✍ Scribed by Anthony F. Hill; John M. Malget; Andrew J. P. White; David J. Williams
No coin nor oath required. For personal study only.
[W(≡CR)Br(CO)~2~(NC~5~H~4~Me‐4)~2~] (R = C~6~H~3~Me~2~‐2,6 1a, C~6~H~2~Me~3~‐2,4,6 1b) react with K[H~2~B(pz)~2~] (pz = pyrazol‐1yl) to provide two interconverting isomers of [W(≡CR)(CO)~2~(NC~5~H~4~Me‐4){H~2~B(pz)~2~}] (2), one isomer having been structurally characterised for R = C~6~H~3~Me~2~‐2,6 (2a). The reactions of [W(≡CR)Br(CO)~2~(CNR′)~2~] (5: R′ = C~6~H~3~Me~2~‐2,6, CNMe~3~) with K[H~2~B(pz)~2~] or of [W(≡CR)Br(CO)~2~(NC~5~H~4~Me‐4){H~2~B(pz)~2~}] (2) with isocyanides are more complex due to the facile formation of unstable ketenyl derivatives. In the absence of light, the reaction of [W(≡CR)Br(CO)~2~(CNR′)~2~] (5) with K[H~2~B(pz)~2~] provides [W(≡CR)(CO)~2~(CNR′){H~2~B(pz)~2~}] (3) in moderate yield, similar yields were obtained from [W(≡CR)(CO)~2~(NC~5~H~4~Me‐4){H~2~B(pz)~2~}] (2) and CNR′. Under mild photolytic conditions both combinations provide primarily the thermally unstable ketenyl complex [W(η^2^‐OCCR)(CO)(CNR′)~2~{H~2~B(pz)~2~}] (4). The picoline ligand in [W(≡CR)Br(CO)~2~(NC~5~H~4~Me‐4){H~2~B(pz)~2~}] (2) is readily replaced by PMe~2~Ph to provide [W(≡CR)(CO)~2~(PMe~2~Ph){H~2~B(pz)~2~}] (structurally characterised for R = C~6~H~3~Me~2~‐2,6 6a). The reaction of either [W(≡CR)(CO)~2~(PMe~2~Ph){H~2~B(pz)~2~}] (6) or [W(≡CR)(CO)~2~(NC~5~H~4~Me‐4){H~2~B(pz)~2~}] (R = C~6~H~2~Me~3~‐2,4,6 2b) with excess PMe~2~Ph provides [W(≡CR)(CO)(PMe~2~Ph)~2~{H~2~B(pz)~2~}] (7). This complex is also obtained from K[H~2~B(pz)~2~] and [W(≡CR)Br(CO)(PMe~2~Ph)~3~] (8), the latter arising from the reaction of [W(≡CR)Br(CO)~2~(NC~5~H~4~Me‐4)~2~] (1b) with PMe~2~Ph. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
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