Polyalkyls and Polyhydrides

FIGURE 15.4 The X-band epr spectrum of the Ir(IV) complex 15.10 (p. 426). Having four different ligands around Ir provides a rhombic symmetry consistent with the resonance pattern seen here. Source From Brewster et al., 2011 [30]. Reproduced with permission of the American Chemical Society. 

A dark red Cr(IV) alkyl [Cr(CH2SiMe3)4] is known, but Cr(III) is the common oxidation state, as in the orange Li3[CrPhe]. WMee was the first homoleptic alkyl of group 6 to have the maximum oxidation state allowed for the group. It can decompose explosively at room temperature but can also give the reactions shown in Eq. 15.4 and Eq. 5.5. 

Only one Mn(IV) alkyl is known, the green Mn(l-norbornyl)4, but rhenium has an extensive series of high oxidation-state alkyls (Eq. 15.6), 

ReOCl4 ----- ReOMc4 ---ReMe6 — ReOMe4 — cw-Re02Mc3 — Re03Me 

ZnNp2 (Np = t-BuCH2) and ReOCl3(PPh3)2 give the unusual dirhenium dioxo tetraalkyl of Eq. 15.7 with a 2.6A Re-Re bond. 

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