title: Carbodiimide insertion reactions of homoleptic heavier alkaline earth amides and phosphides.
abstract: A series of homoleptic guanidinate-type complexes of the heavier alkaline earth (Ae) metals calcium and strontium have been prepared. The six-coordinate compounds [Ae{(i)PrNC(NPh(2))CN(i)Pr}(2)(THF)(2)] (Ae = Ca and Sr) were synthesised through reactions of the appropriate THF-solvated hexamethyldisilazide [Ae{N(SiMe(3))(2)}(2)(THF)(2)] with two molar equivalents of diphenylamine and 1,3-di-iso-propylcarbodiimide. Both compounds were shown to crystallise with a cisoid arrangement of the two THF molecules at the metal centres. In contrast, the (Me(3)Si)(2)N-substituted calcium guanidinate, [Ca{CyNC{N(SiMe(3))(2)}CNCy}(2)(THF)(2)], contains two coordinated THF molecules with a trans disposition. Further reactions of the free amidine [{(2-FC(6)H(4))N}C(NH(i)Pr)(2)] with either [Ca{N(SiMe(3))(2)}(2)(THF)(2)] or its dimeric unsolvated analogue provided monomeric or dimeric derivatives respectively in which the ligands had tautomerised to an anisobidentate form. A further reaction of the phosphaguanidine [CyN=C(PPh(2))N(H)Cy] with [Sr{N(SiMe(3))(2)}(2)(THF)(2)] provided the first example of a phosphaguanidinate complex of this heavier alkaline earth metal. This compound has also been characterised in the solid state and shown to exist with a transoid configuration of the coordinated THF molecules.
authors.affiliation: Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London, UK SW7 2AZ.
authors.forename: Anthony G M
authors.initials: AG
authors.lastname: Barrett
authors.forename: Mark R
authors.initials: MR
authors.lastname: Crimmin
authors.forename: Michael S
authors.initials: MS
authors.lastname: Hill
authors.forename: Peter B
authors.initials: PB
authors.lastname: Hitchcock
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Lomas
authors.forename: Mary F
authors.initials: MF
authors.lastname: Mahon
authors.forename: Panayiotis A
authors.initials: PA
authors.lastname: Procopiou
mesh_terms: D000577:Amides / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002234:Carbodiimides / Q000737:chemistry*; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D019791:Guanidine / Q000737:chemistry; D008673:Metals, Alkaline Earth / Q000737:chemistry*; D008968:Molecular Conformation; D013324:Strontium / Q000737:chemistry
chemical_list: D000577:Amides; D002234:Carbodiimides; D056831:Coordination Complexes; D008673:Metals, Alkaline Earth; D019791:Guanidine; D002118:Calcium; D013324:Strontium