Chemistry in Environmentally Benign Media. 7.1 Chelating Hydroxymethyl-Functionalized Bisphosphines as Building Blocks to Water-Soluble and in-Vitro-Stable Gold(I) Complexes. Synthesis, Characterization, and X-ray Crystal Structures of [Au{(HOH2C)2PC6H4P(CH2OH)2}2]Cl and [Au2{(HOH2C)2PCH2CH2P(CH2OH)2}2]Cl2

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Abstract
The reactions of water-soluble bisphosphines (HOH2C)2PC6H4P(CH2OH)2 (1) and (HOH2C)2PCH2CH2P(CH2OH)2 (2) with NaAuCl4, in aqueous media, or AuClPPh3, in biphasic media (aqueous/organic), produced the water/alcoholic-soluble Au(I) complexes [Au{(HOH2C)2PC6H4P(CH2OH)2}2]Cl (3), [Au{(HOH2C)2PCH2CH2P(CH2OH)2}2]Cl (4), and [Au2{(HOH2C)2PCH2CH2P(CH2OH)2}2]Cl2 (5) in near quantitative yields. Stability and cysteine-challenge studies of 3 indicate the kinetic inertness of these new complexes. Complex 5 is luminescent in the solid state at room temperature. When excited at 280 nm in non-degassed water at room temperature, the emission spectrum shows a high-energy band at 310 nm and a low-energy band at 560 nm. The large Stokes shift for the low-energy band implies that the emission is phosphorescence. The X-ray structures of 3 and 5, reported in this paper, confirm the gold(I) structures of this new generation of water-soluble transition metal complexes. All compounds were characterized by 31P and 1H NMR spectroscopy and mass spectroscopy. X-ray data for 3: monoclinic, P21/m, a = 9.8715(5) Å, b = 9.9465(5) Å, c = 14.5621(8) Å, β = 106.5930(10)°, Z = 2, R = 0.032 (Rw = 0.050). X-ray data for 5: monoclinic, C2/c, a = 29.7128(14) Å, b = 16.7062(8) Å, c = 22.3762 (11) Å, β = 117.6970(10)°, Z = 16, R = 0.051 (Rw = 0.072).