Satish C. Tripathi

Halogen derivatives of triphenylphosphine, triphenylarsine and triphenylstibine substituted molybdenum carbonyls

SummaryHalogen oxidation of several LMo(CO)s andcis-L2Mo(CO)4 (L = Ph3P1Ph3As and Ph3Sb) derivatives has been studied. The LMo(CO)5 complexes react with halogens to give hexacoordinate LMo(CO)3 X2 (X = Cl, Br or I) derivatives which are of very rare occurrence. Similar reactions withcis-L2Mo(CO)4 give heptacoordinate L2Mo(CO)3X2 derivatives. The complexes have been characterised by elemental analysis, i.r. and conductivity measurements.

Syntheses and spectroscopic studies of mono- and di- cyclopentadienylzirconium(IV) derivatives with heterocyclic thiones

Abstract The reactions of dichlorodi-cyclopentadienylzirconium(IV) with two important series of heterocyclic thiones, viz. oxadiazolethione (OxtH) and thiohydantoin (ThtH) in anhydrous tetrahydrofuran (molar ratios 1/1 and 1/3) in the presence of base, led to the formation of derivatives of the types [Cp 2 Zr(Oxt(Cl], [CpZr(Oxt) 3 ], [Cp 2 Zr(Tht)Cl] and [CpZrTht) 3 . The complexes were characterized by elemental analysis, electrical conductance, magnetic measurements and spectral (electronic, infrared and 1 H NMR) studies. Possible structures are proposed for these derivatives.

Syntheses and structural studies on picolinoyl, nicotinoyl and isonicotinoyl hydrazone derivatives of dicyclopentadienylzirconium(IV)

Abstract The reactions of dicyclopentadienylzirconium(IV) dichloride with picolinoyl, nicotinoyl and isonicotinoyl hydrazones derived from the appropriate acid hydrazides and acetone, acetophenone, salicylaldehyde or o -hydroxyacetophenone, have been studied in anhydrous tetrahydrofuran or dichloromethane in the presence or absence of amine using different molar ratios. Tentative structural coclusions are drawn for the reaction products based upon elemental analysis, electrical conductance, magnetic moment and spectral data (electronic, infrared and 1 H NMR). These ligands behave as neutral or deprotonated chelating agents. The coordination behaviour depends upon the pH of the medium, the nature of the substituent and the position of the hydrazone group relative to the pyridine nitrogen nucleus.

Studies on monocyclopentadienyl titanium(IV) dithiocarbamato complexes

Titanium(IV) dithiocarbamato complexes of the typesCpTi(S2CNHR)Cl2 andCpTi(S2CNHR)2Cl, whereR=C8H5N2S, C9H5N2SCl2 and C9H7N2S, have been prepared by the reaction of monocyclopentadienyl titanium(IV) trichloride with the potassium salt of the appropriate dithiocarbamic acid in anhydrous dichloromethane. Conductance and infrared studies indicate that these complexes are non-electrolytes in which all dithiocarbamate ligands are bidentate. Therefore, 5 and 6 coordinate structures can be assigned toCpTi(S2CNHR)Cl2 andCpTi(S2CNHR)2Cl complexes, respectively.1H-NMR spectra indicate that there is rapid rotation of the cyclopentadienyl ring about the metal ring axis.ZusammenfassungEs wurden Titan(IV)-dithiocarbamat-Komplexe vom TypCpTi(S2CNHR)Cl2 undCpTi(S2CNHR)2Cl mitR=C8H5N2S, C9H5N2SCl2 und C9H7N2S mittels der Reaktion von Monocyclopentadienyltitan(IV)trichlorid mit dem Kaliumsalz der entsprechenden Dithiocarbaminsäure in wasserfreiem Dichlormethan dargestellt. Leitfähigkeitsmessungen und IR-Untersuchungen zeigen, daß diese Komplexe Nichtelektrolyte sind, bei denen alle Dithiocarbamat-Liganden zweizähnig sind. Demnach können 5-, bzw. 6-koordinierte Strukturen für die Komplexe des TypsCpTi(S2CNHR)Cl2, bzw.CpTi(S2CNHR)2Cl angenommen werden. Die1H-NMR Spektren zeigen eine rasche Rotation des Cyclopentadienylrings um die Metall-Ring Achse an.

Aliphatic acid dihydrazide derivatives of dicyclopentadienylzirconium(IV) dichloride and their reactions with β-diketones. Formation of cyclic compounds

Abstract The reactions of dicyclopentadienylzirconium(IV) dichloride with bidentate aliphatic acid dihydrazide (LH 2 ) derived from oxalic, succinic, and adipic acids (metal to ligand molar ratios 1 : 1 and 1 : 2, respectively) in anhydrous tetrahydrofuran in the presence of base led to the formation of the [Cp 2 Zr(L)] and [CpZr(LH) 2 Cl] complexes. The complexes were characterized by elemental analyses, electrical conductance, magnetic measurements and spectroscopic studies. These ligands appear to behave as bidentate chelate agents. All the complexes contain terminal amino or terminal hydrazinc nitrogen atoms with an unshared electron pair, enabling nucleophilic condensations. Therefore, the reactions of these complexes with β-diketones (acetylacetone, benzoylacetone, dibenzoylmethane, thenoyltrifluoroacetone) in the presence of glacial acetic acid have been studied viz., ring closure and formation of macrocyclic ligand (mac) complexes. Two types of cyclic products viz., [Cp 2 Zr(mac)] and [CpZr(Mac)Cl] were isolated. The spectral studies of these cyclic products are reported.

Nitrosyl carbonyl derivatives of group VI metals

Abstract [M(CO)2(NO)(o-phen or 2,2′-bipy)]2(M = Mo, W) are formed when a slow stream of NO is passed through a benzene solution of M(CO)4(o-phen or 2,2′bipy). Under similar conditions M(CO)4(Ph2PCH2CH2AsPh2) (M = Cr, Mo) gives M(NO)3(Ph2PCH2CH2AsPh2), but W(CO)4(Ph2PCH2CH2AsPh2) gives the nitrosyl carbonyl complex W(CO)(NO)2(Ph2PCH2CH2AsPh2).

Lanthanum(III) and prasedymium(III) complexes with piperazine dithiosemicarbazones

Lanthanum(III) and praseodymium(III) complexes of the type [Ln(L)Cl(H2O)]2 (Ln = La(III) or Pr(III); LH2 = dithiosemicarbazone ligands derived from piperazine dithiosemicarbazide and benzaldehyde, 4-nitrobenzaldehyde, and 2-methoxybenzaldehyde) have been synthesized in methanol in the presence of sodium hydroxide. The complexes have been characterized by elemental analyses, molecular weight, molar conductance, electronic absorption, IR, and 1H and 13C NMR spectral studies. Nephelauxetic ratio, covalency parameter, and bonding parameter for these complexes have also been calculated. Thermal studies of the complexes have been carried out using TG, DTG, and DSC techniques. Kinetic parameters, such as apparent activation energy and order of reaction, were determined by the Coats-Redfern graphical method. The heats of reaction for different reaction steps were calculated from DSC curves.

Schiff-base derivatives of molybdenum carbonyl

SummaryReactions of five Schiff bases (SB),viz.,N,N′-ethylenebis(benzalideneimine) (SB1),N,N′-ethylenebis(p-anisylideneimine) (SB2),N,N′-ethylenebis(methylphenylketimine) (SB3),N,N′-ethylenebis(diphenylketimine) (SB4) andN,N′-ethylenebis (salicylideneimine) (SB5) with molybdenum hexacarbonyl have been studied. The first four Schiff bases yieldcis-disubstituted derivatives whereas a non-carbonyl complex is obtained for the last one (SB5). [(Ph3E)Mo(CO)5] (E = P or As) after reaction with SB give SB-bridged dinuclear [(Ph3E)(CO)4Mo-μ-(SB)-Mo(CO)4(Ph3E)] derivatives. Halogen-oxidation and nitrosylation ofcis-[(SB)Mo(CO)4] have also been studied.

Tricarbonylbis(?-cyclopentadienyl)diiron and iododicarbonyl(?-cyclopentadienyl)iron amine complexes

SummaryThe monodentate ligands, L, ethylamine, butylamine, cyclohexylamine, benzylamine, piperidine and morpholine, and bidentate ligands, L, 1,10-phenanthroline and 2,2′-bipyridyl react with tetracarbonylbis(η-cyclopentadienyl)diiron to give monosubstituted derivatives, (η-C5H5)2Fe2(CO)3L, and with iododicarbonyl(η-cyclopentadienyl)iron to yield ionic products, [(η-C5H5)Fe(CO)2L]I. I.r. spectral studies suggest that two isomeric (η-C5H5)2-Fe2(CO)3L molecules exist.

Tetraazaadamantane Derivatives of Group VI Metal Carbonyls

SummaryTetraazaadamantane (taad) reacts with group VI metal hexacarbonyls to give mononuclear (taad)M(CO)5 (M=Cr, Mo and W) derivatives. Mixed ligand metal tricarbonyls,cis- (L-L)(taad)M(CO)3 (L-L=o-phenanthroline or 2,2′-bipyridine; M=Cr and Mo) have also been synthesised. Bromine or iodine reacts with (taad)M(CO)5 (M=Cr and Mo) to give [(taad)M(CO)5X]+X− (X=Br or I). Nitrosyl chloride reacts with (taad)M(CO)5 at room temperature to yieldmer- (taad)M(CO)3NOCl while with the mixed (L-L)(taad)-Mo(CO)3 complex, a mixture of (L-L)Mo(NO)2Cl2 and (L-L)Mo(CO)2NOCl was obtained. An analogous reaction with (L-L)(taad)Cr(CO)3, gave only (L-L)Cr(NO)2Cl2 derivatives. The products have been characterised by elemental analysis, i.r. spectra, conductivity data and magnetic measurements.