Lewis base adducts of Group 11 metal compounds. Part 24. Co-ordination of triphenylphosphine with silver nitrate. A solid-state cross-polarization magic angle spinning 31P nuclear magnetic resonance, crystal structure, and infrared spectroscopic study of Ag(PPh3)nNO3(n= 1–4)

Abstract

Solid-state cross-polarization magic angle spinning ³¹P n.m.r. spectroscopy, single-crystal X-ray structure determination, and i.r. spectroscopy have been used to investigate the properties of the adducts of triphenylphosphine with silver(I) nitrate: Ag(PPh₃)NO₃, (1); Ag(PPh₃)₂NO₃, (2); Ag(PPh₃)₃NO₃, (3); and Ag(PPh₃)₄NO₃, (4). The value of ¹J(Ag–P) decreases with increasing co-ordination number: (1), 780; (2), 470; (3), 310; and (4),190 Hz, paralleling solution results. Single-crystal X-ray structure determinations of compounds (2)–(4) have been performed: (2), triclinic, space group P, a= 11.821(3), b= 11.990(3), c= 13.660(3)Å, α= 102.05(2), β= 112.80(2), and γ= 105.30(2)°, yielding R= 0.036 for 4 090 ‘observed’ reflections; Ag–P 2.443(1) and 2.440(1)Å, P–Ag–P 138.21(5)°(3), monoclinic, space group P2₁/n, a= 18.984(5), b= 13.710(3), c= 17.900(4)Å, and β= 94.94(2)°, yielding R= 0.053 for 5126 reflections; Ag–P 2.630(2), 2.525(1), and 2.545(2)Å, P–Ag–P 118.37(5),112.07(4), and 116.44(5)°; (4), trigonal, space group R, a= 19.07(2), and α= 43.77(5)°, yielding R= 0.060 for 1 903 observed reflections; Ag–P 2.643(3) and 2.671(4)Å, P–Ag–P 109.49(12) and 109.45(10)°. Structures (2) and (3)[and (1)] are isomorphous with the analogous triphenylarsine compounds. In all cases the nitrate group is only weakly co-ordinated [and is ionic in (4)]: Ag–O 2.464(4) and 2.649(4) in (2), 2.684(6) and 2.775(6)Å in (3). These weak interactions are reflected in the small splitting observed for the asymmetric N–O stretching vibrational mode compared to the analogous copper(I) compounds.