We have synthesized five zinc complexes of molecular formulae [ZnCl₂(2,6-dimethylphenyl-BIAO)]₂ (1a), [ZnBr₂(2,6-dimethylphenyl-BIAO)]₂ (1b), [ZnI₂(2,6-dimethylphenyl-BIAO)]₂(1c), [ZnBr₂(mes-BIAO)]₂(2b) and [ZnBr₂(dipp-BIAO)] (3b) with rigid unsymmetrical iminoacenaphthenone ligands, (2,6-dimethylphenyl-BIAO) (1), (mesityl-BIAO) (2) and (2,6-diisopropylphenyl-BIAO) (3). The zinc complex 1a was prepared by the reaction of ZnCl₂ and neutral (mesityl-BIAO) (1). However, complexes 1b, 2b and 3b were obtained by the treatment of ZnBr₂ and neutral ligands 1-3 respectively in 1:1 molar ratio in dichloromethane at ambient temperature. In a similar reaction of ZnI₂ 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, ¹H and ¹³C{¹H} 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 complexes 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 bipyramidal 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.

We report here the syntheses and structural studies of dimeric sodium and potassium complexes of composition [Na(THF)₂{Ph₂P(BH₃)N(2,6-ⁱPr₂C₆H₆)}]₂ (2) and [K(THF)₂{Ph₂P(BH₃)N(2,6-_iPr₂C₆H₆)}]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-ⁱPr₂C₆H₃NHP(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 (𝜂¹) and borane group (𝜂¹) attached to the phosphorus atom of ligand 1. In contrast, for compound 2, ligand 1 displays 𝜂⁶𝜋-arene interaction from 2,6-diisopopylphenyl ring with potassium atom along with 𝜂³ interaction of BH₃ group due to larger ionic radius of potassium ion.

We report the syntheses and structural studies of two nickel(II) complexes of imidazol-2-ylidene- N'-phenylureate ligand of composition [{Im^𝑡Bu NCON(H)Ph}₂ Ni(acac)₂] (1) and [(C₆H₅NH₂)₂ Ni(acac)₂] [Im^Mes 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^𝑡Bu NCON(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^Mes NCON(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.