Unilateral Exclusion of Jahn–Teller-Inactive d⁵ Mn(H₂O)₄(C₇H₄NO₃S)₂²⁺ Guests by Strongly Distorted Host d⁹ Cu(H₂O)₄(C₇H₄NO₃S)₂²⁺ Lattice

Abstract

The crystal lattice of the isomorphous tetraaquabis(saccharinate)metal(II) dihydrates was employed as a structurally flexible coordination framework capable of sustaining large internal distortions to study the competitive inclusion of Jahn-Teller (JT) distorted d 9 ions, [Cu(H 2 O) 4 (sac) 2 ] 2+ , and JT-inactive d 5 ions, [Mn(H 2 O) 4 (sac) 2 ] 2+ , in binary solid solutions under thermodynamically controlled conditions of statistical mixing (sac ) saccharinate anion, C 7 H 4 NO 3 S -). Probing of the metal content of the solid phase showed a two-regime inclusion profile: increasing the ratio of the distorted cation relative to the undistorted one in the solution phase of up to about 35% results in linear dependence and preferred inclusion of the former with maximum concentration of 100% in the crystal and complete exclusion of the undistorted ion above that point. A mixed crystal with highest copper ratio of 63% was obtained from solution with 25% copper, which under the P2 1 /c crystal symmetry corresponds to sustainable integrity of the undistorted lattice by substitution of up to 2 / 3 of its sites. This stability limit shows that four out of the six sites around each [Mn(H 2 O) 4 (sac) 2 ] 2+ ion can be substituted by distorted [Cu(H 2 O) 4 (sac) 2 ] 2+ guests under conditions of thermodynamically controlled, statistically averaged exchange. The undistorted host is very tolerant toward inclusion of strongly distorted guests. When acting as host, the distorted ion is more discriminatory toward the undistorted guest. Along with the expectation from the JT theory, structural refinement of seven crystals, including a mixed crystal with composition of [Cu 0.126 Mn 0.874 (H 2 O) 4 (C 7 H 4 NO 3 S) 2 ](H 2 O) 2 , showed that metal-ligand distances are significantly affected by the metal substitution. Inclusion of the JT-active ion results in distortion of the coordination polyhedron by increasing the bond length difference between the two metal-O(water) bonds and also causes shortening of the M-N bond. Due to the rigidness caused by π-conjugation, the overall effect on the endocyclic geometry of the organic ligand is small. The anisotropic distortions around the metal ion are faithfully reflected in the stretching force constants of the coordinated water molecules and thus in the IR spectrum of the mixed crystals.

Synthesis and structure of Zn(II) and Cu(II) complexes derived from 2-(aminomethyl)benzimidazole and glycine

“…Thus, O8 is bonded to 3a [Cu2-O8 bond length is 2.624(13) Å], but this oxygen is distorted and has an occupancy of 0.25. Moreover, the bond length Cu2-O8 and bond angle O8-Cu2-Cl1 [169.9(3)°] support the presence of a Jahn-Teller distortion in this unit [27,28]. Otherwise, the Cu(II) in 3b is embedded in a distorted six-coordinate geometry with Jahn-Teller distorted octahedral geometry, with one of the waters situated around a symmetry center (O3, refined occupancy 0.50).…”

“…Moreover, distorted water O9 is omitted for clarity. , the bands from 3600 to 2660 cm −1 are strong and broad, which suggest the presence of supramolecular hydrogen interactions in these complexes[15,27,34,35]. The presence of water in these compounds is evidenced by ρ r (H 2 O) vibrations at 844 cm −1 for 2 and 846 cm −1 for 3, respectively.…”

Mechanochemical Synthesis of Alkaline Earth Mg – Ba Saccharinates. Connectivity in the Crystal Structures of Mg(sac)2∙7H2O, Ca(sac)2∙7H2O and Ba(sac)2∙4.5H2O (sac = saccharinate)

“…[21] There are also mixed alkaline metal saccharinates such as NaK(sac)2•H2O [23] and NaRb(sac)2•4H2O. [24] The first row transition metal ions form isomorphous coordination type complexes of the type [M(sac)2(H2O)4]•2H2O, with M = V, [11] Cr, [10] Mn, [4,25] Fe, Co and Ni, [4,8] Cu [6,25] and Zn. [4,9] There are also structures with bonding of more covalent character as in Cd, [4,9] Hg, [7] and Pb.…”