Head to head acetylene coupling at a heterobimetallic center to give a rhodacyclopentadieneiron unit. Syntheses and x-ray crystal structures of (tert-Bu2PH)(CO)2Fe(.mu.-CO)(.mu.-tert-Bu2P)Rh(COD)(FeRh), (CO)2Fe(.mu.-tert-Bu2P)(.mu.-.eta.4-C4H2(Ph)2)Rh(HCCPh)(FeRh), and Rh2Fe(CO)3(tert-Bu2PH)(.mu.-CO)2(.mu.-tert-Bu2P)2