title: Synthesis and DFT calculations of spirooxaphosphirane complexes.
abstract: In situ formed Li/Cl phosphinidenoid complexes [Li(12-crown-4)][M(CO)5(ClPC5Me5)] 3a-c (M = Cr, Mo, W) reacted with cyclobutanone (4), cyclopentanone (5) and cyclohexanone (6) in Et2O to yield the first P-C5Me5 substituted C(3)-spirofused oxaphosphirane complexes 7a-c, 8a and 9a,a'. In the case of cyclopentanone and 1a the outcome of the reaction in THF was different: here the formation of 8a along with (anionic) phosphinoate complexes 14a and 15a was observed, the latter possess an unusual ring-opened oxaphosphirane and 2-cyclopentylidenecyclopentanone as co-ligands to the lithium cation. NMR, IR and MS data as well as single-crystal X-ray structures in the case of 7a-c, 8a, 9a and 15a are reported. DFT calculations on the parent 1-oxa-2-phosphaspiro[2.n]alkane pentacarbonylchromium(0) complexes 10 (a: n = 2; b: n = 3; c: n = 4; d: n = 5) revealed that both ring strain energies and G(r) values decrease significantly as the spiroring size increases. This is caused by an increase in the exocyclic α bond angle at the oxaphosphirane C(3) atom, hence decreasing the s-character of the corresponding orbitals involved in endocyclic bonds at C(3) and thus becoming better suited for accommodation of small ring angles.
authors: Institut für Anorganische Chemie der Rheinischen Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn, Germany.
authors: Carolin
authors: C
authors: Albrecht
authors: Eva
authors: E
authors: Schneider
authors: Marianne
authors: M
authors: Engeser
authors: Gregor
authors: G
authors: Schnakenburg
authors: Arturo
authors: A
authors: Espinosa
authors: Rainer
authors: R
authors: Streubel