Text this: OXIDATIVE-ADDITION REACTIONS OF [W2(ETA-C5H4R)2X4] (R = PRI OR ME X = CL OR BR) - REVERSIBLE ADDITION OF DIHYDROGEN TO A TUNGSTEN-TUNGSTEN TRIPLE BOND AND X-RAY CRYSTAL-STRUCTURES OF [W2(ETA-C5H4PRI)2CL4(MU-H)(MU-PPH2)] AND [W2(ETA-C5H4PRI)2CL3(MU-CL)(MU-H)(MU-PPH2)(PME3)]