Synthesis and structural characterization of four dichloridobis(cyclopropylalkynylamidine)metal complexes

Abstract

Deliberate hydrolysis of lithium cyclopropylalkynylamidinates, Li[c-C3H5—C[triple-bond]C(NR′)2] [R′ = iPr, Cy = cyclohexyl)], afforded the hitherto unknown neutral cyclopropylalkynylamidine derivatives c-C3H5—C[triple-bond]C—C(NR′)(NHR′) [R′ = iPr (1), Cy (2)]. Subsequent reactions of 1 or 2 with metal(II) chlorides, MCl2 (M = Mn, Fe, Co), provided the title complexes dichloridobis(3-cyclopropyl-N,N′-diisopropylprop-2-ynamidine)manganese(II), [MnCl2(C12H20N2)2], (3), dichloridobis(3-cyclopropyl-N,N′-diisopropylprop-2-ynamidine)iron(II), [FeCl2(C12H20N2)2], (4), dichloridobis(N,N′-dicyclohexyl-3-cyclopropylprop-2-ynamidine)iron(II), [FeCl2(C18H28N2)2], (5), and dichloridobis(N,N′-dicyclohexyl-3-cyclopropylprop-2-ynamidine)cobalt(II), [CoCl2(C18H28N2)2], (6), or more generally MCl2[c-C3H5—C[triple-bond]C—C(NR′)(NHR′)]2 [R′ = iPr, M = Mn (3), Fe (4); R′ = Cy, M = Fe (5), Co (6)] in moderate yields (30–39%). Besides their spectroscopic data (IR and MS) and elemental analyses, all complexes 3–6 were structurally characterized. The two isopropyl-substituted complexes 3 and 4 are isotypic, and so are the cyclohexyl-substituted complexes 5 and 6. In all cases, the central metal atom is coordinated by two Cl atoms and two N atoms in a distorted-tetrahedral fashion, and the structure is supported by intramolecular N—H...Cl hydrogen bonds.

Keywords

• amidinate ligand
• amidine
• manganese
• iron
• cobalt
• crystal structure
• hydrogen bonding