Structure and Metal Coordination of the Diphosphane 2, 2′-Bis((diphenylphosphino)methyl)-1, 1′-biphenyl (“BISBI”)

2,2′-Bis((diphenyiphosphino)methyl)-1, 1′-biphenyl (1, BISBI) crystallizes in the orthorhombic space group Pca2₁ with a = 22.845 (1) Å, b = 13.3796 (6) Å, c = 19.642 (1) Å, V = 6004 ų, and Z = 8. The X-ray crystal structure analysis of 1 revealed two independent molecules in the unit cell. [2,2′-Bis((diphenylphosphino)methyl)-1,1′-biphenyl]tetracarbonyl-molybdenum (3), prepared in 47% yield from (norbornadiene)Mo(CO)₄ and the ligand BISBI, was also structurally characterized. Crystals of 3-0.92CH₂Cl₂, grown from methylene chloride at room temperature, are monoclinic, with space group P2₁/n, a = 15.444 (1) Å, b = 13.957 (1) Å, c = 18.503 (1) Å, β = 92.55 (1)°, V = 3984 ų, and Z = 4. The structure of 3 shows a nearly octahedral coordination of the molybdenum atom, with the diphosphane ligand in cis positions. The P-Mo-F “bite angle” is 103.54 (2)°. 3 belongs to the very few known complexes that exhibit nine-membered, metal-containing ring systems of diphosphane ligands. BISBI can adopt to any coordination geometry with small (90°) and large “bite angles” (180°) upon miramolecular (chelating) metal attachment while there is no experimental evidence for internolecular complexation.