Carbonylation and amination of .mu.-.eta.2-acetylides in M2(CO)6(.mu.-.eta.2-C.tplbond.CPh)(PPh2): synthesis of .mu.-O:CCHC(Ph)NR2 complexes and the x-ray structure of Ru2(CO)6[.mu.-O:CCHC(Ph)NEt2](PPh2)