Heterometallic Polyhydride Complexes Containing Yttrium Hydrides with Different Cp Ligands: Synthesis, Structure, and Hydrogen‐Uptake/Release Properties

Abstract

A new family of Y4/M2 and Y5/M heterobimetallic rare‐earth‐metal/d‐block‐transition‐metalpolyhydride complexes has been synthesized. The reactions of the tetranuclear yttriumoctahydride complex [{Cp′′Y(μ‐H)2}4(thf)4] (Cp′′=C5Me4H, 1‐C5Me4H) with one equivalent of Group‐6‐metalpentahydride complexes [Cp*M(PMe3)H5] (M=Mo, W; Cp*=C5Me5) afforded pentanuclear heterobimetallic Y4/Mpolyhydride complexes [{(Cp′′Y)4(μ‐H)7}(μ‐H)4MCp*(PMe3)] (M=Mo (2 a), W (2 b)). UV irradiation of compounds 2 a,b in THF gave PMe3‐free complexes [{(Cp′′Y)4(μ‐H)6(thf)2}(μ‐H)5MCp*] (M=Mo (3 a), W (3 b)). Compounds 3 a,b reacted with one equivalent of [Cp*M(PMe3)H5] to afford hexanuclear Y4/M2 complexes [{Cp*M(μ‐H)5}{(Cp′′Y)4(μ‐H)5}{(μ‐H)4MCp*(PMe3)}] (M=Mo (4 a), W (4 b)). UV irradiation of compounds 4 a,b provided the PMe3‐free complexes [(Cp′′Y)4(μ‐H)4{(μ‐H)5MCp*}2] (M=Mo (5 a), W (5 b)). C5Me4Et‐ligated analogue [(Cp′′Y)4(μ‐H)4{(μ‐H)5Mo(C5Me4Et)}2] (5 a′) was obtained from the reaction of 1‐C5Me4H with [(C5Me4Et)Mo(PMe3)H5]. On the other hand, the reaction of pentanuclear yttriumdecahydride complex [{(C5Me4R)Y(μ‐H)2}5(thf)2] (1‐C5Me5: R=Me; 1‐C5Me4Et: R=Et) with [Cp*M(PMe3)H5] gave the hexanuclear heterobimetallic Y5/Mpolyhydride complexes [({(C5Me4R)Y}5(μ‐H)8)(μ‐H)5MCp*] (6 a: M=Mo, R=Me; 6 a′: M=Mo, R=Et; 6 b: M=W, R=Me). Compound 5 a released two molecules of H2 under vacuum to give [(Cp′′Y)4(μ‐H)2{(μ‐H)4MoCp*}2] (7). In contrast, compound 6 a lost one molecule of H2 under vacuum to yield [{(Cp*Y)5(μ‐H)7}(μ‐H)4MoCp*] (8). Both compounds 7 and 8 readily reacted with H2 to regenerate compounds 5 a and 6 a, respectively. The structures of compounds 4 a, 5 a′, 6 a′, 7, and 8 were determined by single‐crystal X‐ray diffraction.

Photochemistry of Transition Metal Hydrides

“…Studies on W­(H) 4 (PRPh 2 ) 4 (R = CD 3 , C 2 D 5 ) also established H 2 loss as the primary photochemical step; the unsaturated species formed underwent intramolecular C–D insertion to form a metal–carbon bond with subsequent HD photoelimination . Finally, the clusters [{(Cp″Y) 4 (μ-H) 7 }­(μ-H) 4 MCp*­(PMe 3 )] (M = Mo, W, Cp′′ = η 5 -C 5 Me 4 H) were found to undergo PMe 3 loss under UV irradiation …”

“…191 Finally, the clusters [{(Cp″Y) 4 (μ-H) 7 }(μ-H) 4 MCp*(PMe 3 )] (M = Mo, W, Cp′′ = η 5 -C 5 Me 4 H) were found to undergo PMe 3 loss under UV irradiation. 192…”

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2013

“…The analogous reaction of the pentanuclear yttriumdecahydride complexes [(C 5 Me 4 R)Y(-H) 2 ] 5 (THF) 2 (R = Me, Et) with Cp * M(PMe 3 )H 5 (M = Mo, W) gave the hexanuclear heterobimetallic Y 5 /M-polyhydride complexes as shown in Scheme 139 [116].…”

“…It was pointed out that concerning the broader strategy of building higher aggregated ternary lanthanide-transition metal polyhydride clusters, the hydride precursors Cp 2 MH 2 represent promising transition-metal building blocks [115]. hexanuclear PMe 3 -free Y 4 /M 2 complexes as illustrated in Scheme 138 [116].…”

Ternary Rare‐Earth Transition‐Metal Polyhydride Cluster Compounds

“…Finally, XRD studies are challenging due to poor/difficult localization of the hydrides next to the electron-rich and heavy diffracting RE (and TM) atoms. [6] To date, heteromultimetallic complexes with bridging hydride ligands to support the RE-TM interaction have been prepared by salt elimination, [7] H 2 elimination, [8] alkane elimination, [9] and C À H bond activation. [10] Furthermore, the class of compounds has been extended to RE-main group metal polyhydrides.…”