Systematische Studie zu den Koordinationseigenschaften des Guanidin‐Liganden Bis(tetramethylguanidino)propan mit den Metallen Mangan, Cobalt, Nickel, Zink, Cadmium, Quecksilber und Silber

Abstract

The transition metal complexes with the ligand 1,3‐bis(N,N,N′,N′‐tetramethylguanidino)propane (btmgp), [Mn(btmgp)Br2] (1), [Co(btmgp)Cl2] (2), [Ni(btmgp)I2] (3), [Zn(btmgp)Cl2] (4), [Zn(btmgp)(O2CCH3)2] (5), [Cd(btmgp)Cl2] (6), [Hg(btmgp)Cl2] (7) and [Ag2(btmgp)2][ClO4]2·2MeCN (8), were prepared and characterised for the first time. The stoichiometric reaction of the corresponding water‐free metal salts with the ligand btmgp in dry MeCN or THF resulted in the straightforward formation of the mononuclear complexes 1–7 and the binuclear complex 8. In complexes with MII the metal ion shows a distorted tetrahedral coordination whereas in 8, the coordination of the MI ion is almost linear. The coordination behavior of btmgp and resulting structural parameters of the corresponding complexes were discussed in an comparative approach together with already described complexes of btmgp and the bisguanidine ligand N1,N2‐bis(1,3‐dimethylimidazolidin‐2‐ylidene)‐ethane‐1,2‐diamine (DMEG2e), respectively.

Synthesis and Characterisation of Novel (Guanidine)manganese Complexes and Their Application in the Epoxidation of 1‐Octene

“…In the case of a C 3 -symmetrical CN 3 unit ρ is equal to 1. As is evident in [11] In case of C2 the former C=N bond is more localised between the C gua atom and one of the N amine atoms whereas in C1 and [MnBr 3 (TMG 2 pyH)] one C-N amine bond is significantly longer than the other two C-N bonds. Generally, the de-localisation in complexes containing aliphatic guanidines (such as btmgp, DMEG 2 e and TMG 3 tren) is less distinct than in complexes with aromatic guanidines (such as DMEGqu and DMEG 2 py).…”

“…Generally, the de-localisation in complexes containing aliphatic guanidines (such as btmgp, DMEG 2 e and TMG 3 tren) is less distinct than in complexes with aromatic guanidines (such as DMEGqu and DMEG 2 py). [11,12] …”

“…Therein the guanidines enable a multitude of coordination modes of manganese and the complexes exhibit a variety of coordination numbers and spacer motifs. [10][11][12] Known (guanidine)manganese complexes are mainly mononuclear and some are dinuclear. C3 and C4 are the first trinuclear (guanidine)manganese complexes.…”

“…[1,8] Encouraged by the promising results with guanidine ligands for the stabilisation of high-valent species, [9,10] we directed our research towards the synthesis of (guanidine)manganese complexes. [11] We envisioned that this ligand family is highly capable to stabilise manganese complexes which act as efficient epoxidation catalysts. Structural studies on (guanidine)manganese complexes have already been performed for few examples with bis-and tris(guanidines).…”

“…Structural studies on (guanidine)manganese complexes have already been performed for few examples with bis-and tris(guanidines). [10][11][12] For our present study we utilise guanidine-pyridine hybrid ligands, which combine the excellent donor properties of guanidines with additional coordination space for the pre-coordination of substrates. Moreover, guanidine ligands exhibit a modular and facile synthesis protocol, which offers different spacer and guanidine groups and thus admits a flexible ligand design.…”