A phenol-based “end-off” compartmental ligand, 2-[N,N-di(2-pyridylmethyl)aminomethyl]-6-{N-[2-(dimethylamino)ethyl]iminomethyl}-4-methylphenol (HL), having an iminic bidentate and an aminic tridentate chelating
arms on the 2- and 6-positions of the phenolic ring, respectively, forms dinuclear nickel complexes [Ni2(L)(AcO)(NCS)2] (1), [Ni2(L)(AcO)2(MeOH)]PF6 (2), and [{Ni2(L)(OH)(MeOH)}2(CO3)](PF6)2 (3). Complex 1
crystallizes in the monoclinic space group P21/c, a = 14.165(5) Å, b=15.198(4) Å, c = 17.395(8) Å, β = 100.62(4)°, V = 3680(2) Å3, and Z = 4. The pair of Ni ions present are bridged by the phenolic oxygen of L- and an
acetate group in syn
−
syn mode (Ni−Ni: 3.373(3) Å). An isothiocyanate nitrogen atom coordinates to each Ni
providing an asymmetric dinuclear core with a mixed {5/6} coordination number set. Complex 2 crystallizes in
the monoclinic space group P21/c, a = 13.505(5) Å, b = 12.028(4) Å, c = 22.774(9) Å, β = 103.78(3)°, V =
3592(2) Å3, and Z = 4. It has a dinuclear core bridged by the phenolic oxygen of L- and two acetate groups in
syn
−
syn mode, providing a μ-phenoxo-bis(μ-carboxylato)dinickel(II) core (Ni−Ni: 3.396(6) Å). A methanol
molecule coordinates to the Ni bound to the bidentate arm, forming a dinuclear core having a {6/6} coordination
number set and an asymmetric donor atom environment. Complex 3 crystallizes in the orthorhombic space group
Pbcn, a = 19.056(5) Å, b = 18.997(4) Å, c = 19.919(6) Å, α = β = γ = 90°, V = 7211(5) Å3, and Z = 8. In
each dinuclear unit a pair of Ni ions are bridged by the phenolic oxygen of L- and a hydroxo oxygen (Ni−Ni:
3.087(2) Å). A carbonate further bridges two of the dinuclear units to present a composite dimer. The Ni bound
to the bidentate arm attains six-coordinate geometry by further interaction with two oxygens of the bridging
carbonato group. The Ni bound to the tridentate arm assumes six-coordinate geometry by further coordination
of a methanol oxygen. Complexes 1−3 react with urea in ethanol to form the isocyanate complexes [Ni2(L)(AcO)(NCS)(NCO)] (1
‘), [Ni2(L)(AcO)(NCO)(EtOH)]PF6 (2
‘), and [{Ni2(L)(NCO)(EtOH)}2(CO3)](PF6)2 (3
‘),
respectively. Complex 3
‘ crystallizes in the triclinic space group P1̄, a = 20.072(7) Å, b = 21.145(6) Å, c =
18.688(6) Å, α = 106.20(2)°, β = 90.01(3)°, γ = 88.73(3)°, V = 7614(4) Å3, and Z = 4. It has a dimeric
structure very similar to that of 3, except for the replacement of the hydroxy bridge and the methanol ligand in
3 by isocyanate bridge and ethanol ligand, respectively, in 3‘.
