Chemistry of [{Cr(cp)(CO) 3 } 2 ], (cp =η 5 -C 5 H 5 ). Reaction with elemental P 4 . A high yield synthesis and crystal structures of [{Cr(cp)(CO) 2 } 2 (µ-η 2 -P 2 )] and [Cr(cp)(CO) 2 (η 3 -P 3 )]

The reaction of [{Cr(cp)(CO)3}2](cp =η5-C5H5) with 1 molar equivalent of P4 in toluene at 90 °C gave [{Cr(cp)(CO)2}2(P2)] and [Cr(cp)(CO)2(P3)](2) in 53 and 40% yields, respectively. A radical mechanism has been postulated. Single-crystal X-ray diffraction studies show that (1) contains a µ-η2-P2 group bridging two metal-metal bonded Cr atoms and (2) contains a tricyclo-η3-P3 ligand. Crystal data: (1) monoclinic, space group P21/n, a= 7.934(2), b= 17.189(3), c= 11.327(2), β= 97.69(2)°, and Z= 4; (2) monoclinic, space group P21/c, a= 11.398(3), b= 14.383(1), c= 13.323(4), β= 115.32(2)°, and Z= 8. The synthetic method, structures, and spectral features of these complexes are compared with those of analogous complexes of other transition metals, particularly Mo.