Template synthesiS: Geometrical and electronic structures of the Fe nitrosyl complex formed by bis(S-methylisothiosemicarbazone)-2,4-pentandione

Sodium acetylacetonate reacts with S-metliylisothiosemicarbazidium nitrate and Fe(NO₃)₃ · 9H₂O in ethanol to make [Fe(HL)NO]NO₃, in which H₃L is bis(S-methyl-isothiosemicarbazone)-2,4-puntandione. The [Fe(HL)NO]⁺ cation has a square pyramidal structure with the HL^2- arranged around the central ion in the basal plane and the nitrogen atom of the NO group in the apical position, with the iron atom diverging from the plane of the base of the pyramid by 0.477 Å. The FeN0 moiety has a linear structure (FeNO = l72.7°). XRD, IR, and Mössbauer spectroscopy have been combined with calculations on the electronic structure to demonstrate that the Fe-NO bond is covalent.Chemical Institute, Academy of Sciences of Moldavian SSR. Applied Physics Institute, Academy of Sciences of the Moldavian SSR. Kishinev. Institute of Crystallography, Academy of Sciences of the USSR. Kurnakov Institute for General and Inorganic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No, 3, pp. 376–381, May–June, 1991. Original article submitted February 18, 1991.     

Synthesis,molecular structures,and thermal decomposition of heterometallic (π-cyclooctadiene)platinum-bis(tricarbonyliron-μ3-chalcogenides)[Fe—Fe], (π-C8H12)Pt(μ3-X)2Fe2(CO)6, where X = S,Se, or Te

Transmetallation of the Fe₃(₃-X)₂(CO)₉ clusters (X = S, Se, or Te) under the action of (-C₈H₁₂)PtCl₂ afforded new heterometallic clusters (-C₈H₁₂)Pt(₃-X)₂Fe₂(CO)₆ (2—4, respectively), which were characterized by X-ray diffraction analysis. The (-C₈H₁₂)Pt fragment in these clusters is bound to two ₃-bridging chalcogen atoms X. The iron atoms are linked to each other. The coordination environment about the Pt atom is planar-square; the Pt...Fe distance is larger than 3.2 . In the synthesis of cluster 4, a new Pt complex was also obtained for which the structure (CO)₂Pt(-Te)₂Pt(CO)₂ (5) was proposed. According to the results of differential scanning calorimetry, thermal decomposition of complex 5 gave rise only to PtTe, whereas complexes 1—4 gave products with the empirical formula Fe₂PtX₂C₂O₂. The influence of the steric effects on the geometry of the clusters is discussed.     

Mass spectrometry of π-complexes of transition metals : V. Dimeric (π-cyclopentadienyl)dicarboxylatovanadium complexes

Mass spectra of dimeric (π-cyclopentadienyl)dicarboxylatovanadium complexes [π-C₅H₅V(OOCR)₂]₂, have been studied. The principal paths of fragmentation of the trihaloalkyl derivatives involve the formation of VHal bonds, whereas VO bonds are formed during decomposition of acetato and formato complexes. An unusual increase in stability of dimeric and monomeric ions of the alkyl derivatives is observed in going from R = CH₃ to R = CF₃. With aromatic complexes, only ions containing a single metal atom occur.     

Antiferromagnetic complexes involving metal---metal bonds III. Synthesis, structure and magnetic properties of heterotrinuclear complexes of the type M(CO)5L (M = Cr, Mo and w) containing [(C5H5CrSCMe3)2S] as unusual antiferromagnetic ligand L

Isostructural heterotrinuclear complexes (C₅H₅CrSCMe₃)₂S · M(CO)₅ (II–IV) were isolated from photochemical reactions between the antiferromagnetic complex (C₅H₅CrSCMe₃)₂S (I) (with the Cr---Cr bond 2.689 Å long and with the exchange parameter −2J = 430 cm⁻¹) and metal hexacarbonyls, M(CO)₆, where M is Cr, Mo, or W. According to the X-ray structural data on III and IV, complex I plays the role of an unusual antiferromagnetic ligand L bound to M through the sulphide bridge (M–S 2.58(2) Å). Its geometry remains practically unaffected by the complex formation (the Cr---Cr bond length in III and IV is 2.73(1) Å). The exchange parameter, −2J (410, 440 and 440 cm⁻¹ in II to IV, respectively), also shifts only insignificantly from that of I, which probably means that indirect exchange via the sulphide bridge in I is of minor importance compared with the direct Cr---Cr exchange. The Cr---Cr bond length may thus be correlated with the observed overall exchange coupling.     

Syntheses,molecular structures,and thermal decomposition of cyclopentadienyldicarbonylmanganese chalcogenide derivatives

Transmetallation of the dichalcogenide complexes [CpMn(CO)₂]₂(-X₂) (X = S or Se) with M(CO)₅(thf) (M = Cr or W) afforded new heterometallic complexes CpMn(CO)₂(-Se₂)Cr(CO)₅, CpMn(CO)₂(-Se₂)[Cr(CO)₅]₂, CpMn(CO)₂(-X₂)[W(CO)₅]₂ (X = S or Se), and CpMn(CO)₂(-Se₂)[Cr(CO)₅][W(CO)₅]. According to the X-ray diffraction data, their molecular structures contain the cyclic MnX₂ fragments coordinated by one or two M(CO)₅ groups via the X atoms. Study of thermal decomposition of the manganese complexes with different Mn : M : X ratios (M = Cr, W; X = S, Se, Te) by differential scanning calorimetry (DSC) and thermogravimetry demonstrated that this process took place at rather low temperatures (100—400 °C) and was accompanied by complete elimination of the CO groups followed by elimination of the Cp groups. At any metal to chalcogen ratio, the resulting inorganic chalcogenides contained no impurities of metal oxides and carbides.     

Heterometallic cluster [CpMn(CO)2]2S2Ni(Dppe) containing the binuclear manganese disulfide complex as a ligand

A reaction of the disulfide complex [CpMn(CO)₂]₂S₂ with the Ni(0) diphosphine acetylene complex, (Dppe)Ni(C₂Ph₂) (I), yielded the heterometallic complex [CpMn(CO)₂]₂S₂Ni(Dppe) (II). An X-ray diffraction study revealed lateral coordination of the disulfide group to the Ni atom in complex II, which results in lengthening of both the S-S and Mn-S bonds against those in the starting complex. However, the Mn-S and Ni-S bonds are still much shorter than the sums of the covalent radii of the corresponding atoms.     

Synthesis and molecular structure of chlorostannyl derivatives of carbonyl(cyclopentadienyl)nitrosylmanganese

The reaction of [CpMn(CO)(NO)]₂ (I) with an equimolar amount of tin dichloride in THF at room temperature gave the product of tin insertion into the Mn-Mn bond, the carbonyl nitrosyl complex [CpMn(CO)(NO)]₂SnCl₂ (II). The same complex was formed on treatment of CpMn(CO)(NO)SnCl₃ with sodium borohydride. Treatment of I with an excess of anhydrous tin dichloride under the same conditions gave the trinitrosyl complex Cp₂Mn₂(NO)(μ-NO)₂SnCl₃ (III). According to X-ray diffraction, II contains a Mn-Sn-Mn chain with highly shortened Mn-Sn bonds (2.5570(2) and 2.5754(2) Å). Compound III contains a Mn-Mn-Sn chain (Mn-Mn, 2.5358(10); Mn-Sn, 2.5604(8) Å) with the Mn-Mn bond supplemented by two nitrosyl bridges and one terminal NO group.