The unit vector which is orthogonal to the vector $\hat{\mathrm{i}}+\hat{\mathrm{j}}+\hat{\mathrm{k}}$ and is coplanar with vectors $\hat{\mathrm{i}}+2\hat{\mathrm{j}}-\hat{\mathrm{k}}$ and $2\hat{\mathrm{i}}+\hat{\mathrm{j}}+3\hat{\mathrm{k}},$ is