We report the monomeric complexes of magnesium and calcium of composition [M(THF)$_n${$\eta^2$-Ph₂P(Se)N(CMe₃)}₂] [M= Mg (3), n = 1 andM = Ca (4), n = 2)] and polymeric complexes of potassium and barium of composition [K(THF)₂{Ph₂P(Se)N(CMe₃)}]$_n$ (2) and [K(THF)Ba{Ph₂P(Se)N(CMe₃)}₃]$_n$(5) respectively. The potassium complex 2 was readily prepared by the reaction of potassium bis(trimethylsilyl)amide with phosphinoselenoic amide ligand (1) at ambient temperature. The calcium complex 4 was prepared by two synthetic routes: in the first method, commonly known as salt metathesis reaction, the potassium complex 2 was made to react with alkaline earth metal diiodide at room temperature to afford the corresponding calcium complex. The metal bis(trimethylsilyl)amides were made to react with protic ligand 1 in the second method to eliminate the volatile bis(trimethyl)silyl amine. The magnesium complex 3 and barium complex 5 were prepared only through the first method. Solid-state structures of all the new complexes were established by single crystal X-ray diffraction analysis. The smaller ionic radii of Mg²⁺ (0.72Å) and Ca²⁺ (0.99Å) ions form the monomeric complex, whereas the larger ions K⁺ (1.38Å) and Ba²⁺ (1.35Å) were found to form onedimensional polymeric complexes with monoanionic ligand 1. Compound 2 serves an example of magnesium complex with a Mg-Se direct bond.

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 highly chemo-selective catalytic addition of N–H bonds from various aromaticamines to carbodiimides and isocyanates using (Ar-BIAO)ZnCl2 complexes [Ar-BIAO = N-(aryl)iminoacenapthenone,Ar = 2,6-$Me_{2}C_{6}H_{3}$ (1), 2,4,6 $Me_{3}C_{6}H_{2}$ (2), $2,6-^{i}$ $Pr_{2}C_{6}_H{3} (3)] as the pre-catalyst to prepareguanidine and urea derivatives in 55-90% yield. The complex 3 showed higher catalytic activity than analogouscomplexes 1 and 2 under similar reaction conditions. The catalytic guanylation of N–H bonds with heterocumulenesdisplays a broad substrate scope. The amines having electron donating groups underwent higher conversionthan the amines having electron withdrawing groups to afford corresponding guanidine or urea derivatives.A possible mechanism involving penta-coordinated zinc transition state for the catalytic reaction is presented.