Linear Coordination Fullerene C60 Polymer [{Ni(Me3P)2}(μ-η2,η2-C60)}∞ Bridged by Zerovalent Nickel Atoms

Coordination nickel-bridged fullerene polymer [{Ni(Me3P)(2)}(mu-eta(2),eta(2)-C-60)]infinity (1) has been obtained via reduction of a Ni-II(Me3P)(2)Cl-2 and C-60 mixture. Each nickel atom is linked in the polymer with two fullerene units by eta(2)-type Ni-C(C-60) bonds of 2.087(8)-2.149(8) angstrom length. Nickel atoms are coordinated to the 6-6 bonds of C60 as well as two trimethylphosphine ligands to form a four-coordinated environment around the metal centers. Fullerene cages approach very close to each other in the polymer with a 9.693(3) angstrom interfullerene center-to-center distance, and two short interfullerene C-C contacts of 2.923(7) angstrom length are formed. Polymer chains are densely packed in a crystal with interfullerene center-to-center distances between fullerenes from neighboring polymer chains of 9.933(3) angstrom and multiple interfullerene C...C contacts. As a result, three-dimensional dense fullerene packing is formed in 1. According to optical and electron paramagnetic resonance spectra, fullerenes are neutral in 1 and nickel atoms have a zerovalent state with a diamagnetic d(10) electron configuration. The density functional theory calculations prove the diamagnetic state of the polymer with a singlet-triplet gap wider than 1.37 eV.