Di‐μ‐Chloro‐Dichlorobis(Ethylene)‐Diplatinum(II), Di‐μ‐Chloro‐Dichloro‐Bis(Styrene)Diplatinum(II), and Di‐μ‐ Chloro ‐Dichlorobis (1 ‐Dodecene)‐Diplatinum(II)