三苯基氢化锡与铑的相互作用。[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)]的结构以及含吡啶衍生物的核磁共振（(1)H、(15)N、(31)P、(103)Rh、(119)Sn）研究

Interaction of Triphenyltin Hydride and Rhodium. Structure of [Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)] and NMR ((1)H, (15)N, (31)P, (103)Rh, (119)Sn) Study of Pyridine-Containing Derivatives.

作者信息

Carlton Laurence, Weber Rosemarie, Levendis Demetrius C.

机构信息

Centre for Molecular Design, Department of Chemistry, University of the Witwatersrand, Johannesburg, Republic of South Africa.

出版信息

Inorg Chem. 1998 Mar 23;37(6):1264-1271. doi: 10.1021/ic970662y.

DOI:10.1021/ic970662y

PMID:11670332

Abstract

The structure of [Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)] (1) (formed from [Rh(NCBPh(3))(PPh(3))(3)] and Ph(3)SnH) was determined by a single-crystal X-ray diffraction study which shows the geometry to be equally well described as a distorted tetragonal pyramid with tin at the apex or a distorted trigonal bipyramid with a hydrogen of one of the phosphine phenyl groups occupying the sixth coordination site. The tin-hydride distance of 2.31(5) Å is consistent with a weak interaction. Crystal data for 1: space group, P2(1)/c; a = 12.564(4), b = 26.942(4), c = 18.000(3) Å; beta = 92.93(2) degrees; V = 6085(2) Å(3); Z = 4; R = 0.050 for 5655 reflections with I >/= 2sigma(I). Complex 1 reacts with pyridine and substituted pyridines L (L = pyridine (py) (a), 4-(dimethylamino)pyridine (4-Me(2)Npy) (b), and 4-carbomethoxypyridine (4-MeO(2)Cpy) (c)) in dichloromethane at -25 degrees C to give trans-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)(L)] (2a-c). With L = 4-Me(2)Npy, the products cis-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)(4-Me(2)Npy)] (3) and cis- and trans-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(4-Me(2)Npy)(2)] (4 and 5, respectively) are also formed. At room temperature, [Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(L)] (6a-c) is the final product, decomposing over a period of hours. The pyridine-containing complexes were not isolated and were characterized by NMR spectroscopy, which showed the magnitude of the spin coupling constant J(Sn-H) to increase by factors of up to 5.5 compared with the value of 29 Hz observed for 1. At 50 degrees C, 6 (in the presence of L and PPh(3) originating from 1) undergoes reductive elimination of Ph(3)SnH to give cis-[Rh(NCBPh(3))(PPh(3))(2)(L)]; at this temperature 1 is stable, decomposing only at temperatures of 85 degrees C and above. A kinetic study of the dissociation of Ph(3)SnH from 6b (L = 4-Me(2)Npy) gave activation parameters DeltaH() = 97 +/- 6 kJ mol(-)(1) and DeltaS() = 1 +/- 20 J K(-)(1) mol(-)(1). The weakened interaction between Ph(3)SnH and rhodium is accounted for in terms of a three-center "agostic" bond.

摘要

通过单晶X射线衍射研究确定了[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)] (1)（由[Rh(NCBPh(3))(PPh(3))(3)]和Ph(3)SnH形成）的结构，该结构显示其几何形状既可以很好地描述为锡位于顶点的扭曲四方锥，也可以描述为膦苯基之一的氢占据第六配位位点的扭曲三角双锥。锡 - 氢距离为2.31(5) Å，这与弱相互作用一致。1的晶体数据：空间群，P2(1)/c；a = 12.564(4)，b = 26.942(4)，c = 18.000(3) Å；β = 92.93(2)°；V = 6085(2) Å(3)；Z = 4；对于5655个I≥2σ(I)的反射，R = 0.050。配合物1在-25℃下于二氯甲烷中与吡啶和取代吡啶L（L =吡啶(py) (a)、4-(二甲氨基)吡啶(4-Me(2)Npy) (b)和4-甲氧羰基吡啶(4-MeO(2)Cpy) (c)）反应，生成反式-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)(L)] (2a - c)。当L = 4-Me(2)Npy时，还会生成顺式-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(2)(4-Me(2)Npy)] (3)以及顺式和反式-[Rh(NCBPh(3))(H)(SnPh(3))(PPh(3))(4-Me(2)Npy)(2)]（分别为4和5）。在室温下，[Rh(NCBPh(三苯基硼氰基)(H)(三苯基锡)(三苯基膦)(L)] (6a - c)是最终产物，会在数小时内分解。含吡啶的配合物未被分离出来，而是通过核磁共振光谱进行表征，结果显示自旋耦合常数J(Sn - H)的大小与在1中观察到的29 Hz值相比增加了高达5.5倍。在50℃时，6（在存在源自1中的L和三苯基膦的情况下）发生三苯基锡氢的还原消除反应，生成顺式-[Rh(NCBPh(3))(三苯基膦)(2)(L)]；在此温度下1是稳定的，仅在85℃及以上的温度下分解。对6b（L = 4-Me(2)Npy）中三苯基锡氢解离的动力学研究给出了活化参数ΔH() = 97±6 kJ mol(-)(1)和ΔS() = 1±20 J K(-)(1) mol(-)(1)。三苯基锡氢与铑之间减弱的相互作用可以用三中心“agostic”键来解释。