  2H MoS2 has been intensively studied because of layer-dependent electronic
structures and novel physical properties. Though the metastable 1T MoS2 with
the [MoS6] octahedron was observed from the microscopic area, the true crystal
structure of 1T phase has not been determined strictly. Moreover, the true
physical properties have not been demonstrated from experiments due to the
challenge for the preparation of pure 1T MoS2 crystals. Here, we successfully
synthesized the 1T MoS2 single crystals and re-determined the crystal structure
of 1T MoS2 from single-crystal X-ray diffraction. 1T MoS2 crystalizes in space
group P-3m1 with a cell of a = b = 3.190(3) {\AA} and c = 5.945(6) {\AA}. The
individual MoS2 layer consists of MoS6 octahedron sharing edge with each other.
More surprisingly, the bulk 1T MoS2 crystals undergo a superconducting
transition of Tc = 4 K, which is the first observation of superconductivity in
pure 1T MoS2 phase.
