Syntheses, Crystal Structure and Magnetic Properties of an Unprecedented One‐Dimensional Coordination Polymer Derived from an {(NiL)2Ln} Node and a Pyrazine Spacer (H2L=N, N′‐Bis(salicylidene)‐1, 3‐propanediamine, Ln=Gd, Tb and Dy). Issue 11 (22nd July 2016)