boring ethyl groups would very much increase if Ni(OEPMe2) were dehydrogenated to , -dimethyloctaethylporphinatonickel(II), Ni(ODM). Therefore, Ni(OEPMe2) is air-stable. Ni(ODM) may be obtained, however, by metal insertion into the parent porphine.19 In Ni(ODM), the methyl • • • methylene carbon contacts are expected to be substantially smaller than the ^3.9A contacts found for Ni(OEPMe2). Indeed, if Ni-(ODM) has the same highly ruffled core of Ni(OEP),31b the nonbonded contacts can be calculated to be an unreasonably tight 2.8 Á. Hence, Ni(ODM) must represent a metalloporphyrin with a severely distorted core.

Tetraphenylporphinecobalt(II) forms 1:1 complexes with trivalent phosphorus ligands. All of the 1:1 complexes have effective axial symmetry with a (d," d"" d^j^d,2)1 ground configuration. Cobalt-59 and phosphorus-31 hyperfine coupling constants are utilized in evaluating the odd electron spin distribution and the phosphorus 3s and 3p character in the coordinated phosphine -donor orbital. The 3s character in the coordinated phosphorus -donor orbital is found to increase substantially with increased electron withdrawing ability of the substituents. Phosphorus ligand spin densities are found to decrease as the donor orbital P3s character increases.Properties of the M-P bonding are discussed and compared with results on the corresponding CO, CH3NC, and C5H5N complexes. Dioxygen complexes (ConTPP• PX3• 02) which exhibit 31P hyperfine coupling are reported and discussed. escriptions of the bonding of trivalent phosphorus ligands with metallo species have resulted in controversies centered on the relative importance ofdonor and -acceptor effects on observed properties such as metal-phosphorus (M-P) bond distances,12 vibrational frequencies,3-6 and 31P nmr shifts and coupling constants.7-10(1) H.

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Untersuchung der EPR‐ und Elektronenspektren.

Phosphorus-3 1 hyperfine splittings in tetra-TETRAPHENYLPORPHYRINCOBALT(II) forms I : 1 complexes phenylporphyrincobalt(I1) complexes with Et,P and with trivalent phosphorus donors. E.s.r. spectra for these (EtO),P and the corresponding dioxygen complexes are adducts indicate an axially symmetric g tensor and are used in evaluating the influence of substituents on the only consistent with ( d ~z , y z ) ~ ( d ~y ) 2(dz2)1 ground configuranature of the phosphorus a-donor orbital.tion (Figure and Table). The g,, and g, transitions are