The carbalkoxymethyl ligand on Cp(CO) [P(OCH3)3] FeCH2C02R (7) (R = CH3, CH2CH3) serves as a C2 template for generating other C2-coordinated ligands and organic molecules. In this study 7 is procured by acid isomerization of the alkoxyacetyl complexes Cp(CO)[P(OCH3)3] FeCOCH2OR (5), which are obtained by P(OCH3)3-induced CO-insertion on Cp(CO)2FeCH2OR. (Overall, the carbalkoxymethyl ligand on 7 derives from two CO groups on Cp(CO)3Fe+.) A mechanism for this alkoxyacetyl-carbalkoxymethyl ligand isomerization is advanced whereby protonation of 5 generates a ligated ketene intermediate that regioselectively adds alcohol and gives 7. In excess acid either 5 or 7 quantitatively releases acetic acid ester, a selective generation of this C2 organic from CO. The carbalkoxymethyl ligand on 7 is activated as a hydride acceptor by converting it to the (dialkoxycarbenio)methyl salt Cp(CO)[P(OCH3)3]FeCH2C(OR)2+ ( 8). (Interestingly, 8 cannot be generated from the alkoxycarbene system Cp(CO)[P(OCH3)3]FeC(OR)CH2OR+ (6).) BH4~c onverts 8 into a mixture of ?/-ethylene and V-ethyl complexes of Cp(CO)[P(OCH3)3]Fe, whereas («c-Bu)3BH'Li+ generates the corresponding ?j1 2-ethyl vinyl ether and '-formylmethyl compounds. The conversion of these latter two into acetaldehyde is discussed.

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This study was designed to assess the contribution of length-dependent activation to the peak isometric twitch tension developed and the maximal rate of tension development (dP/dt) of in situ canine skeletal muscle. Length-developed tension and length-dP/dt relationships were generated for the dog gastrocnemius-plantaris muscle group at three different levels of inotropic state as determined by stimulation frequency. These relationships were then normalized with respect to maximal developed tension and maximal dP/dt and the normalized curves were superimposed for comparison. At progressively shorter muscle lengths the augmentation of tension production by a given increment in inotropic state was greater as measured by either developed tension or dP/dt. Thus, a given change in muscle length produced a greater change in performance in less potentiated muscles. These findings are similar to those from studies of isolated cardiac muscle and illustrate the lack of independence between activational state and muscle length for in situ skeletal muscle.

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