Jp. Jasinski et al., STRUCTURE OF A DICHROMIUM OCTACARBONYL COMPLEX OF CYCLOTETRAKIS[BIS(DIISOPROPYL-AMINO)PHOSPHOXANE], Acta crystallographica. Section C, Crystal structure communications, 49, 1993, pp. 2081-2083
The molecule 2P2,P:2kappa2P6,P8-bis[tetra-carbonylchromium(0)], has an
inversion center that relates the two chromium coordination spheres.
Each metal atom is cis-coordinated to two P atoms of the tetraphosphox
ane ring to form a four-membered Cr-P-O-P chelate ring. The eight-memb
ered phosphoxane heterocycle is a novel twist-boat-twist-boat configur
ational isomer of the alternative adamantanoid cage. Average distances
are Cr-C 1.869 (3), Cr-P 2.337 (4) and P-O 1.65 (2) angstrom.