Octameric and Decameric Aluminophosphates

Abstract

Aluminium satt: Die Titelverbindungen gehören nicht nur zu den größten bislang synthetisierten molekularen Aluminophosphaten, es handelt sich bei ihnen auch um seltene Polyederkäfige mit AlO4‐, AlO5‐ und AlO6‐Koordinationsumgebungen (siehe Struktur; rot O, blau Al, rosa P). Die Kerne dieser Aluminophosphate repräsentieren neue strukturelle Baueinheiten (SBUs) in der Zeolithchemie.

The Clusters [Ma(ECp*)b] (M=Pd, Pt; E=Al, Ga, In): Structures, Fluxionality, and Ligand Exchange Reactions

“…Reaction of [Pd 2 (dvds) 3 ] with ECp*: The reaction of [Pd 2 (dvds) 3 ] (dvds = 1,3-divinyl-1,1,3,3-tetramethyldisiloxane) with excess GaCp* is a vivid example of the subtle influence of the reaction conditions on M a E b cluster formation. At À30 8C in hexane the reaction yields the dinuclear compound [Pd 2 (GaCp*) 2 (m 2 -GaCp*) 3 3 ] with an excess of AlCp* in benzene at 60 8C, the trinuclear compound [Pd 3 (AlCp*) 2 (m 2 -AlCp*) 2 (m 3 -AlCp*) 2 ] (3) is formed with a 3:6 rather than a 3:8 composition for a:b as in the two related above-mentioned cases. Compound 3 was obtained from saturated solutions of the sample in toluene as octahedral shaped deep red-brown single crystals in reproducible yields of 60 %.…”

“…The nature of the saturated transition-metal center in this intermediate, now having two equivalent terminal ligands, can well explain the exchange process of terminal and bridging ligands. The fact that ME 4 clusters are kinetically inert in contrast to M 2 E 5 could be reasoned by taking into account that splitting only one M À E connectivity in the case of the M 2 E 5 unit is of course likely to cost less activation energy per M 2 E 5 molecule than complete dissociation of ME 4 in ME 3 and free E. This situation is comparable to the well-studied classical metal-carbonyl cluster complexes, with the terminally bound carbonyls generally being less reactive than the bridging ones. [26,27] The relative inertness of Pt 2 Al 3 Ga 2 (1 d) in the presence of phosphines is in agreement with this mechanism, as the rupture of the M À E bond of the bridging AlCp* ligand would require more energy in comparison to the bridging GaCp* unit in the related Pt 2 Ga 5 (1 a).…”

“…compounds. [1][2][3] Recently it has been demonstrated, that ECp* (E = Ga, In) is capable of stabilizing certain M a E b clusters (M = Pd, Pt). These new structures and compositions go beyond the previously known mononuclear homoleptic complexes ME 4 (M = Ni, Pd, Pt) [4][5][6] and the heteroleptic compounds of the general formula [M a (ER) b L x ] (M= d-block metal), which contain strongly bound ligands (L) such as CO or Cp that limit their reactivities considerably.…”

“…[14] The ME 4 compounds are rather inert in most cases, especially against ligand substitution which would require a pre-dissociation of E I R. We found that this reaction path cannot be activated without unspecific decomposition of the starting complexes. However, there are some indications that lower coordinated, electronically and sterically unsaturated species like [Ni(AlCp*) 3 ] may exist as short-lived intermediates during the formation of ME 4 . These unsaturated species exhibit interesting reactivity including activation of aromatic Abstract: The synthesis and structural characterization of the novel homoleptic cluster complexes [Pd 2 (GaCp*) 2 (m 2 -GaCp*) 3 ] (1 c), [Pd 3 (GaCp*) 4 (m 2 -GaCp*) 4 ] (2 b) and [Pd 3 (AlCp*) 2 (m 2 -AlCp*) 2 (m 3 -AlCp*) 2 ] (3) (Cp*= C 5 Me 5 ) are presented.…”

“…However, there are some indications that lower coordinated, electronically and sterically unsaturated species like [Ni(AlCp*) 3 ] may exist as short-lived intermediates during the formation of ME 4 . These unsaturated species exhibit interesting reactivity including activation of aromatic Abstract: The synthesis and structural characterization of the novel homoleptic cluster complexes [Pd 2 (GaCp*) 2 (m 2 -GaCp*) 3 ] (1 c), [Pd 3 (GaCp*) 4 (m 2 -GaCp*) 4 ] (2 b) and [Pd 3 (AlCp*) 2 (m 2 -AlCp*) 2 (m 3 -AlCp*) 2 ] (3) (Cp*= C 5 Me 5 ) are presented. Furthermore, ligand exchange reactions of these cluster complexes are explored.…”