The addition of 2 equiv of N,N',N' '-triisopropylguanidine (guanH(2)) to Zr(CH(2)Ph)(4) produced the bis(guanidinato)bis(benzyl)zirconium complex [((i)PrNH)C(N(i)Pr)(2)](2)Zr(CH(2)Ph)(2) (1). The mono(guanidinato) complex [((i)PrN)(2)C(NH(i)Pr)]ZrCl(3) (2) was accessible by the reaction of 2 equiv of guanH(2) with ZrCl(4). Guanidinium hydrochloride, [C(NH(i)Pr)(3)]Cl, is a byproduct of this reaction. When crystallized from THF, complex 2 was isolated as the THF adduct [((i)PrNH)C(N(i)Pr)(2)]ZrCl(3)(THF) (2-THF). The mixed cyclopentadienyl guanidinato complex [eta(5)-1,3-(Me(3)Si)(2)C(5)H(3)][((i)PrNH)C(N(i)Pr)(2)]ZrCl(2) (3) was prepared by treatment of [1,3-(Me(3)Si)(2)C(5)H(3)]ZrCl(3) with the in situ generated lithium triisopropylguanidinate salt. The reaction of guanH(2) with [1,3-(Me(3)Si)(2)C(5)H(3)]ZrMe(3) affords the dimethyl derivative [eta(5)-1,3-(Me(3)Si)(2)C(5)H(3)][((i)PrNH)C(N(i)Pr)(2)]ZrMe(2) (4). Definitive evidence for the molecular structures of these products is provided through single-crystal X-ray characterization of 1, 2-THF, and 3, which are presented. The extent of pi delocalization within the guanidinato ligand is discussed in the context of the metrical parameters obtained from these structural studies.
Reactions of aryl isocyanide with bis(guanidinate) Zr(IV) hydrocarbyl complexes are presented. With
1 equiv of Ar‘NC the ultimate products are the terminal
Zr imido complexes [{(R‘NR‘ ‘)C(NR)2}2ZrN(2,6-Me2C6H3)]
(3, R = R‘ = iPr, R‘ ‘ = H; 5, R = iPr, R‘ = R‘ ‘ = Me),
which are derived via a unique transformation from
intermediate η2-iminoacyl species. With 2 equiv of Ar‘NC,
[{(Me2N)C(NiPr)2}2Zr(η2-Ar‘NCMe)2] (6) was isolated.
Mild thermolysis of 6 generates an enediamido complex
via intramolecular coupling of the iminoacyl groups.
The phase, previously called PrFeT, has been reinvestigated by single-crystal X-ray diffraction methods using data obtained with a diffractometer and molybdenum radiation. As reported earlier, the compound is rhombohedral, space group R3m, with a=8.585, c= 12.464/~; contrary to earlier findings, it has the composition PrzFe17 and an ordered Th2Zn17-type structure. Ce, Nd and Sm in combination with Fe have all been reported previously to form the same structure as the Pr-Fe compound. The composition AB7 reported for these three phases is therefore in doubt. For AB~ compounds of the ThZns.5(ThzZn17) type, no conclusive crystallographic evidence has yet been put forth for x other than 8-5.
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