摘要:
                                The cothermolysis of [CpCr(CO)3]2 (Cp = eta-5-C5H5) with excess gray arsenic in refluxing toluene for 1-1.5 h resulted in the isolation of Cp2Cr2(CO)4(mu-eta-2-As2) (2), CpCr(CO)2(eta-3-As3) (3), Cp2Cr2(CO)4(Cr = Cr) (4), and Cp2Cr2AsO5 (6) in 20.4, 14.2, 5.3, and 13.6% yields, respectively.  The reaction when extended to 16 h gave 3, Cp2Cr2As5 (5), 6, and Cp5Cr5As4O8 (7) in 5, 22, 39, and 8% yields, respectively.  In refluxing xylene for 6 h, the reaction produced 3 (3%) and 7 (15%).  4 likewise reacted with excess elemental arsenic in refluxing toluene, yield 2 (18.5%), 3 (31.9%), and 6 (38.3%) after 1 h but only 2 (18.6%) and 6 (44.2%) after 5 h.  Thermal degradation of 2 at 110-degrees-C for 16 h yielded 6 (46.5%) and 7 (28%).  3 also degrades to 5, but at a much slower rate.  2 crystallizes as dark purple needles.  Crystal data:  space group C2/c (No. 15), Z = 4, alpha = 15.551 (3) angstrom, b = 7.453 (1) angstrom, c = 13.446 (2) angstrom.