Molecular Compounds with Mo‐O‐Bi Moieties

Abstract

Bridging the gap: Encapsulation by “soft” organic ligands is the key to the isolation of complexes containing “hard” MoVI‐O‐BiV and MoVI‐O‐BiIII units (see example), which might be regarded as molecular models for pivotal species on the surfaces of heterogeneous catalysts.

Organometallic Mo–O–Bi complexes

“…Having accessed the area of Mo VI -O-Bi V compounds the next target was obvious: by the majority, it is believed that Bi V ions [8] do not play significant roles under the conditions of the SOHIO process; Bi III centres are thought to be more important within the catalytic cycle [1], so that in the next step the synthesis of the first Mo VI -O-Bi III complex was pursued. We succeeded finally with the isolation of [(Cp * Mo(O) 2 )-l-O-(Bi(o-tolyl) 2 )] n (II), which represents a coordination polymer [7] (Scheme 2).…”

“…Unfortunately, it was not possible to perform an X-ray crystal structure analysis which could have supported that idea. Having experienced that Mo/ Bi alkoxides became accessible when organo molybdenum starting materials were employed [3] we performed the reaction reported by Klemperer replacing the molybdate by an organo molybdenum(VI)oxo anion, namely ½Cp à MoO 3 À : Treatment of Ph 3 BiBr 2 [5] with two equivalents of [NBu 4 ][Cp * MoO 3 ] [6] led to [(Cp * Mo(O) 2 -l-O) 2 BiPh 3 ] (I), and a single crystal X-ray analysis revealed the first structurally authenticated Mo-O-Bi linkages in a molecular compound [7] (Scheme 1). Having accessed the area of Mo VI -O-Bi V compounds the next target was obvious: by the majority, it is believed that Bi V ions [8] do not play significant roles under the conditions of the SOHIO process; Bi III centres are thought to be more important within the catalytic cycle [1], so that in the next step the synthesis of the first Mo VI -O-Bi III complex was pursued.…”

“…[(n-C 4 H 9 ) 4 N][Cp * MoO 3 ][6] and II[7] were prepared according to the literature procedure.3.3. [NBu 4 ] 2 [(MoO 4 ) 2 BiPh 3 ] (1)1 was prepared following a procedure described byKlemperer [4] with some modifications.…”

Iron–molybdenum-oxo complexes as initiators for olefin autoxidation with O2

“…In recent years, we have been interested in molecular heterobimetallic oxo compounds that can mimic certain structural units proposed to occur on the surfaces of corresponding heterogeneous catalysts composed of two metal oxide components. [16][17][18][19][20][21][22] The fact that MoO 3 /Fe 2 O 3 catalysts are employed for the oxidation of methanol to formaldehyde in the so-called FORMOX process has spurred us to investigate Fe-O-Mo compounds. While some purely inorganic polyoxometal aggregates [23][24][25][26][27][28][29][30] and coordination polymers [30][31][32][33][34][35][36][37] featuring Fe-O-Mo entities have been published, so far only five structurally characterised molecular coordination compounds have been reported, where molybdate units are bridging ligated iron ions.…”

Synthesis, Crystal Structure, and Thermal Behavior of [BiAg3Br6(PPh3)6] and [Bi3Ag6(SPh)6Cl3(PPhiPr2)3]

“…B. [BiMo(η 5 ‐C 5 Me 5 ) 2 (OEt) 4 Cl] 6 und das polymer verknüpfte [BiMoO 2 (μ 2 ‐O)(o‐C 7 H 7 ) 2 · (η 5 ‐C 5 Me 5 )] n 7 bekannt. Dikarev et al berichteten von neuartigen heterometallischen Bismutcarboxylaten wie [BiRh(O 2 CCF 3 ) 4 ] und [BiRu(O 2 CCF 3 ) 4 ], in denen die Metallatome nicht nur über verbrückende Sauerstoffliganden miteinander verbunden sind, sondern zusätzlich Metall–Metall‐Bindungen ausgebildet werden 8, 9.…”