The relative rates of displacement of the NR2 group in (dialkylamido)titanatranes R2NTi(OCH2CH2)3N by -OH and -SH compounds is in the order NEt2 » NMe2 > N(/-Pr)2. This unanticipated order is rationalized on the i i postulated prior formation of HR2N+Ti(OCH2CH2)3N (A), which facilitates departure of R2NH upon subsequent nucleophilic attack. For R = Et and /-Pr, the concentration of A is higher than for R = Me, owing to the basicity order Et2N s (i-Pr)2N > Me2N. The greater reactivity of A where R = Me relative to R = /-Pr is attributed to the greater steric protection from nucleophilic attack on the metal afforded by the H(/-Pr)2N+ group. The faster reactions of CF3CH2OH and PhOH compared with their sterically similar but more weakly acidic analogues CH3CH2OH and /-PrOH, respectively, support this hypothesis as do the comparable displacement rates of Et2N and Me2N in the presence of the strong nonnucleophilic base P(MeNCH2CH2)3N and the reactions of 4 and 14 with HBF4 and NH4C1 but not with NaBF4 or Me4NCl. New titanatranyl derivatives reported include five arylates, i-1 two thioarylates, and four diolates. The X-ray parameters for [/-PrSTi(OCH2CH2)3N]2 are as follows: triclinic, space group Pi (No. 2), a = 7.434(5) A, b = 12.540

We have recently described the extraordinary Lewis basicity of the phosphorus in 1 for protons to produce the unexpectedly weak conjugate acid 2.1-7 The transannulation process that

Supplementary Material Available:For Cp*Cr(NO)(O-i-Pr)2, complete listings of the X-ray data collection and refinement parameters, final anisotropic thermal parameters, and H atom coordinates (4 pages); a listing of observed and calculated structure factors (1 3 pages). Ordering information is given on any current masthead page.The synthesis and characterization of a new binucleating porphyrin ligand, a,a-5,15-bis(o-(nicotinoylamido)pheny1)-2,8,12,18tetraethyl-3,7,13,17-tetramethylporphyrin, [H,(DPE)]-(py), is reported. Treatment of [H2(DPE)]-(py), with methanol solutions of Ni(I1) or Cu(I1) leads to the formation of mononuclear metal complexes, [M(DPE)]-(~Y)~, in which the metal has inserted into the porphyrin core, leaving the pyridine binding site free. Addition of a second metal to form a binuclear complex, [M-(DPE)]-(py)2M'C12, can be accomplished using the reagent M'(DMSO)2C12, M' = Pd, Pt, and Zn. [Ni(DpE)j-(~y)~ and [ C U ( D P E ) ] -(~~)~P~C I~ have been characterized by single-crystal X-ray analysis. Crystal data for [Ni(DPE)]-(py),: Ni02N8-Cs6HS2-2CHCl3, triclinic, Pi, a = 14.306 (4) A, b = 14.719 (5) A, c = 14.296 (5) A, OL = 94.86 (3)O, fl = 96.38 (3)O, y = 63.45(1) Que, L.

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