TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Making (M2) the complex (C1) involves: reacting the N-heterocyclic carbene with a silver salt to form a bis-N-heterocyclic carbene silver compound in a first solvent; forming a bis-N-heterocyclic carbene gold complex by reacting the bis-N-heterocyclic carbene silver complex with a gold compound in a second solvent; and forming the complex by reacting the bis-N-heterocyclic carbene gold complex with a copper compound in a third solvent, where the first, second, and third solvents may be the same or different. Preferred Method: The method (M1) further involves: regenerating the first complex by exposing the second complex to the heteroatom-containing ligand of the first complex; subjecting the second complex to a reduced pressure atmosphere to thereby remove the analyte from the second complex to form a third complex; and regenerating the first complex by exposing the third complex to the heteroatom-containing ligand of the first complex. Preferred Components: The third solvent in the method (M2) is the heteroatom-containing ligand (preferably acetonitrile). Preferred Definitions:    X=PF6-, BF4-, AsF6-, SbF6-, or ClO4-;    Y'=water, alcohol, nitrile, ketone, aldehyde, carboxylic ester, carbonic ester, thioether, amine, imine, phosphonic ester, phosphoric ester, or phosphorus ester, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrothiophene, dimethylsulfide, acetonitrile, or phosphorus-containing compound.    SPECIFIC COMPOUNDS - 5 Compounds i.e. bis eta 3- mu 3-1,3-bis((2-pyridyl-1~kN)methyl)-2H-imidazol-2-ylidene-2~kC)tetrakis(acetonitrile-1~kN)dicopper(I)gold(I)tris(tetrafluoroborate) of formula (Ia), bis( eta 3- mu 3-1,3-bis((2-pyridyl-1~kN)methyl)-2H-imidazol-2-ylidene-2~kC)tetrakis(acetonitrile-1~kN)dicopper(I)gold(I)tris(hexafluorophosphate), bis( eta 3- mu 3-1,3-bis((2-pyridyl-1~kN)methyl)-2H-imidazol-2-ylidene-2~kC)tetrakis(acetonitrile-1~kN)dicopper(I)gold(I)tris(perchlorate), bis( eta 3- mu 3-1,3-bis((2-pyridyl-1~kN)methyl)-2H-imidazol-2-ylidene-2~kC)tetrakis(acetonitrile-1~kN)dicopper(I)gold(I)tris(hexafluoroarsenate(V)), and bis( eta 3- mu 3-1,3-bis((2-pyridyl-1~kN)methyl)-2H-imidazol-2-ylidene-2~kC)tetrakis(acetonitrile-1~kN)dicopper(I)gold(I)tris(hexafluoroantimonate(V)) are specifically claimed as complex (C1).    EXAMPLE - A Schlenk tube was charged with MeCN (25 ml) and the solvent was degassed by two freeze-thaw cycles. (Au(im(CH2py)2)2)BF4 (152.6 mg) and (Cu(MeCN)4)BF4 (123.2 mg) were added and stirred for 1 hour. Addition of Et2O (75 ml) deoxygenized by passing N2 through the solvent precipitated a colorless solid of eta 3- mu 3-1,3-bis((2-pyridyl-1~kN)methyl)-2H-imidazol-2-ylidene-2~kC)tetrakis(acetonitrile-1~kN)dicopper(I)gold(I)tris(tetrafluoroborate) (190 mg, yield 78.6%).