Zhao Chang-Qiu, Jennings Michael C, Puddephatt Richard J
Department of Chemistry, University of Western Ontario, London, Canada N6A 5B7.
Dalton Trans. 2008 Mar 7(9):1243-50. doi: 10.1039/b716035f. Epub 2008 Jan 9.
The bis(PNP)-donor pincer ligand 1,4-C(6)H(4){N(CH(2)CH(2)PPh(2))(2)}(2), 1, contains weakly basic nitrogen donor atoms because the lone pairs of electrons are conjugated to the bridging phenylene group, and this feature is used in the synthesis of oligomers and polymers. The complexes Pd(2)X(2)(mu-1)(2), X=Cl, Br or OTf, contain the ligand 1 in bis(pincer) binding mode (mu-kappa(6)-P(4)N(2)), but [Pd(4)Cl(6)(mu(3-)1)(2)]Cl(2) contains the ligand in an unusual unsymmetrical mu(3)-kappa(5)-P(4)N binding mode. The bromide complex is suggested to exist as a polymer [{Pd(2)Br(4)(mu(4)-1)}(n)] with the ligands 1 in mu(4)-kappa(4)-P(4) binding mode. The methylplatinum(II) complexes [Pt(2)Me(4)(mu-1)] and Pt(2)Me(2)(mu-1)(2) contain the ligand in mu-kappa(4)-P(4) and mu-kappa(6)-P(4)N(2) bonding modes, while the silver(I) complex [Ag(2)(O(2)CCF(3))(2) (mu-1)] contains the ligand 1 in an intermediate bonding mode in which the nitrogen donors are very weakly coordinated. The complexes Pd(2)(OTf)(2)(mu-1)(2) and [Ag(2)(O(2)CCF(3))(2)(mu-1)] react with 4,4'-bipyridine to give polymers Pd(2)(micro-bipy)(mu-1)(4) and Ag(2)(mu-bipy)(mu-1)(2).
双（PNP）供体钳形配体1,4-C(6)H(4){N(CH(2)CH(2)PPh(2))(2)}(2)（1）含有弱碱性氮供体原子，因为孤对电子与桥连亚苯基共轭，且这一特性被用于低聚物和聚合物的合成。配合物Pd(2)X(2)(μ-1)(2)，X = Cl、Br或OTf，以双（钳形）配位模式（μ-κ(6)-P(4)N(2)）包含配体1，但[Pd(4)Cl(6)(μ(3-)-1)(2)]Cl(2)以不寻常的不对称μ(3)-κ(5)-P(4)N配位模式包含该配体。溴化物配合物被认为以聚合物[{Pd(2)Br(4)(μ(4)-1)}(n)]形式存在，其中配体1以μ(4)-κ(4)-P(4)配位模式存在。甲基铂（II）配合物[Pt(2)Me(4)(μ-1)]和Pt(2)Me(2)(μ-1)(2)分别以μ-κ(4)-P(4)和μ-κ(6)-P(4)N(2)键合模式包含该配体，而银（I）配合物[Ag(2)(O(2)CCF(3))(2)(μ-1)]以一种中间键合模式包含配体1，其中氮供体的配位非常弱。配合物Pd(2)(OTf)(2)(μ-1)(2)和[Ag(2)(O(2)CCF(3))(2)(μ-1)]与4,4'-联吡啶反应生成聚合物Pd(2)(μ-bipy)(μ-1)(4)和Ag(2)(μ-bipy)(μ-1)(2)。
