Cobalt(II), nickel(II) AND zinc(II) dicarboxylate complexes with hydrazine as bridged ligand

The complexes of chromium and molybdenum with salicylidene-2-aminophenol (shaH₂), salicylidene-2-aminoanisole (salanH₂), salicylidene-2-aminoaniline (salphenH₂) and biquinoline (biq) were studied using the thermogravimetric techniques. The thermal decomposition of all complexes was found to be first order reaction and the thermodynamic parameters corresponding to the different decomposition steps were reported. Molybdenum complexes were found to be more thermally stable and the order of stability was [Mo(CO)₄(biq)]>[MoO(salphen)]>[MoO₂(salphenH)₂]>[MoO₄(salan)₂]>[MoO(sha)]. Similar trend was found for chromium complexes where [Cr(CO)₄(biq)]>[Cr(CO)₂(salphen)] >[CrO₂(CO)₂(shaH₂)]>[CrO₂(CO)₂(salan)₂].     

Reaction of metal carbonyls with 2-hydroxy-1-naphthaldeyde methanesulfonylhydrazone and characterization of the substitution products

Five new complexes, [M(CO)₅(nafmsh)] [M?=?Cr, 1; Mo, 2; W, 3], [Re(CO)₄Br(nafmsh)], 4 and [Mn(CO)₃(nafmsh)], 5 have been synthesized by the photochemical reaction of metal carbonyls [M(CO)₆] (M?=?Cr, Mo, W), [Re(CO)₅Br], and [Mn(CO)₃Cp] with 2-hydroxy-1-naphthaldehyde methanesulfonylhydrazone (nafmsh). The complexes have been characterized by elemental analysis, EI mass spectrometry, FT-IR, and ¹H NMR spectroscopy. The spectroscopic studies show nafmsh is a monodentate ligand coordinating via the imine N donor atom in 1–4 and as a tridentate ligand in 5.     

Photochemical reactions of group VIB metal carbonyls with heterocyclic Schiff bases derived from 4-amino -3-hydrazino-5-mercapto-1,2,4-triazole

The new complexes, M(CO)₅(Schiff base) [M?=?Cr; 1, Mo; 2, W; 3, Schiff base?=?4-salicylidenamino-3-hydrazino-5-mercapto-1,2,4-triazole, SAHMT, a; 4-(2-hydroxynaphthylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 2HNAHMT, b; 4-(3-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 3HBAHMT, c; 4-(4-hydroxybenzylidenamino)-3-hydrazino-5-mercapto-1,2,4- triazole, 4HBAHMT, d; 4-(5-bromosalicylidenamino)-3-hydrazino-5-mercapto-1,2,4-triazole, 5BrSAHMT, e; were synthesized by photochemical reaction of metal carbonyls M(CO)₆ (M?=?Cr, Mo, W) with new heterocyclic Schiff bases derived from 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, a–e. The ligands and complexes have been characterized by elemental analysis, EI-mass spectrometry, FT-IR, ¹H and ¹³C-{¹H}-NMR spectroscopy. The spectroscopic studies show that Schiff bases, a–e, are monodentate and coordinate via azomethine N donor to the central metal atom in M(CO)₅(Schiff base) (M?=?Cr, Mo, W).     

Photochemical reactions of metal carbonyls [M(CO)6 (M=Cr,Mo, W)] with N,N′ -bis(salicylidene)-1,2-bis- ( o -aminophenoxy)ethane

The complexes [M(CO)₄(η²-H₂L)] [M?=?Cr; 1, Mo; 2, W; 3] have been synthesized by photochemical reactions of VIB metal carbonyls [M(CO)₆] [M?=?Cr,?Mo,?W] with N,N′-bis(salicylidene)-1,2-bis-(o-aminophenoxy)ethane (H₂L) in THF and characterized by elemental analyses, FTIR, ¹H?NMR and mass spectra. The H₂L ligand is coordinated to the central metal as a bidentate ligand via the central azomethine nitrogen atoms in 1–3.     

Syntheses and crystal structures of butterfly M2Te2 complexes of molybdenum and tungsten with functionalized cyclopentadienyl ligands

Reactions of singly-bonded dinuclear complexes [(η⁵-CH₃O₂CC₅H₄)₂M₂(CO)₆] (I, M?=?Mo; II, M?=?W) with the diarenylditelluride [4-CH₃C₆H₄Te]₂ in refluxing toluene for 4–6?h afforded dinuclear complexes 1 and 2 trans/ae-[(η⁵-RC₅H₄)₂M₂(CO)₄(μ-ArTe)₂] (Ar?=?4-CH₃C₆H₄Te). Complexes 1 and 2 were also synthesized by reactions of triply-bonded dinuclear complexes [(η⁵-CH₃O₂CC₅H₄)₂M₂(CO)₄] (III, M?=?Mo; IV, M?=?W) with [4-CH₃C₆H₄Te]₂ in refluxing toluene for 1?h. Both complexes have been characterized by elemental analysis, ¹H NMR, ¹³C NMR and IR spectroscopy and X-ray diffraction. Preliminary low-temperature NMR experiments on complexes 1 and 2 have revealed that in solution each complex goes through a rapid inversion of the butterfly four-membered ring M₂Te₂.     

Photochemical reactions of metal carbonyls with heteroaromatic methanesulfonylhydrazone-based ligands

Three new heteroaromatic methanesulfonylhydrazone derivatives: thiophene-2-carboxy aldehydemethanesulfonylhydrazone (msh 1), 2-acetylthiophenemethanesulfonylhdrazone (msh 2), and 2-acetyl-5-methylthiophenemethanesulfonylhydrazone (msh 3) were prepared and their metal carbonyl complexes ([M(CO)₅(msh 1)] M = Cr, 1a; Mo, 1b; W, 1c); ([M(CO)₅(msh 2)] M = Cr, 2a; Mo, 2b; W, 2c); and ([M(CO)₅(msh 3)] M = Cr, 3a; Mo, 3b; W, 3c) were synthesized by photochemical reactions of [M(CO)₆ M = Cr, Mo, W] with msh 1–3. Heteroaromatic methanesulfonylhydrazones, msh 1–3, and their metal carbonyl complexes were characterized by elemental analysis, mass spectrometry, IR, and ¹H and ¹³C–{¹H} NMR spectroscopy. According to all the spectroscopic data, msh 1–3 are monodentate and coordinate via thiophene ring sulfur. The msh 1–3 must act as two-electron donors to satisfy the 18-electron rule.     

Phosphorus(III)-Nitrogen-Sulphur Compounds: Synthesis and Metal Complexes

Abstract

The preparation and X-ray structure (M=Mo) of complexes of the type M(CO)₅(Ph₂PNSO) (M=Cr,Mo) are described. These complexes are used in the synthesis of homo- and hetero-dinuclear complexes of Ph₂PNSNPPh₂. A ³¹P DNMR study of these dinuclear complexes indicates a cis, trans → trans, cis isomerization in solution. The preparation and X-ray structure (M=Cr) of the mononuclear complexes, cis-M(CO)₄(P(Ph)₂NSN(Ph)₂P), (M=Cr,Mo) are also described.     

Chromium,Molybdenum and Ruthenium Complexes of 2-Hydroxyacetophenone Schiff Bases

Interaction of the Schiff base 2-hydroxyacetophenonepropylimine (happramH) with M(CO)₆, M=Cr or Mo under reduced pressure gave the dicarbonyl complex M(CO)₂(happramH)₂. The complex MoO(happram)₂ was isolated from the reaction of Mo(CO)₆ and happramH in air. Ru₃(CO)₁₂ and RuCl₃ reacted with the Schiff base bis-(2-hydroxyacetophenone)ethylenediimine (hapenH₂) to give Ru(CO)₂(hapenH₂) and [RuCl₂(hapenH2)]Cl. Elemental, spectroscopic and magnetic studies of the reported complexes revealed the proposed structures. The thermal properties of the complexes were investigated by thermogravimetric techniques. Cyclic voltammetry of the complexes showed tautomeric redox processes due to ligand-based reduction and metal-based oxidation.     

Reactions of chromium and molybdenum carbonyls with bis-(salicylaldehyde)-1,3-propylenediimine Schiff base

Interaction of a Schiff base, bis-(salicylaldehyde)-1,3-propylenediimine, salpenH₂, with M(CO)₆ (M?=?Cr or Mo) in the presence of oxygen gave the oxo-complexes[M(O)(salpen)]. Magnetic studies for the two oxo-complexes showed chromium and molybdenum in the +4 formal oxidation state. In presence of pyridine, reaction of Cr(CO)₆ with salpenH₂ gave the identical product; [Cr(O)(salpen)]. Reaction of Mo(CO)₆ with salpenH₂ in presence of pyridine (py) resulted in formation of the square-pyramidal complex [Mo(py)(salpenH₂)]. Reactions of M(CO)₆ with salpenH₂ in presence of a ligand L (L?=?bipyridine (bpy) or 3,3-dimethylbipyridine (dmbpy)) gave the octahedral complexes [M(L)(salpenH₂)]. All the complexes were characterized by elemental analyses, IR, mass and ¹H NMR spectroscopy. The spectroscopic studies revealed the proposed structures. UV-Vis spectra of the ligand and its complexes in DMSO exhibited visible bands due to metal-to-ligand or ligand-to-metal charge transfer.     

Novel chromium and molybdenum complexes of a dimerized isonicotinic acid hydrazide

Sunlight irradiation of [M(CO)₆], M?=?Cr and Mo with isonicotinic acid hydrazide (inh) was investigated. The photochemical process resulted in dimerization of inh with elimination of a hydrazine molecule to give N′-isonicotinoylisonicotino hydrazide (ininh). Two complexes with molecular formulas [MO₂(ininh)] were isolated and characterized by elemental analysis, infrared, mass and ¹H NMR spectroscopy. The UV-vis spectra of the complexes in DMSO showed visible bands due to ligand-to-metal charge transfer. Thermal properties of the complexes were investigated by TG thermogravimetry.     

Reactivity of [Mo(NHNRPh)(NNRPh)(acac)X2] (R=Ph,Me; X=Br,I) toward tertiary phosphines

The reactivity of mixed [organohydrazido(1-)][organohydrazido(2-)]molybdenum(VI) complexes [Mo(NHNRPh)(NNRPh)(acac)X₂] {R?=?Ph, X?=?Br (1); R?=?Ph, X?=?I (2) and R?=?Me; X?=?I (3)} with tertiary phosphines as PPh₃, PMePh₂ and PMe₂Ph are examined. The syntheses of [Mo(NNPh₂)₂Br₂(PPh₃)] (4), [Mo(NNPh₂)₂Br₂(PMePh₂)₂] (5), [Mo(NNPh₂)₂Br₂(PMe₂Ph)₂] (6), [Mo(NNPh₂)₂(acac)I(PPh₃)] (7), [Mo(NNPh₂)₂(acac)(PMePh₂)₂]⁺I^? (8) and [Mo(NNMePh)₂(acac)(PMePh₂)₂]⁺I^? (9) are reported. All complexes were characterized by elemental analysis, UV-visible, IR, ¹H and ³¹P{H} NMR spectroscopy.     

Reactions of group 6 metal carbonyls with salicylaldehyde isonicotinic acid hydrazone

Sunlight irradiation of the reactions of [M(CO)₆], M?=?Cr, Mo and W with salicylaldehyde isonicotinic acid hydrazone (H₂salnah) in THF were investigated. Interaction of [Cr(CO)₆] with H₂salnah resulted in formation [Cr₂O₂(H₂salnah)₂]. The corresponding reactions of molybdenum and tungsten carbonyls yielded dinuclear oxo complexes [M₂O₆(H₂salnah)]. All complexes were characterized by elemental analysis, IR, mass spectrometry and ¹H NMR spectroscopy. The IR spectra of complexes exhibited bands due to either terminal or bridged metal oxygen bonds. Magnetic measurement of [Cr₂O₂(H₂salnah)₂] showed it has paramagnetic characteristics with high spin d⁴ configuration and μ_eff of 1.27?BM. Electronic spectra of the complexes in DMF displayed visible bands due to ligand-to-metal charge transfer. Thermal properties of the complexes were investigated by thermogravimetry technique.     

Organosilyl and organogermyl isocyanide complexes of group vib metal carbonyls

Syntheses of twelve M(CO)₅L complexes (M  Cr, Mo, W; L  CNSiR₂R′, CNGeR₂R′ for R,R′  Me,Ph) were accomplished by carbonyl displacement from M(CO)₆ by L. Several cis-Mo(CO)₄L₂ complexes and one fac complex, Mo(CO)₃(CNGeMe₃)₃, are also reported, prepared by displacement of bicycloheptadiene or cycloheptatriene from Mo(CO)₄(bicycloheptadiene) and Mo(CO)₃(cycloheptatriene). Infrared and ¹³C NMR spectra confirm that the ligands are isocyanides rather than cyanides although the latter is the stable and predominate form of the pure ligands. The mono-substituted compounds are only moderately stable when sealed in vacuo; otherwise stored they decompose rapidly probably by virtue of reaction with oxygen. The phenylsilyl and phenylgermyl isocyanide complexes are harder to store than the methyl analogues. The bis and tris complexes were very difficult to study, being thermally very unstable as well as reactive toward oxygen so that characterization of these species was only marginally successful.     

Synthesis and Characterization of the products from reaction of Metal Carbonyls [M(CO)6 (M Cr,Mo, W), Re(CO)5Br,Mn(CO)3Cp] with Salicylaldehyde Methanesulfonylhydrazone

Five new complexes, [M(CO)₅(salmsh)] (M?=?Cr;?1,?Mo;?2,?W;?3), [Re(CO)₄Br(salmsh)], 4, and [Mn(CO)₃ (salmsh)], 5, have been synthesized by the photochemical reaction of metal carbonyls with salicylaldehyde methanesulfonylhydrazone (salmsh). The complexes have been characterized by elemental analyses, EI mass spectrometry, FT-IR and ¹H NMR spectroscopy. The spectroscopic studies show that salmsh behaves as a monodentate ligand coordinating via the imine N donor atom in 1–4 and as a tridentate ligand in 5.     

About the Reaction of C(PPh3)2 with [M(CO)6] (M = Cr,Mo): Unusual Formation of μ-Carbonato Complexes of Mo under Participation of THF

Attempts to synthesize complexes of group 6 carbonyl compounds [M(CO)₆] (M = Cr, Mo, W) with the carbone C(PPh₃)₂ ( 1 ) via the photo chemically created adducts [(CO)₅M(THF)] lead to quantitative formation of the salts [HC(PPh₃)₂]₂[M₂(CO)₁₀] ( 2 , Cr; 3 , Mo; 4 , W). Alternatively, a long-time thermal reaction of [Mo(CO)₆] performed with 1 in THF generates a series of products initiated by a Wittig-type reaction. In addition to 3 , minor amounts of [(CO)₅MoCCPPh₃] ( 8 ), [(CO)₅MoO₂CC{PPh₃}₂] ( 5 ), and the carbonate complexes [HC(PPh₃)₂]₂[(CO)₅Mo(CO₃)Mo(CO)₄] ( 6 ) and [HC(PPh₃)₂]₂[(CO)₄Mo(CO₃)Mo(CO)₄] ( 7 ) were found. Compounds 2 , 3 , 5 , 6 , and 7 were characterized by X-ray analyses, ³¹P NMR, and IR spectroscopy. The water, necessary for the formation of the carbonate, stems from decomposition of THF.     

SYNTHESIS OF ORGANOTRANSITION METAL COMPLEXES CONTAINING p-METHOXYCARBONYLBENZOYLCYCLO-PENTADIENYL AND p-METHOXYCARBONYLPHENYL (HYDROXYMETHYL)CYCLOPENTADIENYL LIGANDS FROM SODIUM p-METHOXYCARBONYLBENZOYLCYCLO-PENTADIENIDE. X-RAY STRUCTURE OF η5-p-MeO2CC6H4COC5H4Mo(CO)3I

Abstract

A new functionally substituted cyclopentadienyl salt p-MeO₂CC₆H₄COC₅H₄Na (1) was prepared from cyclopentadienylsodium and dimethyl terephthalate in THF, and which might be utilized to synthesize a series of novel transition metal complexes containing difunctional group-substituted cyclopentadienyl ligands; 1 reacted with M(CO)₆(M = Mo, W) followed by treatment with PBr₃ or I₂ to give mononuclear organomolybdenum (or tungsten) halides η⁵-p-MeO₂CC₆H₄COC₅H₄M(CO)3X(2, M = Mo, X = Br; 3, M = W, X = Br; 4, M = Mo, X = I; 5, M = W, X = I), whereas reaction of 1 with W(CO)₆ and successive treatment with selenium powder and MeI or PhCH₂Cl afforded mononuclear organotungsten selenolate complexes η⁵-p-MeO₂CC₆H₄COC₅H₄W (CO)₃SeMe (6) and η⁵-p-MeO₂CC₆H₄COC₅H₄W(CO)₃SeCH₂Ph (7). In addition, 1 reacted with M(CO)₆(M = Mo, W) followed by treatment with FeCo₂(CO)₉(μ₃-S) to produce the corresponding polynuclear complexes η⁵-p-MeO₂CC₆H₄COC₅H₄MFeCo(CO)₈(μ₃?S) (8, M = Mo; 9, M = W), which could be converted with NaBH₄ into hydroxyl derivatives η⁵-p-MeO₂CC₆H₄CH(OH)C₅H₄MFeCo(CO)₈(μ₃?S) (10, M = Mo; 11, M = W). All the new transition metal complexes 2–11 have been fully characterized by elemental analysis, IR and ¹H NMR spectroscopy, as well as for 4 by an X-ray diffraction analysis.     

Metal Complexes with Biologically Important Ligands. CLXVI Tetracarbonyl Complexes of Chromium(0) and Molybdenum(0) with Schiff Bases from Pyridine‐2‐carboxaldehyde and α‐Amino Acid Esters as N,N‐Chelate Ligands

The complexes [M(CO)₄(pyridyl‐CH=N‐CHRCO₂R′)] (M = Cr, Mo; R = H, CH₃, CH(CH₃)₂, CH₂CH(CH₃)₂) were obtained by reaction of the Schiff bases from pyridine‐2‐carboxaldehyde and glycine, L‐alanine, L‐valine or L‐leucine esters with the norbornadiene complexes [M(CO)₄(nbd)] and were characterized by IR, ¹H and ¹³C NMR and UV‐vis spectra. The deeply colored complexes exhibit solvatochromism.     

The thermochemistry of carbonyl complexes of Cr,Mo and W with pyridine and acetonitrile

Microcalorimetric measurements at elevated temperatures of the heats of thermal decomposition and of iodination of a number of [M(CO)_nL_6-n] complexes (M = Cr, Mo, W; n = 3, 4; L = py, MeCN) have led to values for the standard enthalpies of formation of the following crystalline compounds (values given in kJ mol^?) at 25°C: fac-[Mo(CO)₃py₃](275 ± 12), fac-[Mo(CO)₃(NCCH₃)₃]  (410 ± 12), fac-[W(CO)₃py₃](250 ± 12), fac-[W(CO)₃(NCCH₃)₃](405 ± 12) and cis-[Cr(CO)₄py₂](505 ± 20). From these and other data, including estimated heats of sublimation, the bond enthalpy contributions of the various metalligand bonds in the gaseous metal complexes were evaluated as follows (values in kJ mol^?): D(Crpy) 102, D(Mopy) 146, DWPy) 173, D(Mo7z.sbnd;NCMe) 135 and D(WNCMe) 169. For a given metal the bond enthalpy contribution decreased in the order D(MCO) > D(Mpy) > D(Mz.sbnd;NCMe). This order is related to the σ- and π-bonding character of the ligand.     

Structural studies of new group 6 complexes of salicylidene-2-aminopyridine

Interaction of salicylidene-2-aminopyridine (Hsap) with [M(CO)₆], M = Cr, Mo and W, in THF under sunlight resulted in formation of dinuclear complexes [Cr₂O₄(sap)], 1, [Mo₂O₄(sap)], 2, and [W₂O₅(sap)₂], 3. Elemental analysis, spectroscopic and magnetic studies of the reported complexes revealed the proposed structures. Magnetic studies of 1 and 2 suggested that the two metal centers have +3 and +6 formal oxidation states, while the tungsten complex 3 has +6 formal oxidation state with d⁰ electron configuration. The thermal properties of the complexes were investigated by thermogravimetry.     

Darstellung und spektroskopische Untersuchungen von M(CO)4L2- und M(CO)3L3-Komplexen (M = Cr,Mo, W; L = Me3SiOCH2PMe2, Me2(CH2CH) SiOCH2PMe2)

Preparation and spectroscopical Investigations of M(CO)₄L₂ and M(CO)₃L₃ Complexes (M = Cr, Mo, W; L = Me₃SiOCH₂PMe₂, Me₂(CH₂?CH)SiOCH₂PMe₂ The coordinating properties of the ligands L¹ (?Me₃SiOCH₂PMe₂) and L² (?Me₂ViSiOCH₂PMe₂)¹) have been studied by synthesis and spectroscopic investigations (IR, NMR, MS) of their complexes M(CO)₄L₂ and M(CO)₃L₃(M = Cr, Mo, W). The complexes are obtained by replacement of norbornadiene (NBD) in M(CO)₄NBD or cycloheptatriene CHT in M(CO)₃CHT. Spectroscopic data (v(CO), δ δ) support the σ-donor/-π-acceptor model of the MP bonds.