[Cp°2ZrCl(PHCy)] (Cy = cyclohexyl, Cp° = η5-C5EtMe4) undergoes insertion of MeCN into
the Zr−P bond, yielding [Cp°2ZrCl{NC(Me)(PHCy)}] (1). Isomers with a Z (1a) or E (1b)
configuration at the C−N double bond are obtained in a ratio of 13:1. At room temperature,
1 slowly decomposes in solution with elimination of a PHCy fragment and formation of [Cp°2(Cl)Zr(μ-NCMe−CMeN)Zr(Cl)Cp°2] (2). Two isomers are obtained with a trans (2a) or
cis (2b) arrangement around the C−N double bonds of the bridging butane-2,3-diimino(2-)-N,N‘
ligand. 1a, 2a, and 2b were isolated and characterized by IR, MS, and NMR spectroscopy
(1H, 31P, 13C), and crystal structure determinations were carried out on 1a and 2a. In the
solid state, the short Zr−N bonds and the almost linear Zr−N−C angles of 1a and 2a indicate
the presence of Zr−N double bonds.
Cp°2ZrCl(PHCy)] (1; Cp°) η 5 -C 5 EtMe 4 , Cy ) cyclohexyl) and [Cp′ 2 ZrCl{PH(TRIP)}] (2; 8)). 3-8 were characterized spectroscopically (IR, NMR, MS), and crystal structure determinations on 4-6 showed an η 2 bonding mode (X,N) of the XC(PHR′)NR (R′ ) Cy, TRIP) ligands. Of the two possible coordination modes of the ligand, 4 and 5 are obtained exclusively as the endo isomer, in which the NR group is adjacent to the Zr-Cl bond, while for 6-8, both isomers (endo and exo) are formed (1:8 (6), 1:30 (7) and 1:5 (8)), whereby the exo isomer is favored. The exo isomer of 6 was structurally characterized.
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