Acetylene undergoes hydrochlorination by gaseous HCI in the absence of a solvent on the surface of pre-ground of K2PtC14 powder. In the DCI atmosphere, trans-D-vinyl chloride is formed. The catalytic reaction proceeds on the active sites, which are lattice defects in the form of rr-acetylene complexes generated by mechanical pre-activation of K(2)PtCl4 salt under acetylene. The limiting step of the reaction is acetylene chloroplatination. It involves a pi-acetylene complex and HCI molecule, producing a new pi-acetylene platinum(II) complex and intermediate beta-chlorovinyl Pt(II) derivative. The protonolysis of the latter species results in vinyl chloride formation. (c) 2007 Elsevier B.V. All rights reserved.