Mass spectra interpretation for monitoring Buchwald–Hartwig coupling

I am conducting a synthesis involving Buchwald-Hartwig coupling. The starting materials are 2,3,5-tribromothiophene (MW=320.83) and 1-aza-18-crown-6 (MW=263.33). I used $\ce{Pd\_2(dba)\_3}$ (MW=915.7) as catalyst, tBuXPhos (MW=424.64), and NaOtBu (MW=96.1) as base. After running the reaction at 80 ℃ during 24 h, the solvent (toluene) turned brown, and first decanted toluene layer using water. Below is the spectrum of decanted toluene layer after filtration and drying. (named Sample3-Oil)


[![spectrum1](https://i.stack.imgur.com/62K1O.png)](https://i.stack.imgur.com/62K1O.png)


And I also separated rest of the toluene layer by separatory funnel. Below is the spectrum of separated toluene layer after filtration and drying. (named Sample3-Sep) Seems similar to the first spectrum.
[![specrtum2](https://i.stack.imgur.com/kwvCF.png)](https://i.stack.imgur.com/kwvCF.png)


It seems that m/z=115, 120, 142 peaks are from methanol, which is used as mobile phase in MS. I presume that m/z=264 peak is 1-aza-18-crown-6 and m/z=286 peak is [1-aza-18-crown-6+Na]$\ce{^+}$. As far as I know P ligands are slowly oxidized during reaction, forming P=O bond. So I presumed that m/z=442 peak is oxidized tBuXPhos (424+16=440≈442). Also this peak was increased after drying the sample, simultaneously m/z=425 peak disappeared. Because the molecular weight of wanted product is 503.25, I expected that m/z=505 would be the peak of the product.


Meanwhile, I also requested MS of the sample which mixed Pd catalyst and P ligand, stirred overnight at 80 ℃. (named Sample0)


[![spectrum3](https://i.stack.imgur.com/yuPM3.png)](https://i.stack.imgur.com/yuPM3.png)


This spectrum also has m/z=505 peak. Therefore I requested MS/MS to determine whether this peak is from the catalyst/ligand or product.


[![spectrum4](https://i.stack.imgur.com/MXCeW.png)](https://i.stack.imgur.com/MXCeW.png)
[![spectrum5](https://i.stack.imgur.com/ZBH9I.png)](https://i.stack.imgur.com/ZBH9I.png)
[![spectrum6](https://i.stack.imgur.com/lGPWM.png)](https://i.stack.imgur.com/lGPWM.png)


In the MS/MS spectrum of m/z=445, one can observe the loss of iPr(m/z=402) and tBu(m/z=388), so it might be oxidized tBuXPhos. The m/z=505 peak of Sample0 has several fragments while that of Sample3-Oil and Sample3-Sep have only one fragment. But they have m/z=425 peak in common. I think this might be the peak of tBuXPhos (MW=424.64). Does this interpretation seem correct? Then should I judge that the reaction was not successful? One alternative interpretation might be loss of Br, but I'm not sure that this is correct interpretation.


----------------- +) additional spectrum


Sample1-Oil (decanted toluene layer right after the reaction)
[![spectrumadd1](https://i.stack.imgur.com/Vej6C.png)](https://i.stack.imgur.com/Vej6C.png)


Sample2-Oil (filtered through Celite, and rotoevapored)
[![spectrumadd2](https://i.stack.imgur.com/mc3tD.png)](https://i.stack.imgur.com/mc3tD.png)


