[(Z)-N-Isopropyl-O-methylthiocarbamato-κS](tri-p-tolylphosphine-κP)gold(I)

In the title compound, [Au(C5H10NOS)(C21H21P)], two independent molecules comprise the asymmetric unit, and these are connected by an aurophilic interaction [Au⋯Au = 3.1351 (3) Å]. Each AuI atom is linearly coordinated within a S,P-donor set with the distortion from ideal linear geometry [S—Au—P = 175.31 (5) and 176.45 (5)°] ascribed to an intramolecular Au⋯O contact in each case [2.974 (4) and 3.027 (4) Å].

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG2584). As a general comment, aurophilic interactions are comparatively rare in phosphinegold(I) carbonimidothioates so the presence of a Au···Au contact in (I) prompted an examination of the structures of the precursor (p-tol) 3 PAuCl structures.
There are two polymorphs reported for this compound for which atomic coordinates are available. In the monoclinic polymorph, no aurophilic interaction was noted (Cookson & Tiekink, 1994) but, in the orthorhombic form, Au···Au contacts [3.375 (1) Å] were observed (Bott et al., 2004). Such vagaries in supramolecular aggregation underscore the difficulties in crystal engineering with these systems.

S2. Experimental
Compound (I) was prepared following the standard literature procedure from the reaction of (p-tol) 3 PAuCl and MeOC(S)N(H)-i Pr in the presence of base (Hall et al., 1993).

S3. Refinement
The H atoms were geometrically placed (C-H = 0.94-0.99 Å) and refined as riding with U iso (H) = 1.2-1.5U eq (C). The maximum and minimum residual electron density peaks of 1.41 and 0.52 e Å -3 , respectively, were located 0.96 Å and 1.25 Å from the Au2 and H29c atoms, respectively.  Molecular structure of (I) showing atom-labelling scheme and displacement ellipsoids at the 50% probability level.

[(Z)-N-Isopropyl-O-methylthiocarbamato-κS](tri-p-tolylphosphine-κP)gold(I)
where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 1.41 e Å −3 Δρ min = −0.52 e Å −3 Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. 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 > 2σ(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.