CLUSTER CHEMISTRY. STUDY OF THE PYROLYSIS OF RU3(MU -DPPF)(CO)10 (DPPF = 1,1'-BIS(DIPHENYLPHOSPHINO)FERROCENE). X-RAY STRUCTURES OF RU3(MU -H)MU 3-(ET A 1,ETA 2-C6H4)PPH(ETA -C5H4)FE(ETA -C5H4PPH2)(CO)8, RU3(MU -P(C6H4)-ETA -C 5H4)FE(ETA -C5H4PPH2)(MU -CO)(CO)8, RU3(MU 3-ETA 1,ETA 1,ETA 2-C6H4) (MU