Toward Highly Metallized Polymers: Synthesis and Characterization of Silicon-Bridged [1]Ferrocenophanes with Pendent Cluster Substituents
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posted on 2003-09-15, 00:00 authored by Wing Yan Chan, Andrea Berenbaum, Scott B. Clendenning, Alan J. Lough, Ian MannersThe acetylide-substituted sila[1]ferrocenophanes [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me)C⋮CR] (R = Ph (<b>2a</b>),
<sup>n</sup>Bu (<b>2b</b>)) reacted with [Co<sub>2</sub>(CO)<sub>8</sub>], [{MoCp(CO)<sub>2</sub>}<sub>2</sub>], or [Ni(cod)<sub>2</sub>]/L selectively at the triple
bond to give pendent organocobalt [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me){Co<sub>2</sub>(CO)<sub>6</sub>C<sub>2</sub>R}] (R = Ph (<b>4a</b>), <sup>n</sup>Bu (<b>4b</b>))
or organomolybdenum [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me){Mo<sub>2</sub>Cp<sub>2</sub>(CO)<sub>4</sub>C<sub>2</sub>Ph}] (<b>9</b>) clusters or mononuclear
organonickel [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me){Ni(L)C<sub>2</sub>Ph}] (L = dmpe (<b>11</b>), L = dppe (<b>12</b>)) complexes.
The bis(acetylide)-substituted sila[1]ferrocenophanes [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(C⋮CR)<sub>2</sub>] (R = <sup>n</sup>Bu (<b>6a</b>),
Ph (<b>6b</b>)) reacted with [Co<sub>2</sub>(CO)<sub>8</sub>] in an analogous fashion, forming the novel pentametallic
silicon-bridged [1]ferrocenophanes with two pendent cobalt clusters [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si{Co<sub>2</sub>(CO)<sub>6</sub>C<sub>2</sub>R}<sub>2</sub>] (R = <sup>n</sup>Bu (<b>7a</b>), R = Ph (<b>7b</b>)). Compound <b>7b</b> subsequently underwent rapid
hydrolytic ring-opening to yield an unusual, highly metallized silanol, [(η-C<sub>5</sub>H<sub>5</sub>)Fe(η-C<sub>5</sub>H<sub>4</sub>)Si(OH){Co<sub>2</sub>(CO)<sub>6</sub>C<sub>2</sub>Ph}<sub>2</sub>] (<b>8b</b>). This reaction was found to be much slower for the hexynyl
analogue (<b>7a</b>). The organonickel complexes (<b>11</b> and <b>12</b>) described in this work represent the
first examples of mononuclear complexes prepared directly from an alkyne and [Ni(cod)<sub>2</sub>].
We postulate that steric factors prevent the addition of a second nickel fragment to the
alkyne. The synthesis of a sila[1]ferrocenophane with a pendent platinum moiety was also
attempted. However, reaction of <b>2a</b> with [Pt(PEt<sub>3</sub>)<sub>3</sub>] instead gave the platinasila[2]ferrocenophane [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Pt(PEt<sub>3</sub>)<sub>2</sub>Si(Me)C⋮CPh] (<b>15</b>) via oxidative insertion of the
platinum(0) fragment into a strained <i>ipso</i>-cyclopentadienyl carbon−silicon bond of the sila[1]ferrocenophane.
