In ${\mathrm{BF}}_3$, the $\mathrm{B}-\mathrm{F}$ bond length is $1.30 \stackrel{\mathrm{o}}{\mathrm{A}}$, when ${\mathrm{BF}}_3$ is allowed to be treated with ${\mathrm{Me}}_3\mathrm{N}$, it forms an adduct, ${\mathrm{Me}}_3\mathrm{N}\to {\mathrm{BF}}_3$, The bond length of $\mathrm{B}-\mathrm{F}$ in the adduct is :