Fragmentierung des schwefeldiimidsystems in tBu2PN=S=NPtBu2 an dreikernigen osmiumclustern. Synthese, feströrperstruktur und dynamische eigenschaften von Os3(CO)11[PtBu2(NH2)] und HOs3(CO)9PtBu2N(H)S]

Conformational Isomerism in Triosmium Clusters: Structures of Yellow and Red Os3(CO)11[P(p-C6H4F)3] and Os3(CO)11(PBut3)

“…With the exception of one form of Os 3 (CO) 11 [P( p -C 6 H 4 F) 3 ] and the PBu t 3 analogue, the clusters are yellow or orange. Crystal structures of the yellow and orange Os 3 (CO) 11 (PR 3 ) compounds by ourselves and others show a geometry based on Os 3 (CO) 12 with one of the equatorial carbonyls replaced by the phosphorus ligand; that is, the syn axial carbonyls are in an approximate eclipsed ( E ) orientation. ,− , Here we describe the structures of the two exceptions (which are red) that reveal that they have the twisted S conformation, that is, with the syn axial carbonyls staggered with respect to each other. We also report the structure of two yellow forms of Os 3 (CO) 11 [P( p -C 6 H 4 F) 3 ] that have the common E configuration.…”

“…Derivatives of the type M 3 (CO) 11 (PR 3 ) (i.e., M = Ru, Os, not Fe) usually have close to E structures (i.e., based on the D 3 h conformation). − The distortion toward the S configuration can be measured by the C(ax)−M−M−C(ax) dihedral angles. Bruce and co-workers found these angles ranged from close to 0° to 16.8° (in Os 3 (CO) 11 [PPh(OMe) 2 ]) in the five Os 3 (CO) 11 (PR 3 ) structures determined at the time; in similar Ru compounds this dihedral angle was as high as 24.4° (in Ru 3 (CO) 11 [P(OCH 2 ) 3 CEt]) .…”

The structure of a triosmium carbonyl cluster-phenylarsine oxide derivative

“…The three OseOs bond lengths have values in the range for this kind of clusters (2.753e3.104 Å) [25,31]. However, the three bond lengths are different, i.e., Os(1)eOs(3) 2.8770(5) Å, Os(1)eOs(2) 2.8822(4) Å and Os(2)eOs(3) 2.9741(2) Å.…”

“…The infrared spectrum in the solid state (KBr) shows bands due to the phenyl rings and vibrations (AseOeAs) at 738 and 548 cm À1 and (As]O) at 692 cm À1 [26]. Due to the stability of compound (1), the dimeric subunit PAO group could be considered as a five electron donor, resulting in a saturated triosmium cluster with 48 electrons, similar to other species [27,31].…”

“…The 13 C NMR carbonyl region reveals nine signals in the range of 179e160 ppm, which were assigned by comparison with those reported in the literature [25,31,34], and the low field resonances were assigned to C-2, C-4, and C-7. This assignment is based on the general trend that axial carbonyl resonances shift to lower fields than those of equatorial and by considering that As(1) is more electronegative than As(2), as was observed in IR spectroscopy [26,33].…”