Cooperative Binding of Nitrile Moieties Within a Bimetallic Pocket: Enforcing Side‐On π‐Interaction With a High‐Spin Nickel(II) Site

摘要: Different cooperative binding modes of nitriles within the bimetallic pocket a pyrazolate-based compartmental dinickel(II) site have been studied. The H3O2-bridged dinuclear complex 1 reacts with cyanamide to yield 4, in which secondary hydrogencyanamido(1–) bridge spans two metal centers at an unusually short metal–metal distance imposed by primary ligand matrix. In 5, single 2-cyanoguanidine (cnge) molecule is N-bound one nickel(II) ion through its nitrile part and coordinated adjacent amido nitrogen. characteristics coordination spheres suggest additional side-on π-bonding interaction moiety second high-spin ion. This unusual corroborated comparing IR bands for ν(C≡N) stretching vibration 5 those 6, has end-on bound cnge molecules, related mononuclear 7, lacks nature further analyzed DFT calculations on relevant model systems. Even though found be very weak, it does include some backbonding from occupied 3d MOs π* nitrile. Such unconventional π-interaction suggested enforced constrained fixation unit highly organized framework. contrast, bifunctional 2-hydroxybenzonitrile accommodated distinct phenolate functions different 8, confirms that simultaneous both OR-function indeed feasible active pocket. situation reminiscent effect assumed enable hydration 1. Complexes 4·(ClO4)2, 5·(ClO4)2, 6·(ClO4)3, 7·(ClO4)(BPh4), 8·(ClO4)2 characterized structurally X-ray crystallography.