Structural Flexibility of the Hydrogen-Free Acceptor Ligand Octachloro-1,10-phenanthroline in Its Complexes with d¹⁰ Metal Ions

Abstract

A remarkable pattern of structural diversity has been observed for the conformation of octachloro-1,10phenanthroline (ocp) in its free form and in its d 10 metal complexes [M(ocp) 2 ] + , M ) Cu, Ag, and Cl 2 Hg(ocp). Ocp: C 12 Cl 8 N 2 , monoclinic, space group P2 1 /c, a ) 5.6390(10) Å, b ) 24.970(3) Å, c ) 10.4660(10) Å, β ) 101.33°, Z ) 4; [Ag(ocp) 2 ](PF 6 )‚CH 2 Cl 2 , C 25 H 2 AgCl 18 F 6 N 4 P, monoclinic, space group P2/n, a ) 13.185(2) Å, b ) 9.4740(10) Å, c ) 16.106(2) Å, β ) 92.05°, Z ) 2; Cl 2 Hg(ocp)‚2.5C 6 H 6 : C 27 H 15 Cl 10 HgN 2 , triclinic, space group P1 h, a ) 10.391While ocp is virtually planar in the previously characterized ion [Cu(ocp) 2 ] + , the analogous silver(I) complex contains slightly twisted ocp ligands. In contrast, both the free, noncoordinated ligand and its dichloromercury(II) complex exhibit distincly saddle-shaped ocp. Cl 2 Hg(ocp) in particular contains a rather distorted chelate ligand. Ab initio calculations at the 6-31G** level show a flat energy hypersurface for ocp with an absolute minimum at a saddle-shaped conformation and a second energy minimum, 2.7 kcal/mol higher, for the coplanar arrangement. Nonbonded interactions between the chlorine atoms are responsible for the structural flexibility and limited coordination ability of ocp; electronically, ocp is a good acceptor ligand with two stabilized and close-lying unoccupied π* orbitals but much reduced σ donor capacity.

The Diiodine Basicity Scale: Toward a General Halogen‐Bond Basicity Scale

“…Indeed, the proximity of the two nitrogen lone pairs creates a very negative electrostatic potential (V S,min = À245 kJ mol À1 whereas it is only À158 kJ mol À1 for pyridine with one lone pair) midway between N1 and N10. So, in the solid state, the chlorine bond in 1,10-perchlorophenanthroline [87] is quasi-three-centre (N1···Cl···N10 with N1···Cl = 3.21 and N10···Cl = 3.27 ) as well as the iodine bond in the complex of 1,4-diiodotetrafluorobenzene with 1,10-phenanthroline (N1···I···N10 with N1···I = 3.01 and N10···I = 3.27 ). [88] However, the chlorine bond in the complex of chloroform with bis-1,10-phenanthroline [89] is clearly two-centre (N1···Cl = 3.28 , whereas N10···Cl = 4.09 ).…”

Spectroelectrochemical Evidence for the Nitrosyl Redox Siblings NO+, NO., and NO− Coordinated to a Strongly Electron‐Accepting FeII Porphyrin: DFT Calculations Suggest the Presence of High‐Spin States after Reduction of the FeII–NO− Complex

“…It is therefore assumed that this is a porphyrin-based reduction that leads to a species best formulated as [{Fe-NO} . [23] Experimental Section Syntheses: 5, 10, 15, 20-Tetrakis(pentafluorophenyl)porphyrin (H 2 TFPP) was purchased from Frontier Scientific and used as received. All solvents were distilled and dried according to conventional procedures.…”

Syntheses and crystal structures of novel silver(I) coordination polymers based on linear or tetrahedral coordination environments

“…The Ag(I) centre is coordinated by four nitrogen atoms of 3-pia ligands, two N C and two N N , in a distorted tetrahedral fashion, with N-Ag(I)-N angles of 97.4(2)-132.0(1)°. The distances of Ag(I)-N N (Ag(1)-N(2) = 2.441(4) Å and Ag(1)-N(5) = 2.351(4) Å) are greater than those of Ag(I)-N C (Ag(1)-N(1) = 2.273(4) Å and Ag(1)-N(4) = 2.266(3) Å); the distances are typical of those found in tetrahedral Ag(I) complexes[15]. As shown inFig.…”