STRUCTURES OF (1,3-BIS(DIPHENYLPHOSPHINO)PROPANE)TETRACARBONYLMOLYBDENUM(0) (1) AND (1,4-BIS(DIPHENYLPHOSPHINO)BUTANE)TETRACARBONYLMOLYBDENUM(0) (2)

(1) C31H26MoO4P2, [Mo{C6H5)2PC3H6P(C6H5)2}(CO)4], M(r) = 620.4, orthorhombic, Pnma, a = 16.854 (4), b = 21.970 (4), c = 7.723 (2) angstrom, V = 2860 (1) angstrom3, Z = 4, D(m) = 1.47 (3), D(x) = 1.48 Mg m-3, lambda(Mo K-alpha) = 0.7093 angstrom, mu = 0.59 mm-1, F(000) = 1264, T = 298 K, final R = 0.033 for 1871 observed reflections. (2) C32H28MoO4P2, [Mo{(C6H5)2PC4H8P(C6H5)2}(CO)4], M(r) = 634.3, monoclinic, P2(1)/n, a = 12.072 (2), b = 15.379 (5), c = 16.607 (5) angstrom, beta = 104.65 (2)degrees, V = 2983 (1) angstrom3, Z = 4, D(m) = 1.36 (3), D(x) = 1.35 Mg m-3, lambda(Mo K-alpha) = 0.7093 angstrom, mu = 0.57 mm-1, F(000) = 1296, T = 298 K, final R = 0.032 for 3888 observed reflections. The molecular structures of both compounds are similar, but the numbers of the ring members are six in (1) and seven in (2). In the order of compound (1), (2), the following changes occur: P-Mo-P = 89.74 (4), 91.65 (4)degrees; cis C-Mo-C = 88.7 (2), 86.1 (2)degrees; trans C-Mo-C = 174.8 (3), 176.8 (2)degrees. The increase in P-Mo-P and the decrease in cis C-Mo-C angle are attributed to the ring effect. The variety of the trans C-Mo-C angle is probably due to the rotational orientations of the phenyl groups of the bidentate ligands.