Studies of Rhenium β-Diketone Complexes. III. The Crystal and Molecular Structure of Bis(μ-O-1,3-diphenylpropane-1,3-dionatotricarbonylrhenium(I))

Abstract

One of a series of compounds obtained by the reaction of chloropentacarbonylrhenium (1) with [3-diketones has been shown by single crystal X-ray diffraction to be bis(p-0-1,3-diphenylpropane-1,3-dionatotricarbonylrhenium(1)f. The crystals are monoclinic with lattice parameters a = 11.988(A) A, b = 14.441(9) A, c = 10.298(7) A, = 115.25(7)'. The space group is PZ,!c and there are two dimers per unit cell. A total of 1563 independent reflections were measured on a single crystal X-ray diffractometer and the structure was refined by least squares analysis to a weighted R, value of 0.0427. The dimer units are held together by two bridging oxygen atoms, one from each of the a-ketoenolate groups; the distance of the bridging oxygen from the rhenium atom to which it is chelated (2.162(9) A) is shorter than the distance to the other rhenium atom (2.204(7) A). The main part of the B-ketoenolate ring is 37" from the OReO plane.L'un des coinposCs obtenu par la reaction du chloropentacarbonylrheni~~n~(I) sur les a-dicetones a CtC identifie par diffraction aux rayons X sur un monocristal au bis (fi-0-diphenyl-I ,3-propanedionato-1,3 tricarbonylrhenium(1)). Ees cristaux sont monocliniques, les parametres du reseau sont: a = 11.988 A, b = 14.441(9) A, c = 10.298(7) A, [3 = 115.25(7)'. Le groupe spatial est P2,lc et il y a deux dimeres par maille. Un total de 1563 reflexions independantes a ete mesure au diffractometre aux rayons X sur un monocristal, la structure a Cte raffinee par la methode des moindres carrCs jusqu'a obtention d'une valeur ponderee sur R, de 0.0427. Les dimeres dans la maille sont relies entre eux par deux atomes d'oxygeile formant un pont, chacun d'eux provenant des groupes p-~Ctoenolates; la distance de I'oxygene pont B l'atome de rl~kniun~ auquel il est chelate (2.162(9) A) est plus courte que celle qui le separe de

The Crystal and Molecular Structure of Pentane-2,4-dionato-(2,3,5,6-tetrahepto-2,3-dicarbomethoxo[2.2.1]bicycloheptadiene)rhodium(I), Rh(C5H7O2) (C7H6(CO2CH3)2)

“…An M-X bond, where X has some K-acceptor properties, trans to an olefinic group substituted with electron-withdrawing ligand, (C(B)), should be longer than a similar bond trans to an unsubstituted olefinic 'group, (C(A)), because in the competition for d-K electrons, the increased K-back bonding to the olefin would weaken the trans K-bond (9). We have shown previously that P-ketoenolates in low valence compounds of rhenium were K-acceptors (22), and that when P-ketoenolate oxygen atoms were trans to a group with good K-acceptor ability (CO) the Re-0 distance was larger than normal (23). Further, Mason and Tow1 (lo), have suggested that, for a system L-M-X, a strong L-M bond caused the M-X bond to become more ionic, and weaker, giving rise to localization of negative charge on X.…”

Studies of β-Diketone Complexes of Rhenium. VIII. The Reaction of β-Diketones with Chloropentacarbonylrhenium(I), and the Preparation of Complexes of the Type Re(CO)4(dik), Re2(CO)6(dik)2, Re2(CO)6Cl2(dikH)2, Re(CO)3L(dik), and Re(CO)2(dik)L2

“…A calculation, assuming the P-diketone- P-diketone contacts were greater than twice the carbon van der Waals radius, and based on the geometries determined previously (12,13), showed that for cis-Re,(CO),dik, the P-diketone plane would be bent about 55" from the OReO plane (cf. the previous highest value of 34" (12)) and thus would make the ReOC angles about 100 and 80", far smaller than any previously reported value for MOC angles in metal P-ketoenolate complexes.…”