Nickel(II) complexes having Imidazol-2-ylidene-N′-phenylurea ligand in the coordination sphere - Syntheses and solid state structures

We report the syntheses and structural studies of two nickel(II) complexes of imidazol-2-ylidene- N′-phenylureate ligand of composition [{Im tBuNCON(H)Ph}2Ni(acac)2](1) and [(C6H5NH2)2Ni(acac)2][ImMes NCON(H)Ph] (2). The nickel complex 1 was readily prepared by the reaction of nickel(II) acetylacetonate [Ni(acac)2] with imidazol-2-ylidene-N′-phenylureate ligand [Im tBuNCON(H)Ph] (L1) in THF under reflux condition for 72 h. The nickel complex 2 was obtained by the reaction of [Ni(acac)2], mesityl derivative of imidazol-2-ylidene-N′-phenylureate ligand [Im MesNCON(H)Ph] (L2) in the presence of aniline as base under reflux condition in THF. Both the paramagnetic complexes have been characterized by FT-IR spectroscopy and elemental analyses. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 1 and 2, each nickel(II) ion is six fold coordinated and form a distorted octahedral geometry. The optical properties of both complexes have been explored. The Hirshfeld surfaces are used to view and analyze the intermolecular contacts in crystalline state for complex 2

Syntheses and structures of dimeric sodium and potassium complexes of 2,6-diisopropyl-Anilidophosphine borane ligand

We report here the syntheses and structural studies of dimeric sodium and potassium complexes of composition [Na(THF)2{Ph2P(BH3)N(2,6- i Pr2C6H6)}]2 (2) and [K(THF)2{Ph2P(BH3)N(2,6- i Pr2C6H6)}]2 (3). The sodium complex 2 was readily prepared by the reaction of sodium bis(trimethylsilyl)amide with 2,6-diisopropylanilidophosphine-borane ligand [2,6- i Pr2C6H3NHP(BH3)Ph2] (1-H) at ambient temperature. The potassium complex 3 was prepared by two synthetic routes: in the first method, the ligand 1-H was made to react with potassium hydride at room temperature to afford the corresponding potassium complex. The potassium bis(trimethylsilyl)amides were made to react with protic ligand 1-H in the second method to eliminate the volatile bis(trimethyl)silyl amine. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 2, the sodium metal is coordinated by the anilido nitrogen (η 1) and borane group (η 1) attached to the phosphorus atom of ligand 1. In contrast, for compound 2, ligand 1 displays η 6 π-arene interaction from 2,6-diisopopylphenyl ring with potassium atom along with η 3 interaction of BH3 group due to larger ionic radius of potassium ion

Imidazol-2-ylidene-N′-phenylureate ligands in alkali and alkaline earth metal coordination spheres - heterocubane core to polymeric structural motif formation

The synthesis and isolation of two potassium, one lithium and two calcium complexes of imidazol-2-ylidene-N′-phenylureate ligands [ImRNCON(H)Ph] [(R = tBu (1a); Mes (1b) and Dipp (1c); Mes = mesityl, Dipp = 2,6-diisopropylphenyl] are described. Potassium complexes, [{κ2-(ImMesNCONPh)K}4] (2b) and [{κ3-(ImDippNCONPh)K}2{KN(SiMe3)2}2]n (2c), were prepared in good yields by the reactions of 1b and 1c, respectively, with potassium bis(trimethyl)silyl amide at ambient temperature in toluene. Lithium complex [{(2,6-tBu2-4-Me-C6H2O)Li(ImtBuNCON(H)Ph)}2{ImtBuNCON(H)Ph}] (3a) was isolated by a one-pot reaction between 1a and LiCH2SiMe3, followed by the addition of 2,6-tBu2-4-Me-C6H2OH in toluene. Calcium complex [{κ2-(ImtBuNCONPh)Ca{N(SiMe3)2}-{KN(SiMe3)2}]n (4a) was isolated by the one-pot reaction of 1a with [KN(SiMe3)2] and calcium diiodide in THF at ambient temperature. The solid-state structures of ligand 1a and complexes 2b, 2c, 3a and 4a were confirmed by single-crystal X-ray diffraction analysis. It was observed that potassium was coordinated to the oxygen atom of urea group and to the nitrogen atom of the imidazolin-2-imine group, in the solid-state structure of 2b. In complex 4a, the calcium ion was ligated to the monoanionic imidazol-2-ylidene-N′-phenylureate ligand in a bi-dentate (κ2) fashion through the oxygen and nitrogen atoms of the isocyanate building block leaving the imidazolin-2-imine fragment uncoordinated. In the solid state of the potassium complex 2c, tri-dentate (κ3) coordination from the imidazol-2-ylidene-N′-phenylureate ligand was observed through the oxygen and nitrogen atoms of the isocyanate building block and of the imidazolin-2-imine fragment. In contrast, in the dimeric lithium complex 3a, the neutral imidazol-2-ylidene-N′-phenylureate ligand was bound to the lithium centre in a mono-dentate fashion (κ1) through an oxygen atom of the isocyanate moiety. It is to be noted that in each complex thus observed, the elongated carbon-nitrogen bond distances indicate substantial electron delocalisation from the imidazole ring to the ureate group present in ligand 1

Syntheses and solid state structures of zinc (II) complexes with Bi-dentate N-(Aryl)imino-acenapthenone (Ar-BIAO) ligands

We have synthesized five zinc complexes of molecular formulae [ZnCl 2 (2,6-dimethylphenyl- BIAO)] 2 ( 1a ), [ZnBr 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1b ), [ZnI 2 (2,6-dimethylphenyl-BIAO)] 2 ( 1c ), [ZnBr 2 (mes- BIAO)] 2 ( 2b) and [ZnBr 2 (dipp-BIAO)] ( 3b) with rigid unsymmetrical imi noacenaphthenone ligands, (2,6- dimethylphenyl-BIAO) ( 1 ), (mesityl-BIAO) ( 2 ) and (2,6-diisopropylphenyl-BIAO) ( 3 ).Thezinccomplex 1a was prepared by the reaction of ZnCl 2 and neutral (mesityl-BIAO) ( 1 ). However, complexes 1b , 2b and 3b were obtained by the treatment of ZnBr 2 and neutral ligands 1 – 3 respectively in 1:1 molar ratio in dichloromethane at ambient temperature. In a similar reaction of ZnI 2 with (2,6-dimethylphenyl-BIAO) ( 1 ) in dichloromethane the corresponding iodo-complex 1c was obtained in good yield. All the zinc (II) complexes are characterized by FT-IR, 1 Hand 13 C{ 1 H} NMR spectroscopic techniques. The solid state structures of the complexes 1a , 1b , 1c , 2b and 3b are confirmed by single crystal X-ray diffraction analysis. The molecular structures of com- plexes 1a , 1b , 1c and 2b reveal the dimeric nature of the complexes and subsequently the centre atom zinc is penta-coordinated to adopt distorted trigonal bipyr amidal geometry around it. In contrast, the complex 3b is in monomeric in nature due to bulkier size of the ligand and zinc ion is tetra coordinated to adopt distorted tetrahedral geometry

Synthesis and solid state structures of Chalcogenide compounds of Imidazolin-2-ylidene-1,1-Diphenyl-phosphinamine

We report the synthesis and solid state structures of 1,3-di-aryl-imidazolin-2-ylidine-1,1-diphenylphosphinamine [(aryl = mesityl (1a) and aryl = 2,6-diisopripyl (1b)] and their chalcogenide compounds 1, 3-di-aryl-imidazolin-2-ylidine- P,P-diphenylphosphinicamide (2a,b), 1,3-di-aryl-imidazolin-2-ylidine-P,P-diphenyl-phosphinothioicamide (3a,b) and 1,3-diaryl-imidazolin-2-ylidine- P,P-diphenyl-phosphinoselenoic-amide (4a,b). The compounds 1a,b were prepared in good yield by the reaction of 1,3-di-aryl-imidazolin-2-imine and chlorodiphenylphosphine in the presence of triethylamine in toluene. The reactions of 1a,b with elemental sulphur and selenium afforded the corresponding chalcogenide compounds 3a,b and 4a,b respectively. The corresponding oxo- derivative (2a,b) was obtained by reacting compound 1a,b with 30% aqueous hydrogen peroxide in THF. The molecular structures of 1a, 2a, 3a and 4a,b have been established by single crystal X-ray diffraction analyses. The molecular structures reveal that even C1–N1–P1 angle (124.62 ∘) in compound 1a is less obtuse compared to the corresponding C1–N1–Si1 angles (157.8 ∘) observed in related N-silylated 2-iminoimidazolines and trimethylsilyl iminophosphoranes. C1–N1–P1 angles are further widened in compounds 2a, 3a, and 4a,b due to the attachment of chalcogen atoms onto phosphorus atom

Functionalisation of Imidazolin-2-imine to Corresponding Phosphinamine, Chalcogenide (O, S, Se, Te), and Borane Compounds

1,3-Di-tert-butyl-imidazolin-2-ylidine-1,1-diphenylphosphinamine (2) was prepared from 1,3-di-tert-butyl-imidazolin-2-imine (1) and chlorodiphenylphosphine. Compound 2 was treated further with elemental sulfur, selenium, and tellurium to afford the corresponding chalcogenide derivatives, 1,3-di-tert-butyl-imidazolin-2-ylidine-P,P-diphenyl-phosphinothioicamide (4), 1,3-di-tert-butyl-imidazolin-2-ylidine-P,P-diphenyl-phosphinoselenoicamide (5), and 1,3-di-tert-butyl-imidazolin-2-ylidine-P,P-diphenyl-phosphinotelluroicamide (6) in good yield. 1,3-Di-tert-butyl-imidazolin-2-ylidine-P,P-diphenylphosphinicamide (3) was obtained by dissolving compound 2 in hydrochloric acid solution in THF. The corresponding borane adduct, 1,3-di-tert-butyl-imidazolin-2-ylidine-P,P-diphenyl-phosphinaminoborane (7) was isolated by the reaction of compound 2 and sodium borohydride in good yield. The molecular structures of compounds 2 and 4–7 were established by X-ray diffraction analyses. To analyse the electronic structure of chalcogenides of imidazolin-2-imine ligands, the protonation energies of the oxygen, sulfur, and selenide derivative of ligand 2 were calculated by means of density functional theory. Finally, the charge distribution in compounds 3, 4, and 5 were determined using natural bond orbital analysis

Diversity of Imidazolin-2-iminato Ligands in Group 2 and 4 Metal Coordination Sphere– Syntheses, Structures & Reactivity

For over 3 decades, transition-metal complexes containing multiply bonded ligands have generated considerable interest and considerable advances have been made in understanding and developing their structures and reactivity. The impressive variety of structural types and, in particular, reactivity properties of such complexes is an evidence to the wide range of ancillary ligand environments available to support these multiply bonded functional groups. In my dissertation thesis we focus on titanium imido chemistry in particular. The Ti=NR linkage has been shown to couple stoichiometrically with a variety of unsaturated substrates including CO2, carbodiimides, isocyanates, isocyanides, acetonitrile, phosphaalkynes, alkynes, alkenes, and allenes. Especially recently, there has been much interest in using titanium imides as catalysts for hydroamination and olefin polymerization. Likewise tremendous research efforts have been devoted to the development of various types of ancillary ligands as alternatives for cyclopentadienyl ligands. Among those cyclopentadienyl alternatives, novel and versatile imidazolin-2-iminato ligand which can be regarded as monodentate analogues to cyclopentadienyls, due to their capability to act as 2σ, 4π-electron donors. We have established a general method for the synthesis of related imidazolin-2-iminato titanium amide complexes. We also explore the reactivity properties of these imidazolin-2-iminato titanium amide complexes. We present a method for the preparation of imidazolin-2-iminato supported titanium imido complexes. With this contribution, we have functionalised imidazolin-2-imine ligand include p-donors such as phosphoraneimides and ureate and thioureate ligands from readily available starting materials chorodiphenylphosphine, phenyl isocyanate and phenyl isothiocyanate. As a development of our work in imidazolin-2-iminato titanium chemistry we have become interested in exploring the apparently related ureate and thioureate ligands employing in group 2 chemistry. Group 2 metal complexes have been received considerable attention as initiators for the Ring-opening polymerization (ROP) of cyclic esters and some of them have demonstrated impressive results. Ring-opening polymerization of cyclic esters promoted by alkaline-earth & rare-earth metal initiators proved to be the most efficient way for preparing polyesters with controlled molecular weight and microstructure and narrow molecular-weight distribution

Diversity of Imidazolin-2-iminato Ligands in Group 2 and 4 Metal Coordination Sphere– Syntheses, Structures & Reactivity

For over 3 decades, transition-metal complexes containing multiply bonded ligands have generated considerable interest and considerable advances have been made in understanding and developing their structures and reactivity. The impressive variety of structural types and, \ud in particular, reactivity properties of such complexes is an evidence to the wide range of ancillary ligand environments available to support these multiply bonded functional groups. In my dissertation thesis we focus on titanium imido chemistry in particular. The Ti=NR \ud linkage has been shown to couple stoichiometrically with a variety of unsaturated substrates including CO2, carbodiimides, isocyanates, isocyanides, acetonitrile, phosphaalkynes, alkynes, alkenes, and allenes. Especially recently, there has been much interest in using titanium imides as catalysts for hydroamination and olefin polymerization. Likewise tremendous research efforts have been devoted to the development of various types of ancillary ligands as alternatives for cyclopentadienyl ligands. Among those cyclopentadienyl alternatives, \ud novel and versatile imidazolin-2-iminato ligand which can be regarded as monodentate analogues to cyclopentadienyls, due to their \ud capability to act as 2σ, 4π-electron donors. We have established a general method for the synthesis of related imidazolin-2-iminato \ud titanium amide complexes. We also explore the reactivity properties of these imidazolin-2-iminato titanium amide complexes. We present a \ud method for the preparation of imidazolin-2-iminato supported titanium imido complexes. With this contribution, we have functionalised \ud imidazolin-2-imine ligand include p-donors such as phosphoraneimides and ureate and thioureate ligands from readily available starting \ud materials chorodiphenylphosphine, phenyl isocyanate and phenyl isothiocyanate. As a development of our work in imidazolin-2-iminato \ud titanium chemistry we have become interested in exploring the apparently related ureate and thioureate ligands employing in group 2 \ud chemistry. Group 2 metal complexes have been received considerable attention as initiators for the Ring-opening polymerization (ROP) \ud of cyclic esters and some of them have demonstrated impressive results. Ring-opening polymerization of cyclic esters promoted by \ud alkaline-earth & rare-earth metal initiators proved to be the most efficient way for preparing polyesters with controlled molecular \ud weight and microstructure and narrow molecular-weight distribution

Synthesis and structural studies of dimeric sodium compounds having pentametallacyclooctane and hexametallacyclo undecane structure using different phosphinamine derivatives

The treatment of two bulky phosphinamines [Ph2PNH(CHPh 2)] (1) and [Ph2PNH(CPh3)] (2) with 30% hydrogen peroxide afforded phosphinicamides [Ph2P(O)NH(CHPh 2)] (3) and [Ph2P(O)NHCPh3] (4) in good yield. When the same phosphinamines are reacted with elemental sulfur, corresponding sulfur compounds [Ph2P(S)NH(CHPh2)] (5) and [Ph 2P(S)NHCPh3] (6) are obtained. Further reactions of 4-6 with sodium bis(trimethylsilyl)amide in THF solution afforded corresponding sodium salts of molecular formula [{(THF)2Na(Ph2P(O) NCPh3)}2] (8), [{(THF)2Na(Ph 2P(S)NCHPh2)}2] (7) and [{(THF) 2Na(Ph2P(S)NCPh3)}{(THF)Na(Ph 2P(S)NCPh3)}] (9) and all the sodium complexes 7-9 are dimeric and form highly strained polymetallacyclic motif in solid state structures. Molecular structure of all the complexes are established by single crystal X-ray diffraction analysi

Heavier Group 2 Metal Complexes with Flexible Scorpionate Ligand based on 2-Mercaptopyridine

We report the synthesis of novel alkaline earth metal complexes [2-SS-(Bmp)2M(THF)n] [M = Ca (2), Sr (3) n = 2; M = Ba (4), n = 3] of flexible dihydrobis(2-thiopyridone)borate (Bmp) ligand based on 2-mercaptopyridine. Complexes 2–4 were isolated in good yield by the reaction between sodium dihydrobis(2-thiopyridone)borate, [{(Bmp)Na(THF)}2]n (1) and corresponding alkaline earth metal diiodides in toluene at ambient temperature. The solid-state structures of strontium and barium complexes, complexes 3 and 4 respectively, were established using single-crystal X-ray diffraction analysis. The solid-state structure of sodium complex 1 was also confirmed using X-ray. The solid-state structures of complexes 3 and 4 revealed that the Bmp ligand coordinates through sulphur atoms to the metal ions in 2 fashion. The strontium ion is attached symmetrically and the barium ion is asymmetrically linked with the Bmp ligand, manifesting the 2-thiopyridone and pyridine-2-thiolate tautomeric form of the Bmp ligand. The strontium ion in complex 3 adopts a distorted octahedral geometry whereas the geometry around the barium ion can best be described as a distorted pentagonal bipyramidal. Both complexes 3 and 4 also have short B...H...M interaction due to the presence of BH2 group in the ligand. In the solid state, sodium complex 1 is polymeric in nature and in the asymmetric unit each sodium ion is bonded to two sulphur atoms through and modes. The adjacent BH2 group is also linked with each sodium ion through hydrogen atoms via 2 and