The photoelectron spectra of oxetane, 3-chloromethyl-3-methyloxetane, 3-bromomethyl-3-methyloxetane, and 3-iodo-3-methyloxetane were studied using He I (21.22 eV) photons. Satisfactory agreement was obtained with ab-initio MRDCI molecular orbital calculations permitting an assignment of the observed bands.
IntroductionThis work was undertaken in connection with an earlier quantum chemical studylJ of the mechanism of ionic polymerization of oxetane and some of its related compounds in the syn-
cioso-l-Ge-2-(Si(CH3)3)-3-R-2,3-C2B4H4 (R = Si(CH3)3 (I), CH3 (II), and H (III)) and c/oso-l-Pb-2-(Si(CHs)3)-3-R-2,3-C2B4H4 (R = Si(CH3)3 (VII), CH3 (VIII), and H (IX)) react with (ferrocenylmethyl)dimethylamine (ferrocene amine) in dry benzene to give the corresponding donor-acceptor adducts IV-VI and X-XII, respectively, in yields ranging from 56% to 79%. Complex X was converted into two crystal modifications, X(A) and X(B), by slow crystal growth from ferrocene amine and by slow sublimation in vacuo, respectively. The crystal structures of IV, X(A), and X(B) were determined by single-crystal X-ray diffraction. All show that the nitrogen of the ferrocene amine base bonds to the capping metal of the metallacarborane. The metal is not symmetrically bonded to the atoms of the C2B3 face but is slipped toward the boron side of the face, giving a distorted-pentagonal-bipyramidal MC2B4 cage. Similarities in the NMR and IR spectra of IV-VI and X-XII indicate that all complexes have similar structures. The unit cells of both IV and X(B) contain two crystallographically independent molecules; in one the metal-base nitrogen bond is in the mirror plane of the MC2B4 cage, while in the other the bond is slightly rotated out of this plane. The molecules in the unit cell of X(A) are identical. In all structures the ferrocenyl groups are rotated toward the metallacarboranes so that some of the metal-ferrocene distances are within their van der Waals radii. Fenske-Hall molecular orbital calculations show that there are direct interactions between the metal and the Cp(z-) orbitals of the ferrocenyl group. It is suggested that the stability gained by such interactions is responsible for the non sterically favorable positions of the ferrocenes. Complexes IV, X(A), and X(B) all crystallized in the triclinic space group PI with a = 12.633 (3), 10.106 (3), and 12.677
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