Chlorido{[(E)-2-(diphenylphosphanyl)benzylidene](furan-2-ylmethyl)amine-κP}gold(I)

In the title complex, [AuCl(C24H20NOP)], the ligand has N, P and O electron-donating atoms but the AuI atom is coordinated only by the ‘soft’ P atom and an additional Cl atom in an almost linear fashion. Important geometrical parameters include Au—P = 2.2321 (13) Å, Au—Cl = 2.2820 (13) Å and P—Au—Cl = 176.49 (5)°. The furan ring is disordered over two positions in a 0.51 (2):0.49 (2) ratio.

In the title complex, [AuCl(C 24 H 20 NOP)], the ligand has N, P and O electron-donating atoms but the Au I atom is coordinated only by the 'soft' P atom and an additional Cl atom in an almost linear fashion. Important geometrical parameters include Au-P = 2.2321 (13) Å , Au-Cl = 2.2820 (13) Å and P-Au-Cl = 176.49 (5) . The furan ring is disordered over two positions in a 0.51 (2):0.49 (2) ratio.

Haleden Chiririwa and Wade L. Davis Comment
There is a growing interest in the co-ordination chemistry of ligands containing both hard (N donor) and soft (P donor) Lewis bases. Such ligands have the potential to bind to soft metal centers such as those of the platinum group metals strongly via phosphorus and weakly via nitrogen, which allows for the displacement of the chelating N-moiety. This is very desirable in homogenous catalytic reactions and the catalytic application of P-N based ligands is being thoroughly investigated by our group.
Among the 'hard′ donor type atoms, the co-ordination chemistry of gold(I) shows a distinct paucity in the literature. In this scenario the potentially bidentate ligand is chelated to the metal through only the phosphorus atom (Fig. 1). The gold complex showed a closely linear P-Au-Cl system (bond angle of 176.49°). Another important geometrical parameter includes the C22-N23 = 1.254 (6) Å which is consistent with C=N double bonding. The Au-P bond distance of 2.2321 (13) Å agrees with that reported by Williams et al..

Experimental
To a dry CH 2 Cl 2 (10 ml) solution of the precursor [Au(tht)Cl] (tht = tetrahydrothiophene) was added an equimolar amount of N-{(E)- [2-(diphenylphosphanyl)phenyl]methylidene}-2-furan-2-ylethanamine in CH 2 Cl 2 (10 ml), and stirred at room temperature for 2 hrs. The solvent was reduced under reduced pressure and on addition of hexane, the product was filtered off and washed with Et 2 O (2 X 5 ml)and dried under vacuum for 4 hrs affording a yellow precipitate. Crystals suitable for X-ray structure determination were obtained by recrystallization from a CH 2 Cl 2 -hexane mixture at room temperature.

Refinement
The methine and aromatic H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with with C-H = 0.95 Å and U iso (H) = 1.2U eq (C) for aromatic, C-H = 0.99 Å and U iso (H) = 1.2U eq (C) for CH 2 C-H = 0.95 Å and U iso (H) = 1.2U eq (C) for CH. A disorder refinement model was applied to the furyl ring in the asymmetric unit. Geometrical (FLAT) restaraints were applied to keep the ring planar.Bond distance (DFIX) and distance similarity restraints (SADI) were applied to obtain reasonable geometries. Ellipsoid displacement (SIMU and DELU) restraints were also applied to the disordered moiety. Free variables were connected to the disordered component to add to unity.   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.