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

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The reaction of TaCl 5 with 2 equiv of Li 2 [C 2 B 9 H 11 ] in refluxing toluene yields {(µ-H)-(C 2 B 9 H 10 ) 2 }TaCl 2 (1), which contains the unusual linked bis(carboranyl) ligand [(µ-H)-(C 2 B 9 H 10 ) 2 ] 3-, which is formed by formal oxidative coupling of two C 2 B 9 H 11 2ligands. Alkylation of 1 with ZnMe 2 yields {(µ-H)(C 2 B 9 H 10 ) 2 }TaMeCl (2), which retains the linked bis(carboranyl) ligand.