Gold(I) and Silver(I) Metallocryptates Based on 2,9-Bis(diphenylphosphino)-1,8-naphthyridine

In acetonitrile the rigid diphosphine ligand 2,9-bis(diphenylphosphino)-1,8-naphthyridine (dppn) reacts with (SMe2)AuCl in the presence of NaPF6 to produce a pale-yellow material identified as [Au2Na(μ-dppn)3](PF6)3 (1). In
acetonitrile dppn reacts with 2 equiv of (SMe2)AuCl to form the simple Au−Cl adduct of the ligand, Au2Cl2dppn
(2). In a fashion analogous to that of the synthesis of 1, the reaction of equimolar AgNO3 with dppn produces the
trimetallic species [Ag2(μ-dppn)3Ag](PF6)3 (3) as a bright-yellow material. 1, 2, and 3 were characterized by
31P{1H} NMR spectroscopy, electronic absorption spectroscopy, X-ray crystallography, emission spectroscopy,
and elemental analysis. Additionally 1 was further characterized by cyclic voltammetry and mass spectrometry.
1·4.5CH3CN·0.5(C2H5)2O (C107H72Au2F18N10.5NaO) crystallizes in the triclinic space group P1̄ with a = 15.408(3) Å, b = 17.295(3) Å, c = 22.425(5) Å, α = 73.68(1)°, β = 77.32(1)°, γ = 74.18(1)°, V = 5451.4(19) Å3, and
Z = 2. C32H24Au2Cl2N2P2 (2) crystallizes in the monoclinic space group Cc with a = 10.936(2) Å, b = 19.860(5)
Å, c = 20.864(2) Å, β = 118.182(1)°, V = 3127.3(8) Å3, and Z = 4. Compound 3 crystallizes as the bis-DMSO
adduct (C101H84Cl2F18N6O2P9S2) in the monoclinic space group C2/c with a = 28.825(7) Å, b = 17.013(3) Å,
c = 23.916(7) Å, β = 115.23(1)°, V =10609.6(44) Å3, and Z = 4. The structures of 1 and 3 contain a three-coordinate metal capping the metallocryptate with an encapsulated ion. The central Ag(I) ion in 3 is positioned
off-center to form a short Ag···Ag interaction of 3.145(2) Å, while the central Na+ ion of 1 is centrally positioned
with long Au···Na interactions of ∼3.5 Å. The solution-state properties of 1 were probed. 1 is emissive, as are
the Li, K, and Cs analogues.