[Bibinou]

Good morning,

I have problems in equilibrating a synthesis reaction. The pathway is given :
(NH4)6Mo7024.4H2O +28 H2S+8 NH4OH--> 7(NH4)2MoS4 + 36 H20
NH4)2MoS4 (CuCN/KCN/[Pr4N)Br]) --> (Pr4N)2[(CN)CuS2MoS2]
(Pr4N)2[(CN)CuS2MoS2] + Cu(PPh3)2(NO3) --> [(Ph3P)2CuS2MoS2Cu(PPh3)]

I don't really see how to equilibrate the 2 last ones and I have also problems to explain really what occurs during this synthesis. I found on a contribution from the department of chemistry  in Australia. The follwing paragraph explains how works the second reaction :

Synthesis of (n-Pr4N)2[(CN)CuS2MoS2]

a solution of  KCN (O.64g 9.8mmol) in H2O (7 cm3) is added to a suspension of NH4CuMoS4 (3g 9.8mmol) in H2O (30 cm3) to produce a deep red solution.
A solution of (n-Pr4N)Br (5.2g 19.6 mmol) in H20 (10cm3) is added dropwise producing a red precipitate.
The mixture is stirred 15min before the compound which is washed with H2O, EtOH and ether and dried in air, is isolated. (yield 65% 4.35g)

Ph4As+ et Et4N+ may be prepared in a similar manner. The compounds may also be prepared by combinating equimolar aqueous solution of (NH4)2[MoS4] and [Cu(CN)x ]^(1-x) (produced by combinatingCuSO4.5H20 orCuCN with KCN) followed by the addition of 2-3 equivalents of the quaternary cation.

Thank you very much for your help.

[AWK]

Do you mean balancing under equilibrating?
NH4)2MoS4 + CuCN + 2Pr4NBr --> (Pr4N)2[(CN)CuS2MoS2] + 2NH4Br
(Pr4N)2[(CN)CuS2MoS2] + 2Cu(PPh3)2(NO3) --> [(Ph3P)2CuS2MoS2Cu(PPh3)]  +  CuCN + 2Pr4NNO3

[Bibinou]

But how do we explain the fact that we use KCN AND CuCN? Without Copper(I)-Salz and Cyanid-Ion the copper(I)-ligand won't form the Cyano-Sulfido-Komplex...?

Couldn't we also form KBr and NH4CN?

Is this possible ? (NH4)2MoS4 ( CuCN / 2KCN / 2[Pr4N)Br]) --> (Pr4N)2[(CN)CuS2MoS2] + 2KBr + 2NH4CN

[AWK]

I think, CuCN is polymeric  and insoluble. To obtain a resonable time for reaction you should have both reagents in solution and in monomeric form. This is achieved by forming Cu(CN)2-, and ratio 1 mole of KCN to 1 mole of CuCN is needed.
According to my second reaction in a previous post - my sugestion that CuCN is is formed, is still reliable because of CuCN negligeable solubility (or its engaging in soluble Cu(CN)2- complex). May be you can obtain also good yield of complex using additional PPh3 instead of 2 molar excess of Cu(PPh3)2(NO3) according to this reaction,
(Pr4N)2[(CN)CuS2MoS2] + Cu(PPh3)2(NO3) + 2PPh3--> [(Ph3P)2CuS2MoS2Cu(PPh3)]  +  Pr4NCN + Pr4NNO3
I think, you can treat CN- anion as a catalyst of your reaction

[Bibinou]

Assume I already prepared NH4CuMoS4

a solution of  KCN (O.64g 9.8mmol) in H2O (7 cm3) is added to a suspension of NH4CuMoS4 (3g 9.8mmol) in H2O (30 cm3) to produce a deep red solution.

What is really in my flask at this moment?

Thank you very much for your help

[AWK]

May be:
KCN + NH4CuMoS4 = NH4K(CuCN)MoS4