S. E. Nefedov

IMIDO/NITRENE LIGANDS IN THE COMPLEXES OF PLATINUM METALS

A synthetic search for palladium and platinum complexes with nitrene ligands via reaction of tetranuclear cluster Pd 4 ( μ 2 -CO) 4 ( μ 2 -OAc) 4 with nitrosobenzene and reactions of mononuclear complexes [MX 4 ] 2− (M=Pt, Pd; X=Cl, NO 2 ) with o -phenylenediamine and its N -phenyl derivative have been carried out. The complexes obtained, [Pd(OAc) o -(PhN)(NO)C 6 H 4 ] 2 , Pd[ o -(NPh)(N)C 6 H 4 ] 2 , Pt[ o -(NPh)(N)C 6 H 4 ] 2 , Pt 2 [ o -(NPh)(N)C 6 H 4 ] 4 [O 3 SCF 3 ] 2 , and Pt 2 [ o -(NPh)(N)C 6 H 4 ] 4 Br 2 , have been structurally characterized by single crystal X-ray diffraction studies. The oxidation of complex Pt[ o -(NPh)(N)C 6 H 4 ] 2 by excess AgO 3 SCF 3 afforded a heterotricyclic quinoxaline derivative, whose structure has been determined by X-ray analysis. The data obtained suggest that labile nitrene species coordinated to Pd and Pt complexes are possible intermediates in the reactions under study.

New polynuclear cobalt trimethylacetate complexes: synthesis and structure

Extraction of polymer (1), formed in the reaction of CoCl2 with KOOCBut, with boiling hexane gives crystals of hexamer Co6(μ3-OH)2(OOCBu1)10(HOOCBu1)4 (2). According to data of X-ray study, four Co11 atoms in the hexanuclear molecule2 have an octahedral ligand environment and two Co11 atoms have a tetrahedral one. Dissolution of polymer1 in EtOH results in its splitting into Co4(μ3-OH)2(OOCBu1)6(HOEt)6 tetramers (3). In molecule3, two asymmetric dimeric (η2-OOCBut)(EtOH)Co(μ-OOCBut)Co(HOEt)2 fragments are bound by two tridentate bridging OH groups.

TRIMETHYLACETATE NICKEL COMPLEXES

The present review is devoted to the chemistry of trimethylacetate NiII complexes with various nitrogen-containing ligands. Pathways of formation of complexes containing the Ni2(μ-OH2)(μ-OOCCMe3)2 and Ni2(μ-OOCCMe3)4 fragments are discussed. Pathways of degradation of the nine-nuclear complex Ni9(HOOCCMe3)4(μ4-OH)3(μ3-OH)3)3(μ4-OOCCMe3)12 under the action of primary amines (aniline or propargylamine) as well as the process of dehydration ofN-phenyl-o-phenylenediamine up to the bischelate mononuclear complex [1,2-(NH)(NPh)C6H4]2Ni are demonstrated.

Synthesis, structures, and magnetic properties of binuclear carboxylate complexes with NiII and NiIII atoms

The reaction of NiCl2·6H2O with Me3CCOOH and KOH taken in a molar ratio of 1:2:2 in water afforded the nonanuclear antiferromagnetic complex Py2Ni2(Me3CCOOH)2(OOCCMe3)2(μ-OOCCMe3)2(μ-OH2), which apparently contains NiII and NiIII atoms. The complex was isolated by extraction with CH2Cl2, benzene, or hexane. The reactions of this complex with pyridine bases (pyridine (Py), 3,4-lutidine (Lut), and nicorandil (Nic)) gave the adducts L4Ni2(OOCCMe3)2(μ-OOCCMe3)2(μ-OH) (L=Py, Lut, or Nic, respectively). According to magnetic measurements, intramolecular ferromagnetic exchange interactions in these adducts are complemented by intermolecular antiferromagnetic interactions. Pyrolysis of the pyridine adduct in air or under an inert atmosphere in xylene yielded the antiferromagnetic complex Py2Ni2(Me3CCOOH)2(OOCCMe3)2(μ-OOCCMe3)2(μ-OH2), which contains NiII atoms. The structures of all the complexes synthesized were established by X-ray diffraction analysis. The electronic absorption spectra of these compounds are considered.

Antiferromagnetic complexes with the metalmetal bond: XIX. Influence of the nature of bridging ligands on geometry and magnetic properties of the metallotetrahedral clusters (MeC5H4)4Cr4(μ3-E)4 where E = O, S, Se☆

Abstract Interaction of (MeC 5 H 4 ) 2 Cr with oxygen or selenium results in formation of 60-electron clusters (MeC 5 H 4 ) 4 Cr 4 (μ 3 -O) 4 (I) and (MeC 5 H 4 ) 4 Cr 4 (μ 3 -Se) 4 (III). Their structures were determined by X-ray diffraction study (I: space group I 4, a = b = 13.0857(7), c = 7.0538(4) A, V = 1207.9 A 3 , Z = 2, R 1 = 0.058, R w = 0.066; III: space group Pbca, a = 18.456(2), b = 17.164(1), c = 16.227(2) A, V = 5140.4 A 3 , Z = 8, R 1 = 0.054, R w = 0.047). In contrast to the relatively symmetrical structure of sulfide (MeC 5 H 4 ) 4 Cr 4 (μ 3 -S) 4 (II) (CrCr 2 × 2.848 and 4 × 2.822 A) and selenide III, in I a pronounced tetrahedral distortion of the metal core is observed (CrCr 2 × 2.896(3) and 4 × 2.759(3) A). All the CrCr bonds in III are elongated, compared with those in II (up to ∼ 3.00–3.04 A). The oxide cluster I is antiferromagnetic whereas the analogous sulfide and selenide clusters are diamagnetic.

Platinum-Catalysed Cyclopropanation of Olefins with Ethyl Diazoacetate

Abstract The addition of ethyl diazoacetate to olefins in the presence of a catalytic amount of platinum complexes provides the corresponding cyclopropanes in good to excellent yields.

Antiferromagnetic complexes with metal—metal bonds XX. Synthesis, molecular structure, electronic structure and magnetic properties of the cyclopentadienyl-alkoxide complexes Cp2Cr2(μ-OR)2[OCCo3(CO)9] and Cp2Cr2(OR)2(μ-OR)2 (R = CMe3)☆

Interaction of the binuclear complex Cp2Cr2(μ-OCMe3)2 (I) with Co2(CO)8 in the molar ratio 11 in benzene at room temperature yields the cluster Cp2Cr2(μ-OCMe3)2[OCCo3(CO)9] (II) (space group P21/n, a 10.377(4), b 17.879(7), c 18.115(7) A, β 101.39(3)°, V 3294.7 A3, Z = 4, T − 100°C). One of the chromium atoms of the Cp2Cr2(μ-OCMe3)2 fragment (CrCr 2.766(1), CrOCMe3 1.950(3) A) in complex II is bonded to the oxygen atom of the μ3-CO group of the cluster fragment Co3(μ3-CO)(CO)9 (CrO 1.988(3), CO 1.247(6) A, CoCo 2.483(1)–2.489(1) A), which is an analogue of the alkoxide group. Compound II is treated as a Cp2Cr2(OR)(μ-OCMe3)2 complex with chromium atoms of different oxidation states; its properties are compared with the characteristics of the binuclear tetraalkoxide Cp2Cr2(OCMe3)2(μ-OCMe3)2 (III) which is formed along with the well-known cluster Cp4Cr4Te4 in the reaction of I with tellurium. Complex III has been characterized by an X-ray diffraction study (space group Pna21, a 22.4539(12), b 11.7514(6), c 10.7303(5) A, V 2831.3 A, Z = 8, T 20°C). Both CrIII atoms of the binuclear fragment Cp2Cr2(μ-OCMe3)2(Cr...Cr 3.004(3) A, CrO(average) 2.000(9) A) in III are bonded to the terminal alkoxide group (CrO(average) 1.852(8) A). Complexes I–III are antiferromagnetic. Calculations of the MOs for I–III compared with the well-known complex Cp2Cr2(OMe)2(NO)2 have been carried out by the extended Huckel method.

Phenylacetylene transformations in clusters with Re2Fe and Re2Ni2 core. Synthesis and molecular structure of Re2Fe(CO)9(μ3,η4-CHCHC6H4) and Cp2Ni2Re2(CO)6− (μ4-PhCCCHCHPh)

Abstract Interaction of the binuclear complex Re2(CO)8(μ-H)(μ-CCPh) (I) with Fe3(CO)12 and Cp2Ni has been studied. Reaction of I with Fe3(CO)12 in refluxing toluene results in formation of a heterometallic cluster Re2Fe(CO)9 (μ3,η4-CHCH-C6H4) (II). According to the X-ray structural data, in this cluster ortho-metallation of the phenyl ring occurs and results in the appearance of the metalcyclopentadiene fragment. The core of the cluster II is an angular metal chain Re2Fe with equal ReFe bond lengths of 2.671(2) A and nonbonding Re(1)⋯Re(2) distances of 3.893(7) A. Reaction of I with Cp2Ni in refluxing o-xylene results in formation of the heterometallic cluster Cp2Ni2Re2(CO)6(μ4-PHCCCHCHPh) (III) (70%) along with the trinuclear cluster Cp3(μ-CO)2 and Re2(CO)10. According to the X-ray structural data cluster III contains a heterometallic Re2Ni2 “butterfly” core with a dihedral angle of 122° between the Re2Ni planes. Dimerisation of the two acetylene fragments gives a ligand which is coordinated between the ReNi2 “wings” only by a CC triple bond (with the length of 1.48(2) A), the second hydrocarbon fragment CHCHPh is non-coordinated.

Nano-sized octa-nuclear nickel cationic complex: self-assembly on supramolecular level

Abstract Microporous one-dimensional material was synthesized by reacting Ni-9 cluster compound Ni9(HOOCCMe3)4(μ4-OH)3(μ3-OH)3(OOCCMe3)12 with organic ligand 3-(3,5-dimethylpyrazol-1-yl)-6-(3,5-diamino-1,3,4-thiadiazolyl)-1,2,4,5-tetrazine) (L). According to X-ray data, the nano-sized endless tubes of the material consist of stacked cationic Ni(II) octa-nuclear cyclic complexes of formula [Ni8(μ-OH2)4(μ-OOCCMe3)4(η2-OOCCMe3)(OOCCMe3)10L4]+ and pivalate anions ordered regularly aside the tubes. The channels of the tubes are filled with acetonitrile molecules forming an inclusion compound.

Rupture of the triple CC and CO bonds in the mixed-metal clusters with Ni2Mo2 and MO4Co3 cores. Synthesis and molecular structures of Cp4Ni2Mo2(μ3-CPh)2(μ3-CO)2 and Cp4Mo4(μ3-OH)(μ3-CPh)2(μ6-C)Co3(μ-CO)3(CO)3

Mixed-metal cluster Cp4Ni2Mo2(μ3-CPh)2(μ3-CO)2 (I), in which the carbyne bridges under the “butterfly” Mo2Ni2 (Mo-M 2.674(2), Mo-Ni 2.664(2) A) wings are formed due to splitting of the CC bonds, has been synthesized by reaction of CP2Ni2(Ph2C2) and Cp2Mo2(CO)6 in refluxing o-xylene and characterized by X-ray structural analysis. In the reaction of CpNiCo(CO)3(Ph2C2) with CP2Mo2(CO)6, the tolan (diphenylacetylene) molecule is transferred with formation of the well known CP2Mo2(CO)4(Ph2C2). An unusual seven-nuclear diamagnetic cluster CP4Mo4(μ3-OH)(μ3-CPh)2(μ6-C)CO3(μ-CO)3(CO)3 (III) in which the simultaneous rupture of CC and CC bonds takes place has been synthesized by reaction of CO2(CO)6(Ph2C2) with Cp2Mo2(CO)6 in refluxing o-xylene. Cluster III is a combination of the distorted tetrahedral Cp4Mo4(μ3-CPh)2(μ-OH) (Mo-Mo 2.761(4)–2.939(4) A) and triangular Co3(μ-CO)3(Co)3 (Co-Co 2.463(3) A) fragments bonded by μ6-carbide bridges and CoMo bonds (2.909(6)–2.946(5) A).