Finally solved this issue. It appears when my external exe was being executed a pop up relating to another exe failure was being thrown "Application popup: csc.exe - Application Error : The application failed to initialize properly (0xc0000017). Click OK to terminate the application. " As my exe execution was encapsulated under the SSIS package I assume it and the pop up were automatically terminated giving the "-2147023895" exit code. The resolution however was in finding what was causing the csc.exe to fail and as it turned out that was due to the memory allocation for the remote powershell session which by default appears to be 150mb. Setting this to 512 on the server solved the problem.
set-item wsman:localhost\Shell\MaxMemoryPerShellMB 512