Thammavongsy Zachary, Kha Ivy M, Ziller Joseph W, Yang Jenny Y
Department of Chemistry, University of California, Irvine, California 92697, USA.
Dalton Trans. 2016 Jun 14;45(24):9853-9. doi: 10.1039/c6dt00326e.
The Tolman electronic parameters (TEP) and cone angles were experimentally measured for a series of substituted proazaphosphatrane ligands by synthesizing their respective Ni(L(R))(CO)3 complexes, where L = P(RNCH2CH2)3N and R = Me, iPr, iBu and Bz. The complexes Ni(L(Me))(CO)3 (), Ni(L(iPr))(CO)3 (), Ni(L(iBu))(CO)3 () and Ni(L(Bz))(CO)3 () display CO vibrational frequencies (A1 mode) at 2057.0, 2054.6, 2054.9 and 2059.1 cm(-1), respectively. The TEPs for the phosphine ligands in are among the lowest measured, with values close to P(tBu)3 the most donating phosphine measured by Tolman. The cone angles of L(R) measured in are 152, 179, 200 and 207° for R = Me, iPr, iBu and Bz, respectively. The substituted proazaphosphatranes have larger cone angles compared to the analogous trialkyl subsituted monophosphines. Our study demonstrates that while the cone angles have a significant dependence on R, all of the substituted proazaphosphatranes are strong electron donors. Additionally, in order to determine the electronic donor strength of our previously reported multidentate ligand, TPAP, Ni(TPAP)(CO)2 () (TPAP = tris(2-pyridylmethyl)azaphosphatrane) and Ni(L(Me))2(CO)2 () were also synthesized and evaluated in a similar fashion.
通过合成一系列取代的氮杂环磷烯配体各自的Ni(L(R))(CO)₃配合物,对其托尔曼电子参数(TEP)和锥角进行了实验测量,其中L = P(RNCH₂CH₂)₃N且R = 甲基、异丙基、异丁基和苄基。配合物Ni(L(甲基))(CO)₃ ()、Ni(L(异丙基))(CO)₃ ()、Ni(L(异丁基))(CO)₃ ()和Ni(L(苄基))(CO)₃ ()的CO振动频率(A₁模式)分别为2057.0、2054.6、2054.9和2059.1 cm⁻¹。 中膦配体的TEP是测量到的最低值之一,其值接近托尔曼测量的给电子能力最强的膦P(tBu)₃。 中测量的L(R)的锥角对于R = 甲基、异丙基、异丁基和苄基分别为152°、179°、200°和207°。与类似的三烷基取代单膦相比,取代的氮杂环磷烯具有更大的锥角。我们的研究表明,虽然锥角对R有显著依赖性,但所有取代的氮杂环磷烯都是强电子给体。此外,为了确定我们先前报道的多齿配体TPAP的电子给体强度,还合成了Ni(TPAP)(CO)₂ () (TPAP = 三(2 - 吡啶甲基)氮杂环磷烯)和Ni(L(甲基))₂(CO)₂ (),并以类似方式进行了评估。