, a = 11.0554(6) Å, b = 12.2761(7) Å, c = 17.7096(8) Å, α = 77.457(2)°, β = 85.557(2)°, γ = 69.659(2)°, V = 2199.8(2) ų, Z = 2; (3) \(P\bar 1\) space group, a = 10.8814(3) Å, b = 12.2852(4) Å, c = 18.3590(6) Å, α = 80.463(1)°, β = 87.587(1)°, γ = 68.640(1)°, V = 2253.6(1) ų, Z = 2. The structures of the complexes are molecular and involve isolated [Tb₂(tmhd)₆] (1), Tb(tmhd)₃·Bipy (2), and Tb(tmhd)₃·Phen (3) molecules. The thermal properties of the obtained terbium complexes are studied by TG-DTA.     

New potential anti-SARS-CoV-2 and anti-cancer therapies of chitosan derivatives and its nanoparticles: Preparation and characterization

Chitosan (CS) is a biopolymer and has reactive amine/hydroxyl groups facilitated its modifications. The purpose of this study is improvement of (CS) physicochemical properties and its capabilities as antiviral and antitumor through modification with 1-(2-oxoindolin-3-ylidene)thiosemicarbazide (3A) or 1-(5-fluoro-2-oxoindolin-3-ylidene)thiosemicarbazide (3B) via crosslinking of poly(ethylene glycol)diglycidylether (PEGDGE) using microwave-assisted as green technique gives (CS-I) and (CS-II) derivatives. However, (CS) derivatives nanoparticles (CS-I NPs) and (CS-II NPs) are synthesized via ionic gelation technique using sodium tripolyphosphate (TPP). Structures of new (CS) derivatives are characterized using different tools. The anticancer, antiviral efficiencies and molecular docking of (CS) and its derivatives are assayed. (CS) derivatives and its nanoparticles show enhancement in cell inhibition toward (HepG-2 and MCF-7) cancer cells in comparison with (CS). (CS-II NPs) reveals the lowest IC₅₀ values are 92.70 ± 2.64 μg/mL and 12.64 µ g/mL against (HepG-2) cell and SARS-CoV-2 (COVID-19) respectively and the best binding affinity toward corona virus protease receptor (PDB ID 6LU7) ?5.71 kcal / mol. Furthermore, (CS-I NPs) shows the lowest cell viability% 14.31 ± 1.48 % and the best binding affinity ?9.98 kcal/moL against (MCF-7) cell and receptor (PDB ID 1Z11) respectively. Results of this study demonstrated that (CS) derivatives and its nanoparticles could be potentially employed for biomedical applications.     

Syntheses and X-Ray Crystal Structures of 2-Aminoindenes and Aminocymantrenes

Substituted 2-aminoindenes have been synthesized in almost quantitative yields by reactions of amines such as methylpiperazine, trimethylethylenediamine, 1,4-diaza-cycloheptane and N,N′-dimethylethylenediamine with 2-indanone. The 2-aminoindenes can be deprotonated and reacted with BrMn(CO)₃(Py)₂ to produce the respective aminoindenyl-cymantrenes in yields between 55–70%. The X-ray crystal structures of 2-(methylpiperazine)indenyl-cymantrene 5 (P1 , a = 12.667(3) Å, b = 16.630(3) Å, c = 17.382(3) Å, α = 72.70(3)°, β = 74.59(3)°, γ = 88.66(3)°, V = 3364.1(12) Å ³, Z = 8, R1(2σ(I)) = 4.02%, wR2(2σ(I)) = 10.30%) and the HClO₄ adduct of 2-(trimethylethylenediamine)-indenyl-cymantrene 6 (Cc, a = 23.722(5) Å, b = 6.9080 Å, c = 13.264 Å, β = 111.77(3)°, V = 2018.6(7) Å 3, Z = 4, R1(2σ(I)) = 2.94%, wR2(2σ(I)) = 7.90%) were determined. In both complexes the indenyl-carbon bonded to nitrogen displays significantly longer bonds to manganese [223.5(3)–225.8(3) pm] than the other four carbon atoms [213.3(3)–219.1(3) pm]. The short indenyl-nitrogen bonds of 136.2(4) and 137.8(4) pm are indicative of a substantial multiple bond character. The complexation of Zn²⁺ by the nitrogen atoms of 6 results in significant shifts of the CO stretching frequencies.     

Bis(tetraphenylantimony) succinate,malate, and tartrate: Syntheses and structures

The reactions of pentaphenylantimony with succinic, malic, and tartaric acids (mole ratio 2: 1) in toluene afford bis(tetraphenylantimony) succinate (I), malate (II), and tartrate (III) in yields of 98, 92, and 94%, respectively. According to the X_ray diffraction analysis results, molecules I and II are centrosymmetric. In compound II, the hydroxy group in the acid residue is disordered over two positions. Crystal III includes two types of crystallographically independent molecules (a and b). The antimony atoms in compounds I, II, IIIa, and IIIb have distorted trigonal bipyramidal coordination modes. The axial angles C_axSbO_ax are 166.80(8)° (I); 174.8(2)° (II); 176.4(4)°, 177.4(3)° (IIIa); and 173.3(4)°, 172.7(4)° (IIIb). The equatorial angles C_eqSbC_eq vary in the ranges 99.3(1)°–154.5(1)° (I); 115.2(2)°–123.3(2)° (II); 115.7(4)°–123.3(4)° 115.2(5)°–125.6(5)° (IIIa); and 107.9(4)°-129.1(4)°, 113.7(4)°-124.8(5)° (IIIb). The Sb-C and Sb-O bonds are 2.138(3)-2.176(3), 2.319(2) Å (I); 2.111(6)–2.163(5), 2.243(4) Å (II); 2.072(13)–2.169(11), 2.252(7), 2.284(7) Å (IIIa); and 2.047(11)–2.190(11), 2.224(7), 2.256(7) Å (IIIb). The intramolecular distances Sb…O=C are 2.528(3) (I); 3.267(7) (II); 3.381(7), 3.436(7) (IIIa); and 3.351(7), 3.162(7) Å (IIIb). For structures I, II, and III, the CIF files are CCDC 929151, 941542, and 941543, respectively.     

Synthesis and Characterization of Heterodinuclear IrCo, RuCo, IrNi, and RuNi Complexes Containing Pyrazolate and Pyrazolylborate Ligands

Treatment of the metallo ligands [ML(pz)(2)(Hpz)] (pz = pyrazolate; L = C(5)Me(5), M = Ir (1); L = mesitylene, M = Ru (3)) with [M'Cl{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (4), Ni (5)) yields heterodinuclear complexes of formula [LM(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (L = C(5)Me(5); M = Ir; M' = Co (6), Ni (7). L = mesitylene; M = Ru; M' = Co (8)). The related complex [Ru(eta(6)-p-cymene)(pz)(2)(Hpz)] (2) reacts with equimolar amounts of 4 or 5 to give mixtures of the corresponding bis(&mgr;-pyrazolato) &mgr;-chloro complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (9), Ni (10)) and the triply pyrazolato-bridged complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(3)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (11), Ni (12)). Complex 1 reacts with 5 in the presence of KOH to give the IrNi complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(3)Ni{HB(3-i-Pr-4-Br-pz)(3)}] (13) whereas its reaction with 4 and KOH rendered the bis(&mgr;-pyrazolato) &mgr;-hydroxo complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(2)(&mgr;-OH)Co{HB(3-i-Pr-4-Br-pz)(3)}] (14). The molecular structure of the heterobridged IrCo complex (6) and those of the homobridged RuNi (12) and IrNi (13) complexes have been determined by X-ray analyses. Compound 6 crystallizes in the monoclinic space group P2(1)/n, with a = 10.146(5) ?, b = 18.435(4) ?, c = 22.187(13) ?, beta = 97.28(4) degrees, and Z = 4. Complex 12 is monoclinic, space group P2(1), with a = 10.1169(7) ?, b = 21.692(2) ?, c = 11.419(1) ?, beta = 112.179(7) degrees, and Z = 2. Compound 13 crystallizes in the monoclinic space group Cc, with a = 13.695(2) ?, b = 27.929(6) ?, c = 13.329(2) ?, beta = 94.11(4) degrees, and Z = 4. All the neutral complexes 6, 12, and 13 consist of linear M.M'.B backbones with two (6) or three (12, 13) pyrazolate ligands bridging the dimetallic M.M' units and three substituted 3-i-Pr-4-Br-pz groups joining M' to the boron atoms. The presence in the proximity of the first-row metal M' of the three space-demanding isopropyl substituents of the pyrazolate groups induces a significant trigonal distortion of the octahedral symmetry, yielding clearly different M'-N bond distances on both sides of the ideal octahedral coordination sphere of these metals.