Would BH3 form a stronger complex with NMe3 than AlH3? Initially I thought so because B is more electronegative than Al and so it should form a bond more easily. But when I thought more about the this, B should be able to pull more electrons in the B-H bond towards itself than in the Al-H bonds (even though H is more electronegative than either, but the pull effect of B should be greater). So wouldn't the Al in AlH3 be more partially positive and as such be more attractive to the NMe3 and so forms a stronger bond?
These 2 seem ideas seem to contradict each other, but they both stem from electronegativity so I don't really know what's the right answer for this.