Publication:

A Homologous Series of Alkaline Earth Phosphanides: Syntheses, Crystal Structures, and Unusual Dynamic Behavior of (THF)nM[P{CH(Si- Me3)2}(C6H4-2-CH2NMe2)]2 (M = Mg, Ca, Sr, Ba) (2002)

Author(s): Izod K; Clegg W; Blair S

    Abstract: The secondary phosphine R(Me2NCH2-2-C6H4)PH reacts with Bu2Mg to give the homoleptic complex Mg{PR(C6H4-2-CH2NMe2)}2 (1) [R = CH(SiMe3)2]. The analogous heavier alkaline earth metal complexes (THF)nAe{PR(C6H4-2-CH2NMe2)}2 [Ae = Ca (2), n = 0; Ae = Sr (3), Ba (4), n = 1] have been synthesized by metathesis reactions between K{PR(C6H4-2-CH2NMe2)} and 0.5 equiv. of the respective alkaline earth metal diiodide. Compounds 1 – 4 have been characterized by X-ray crystallography and multi-element NMR spectroscopy. In the solid state compounds 1-4 are monomeric, complexes 1 and 2 adopting a distorted tetrahedral geometry and complexes 3 and 4 adopting a distorted square pyramidal geometry (1: orthorhombic, P212121, a = 11.413(3), b = 12.072(3), c = 32.620(11) Å, Z = 4. 2: monoclinic, P21/c, a = 9.5550(4), b = 17.4560(7), c = 24.5782(10) Å,  = 91.673(2), Z = 4. 3: monoclinic, C2/c, a = 15.0498(9), b = 13.0180(8), c = 24.3664(14) Å,  = 104.593(2), Z = 4. 4: monoclinic, C2/c, a = 15.2930(10), b = 13.0326(9), c = 24.6491(17) Å,  = 105.542(2), Z = 4). In toluene solution compounds 2 – 4 are subject to dynamic processes which are attributed to a monomer-dimer equilibrium for which bridge-terminal exchange of the phosphanide ligands in the dimer may be frozen out at low temperatures.

      • Date: 26-06-2002
      • Journal: Inorganic Chemistry
      • Volume: 41
      • Issue: 15
      • Pages: 3886-3893
      • Publisher: American Chemical Society
      • Publication type: Article
      • Bibliographic status: Published
      Staff

      Emeritus Professor William Clegg
      Senior Research Investigator

      Dr Keith Izod
      Reader in Main Group Chemistry