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The coordination chemistry towards silver(I) of the small-ring macrocycles [9]aneN2S (1-thia-4,7-diazacyclononane) and [9]aneNS2 (1,4-dithia-7-azacyclononane) incorporating nitrile-functionalized pendant arms is considered both in the presence and the absence of exogenous bridging ligands. The aim is to understand the influence of the number and length of the pendant arms on the nuclearity and dimensionality of the resulting complexes. The X-ray crystal structures of the complexes bis[4,7-bis(cyanomethyl)-1-thia-4,7-diazacyclononane-κ3 N,N′,S]silver(I) tetrafluoridoborate, [Ag(C10H16N4S)2]BF4 or [Ag(L1 )2]BF4, [4,7-bis(2-cyanoethyl)-1-thia-4,7-diazacyclononane-κ3 N,N′,S](thiocyanato-κS)silver(I), [Ag(C12H20N4S)(NCS)] or [Ag(L2 )(SCN)], and μ-thiocyanato-κ2 S:S-bis{[7-(2-cyanoethyl)-1,4-dithia-7-azacyclononane-κ3 N,S,S′]silver(I)} tetrafluoridoborate, [Ag2(C9H16N2S2)2(SCN)]BF4 or [Ag2(L3 )2(μ-SCN)]BF4, are discussed in relation to analogous compounds in the literature.

Ruthenium complexes of hemilabile phosphinocarboxamide ligands, and their use to form metallacycles using halide abstraction/deprotonation reactions are reported. Thus, [Ru(p-cym){PPh2C(=O)NHR}Cl2; R = iPr (1), Ph (2), p-tol (3)] and [Ru(p-cym){PPh2C(=O)N(R)C(=O)N(H)R}Cl2; R = Ph (4), p-tol (5)] were synthesized from [(p-cym)RuCl2]2 (p-cym = para-cymene) and phosphinocarboxamides or phosphinodicarboxamides, respectively. Single crystal X-ray diffraction measurements on 1–5 reveal coordination to ruthenium through the phosphorus donor, with an intramolecular hydrogen bond between the amine-bound proton and a metal-bound chloride. Six-membered metallacycles formed by halide abstraction/deprotonation of complexes 4 and 5 afforded [Ru(p-cym){κ2-P,N-PPh2C(=O)N(R)C(=O)NR}Cl] [R = Ph (6), p-tol (7)]. These species exist as a mixture of two rotational isomers in solution, as demonstrated by NMR spectroscopy.