Structure of a bis-bidentate metal complex, bis-(N-t-butylpyrrole-2-carbaldimino)nickel(II). Analysis of its configurational disorder in the crystalline state

Abstract

The crystal and molecular structure of a bis-bidentate nickel complex, (CgHI3N2)zNi(II), has been determined from a single-crystal X-ray analysis. The unit-cell data are a= 16-777 (13), b=7.507 (6), c= 15.378 (11) A, Z=4, space group Pbcn. Counter data to 20=48 ° (Mo K~ radiation) were measured with an Oak Ridge computer-controlled diffractometer. The structure was solved by heavy-atom techniques and refined by the full-matrix least-squares method to R(F)= 0"102, based on 1160 independent nonzero reflections, or 0.049 for the 649 reflections with Fo2_> 3tr(F2). The molecule has C2 symmetry with a crystallographic twofold axis passing through the metal atom. The structure is partly disordered in that the t-butyl group appears to have two alternative orientations of equal occupancy. The configuration around the nickel atom is pseudo-tetrahedral with a dihedral angle of 88-7 (3) ° between the plane defined by the Ni, N(I), and N(2) atoms and the plane defined by the Ni, N(I'), and N(2') atoms. The two independent Ni-N bond distances, 2.032 (4) and 1.935 (5) ,~,, are distinctly different. The intrachelate N-Ni-N angle of 83.7 (4) ° is much smaller than any of the interchelate N-Ni-N angles, which range from 116.7 to 132"7 °. The N...N 'bite' distance in the five-membered ring NiN2C~ is 2.647 (7) ~. The pyrrole-2.carbaldimine ligand is nearly planar.

Complexities of the Interaction of NiII, PdII and PtII Pyrrole‐Imine Chelates with Human Serum Albumin**

“…[4][5][6] Such ligands stabilize metal ions in a range of oxidation states. [7] Examples include structurally characterized Co II/III , [8][9][10][11] Rh I/III , [12][13][14][15] Ir III , [16,17] Ni II , [18][19][20] Pd II , [20][21][22] Pt II , [23][24][25] Cu II , [26][27][28][29] Ag I , [30] and Au III complexes. [31] While pyrrole compounds are key building blocks for organic pharmaceuticals, [32] for example, Tolmetin, [33] Sunitinib, [34] and Glimepiride, [35] studies over the last two decades suggest that pyrrole-imine metal chelates exhibit significant medicinal potential.…”

Complexities of the interaction of Ni(II), Pd(II) and Pt(II) pyrrole-imine chelates with human serum albumin

“…[4][5][6] Such ligands stabilize metal ions in a range of oxidation states. [7] Examples include structurally characterized Co II/III , [8][9][10][11] Rh I/III , [12][13][14][15] Ir III , [16,17] Ni II , [18][19][20] Pd II , [20][21][22] Pt II , [23][24][25] Cu II , [26][27][28][29] Ag I , [30] and Au III complexes. [31] While pyrrole compounds are key building blocks for organic pharmaceuticals, [32] e.g., Tolmetin, [33] Sunitini, [34] and Glimepiri, [35] studies over the last two decades suggest that pyrrole-imine metal chelates exhibit significant medicinal potential.…”

Metal Complexes of Novel Symmetrical Schiff Base Ligands

“…5). It has been reported on the basis of X-ray single crystal studies of Ni(II) Schiff base complexes containing bulky groups attached to the coordinated azomethine nitrogen atoms, that they have distorted tetrahedral cores 8 . .…”