Synthesis and Reactivity of Nickel(II) Complexes of the Pyridine-Based Phosphorus-Containing Macrocycle 6-Phenyl-15-aza-6-phospha-3,9-dithiabicycio[9,3,1]pentadeca-1(15),11,13-triene

The reactivity of the phosphomacrocycle 6-phenyl-15-aza-6-phospha-3,9-dithiabicyclo[9,3,1]pentadeca-1(15), 11,13-triene (L) toward different Ni(II) salts has been studied. The reaction of L with 1 molar equiv of Ni(II) perchlorate in acetonitrile solution gives the complex [Ni(L)(CH3CN)2](ClO4)2 (1), which crystallizes in the monoclinic space group P21/c (No. 14) with a = 12.704(2) Å, b = 13.538(2) Å, c = 17.377(2) Å, β = 107.554(8)°, and Z = 4. The Ni(II) atom in 1 shows an octahedral environment defined by the four donor atoms of L and two acetonitrile molecules in a cis disposition. The reaction of L with Ni(II) perchlorate in 2:1 molar ratio yields the green complex [Ni(Lox)2](ClO4)2 (2) in which the phosphine groups of the ligand L are in their phosphine-oxide form (Lox). The same complex is also obtained by adding more ligand L to an acetonitrile solution of 1. Complex 2 crystallizes in the triclinic space group P1̄ (No. 2) with a = 10.564(1) Å, b = 11.975(2) Å, c = 9.124(2) Å, α = 109.79(1)°, β = 95.67(2)°, γ = 109.19(1)°, and Z = 1. The octahedral coordinated Ni(II) atom in 2 lies on a crystallographic center of symmetry, and it is surrounded by two pyridine nitrogen atoms, two thioether sulfur atoms, and two phosphine-oxide oxygen atoms provided by two facially coordinated Lox ligands. The reaction of L with Ni(II) chloride and Ni(II) thiocyanate yields the complexes [NiCl2(L)] (3) and [Ni(NCS)2(L)] (4), respectively, which are also obtained by adding Me4NCl or KSCN to an acetonitrile solution of 1. Complex 4 crystallizes in the monoclinic space group P21/n (No. 14), with a = 11.139(2) A°, b = 13.270(2) A°, c = 14.885(1) A°, β = 92.34(1)°, and Z = 4. and its structure is similar to that of complex 1, simply replacing the two acetonitrile molecules by two SCN- anions. The reactions of the complex 1 with different chelating (en, bipy, o-phen) and nonchelating (py) N-donor ligands have also been carried out. In all cases the two acetonitrile molecules of 1 are easly replaced by the N-donor ligands, but the macrocycle L molecule remains coordinated to the Ni(II) atom. The crystal structure of the complex [Ni(L)(py)2](ClO4)2 (5) is also elucidated. Crystal data: monoclinic space group P21/c (No. 14) a = 13.063(2) A°, b = 16.615(3) A°, c = 14.973(3) A°, β = 91.76(2)°, Z = 4.